The present invention pertains to a control system according to the preamble to pa.tent claim 1. The p esent i vention also pertai s to a method according to the preamble to patent claim 37, and to a computer program and a. computer program product which implement the method according- to the invention.

Background

The following background description constitutes a description of the background to the present invention, which background must not constitute prior art.

Control systems comprising one or several regulators are used today to control a large number of different types of systems, for example in a vehicle. The control often comprises a state being controlled, toward a reference value for this state.

Many of the systems which are controlled by such control systems have an inertia /, such as for example a mass inertia., a thermal inertia K or a moment of inertia /. Inertia as used herein means a resistance to change, for example to a motion change or a

temperature change, which means that changes do not occur

momentarily, i.e. the change occurs over a period of time.

A speed cruise control system, is an example of a vehicle system, comprising an inertia / related to a vehicle mass tn, in which one or several regulators are used to regulate an actual speed v _act for the vehicle. An engine system is another example of a system, with an inertia. / related to a moment of inertia / for the engine in the vehicle, in -which one or several regulators are used, to regulate an actual speed w _act for the engine.

Another example is a temperature regulation system with a thermal inertia K, where an actual temperature T _act for a limited volume is regulated with the use of one or several regulators. Another example is a system for acceleration restriction for a vehicle, with an inertia. / related to a vehicle mass m , through which system a.n actual acceleration a _act of the vehicle is regulated by the one or several regul.ato.rs. In a system for the braking of a vehicle, with an. inertia I related, to tne ven.ic.le mass ?¾, rhe actual speed v _ac t for the vehicle is regulated with the one or several regulators.

Another system is a system for PTO with an open drive line in a vehicle, where the engine speed for an engine in the vehicle is regulated, but where the inertia / is also related to eoruipment which is connected to the PTO in the vehicle. Such equipment may for example comprise pumps, cocks or other equipment, which is driven via the vehicle' s PTO.

Control systems use, and are therefore dependent on access to, a number of parameters in order to be able to control various

functions correctly and efficiently. Examples of such pa.ramet.ers, on which control systems base their control functions, comprise vehicle mass m, the engine's moment of inertia J , the thermal inertia K for a limited volume and a total moment of inertia J _tot for the engine and the PTO.

A weight m of a vehicle system, such as a vehicle weight, where the vehicle may consist of a vehicle platoon, constitutes an important parameter in many functions in a vehicle's control system. The vehicle' s weight impacts the vehicle considerably in many

situations, making it very important to correctly be able to estimate this weight. The vehicle's /eight is typically included in models of the vehicle, which are used for various calculations and controls in the vehicle.

For a vehicle which may transport big loads, such as buses, -which may transport, a. large number of people, or trucks, which may transport different types of loads with heavy weights, weight may vary considerably. For example, an unloaded, truck weighs

considerably less than the same truck with its maximum load. An empty bus also has considerably less mass than the same bus when it is full with passengers. For a car, for example, the variations in mass are smaller than for vehicles designed to carry big loads, but here too, the difference between an empty and a fully loaded, car, where the fully loaded car may also comprise a connected and loaded trailer, may be relati ely large in relation to the car' s low weigh .

The vehicle mass m impacts a driving resistance regarding the vehicle, which, means that the vehicle's weight is an important parameter, for example for automatic gear selection. Automatic gear selection is carried out for example in an automated manual, gearbox, for which it is important to be able to determine a current driving resistance and thus which gear should be selected at a given time. The engine's moment of inertia / is also an important parameter for gear selection.

Further, how a road section's topography impacts the vehicle is strongly dependent on the vehicle's weight, i.e. of the vehicle's mass, since the weight is decisive to how much a down- or uphill slope accelerates or decelerates the vehicle, , respectively. Hence, the vehicle' s weight is an important parameter also in cruise controls which take into consideration the topography of a road section, so-called Look-Ahead-cruise controls, where the size of a requested engine torque on a specific occasion is dependent on how the topography of road sections ahead will, impact the vehicle' s speed. Naturally, the weight of the vehicle m and the engine's moment of inertia / are important parameters also in conventional, cruise control .

The thermal, inertia K is an important parameter relating to

essentially all types of temperature control, which impact for example driver and. passenger comfort, and safety in a vehicle. Both the driver and passengers of a vehicle, for example in a bus, should not be disturbed by strong and undesired temperature variations. In addition, for safety reasons it is important that a cabin

temperature desired by the driver is maintained, since for example a higher temperature may have an influence on tiredness in the driver. For cooling spaces, for example in vehicles where the load, must be stored and/or transported at a certain temperature, for example food transports, achieving a. correct estimation of the thermal inertia K is also decisive in order to provide an exact temperature control.

For vehicles where it should be possible to provide a PTO, it is important that the equipment connected to the PTO in the vehicle may be driven by the PTO, that is to say that an engine in the vehicle is able to maintain an essentially constant speed during the PTO operation .

Brief description of the invention

Below is a description of previous art solutions and problems, primarily for estimation of the vehicle weight m, with these. A person skilled in the art will realise that similar problems exist for previous estimations of the mass for other vehicle systems, and for the engine's moment of inertia /, for the thermal inertia K and for the total moment of inertia J _tot which is required to operate equipment, connected to the PTO, that is to say for all the inertias I which are estimated by the present invention.

Today there are several methods which are applied to estimate the vehicle mass m, that is to say the vehicle's weight m. One such method uses information from an air suspension system in the vehicle. The air suspension system measures the shaft pressure of all shafts having- air suspension, and reports this load to a control device, which based on these loads may calculate the mass of the vehicle. This method functions well if all the shafts have air suspension. However, the method functions unsatisfactorily or not. at all, if one or several shafts are lacking air suspension. This method is for example especially problematic in "vehicle platoons comprising trailers, which do not report shaft loads. This may occur relatively often, as more or less unknown trailers are often connected to the vehicle platoon with the use of the vehicle. This method is also problematic during operation of the vehicle, since the shaft pressures vary as the -vehicle drives o er uneven surfaces in the road, which may lead to inaccurate weight estimation due to the changing shaft pressures . Other prior art methods for mass estimation comprise acceleration based mass estimations. These use the fact that it is possible to calculate the mass based on the force which the engine provides to the vehicle, and an acceleration which is the result of this force. The force from the engine in the vehicle is known, but for these methods the acceleration needs to be measured or estimated.

According to one method, the acceleration is estimated by carrying out a derivation of the vehicle' s speed. This method functions well at. high accelerations, that is to say on .low gears at relatively low speeds, but it is a disadvantage of the method that it is impacted by the road incline, which is what requires derivation, since the road incline is an unknown parameter for the system.

According to another method, the acceleration is estimated with the help of an accelerometer . The accelerometer-based method has one advantage in that acceleration is measured directly. However, only a limited number of vehicles today comprise an accelerometer, whrch means that this method is not generally applicable to all vehicles. The current accelerometer-based method also suffers from the fact that the accelerometer signal is noisy, which reduces the method' s accuracy .

According to another method, the acceleration is measured during gear shifting. This method uses the assumption that the driving resistance is unchanged during a gear shift and therefore compares the vehicle's acceleration before, during and. after a gear shift to determine the vehicle's weight. This method results in very

unsatisfactory estimations of the vehicle's mass.

The acceleration based mass estimations are generally

disadvantageous in that certain driving conditions must be met in order for a good estimation to be carried out. It is not at all certain that these conditions are met during a drive, in which case a good mass estimation is not possible. For example, the

acceleration based, mass estimations require full throttle

acceleration at low gears in order to achieve a reliable result. Since such a full throttle acceleration does not always occur during a drive - such as where the vehicle starts the drive on a downhill slope, for example from a filling station at. a motorway entrance, where, with the help of a downhill slope it may accelerate

relatively slo ly in order to then essentially main ain a constant speed during the rest of the journey - these methods often do not provide a good estimation of the vehicle weight. Thus, the prior art methods for mass estimation are not always possible to apply and/or do not provide reliable estimations for all drives.

Prior art solutions for estimation of the thermal inertia K and of the total moment of inertia j _t0[ related to ΡΊΌ are likewise

inadequate. The total moment of inertia ] _tot for the PTO is typically unknown, since equipment of different types may be connected to this PTO, where the vehicle may not kno or be prepared, for all this unknown equipment of differing type. These solutions provide inadequate estimations and/or estimations which, require a large amount of additional complexity in the vehicle.

It is one objective of the present invention to provide a control system, and a method for the control of a state, which solve the above mentioned problems with prior art estimations and controls of states .

This objective is achieved, -with the above mentioned, control system according to the characterising portion of patent claim 1, The objective is also achieved through the above mentioned method according to the characterising portion of patent claim 37, and with the above mentioned computer program and computer program product.

Through the present invention an analysis of an actual transient S _trans _ _act is used for at least one actual state S _act against at least one respective corresponding reference value S _re in order to estimate an inertia 1 for a state in a system. Thus, comparing the appearance for this at least one actual transient S _trans _ _act with at least one respective corresponding expected transient S _transexpl which, has an appearance that assumes correct estimations of the state, the inertia / for the state may be estimated according to the present i ventio , This gives a very exact estimation of the state, which is also robust since the system on which the estimation is based is well defined. The estimation may be implemented with a very small additional cost and complexity for the control system.

A regulator in the control system then uses this estimated inertia / for steering the at least one actual state value ¾. _t toward the at least one respective corresponding reference value S _re f . In other words, the regulator bases its control of the at. least one actual state value S _act on the estimated inertia I. The fact that the control via the regulator here is based on the inertia, means that the control becomes related to a change in the at least one actual state value S _actl since this change depends on the inertia for the state to which the at least one actual state value S _act relates. In other words, the resistance to change in the at least one actual state value S _actl i.e. the inertia I for the state /state value S _act ,

determines how easy or difficult the change is to implement, meaning that the inertia / determines the change and/ or the appearance of the change. According to one embodiment the inertia estimation according to the present invention may be used to estimate a mass m related to the system, such as for example a vehicle mass. Thus reliable estimations of the mass m are obtained, for example of the vehicle mass in a vehicle, -which a large number of systems and functions in the vehicle may be able to use, such as for example cruise control and gear selection. Thus, the vehicle's fuel

consumption may be reduced, and/or the vehicle' s performance may be increased, since well based and well-grounded selections may be made in these systems, which, may overall reduce the fuel consumption and/or improve the performance.

According to one embodiment the estimation of inertia according to the present invention may be used to estimate an engine' s moment, of inertia /, through which for example a vehicle's fuel consumption may be reduced and/or a vehicle' s performance may be improved, since well based, and well-grounded, selections may be made in these systems, for example for cruise control and gear selection. According to one embodiment, estimation of inertia according to the present invention may be used to estimate thermal inertia K for delimited volumes, through which temperature control of for example office premises, a cooling room, a driver's cabin or a loading space may be controlled very exactly, based on knowledge about the thermal inertia K . Increased comfort for office staff and. driver, as well as safe transport of for example food, may thus by secured.

According to one embodiment the estimation of inertia according to the present invention may be used to estimate the total moment of inertia J _TOT a.t one PTO. According to the present invention the total moment of inertia / , which comprises both the engine' s moment of inertia, / and the moment f inertia of the PTO JPTO / J'tot ^ / J pro ^s estimated. Thus an estimation of the total moment of inertia / is obtained, which may be used to regulate the engine speed of the engine, so that sufficient and essentially constant power to operate the equipment connected to the PTO may be provided, since this regulation is facilitated by a knowledge of the total moment of inertia / . Thus, with the present invention more or less unknown equipment of different types may be operated via a constantly we1.1 dimensioned PTO in the vehicle, something which previously has been very difficult. The regulator may also calibrate itself

automatically toward a better estimation of the total moment of inertia J _tot , so that it is always set at the correct regulator a.ggressiveness .

The present invention may, according to one embodiment, be used for systems where a control of the system is based on a model comprising a force equation or another equation related to the system that is to be regulated. Thus, the control of the various states is based on the systems which comprise the respective states. In other -words, the systems are regulated based on the systems themselves, since the regulation of the systems is carried, out. based on models of the systems that are subject to regulation. Thus, there is a good knowledge of the systems subject to regulation within the regulation algorithm, which means that the estimation is robust. The present invention may, according to one embodiment, also be used for systems where a control of the system is carried out by a PID- regulator or by a differential Pi-regulator . The estimation of inertia according- to the present invention may therefore be applied where a large number of different regulation systems are used to control systems in a vehicle.

Brief list of figures

The invention will be described in further detail below, with reference to the enclosed drawings, where similar references are used for similar parts, and wherein:

Figure 1 shows a flow diagram for a method according to the

invention, igure 2 shows an e ample of transie ts toward a eference value,

Figure 3 shows an example of transie ts toward a eference value,

Figures 4a and 4b show an example of determination of mass of a vehicle,

Figure 5 shows a control device, and

Figure 6 s ows an example vehicle in which the present invention may be implemented.

Description of preferred embodiments

According- to one aspect of the present invention a regulation system comprising a regulator is provided. The regulator is here arranged to control at least one actual state varue S _ac i- toward at least one respective corresponding reference value S _re f in a vehicle system, where the vehicle system comprises an inertia I for the at least, one actual state value S _act .

The regulation system comprises a determination device 131 (shown in figure 6), arranged to determine at least one actual transient

$trans act for the at least one actual state value S _act , toward the at least one respective corresponding reference value S _ref . The regulation system, also comprises a comparing device 132

(displayed in figure 6) arranged to carry out at least one

comparison of the at least one actual transient S, trans_act with at least one respective corresponding expected transient S, trans_exp * The expected transient 5t,ransjexp has an appearance which would have been the result of the actual transient S, trans _act > if complete knowledge about of the inertia / had been obtained, i.e. if the regulation system had had access to correct values for the inertia /.

The regulation system, also comprises an estimation device 133

(displayed in figure 6), arranged to estimate the inertia I based on the at least one comparison of the at least one actual transient Strans _j act ^anc the at least one respective corresponding expected transient S _transj;xp .

The regulation system also comprises a regulator 134 (displayed in figure 6) arranged for steering the at least one actual state value S _a ., _t toward the at least one respective corresponding reference value S _re f based, on inertia /. Since the inertia is related to the change propensity in the at least one actual state value S _act , according to the present invention the control of the at least one actual state value S _act is related to the change propensity of the at least one actual state value S _act ,

A person skilled in the art will also realise that the regulation system, may be modified according to the various embodiments of the invention. In addition, the invention pertains to a motor vehicle, for example a truck or a bus, comprising at least one regulation system according- to the invention.

The present invention also pertains, according to one aspect, to a method for a regulation system comprising a regulator, where the at least one regulator is arranged for steering at least one actual state value S _{act L} toward at. least one respective corresponding reference value S _re in a vehicle system. The vehicle system here comprises an i.nertia. / nor the at least one actual sta.te value §act _' The states for which, according to the present invention, an inertia / may be estimated and used in the control of actual state values S _act , such as described below, have a resistance to change for the state, for example a resistance against a motion cha ge or a temperature change. Changes of these states thus occur over a period of time and essentially not momentarily.

The present invention assumes that at least one regulator is arranged to regulate at least one actual state value S _act in the system toward at least one respective corresponding reference value S _ref .

Figure 1 shows a flow diagram for a method according to the present invention ,

In a first step 1001 of the method., at least one actual transient Strans act - ^s determined for the at least one actual state value S _act , toward the at least one respective corresponding reference value S _re f . As the at. least one actual state value S _act is regulated toward the at least one respective corresponding reference value S _reff at least one actual transient S _{[rans act} arises, this at least one actual transient S _{[rans act} describing how the at least one actual state value S _act approaches and tends toward the at least one respective

corresponding reference value S _re f. The appearance of this at least one actual transient S _{tra act} depends among others on the inertia / of the state.

In a second step 1002 of the method, at least one comparison of the at least one actual transient S _trans _ _act with at least one respective corresponding expected transient S _act is effected This expected transient S _{trans exp} has an appearance which would have been the result of the actual transient S _{trans act} if the regulation system had had access to a correct value for the inertia I. If, for example, the inertia I is related to the vehicle mass ni and. if the regulation system, has access to a correct estimation of the vehicle mass ra, the actual transient S _{trans act} will be identical to the expected transient S _trans _ _exp . Similarly, the appearance of the expected

transient S _{irflns e¾} . _p corresponds to an actual transient S _{trans act} based on correct estimations of the moment of inertia /, the thermal inertia K, or the total moment of inertia J _{t t} at. a PTO.

However, the actual transient S _{tratls act} often differs from the

corresponding expected transient S _{fms exO} since completely correct estimations are .rarely available, which fact is used by the present invention to estimate inertias in vehicle systems.

According- to one embodiment of the present invention, the at least one actual transient S _transjact may be compared to the at least one respective corresponding expected transient S _{trans exp} by determining, at one or several points, which may for example consist of

positions, distances, points in time or durations, the actual state value S _ac[ for the actual transient S _{trans act} and then comparing this in a suitable manner with the corresponding state values at the same point for the expected transient S _{trans exp} . The comparison may be carried out over a predetermined suitable time interval, for example by a summation and/or an integration of the respective state values for the actual transient S _{trans act} and for the expected transient

S _{tra s exp!} or for the difference between the respective state values for the actual transient. S _trans _ _act and. for the expected transient

The values which these comparisons of the actual transient

S _trar , _s _ _act and the expected transient S _traris _ _ezp give, such as a sum or an integrated value, may then be compared with one or several threshold values to determine whether a previous estimation /* of the inertia / should be deemed correct/exact or not. If the previous estimation /* of the inertia. / is deemed to be incorrect/ inexact, a. new value for the inertia / may be determined by determining at least, one ratio μ—— ^~ between the previous estimation / ^* of the inertia and the inertia /, based on the analysis of the at least one actual

transient S _{trans act} , Since the previous estimation /* of inertia is known, a new and correct value for the inertia. / may easily be determined, for example with the use of the embodiment, according to

I*

/ =—. In some embodiments, however, this tormula for the

determination of the inertia may be too aggressive, that is to say it may cause excessive changes and/or fluctuations in the value of the inertia /, which is why some type of average value formation may also be used in the determination of the inertia 1 . These average value formations then dampen the aggressiveness in the determination of the inertia I , which thus leads to less sharp changes and/or fluctuations for the value of the inertia /. This average value formation may also be seen as a lowpass-filtration of a signal corresponding to the value of the inertia /. The determination of the value of the inertia / is described in more detail below.

By comparing the appearance of this at least one actual transient ^ transact with at least one respective corresponding expected transient Strans _j exp > which has an appearance which assumes correct estimations of the state, the inertia / for the state may thus be estimated according to the present invention. This provides a very exact and robust estimation of the state.

The comparison of the transients, and. the determination of the ratio μ, are exemplified regarding mass estimations in figures 4a and 4b, which are described in more detail below in connection with the equations 11 and 13. As a person skilled in the art -will realise, the exa.Ep.le of mass estimation, displayed in figures 4a and 4b may be generalised to all types of estimations for which the present inVention is useful.

The solid curve in these rigures corresponds to a transient ^tr ns act _! where the mass estimation is correct, and the dashed, curve

corresponds to a transient S _{trans act} corresponding to mass

underestimated by 50%. Figure 4b snows clearly that the mass ratio obtains the value 1, μ=1, for the correct mass estimation, where the transient S _trans _ _act (solid.) then has the expected, appearance S _trans _ _exp . Similarly, figure 4b shows clearly that the mass ratio obtains the value 0,5, μ=0,5, for the incorrect mass estimation, where the mass is thus underestimated by 50%. This clear non-limiting example snows that the algorithm according to the present invention is very useful for correcting incorrect estimations of states, since the thus determined value for the ratio μ may easily be used to determine the inertia /. The resulting correlations in this respect are described in further detail below in connection with the equations 11 and 13.

In a third step 1003 of the method, the inertia. / is estimated based on the at least one comparison of the at least one actual transient S trans act with the at least one respective corresponding expected transient S _trans _ _exp .

In a fourth step 1004 of the method the at least one actual state value S _act is steered toward the at least one respective

corresponding reference value S _re f based on the inertia /. Since inertia is related to the change propensity in the at least one actual state value S _act , the control of the at least one actual state value S _act is thus related, to the change propensity in the at least one actual state value S _act .

Thus, according to the present invention the transient $ trans act f° ^r the at least one actual state value S _act toward the at least one respective corresponding reference value S _ref is used to determine the inertia / in the state. Thus a very reliable estimation of for example the mass , the engine's moment of inertia /, or the thermal inertia K of for example the driver's cabin may be obtained.

Many systems have integrated inertias for their states. Essentially all such inertias may be estimated with the use of the present invention. A couple of embodiments of the present invention will be described below. However, a person skilled in the art will realise that the present invention may generally be applied to essentially all systems where the state of the systems has some type of

resistance to change, that is to say some type of inertia. According to o e embodiment of the invention, the control of the at least one state in the system which is subject to regulation by the regulator is model based. The model which is used herein is related to the system subject to regulation, by the model comprising a force equation or another equation which is related to this system and comprises the at least one actual state value S _act . Thus, a model of the system is prepared, at least, partly, by setting up a force equation or another equation for at last a part of the system.

Further, during the regulation of the system the control of the state is carried out with the use of a control signal, the model based, control meaning that a size of this control signal is

proportionate to a change in the at least one state, that is to say, it is proportionate to a change in said at least one actual state value S _act . Thus a control device provides a control signal based on the model, the signal's size being proportionate to a change in the state ,

With such a regulation system, where it is implemented in a

temperature regulation system, an actual temperature T _act may, for example, be steered, toward, a temperature reference value T _re f . n an engine regulation system in a vehicle, an actual engine speed <y _act may be steered toward a reference engine speed o _re f . In a cruise control in a vehicle, an actual engine speed v _act may be steered tovjard a. reference speed v _re f . In. a regulation system, for

acceleration restriction, an actual acceleration a _act may be steered toward a reference acceleration a _re f . In a braking system in a vehicle, an actual speed v _act may be steered toward a reference value in the form of a maximum speed v _max . Embodiments of the invention in which these controls are used, to determine inertia -will be described, in more detail below.

According to one embodiment of the invention the vehicle system being subject to regulation is a cruise control in a vehicle, which has an inertia / related to a mass m related to the system, for example a mass of the vehicle. The model on which the regulation is based, takes into consideration to a difference between an actual acceleration a _act related to the system and. a reference acceleration r _e f for the vehicle, where the difference depends on a time

parameter τ.

The actual state value S _act! which is subject to regulation by the regulator, here consists of an actual speed v _{a t} related to the system., for example an actual vehicle speed, that is to say the actual speed which the vehicle will maintain as a result of the cruise control. The reference value S _re f toward which the state is steered, here constitutes a reference speed v _re f for the system.

Since the mass m related to the system is here related to the inertia /, according to this embodiment the mass m may be estimated reliably by analysing a transient. S _{trans act} for the actual state value S _art toward a corresponding reference value S _re f .

There are various different types of cruise controls for vehicles. In some of these cruise controls the driver sets the reference speed v. _t ,f . In other types of cruise controls the driver sets a set-speed v _setf based on which the cruise control then determines the size of the reference speed v _ref which is sent to the speed regulator, so that the reference speed v _rei - may have another value than the set- speed v _set .

The model/regulator takes into consideration a. difference between an actual acceleration a _act related to the system., for example an actual vehicle acceleration, that is to say the real acceleration which results from the cruise control, and a reference acceleration a _re f for the system. This difference depends on a time parameter r, which is described in further detail below. The time parameter T

determines how the appearance of the transient S _{trans act} for the actual speed v _act toward the reference speed v _re >- appears; a smaller value of the time parameter τ givi g a fast transient, and. a larger value of the time parameter τ giving a. slow transient. This is displayed schematically in Figure 2 for one example, where the dashed straight horizontal line is a reference speed v _ref toward which actual speeds for different values of τ turn. As illustrated in Figure 2, the smallest value of the time parameter τ=2 (solid curve) gives the fastest, transient S _{[rans act} , the larger value of the time parameter r=5 (dashed curve} gives a slower transient S _{trans act} , and the largest value of the time parameter τ-8 (dashed curve) gives the slowest transient $transact-

According to one embodiment of the present invention the value of the time parameter T is related to a run mode, also called driving mode, for example for a. vehicle. This is displayed, schematically in Figure 3, where the dashed straight horizontal line is a reference speed v _re f toward which actual speeds for various values of τ turn.

The value of the time parameter r is here seen as related to an aggressiveness of the regulation. Therefore, at a normal driving mode, for example named "standard" (dashed curve) , the time

parameter τ may be given a medium size value.

For a more aggressive dri ing mode, for example called "power" (dashed curve) , the time parameter τ is given a relatively small value if the actual speed v _act is lower than the reference speed v _ref . For this driving mode, the time parameter τ is given a relatively large value if the actual speed v _act is higher than the reference speed v _re f , as displayed in figure 3. The more aggressive driving mode power thus turns inwards quickly when it approximates the reference speed v _re f from below (from a lower speed.) , but turns inwards slowly when it approximates the reference speed v _re f from above (fro a higher speed) . The driving mode power thus quickly tries to achieve the reference speed v _re rfrom below and meets up early fro above, which gives a. powerful impression, a. higher average speed and a time saving compared to the other driving modes.

For a less aggressive driving mode, for example called "eco" (solid curve) , the time parameter τ is given a relatively large value if the actual speed v _act is lower than the reference speed v _re f . Similarly, the time parameter τ for this driving mode is given a relatively small value if the actual speed v _act is higher than the reference speed v _{ref s} as shown in figure 3. The less aggressive driving mode eco thus turns inwards quickly when it approximates the reference speed v _rei - from above (from a higher speed} , but turns inwards slowly when it approximates the reference speed v _ref from below (from a lower speed) , which gives a soft impression, and a lower average speed and th s a. lower total fuel consumption. In addition the amount of energy braked away is reduced with the driving mode eco for a. vehicle, since the vehicle, for example during a road section comprising an uphill slope followed by a downhill slope, has a lower speed at the top of the hill. Due to the lower speed at the top, less braking is required downhill, whereby less energy is braked away.

In connection with figures 2 and 3, a description has been given above of how the time parameter v _act impacts the transient S _{trans act} for the actual state value S _actf here the actual speed v _actf toward the corresponding reference value $ _re f, here the reference speed v _re †, for a cruise control system. The time parameter τ has a corresponding impact on the transient S _{trans act} for the engine system, temperature regulation system, acceleration restriction system, brake system and PTO-system described below.

According- to one embodiment, where the invention is applied in cruise control, the model related to the system subject to

regulation comprises a force equation which looks as follows:

F _k+1 = in - a _act ) +F _kr where (equation 1)

F _kJrl is a force which will act on said vehicle as the next iteration of the equation is calculated;

m is the mass of the vehicle;

v _re f is the reference speed;

vaci is the actual speed;

τ is the time parameter; a _act is the actual acceleration of the vehicle; and F _k is a current force which acts on the vehicle.

If the masses of these vehicle systems change, that is to say, if for example the vehicle mass changes in connection with reloading, this model based regulator will also recalibrate itself according to the new masses.

According to one embodiment of the present invention, the vehicle system subject to regulation by the regulator is an engine system, where the model of the engine system takes into consideration a difference between a change ω _t of an actual engine speed for the engine and a change ^ _re f of a reference engine speed, for the engine, where the difference depends on the time parameter τ . The actual state value S _act which is to be controlled here constitutes an actual engine speed i<) _act for the engine and the corresponding reference value S _re f constitutes a reference engine speed ω,. _βί for the engine. The inertia / is based here on a moment of inertia / for the engine, wherefore this moment of inertia / may be estimated based on a comparison of the actual transient S _trmsjlct with the expected

transient S _trans _ _exp ,

According to one embodiment of the present invention, the vehicle system subject to regulation by the regulator is a system for acceleration restriction, where the model of the acceleration restriction system takes into consideration a difference between the actual acceleration a _act and the reference acceleration a _re f. The actual state value S _act which is to be controlled thus constitutes an actual acceleration _act related to the system and the reference value S _re f, which is used for the control, constitutes a reference acceleration a _re r related to the system, for example a reference acceleration a _re r for the vehicle. The inertia / in the system for acceleration restriction is here based on a mass m related to the system, for example the vehicle mass m, which means that the mass m may be estimated based on the comparison of the actual transient. S trans act with the expected transient S _{trans exp} .

The physical model on which the regulation is based, comprises a force equation which looks as follows:

F _k+1 — m · (firef ^{~~ a} act) ⁺ F _K , where (equation 2)

- fc ₊₁ is the force which will be related to the system at the next iteration;

- m is the mass related to the system;

- a _re f is the reference acceleration;

- a _act is the actual acceleration; and

- F _K is a previous current force which acts on the vehic1e .

Here the actual acceleration a _act is thus steered toward the

reference acceleration _rei - so that a restriction of the actual acceleration a _act is obtained, which gives a transient S _trans _ _exp , which may be used to determine the mass m, for example a vehicle mass, if the system relates to a vehicle.

As described above, the size of the time parameter τ determines how the transient S _{tra exp} appears when the actual acceleration a _act

approximates the reference acceleration (i _re f, so that different values of the time parameter τ give different behaviours in the system for acceleration restriction.

According to one embodiment of the present invention the vehicle system to be regulated is a system, for braking. Essentially any type of vehicle braking system, for example a brake, a retarder, or an electromagnetic brake, which may for example consist of an electric engine in a hybrid vehicle, may be regulated according to this embodiment. Different types of braking systems are described below in connection with figure 6. The actual state value S _act here constitutes an actual speed. ¾ and the reference value S _ref cons itutes a maximum speed v _max , whose value, for example for a vehicle, may be based on a speed limit for a road section. The inertia for the brake system is based on the mass m related to the brake system, for example a vehicle mass, which means that the mass m, for example the vehicle mass, here may be estimated based on a comparison of the actual transient S _{trans act} with the expected

transient S _{trans exp} .

For this embodiment of the invention, the model of the brake system, takes into consideration a difference between the actual

acceleration a _act and. the reference acceleration a. _re >- for vehicles, the force equation appearing as follows:

_{Bk+i = m} . ₍ 2 ZH2£L_ _flact) + _{Bk! where}

{equation 3)

¾+i is the force which will be related to the system at. the next iteration of the algorithm;

m is the mass;

v _re f is the reference speed;

v _act is the actual speed;

T is the time parameter;

(i _actt is the actual vehicle acceleration; and

B _k is the current braking force related to the system.

As shown by equation 4, the difference between the actual vehicle acceleration a _act and the reference acceleration a _re f depends on the time parameter τ , since the reference acceleration corresponds to the term . Similarly, as described, above, the size of the time parameter τ determines ow the transient S _{trans act} appears when the actual speed v _act approximates the maximum speed v _max .

According to one embodiment of the present invention, the vehicle system subject to regulation consists of an engine system. The actual state value S _act subject to control by this regulation thus constitutes an actual engine speed o) _act for the engine and the .reference value S _ref toward which the actual engine speed > _act will be steered constitutes a reference speed co _re f for the engine. The inertia of the engine system here consists of a moment of inertia / for the engine, which means that the engine's moment of inertia J may be estimated based on a comparison of the actual transient ■5trans act with the corresponding expected transient S _{trans exp} .

The model for the engine system, on which the regulation is based, here takes into consideration a difference between a change ω _α ¾ of an actual speed for the engine and a change os _re - _f of a reference speed for the engine. The difference here depends on a time parameter τ, since the term — —— comprises the time parameter τ, which is why the process for the actual engine speed's o) _act transient Strans act toward the reference speed co _re r may be controlled through the size of the time parameter τ, in the same manner as described above for the other embodiments.

According to the embodiment, the model's power equation looks as follows : j _k÷1 = j . (' ^>re ' _ ^Uacc - +T _ki where

(equation 4)

T _k÷1 is a torque which will be produced by the engine at the next iteration of the algorithm;

- / is the moment of inertia for the engine;

ω,- _g f is the reference speed for the engine;

i0 _act is the engine's actual speed;

τ is the time parameter;

a) _ac - _t is a change of the actual engine speed; and

T _k is the torque which is currently produced by the engine.

According to one embodiment of the present invention, the vehicle system which is subject to regulation consists of a temperature regulation system for a limited volume, where the temperature regulation system' s inertia / is based on a thermal inertia K for the volume, wherefore the thermal inertia K may be estimated based on the comparison of the actual transient S _lransjact with the

corresponding expected transient S _{trans exp} . The actual state value S _act here constitutes an actual temperature T _act for the limited volume and. the actual temperature _act is steered toward the reference value S _re f, which consists of a reference temperature T _re f£ox the volume.

The model for the temperature regulation system takes into

consideration a difference between a change i _flCt or an actual temperature for the volume and a change T _re f of a reference

temperature for this volume. The difference here depends on the time parameter τ and the equation according to the model of the

temperature regulation system, which appears as follows: p _{k+1 =} j . .... T _act) p _{k f where} (equation

5)

Pji+i is a thermal effect which will be emitted in the limited volume at the next iteration of the algorithm;

K is the thermal inertia for the limited volume;

T _re f is the reference temperature;

Tact is the actual temperature;

T is the time parameter;

T _act is a change of the actual temperature; and

Ρ¾ is a current thermal effect which is produced in the

1imited vo1ume .

The aggressiveness of the transient for the actual temperature T _act toward the reference temperature T _re f may easily be set by adjusting the value for the model's time parameter τ, whereby the transient's character changes as described in detail above.

According to one embodiment of the present invention, the vehicle system subject to regulation constitutes any suitable system connected to a PTO in a vehicle. Certain vehicles, for example trucks and tractors, have PTOs to which a user may connect practically any equipment, such as for example a crane, a concrete mixer, or different types of power aggregates. The large variation between the various types of systems which may be connected to the ΡΊΌ means that a regulator with a relatively large number of different features is required in order to operate these systems in a satisfactory manner.

A total moment of inertia J _tot including a moment of inertia / for an engine in the vehicle and a moment of inertia J _PT0 for the PTO- system is, according to this embodiment, estimated based on the actual state value 5^, which constitutes an actual engine speed <¾,..<- for an engine in the vehicle and which turns inwards toward a respective corresponding reference value S _re f which constitutes a reference engine speed o) _re f for the engine. By estimating the total moment of inertia ] _tQt for both the engine and the PTO, the actual engine speed oi _act required to drive the PTO may be

regulated.

The model of the system here takes into consideration a

difference between a change ai _act of an actual engine speed for the engine and a change > _re f of a reference speed for the engine, where the difference depends on a time parameter τ. The

regulation of the system which is connected to the PTO may here be given a desired, character/aggressiveness by a simple

adjustment of the time parameter τ.

According to this embodiment the regulation of the system according to the above described embodiments is made oscillation- free, that is to say the control of the state is made non- oscillative, by giving the time parameter r a value which is at least four times larger than the value for the calibration time Yr τ>4*γ. Where τ>4*γ, the transient S _{trans act} for the actual state value 5 _art toward the reference value S _re f is entirely without overshoots or descenders. Oscillations in the transient

S _{trans act} itself regarding the actual value toward the reference value are thus avoided where τ>4*γ. According to another embodiment, the time parameter τ is given a value which is at least, more than four times as large as the value for the calibration time γ, τ>4*γ. For example, the time parameter τ may here be given the value 5*γ, τ=5*γ, which gives another 20% stability margin compared to the value τ-4*γ. Higher values for the time parameter T may also be used, for example ι=6*γ, or τ ^' 7*γ, which gives further margins guarding against oscillation in the regulation. The higher values for the time parameter τ may be used to give further margins guarding against inaccurate estimations of the vehicle mass m .

According to one embodiment a. previous estimation / ^* of the inertia I may be inexact and/or unreliable if the actual- transient Straw act differs from the corresponding expected transient

S _transexp , for example if a value for the comparison exceeds a predetermined limit value. At least one rat.ro μ ^~ ~ between a previous estimation Γ of the inertia and the actual value for the inertia I may be determined based on an analysis of the actual transient S _transact! as will be shown below. Since the previous estimation / ^* of the inertia is known and. since the ratio μ~— ¹ may be calculated, as described for various embodiments below, a new and correct value for the inertia / may also easily be determined

i"

with the use of the embodiment, according to J =— .

μ

According to one embodiment, an average value formation, which may also be seen as a. lowpass-filtration, may also be used to determine the inertia /. The average value formation/ filtration then dampens the aggressiveness for the determination of the inertia /, that is to say reduces changes and/or fluctuations for the value of the inertia !. This embodiment is suitable for applications where large changes and/or fluctuations in the value of the inertia / are unsuitable and/or damaging in the

determination .

This estimation resulting in average value formation may be called !f _cer and. may be determined according to the formula Ifi _lt er — cl ^* + (1 - c) ~ ^' , where c is a weighting coefficient with a value of between 0 and 1, which determines the aggressiveness of the estimation and thus also determines how quickly the update of the estimation occurs. A high value for the weighting coefficient c, for example 1, here gives a relatively slow and passive/non- aggressive update of the estimation, where the average value- forming value of the estimation Ifu _ter is near the previous estimation's Γ value. A low value for the -weighting coefficient, c on the other hand results in a more aggressive update of the estimation Ifn _ter , which is thus quicker but also results in larger- fluctuatio s. According to one embodiment of the present

invention the weighting coefficient c may have a value of around 0.9 which results in a balanced aggressiveness and. quickness for the update of the estimations.

The average value formation described herein may be seen as a first order lowpass-filtration of the value for inertia /. Other suitable types of lowpass-filtration may also be used here in order to achieve this positive characteris ic.

The value of the ratio μ may be calculated relatively easily, for example as described in connection with the equations 11 and 13 below. Therefore, according to the embodiment of the present invention, the inertia / may be easily determined, since the value for the previous estimation Γ of the inertia is known, and since the correlations between the ratio μ and the inertia / are known through the present inventio .

According to the present invention, during an analysis of the transient ^ for actual state values toward the reference value S _re the appearance of the actual transient S _{trans act} i s compared, for example for the actual speed v _{act l} with an expected, appearance for the same transient, for example an expected appearance for this speed S _tra . _ns _ _exp . If these two transients differ, this may be due to an error in the estimation of the mass, which means that the regulation according to the invention becomes somewhat inexact, so that the actual speed v _act gets a different appearance than it should have. Therefore the estimation of the mass m may be adjusted based on this analysis of the transient Strans _j exp · - ^Cn order to estimate a ratio μ between the actual mass m related to the system and the estimated mass m ^* , a mathematical analysis of a transient is carried out, as described below.

The system, for example a vehicle, follows the force equation ( ^' Newton' s second law) : m- a = F _drive --- ¥ambient (equation 6)

Where the system is really controlled by the regulator, that is to say where the regulator receives what it requests and where the regulation system is not in saturation regarding the maximum torque or the drag torque, the speed profile for the actual speed v _act will follow a predefined profile which only depends on the two parameters τ and γ , which may be deduced according to the below .

The system is controlled, when the regulator really controls, by the equation:

= -y{ < ct,fc J + Pk> (equation / 1 where

F _fc+1 is a force which will be related to the system at the next ite ation;

h is a discretion factor;

y is a calibration time;

m is the mass related to the system;

v _re f is the reference speed;

v _{art r k} is the actual speed;

τ is the time parameter;

aact,k is the actual acceleration; and

F _k is a current force which is related to the system. By combining the force equation (equation 6) and the power update equation (equation 7) the following expression is obtained : ^ma ct,k+l + *'ambientk + l — ^~ 7T ^" \ ~ _τ ^a act,k ) + ^ ambientk ⁺ T^actjt Iequation fa)

The assumption is that the ambient force F _ambient is constant from one sample to another, which is a reasonable assumption in for example a cruise control system, which is relatively slow. In that case, following some algebraic reshuffling, the following expression is obtained:

1 m* fVref-Vact.k \ fa _{act k} - _{act k+1} \

0 ₌ - «„,,.,)·( 1 J (equation 9,

If the speed error is defined as above ε ~ v _re f— v _act and use is made of the fact, that the term ~x££&~~~££& is the numerical derivative of acceleration, the following ordinary differential equation of the second order is instead obtained for the speed error, where there further is a transition from discrete time to continuous time:

0 =~(~+ + έ ^' , (equation 10) where μ = ~ is the ratio between the hitherto estimated mass m*

m

and the actual mass m.

From equation 10, the mass ratio μ may be easily resolved and calculated. It is problematic that both sand έ are often very noisy, so that, the estimation also often becomes noisy.

In order to minimise the problem with noise in measuring signals, the equation is integrated as of when the regulator actually starts to control the vehicle at the time t=0, until the system has stabilised around the reference after the time t=T .

The following expression for the mass ratio is then obtained: _u — _τ . γ —-^"' , (equation 11) wnere : e=S _ref -S _act is an error in a state;

έ is a derivative of the error in the state ε;

- V is a calibration time;

τ is a time parameter; and

the time period [0,T] is of a length which ensures that the actual state value S _act is able to stabilise around the corresponding reference value S _re f.

In, for example, a cruise control system, where the actual state value S _act constitutes an actual speed v _act and the corresponding reference value S _re f constitutes a reference speed v _re f, the state error ε constitutes a speed error, i'-v _r ef ^~v act■

In for example a braking system, where the actual state value

Sort constitutes an actual speed v _act and the corresponding reference value S _ref constitutes a maximum, speed v _maxl the state error ε constitutes a speed error, ε= v _max ~v _act .

If the equation 10 is resolved, the expected transient S _{trans gxp} is also obtained. The expected transient S _transjBxp has an appearance which the actual transient S _tranSn would have had if the regulation system had had access to a correct value for the inertia /.

For systems where the state error ε constitutes a speed error, such as the cruise control system and the braking system, according to one embodiment of the invention, the ratio μ = y ma be used in order to determine a new estimation w^ _iew of a mass related to the system, for example a vehicle mass, by updating a previous estimation m* of the mass by multiplying the old estimation m ^* with the calculated mass ratio μ: m^ _ew = m* · μ (equation 12) This may be repealed at each transient S^- _{rans act} toward, tne

reference S _re f .

In the same way as described above, according to one embodiment an average value formation/lowpass filtration may also be used here in the estimation of the mass, which then dampens the aggressiveness for the estimation.

This estimation forming an average value may be called m _{f ter} and may be written according to the formula mfu _ter — ^c ' ^{* +} (l-c)-jj- , where c is a weighting- coefficient with a value of between 0 and 1, which determines the aggressiveness of the estimation and thus also determines how quickly the estimation is updated. As

described above, a high value of the weighting coefficient c, for example 1, gives a relatively slow and passive/non-aggressive update of the estimation, while a low value of the weighting coefficient c on the other hand gives a more aggressive updating of the estimation. According to one embodiment of the present invention, the weighting coefficient c may have a value of around. 0.9, which gives a balanced aggressiveness and speed in the update of the estimations. A person skilled in the art will realise that a similar deduction may be made for the braking system if the reference speed v _re f is replaced with the maximum speed v _max .

Equation 12 is simple to realise in a discrete control system and it is guaranteed to converge as long as the actual speed v _act converges toward, the reference speed v _re f

A non- limiting simulated example of mass estimation according to this embodiment is displayed in the figures 4a and 4b, where the solid curve corresponds to a transient S _[rans _ _ac[ , -where the mass estimation is correct, and the dashed curve corresponds to a transient S _{trans act} with an incorrect mass estimation. For the correct mass estimation the transient S _{[rans act} becomes oscillation- free (as shown in figure 4a) and the mass ratio μ=1 (as shown in figure 4b) . For the incorrect mass estimation the transient, obtains an overshoot (as shown in figure 4a) and the mass ratio μ=0 , 5 (as shown in figure 4b) . The mass is thus underestimated by 50% here.

Figure 4b shows clearly that the algorithm converges toward the mass ratio values μ-l and. μ-0.5 for correct and incorrect mass estimations, respectively, which means that the algorithm becomes very useful for correcting incorrect mass estimations. In addition, the algorithm may be implemented with a very low added com lexity .

For an acceleration limiting system, where the actual state value S _act constitutes an actual acceleration a _act and the reference value S _re f constitutes a reference acceleration (i _re f , the analysis may be based on a force equation related to the system, for example for a vehicle, according to: u = ;.·'— ^{aact(r 0)} (equation 13)

j ₀ a _ref it)dt+v _act {<S) -v _act {T) where : a _act is an actual acceleration;

ci _yg f is a reference acceleration;

vaci is an actual speed;

- V is a calibration time; and

the time period [0,T] is of a length which ensures that the actual acceleration a ' ^■ _n a _r c _† t is able to stabilise around the reference acceleration a _re r . Equation 13 appears different from equation 11 since the acceleration limiting system is here steered toward a reference acceleration _rei - and not toward a reference speed v _re f .

For the acceleration limiting system as well, the ratio μ—— ^' may be used, to determine a new estimation ninew of the mass, by updating a previous estimation m* ; ti _iew = m ^t · μ, which may be deduced in a similar way as for the cruise control system, above.

For an engine system in the vehicle, where the actual state value S _act constitutes an actual engine speed o) _act for the engine and the corresponding reference value S _re f constitutes a reference engine speed co _re f for the engine, the state error ε in the equation 6 constitutes an engine speed, error, ε= <x) _re f— a> _act . Here, in the same r

manner as tor the mass, the ratio μ =— may be used to determine a new estimation j _ew of the moment of inertia by updating a previous estimation j ^* jnew j ^* " , ^u _> which may be deduced in the same manner as for the mass estimation above.

For a temperature regulation system in the vehicle, where the actual state value S _act constitutes an actual temperature T _act for a limited volume and the corresponding reference value S _re f constitutes a reference temperature T _ref for the volume, the state error ε

constitutes a temperature error, s=T _re f-T _act , Here, in the same manner as for the mass, the ratio μ =™ may be used to determine a new estimation K _ew of the thermal inertia by updating a previous estimation K ^* , Κ _η ,.. _Λ , Κ ^* ·μ, which may be deduced in the same way as for the mass estimation above.

For a PTO in the vehicle, where the actual state value S _act

constitutes an actual engine speed o) _act for en engine in a vehicle, and the respective corresponding reference value S _re f constitutes a reference speed co _re f for the engine, the state error ε constitutes an engine speed error ε~ _re f ^■■■■ o) _act . Here, in the same manner as for the

r*

mass, the ratio μ— ~ may oe used to determine a new estimation J tot-new °f the total moment of inertia by updating a previous estimation H _ot , J tot-new ^J tot ' i w ich may be deducted in the same manner as for the mass estimation above.

According to one embodiment of the present invention the regulator, which is arranged to regulate at least one actual state value S _act toward at least one respective corresponding reference value S _re f consists of a PID-regulator, or of a differential Pi-regulator .

A PID-regulator is a regulator which provides an in-signal u(t) to a system that is to be controlled based on a divergence e{t) between a desired out-signal r (t) , that is to say the reference value, and an actual out-signal y(t) . In the formula below, e(t)=r(t) -y(t) as follows : cte(r)

u(t) - K _p e t) T K, / ₀ ^" e(r)dT {equat on 14)

dt where :

K _p is a gain constant;

K _j is an integration constant; and

K _D is a derivation constant.

A PID-regulator regulates in three ways, through a proportionate gain (P;K _P ) , through an integration (I; K.) and through a derivation

(D; K _d ) .

The constants K _p , K _ir and K _d impact the system as follows.

An increased value for the gain constant K _p leads to the following change of the PID-regulator:

Increased rate;

Reduced stability margins;

Improved compensation of process disturbances; and. Increased control signal activity.

An increased value for the integration constant ¾ leads to the following change of the PID-regulator :

Better compensation of low-frequency process disturbances (eliminates remaining errors in step disturbances) ; Increased rate; and

Reduced stability margins.

An increased, value for the derivation constant K _d leads to the following- changes in the PID-regulator :

Increased ra.te ;

Increased stability margins; and

Increa.sed control signal activity. There are also other types/variants of .regulators/regulation algorithms which have a function similar to that of the PID- regulator. Also, when regulating with these other types/variants of regulators/regulation algorithms the estimation of inertia according to the present invention may be used, as a person skilled in the art will realise.

A differential ΡΙ-regulator is a PI- regulator, without the D-part in the PID-regulator, which is expressed in differential form. The differential Pi-regulator may be implemented in a discrete system,

PID- and PI- regulators may thus be said to control states through the use of a control signal, where the control signal has a size which is the sum of three terms, which are proportionate to the difference between the reference value and the state, the integral of the error, and the derivative of the error, respectively. PID- and Pi-regulators may be deemed to be comprised in the model based regulators described above, since PID- and Pi-regulators , with the help of equation 14 above (and in a corresponding manner for the PI- regulator, may control states in the vehicle systems.

According to one embodiment of the present invention, the estimation of inertia / is likewise effected based on information related to a road section where a vehicle is present, where this information may comprise a road incline a for the road section. The road incline may be obtained based on one, or several, of map data, a positioning device such as GPS (Global Positioning System) , an accelerometer , a force equation and an elevation change.

A person skilled in the art will realise that the above described method/regulation system according to the present invention may also be implemented in a computer program., which -when executed in a computer will achieve that the computer carries out the method. The computer program usually consists of a computer program product 503 stored on a digital storage medium., where the computer program is comprised in a computer program product' s computer readable medium. The said computer readable medium consists of a. suitable memory, such as for example: ROM (Red-Only Memory), PROM (Programmable Read- Only Memory) , EPROM (Erasable PROM) , Flash-Memory, EEPROM (electrically Erasable PROM), a hard disk device, etc.

Figure 5 shows a schematic view of a control device 500. The control device 500 comprises a calculation device 501, which may consist of essentially any suitable type of processor or microcomputer, e.g. a circuit for digital signal processing (Digital Signal Processor, DSP) , or a circuit with, a predetermined specific function

(Application Specific Integrated Circuit, ASIC. The calculation device 501 is connected to a memory device 502 arranged in the control device 500, which provides the calculation device 501 e.g. with the stored program code and/or the stored data which the calculation device 501 needs in order to be able to carry out calculations. The calculation device 501 is also arranged to store partial or final results of calculations in the memory device 502.

Further, the control device 500 is equipped with devices 511, 512, 513, 514 for the receipt and sending, respectively, of in- and out- signals, respecti ely. These in- and out-signals, respectively, may contain waveforms, pulses, or other attributes, which may be detected as i formatio by the devices 511, 513 for the receipt of in-signals, and converted into signals that may be processed by the calculation device 501. These signals are then provided to the calculation device 501. The devices 512, 514 for the sending of out- signals are arranged to convert signals received, from the

calculation device 501 for the creation of out-signals e.g. by modulating the signals, which may be transferred to other parts of the regulation system and/or to systems regulated according to the present invention .

Each one of the connections to the devices for the receipt and sending of in- and out-signals, respectively, may consist of one or several of a cable, a data bus, such as a CAN-bus (Controller Area Network bus), a MOST-bus (Media Oriented Systems Transport bus), or some other bus configuration; or of a wireless connection.

A person skilled in the art will realise that the above mentioned computer may consist of the calculation device 501 and that the above mentioned memory may consist of the memory device 502. Generally, control systems in modern vehicles consist of a communications bus system consisting of one or several

communications buses to connect a number of electronic control devices (ECUs) ., or controllers, and different components localised on the vehicle. Such a control system may comprise a large number of control devices, and the responsibility for a specific function may be divided over more than one control device. Vehicles of the type displayed thus often comprise significantly more control devices than displayed in figure 5, which is well known to persons skilled within the art.

The present invention is, in the embodiment displayed, implemented in the control device 500. The invention may however also be implemented wholly or partly in one or several other already existing control devices in the vehicle or in a control device dedicated to the present, invention.

Figure 6 shows an example vehicle in which the present invention may be imp1e ented .

The vehicle 100 comprises a drive line. The drive line comprises a combustion engine 101, which in a customary manner, via an output shaft 102 of the combustion engine 101, usually via a flywheel, is connected to a gearbox 103 via a clutch 106.

The vehicle 100 also comprises drive shafts 104, 105, which are connected to the vehicle's driving wheels 11, 112, and which are driven by an output shaft 107 from the gearbox 103 via a shaft gear 108, such as e.g. a customary differential. The vehicle 100 also comprises additional wheels 113, 114, which may be driving or non- driving and may be arranged to control the vehicle.

The vehicle 100 further comprises various different brake systems 150. The brake systems 150 may comprise a customary brake system, which may e.g. consist of wheel brakes 151, 152, 153, 154 comprising brake pads and/or brake drums with associated brake fittings or similar arranged by the vehicle's wheels 111, 112, 113, 144, The brake system 150 may also comprise one or several auxiliary

brakes/retarders , for example a brake which acts on the vehicle's drive line 155, such as a retarder, an electromagnetic brake, a decompression brake, or an exhaust brake. A retarder may comprise one or several of a primary retarder, placed between the engine and the gearbox, and a secondary retarder, placed after the gearbox. An electromagnetic brake may be placed in any suitable location where it may act on the vehicle's drive line.

A decompression brake may be integrated in the engine. An exhaust brake uses a damper fitted in the exhaust outlet in order to increase the engine' s pump losses and thus its braking torque to achieve a braking action. The exhaust brake may be seen as

integrated in the engine 101, or at least in the engine 101 and its exhaust treatment system. In this document, exhaust brakes and decompression brakes are included in the term engine-fitted

auxiliary brakes, which are arranged/fitted in connection with an exhaust stream from the engine 101. These engine-fitted auxiliary brakes may also be arranged at essentially any location along the exhaust stream's passage out from the engine 101 to the exhaust treatment system. The brakes 155 which act on the drive line are here schematically drawn, as if they act on the gearbox' s output shaft 107. However, these brakes 155 may be arranged at esse tially any location along the vehicle's drive line and may impact

essentially anywhere, where a braking action may be achieved.

The engine 101 may be controlled based on instructions from, a cruise control 120, in order to maintain a constant actual vehicle speed and/or to vary the actual vehicle speed, such that, for example, a fuel consumption optimised within reasonable speed limits is achieved .

The vehicle 100 also comprises at. least one control device 130, arranged to control a number of different functions in the vehicle, such as among others the engine 101, the brake system 150, a cooling system 160 which provides a temperature for a volume in the vehicle, and a system for PTO 170.

As described in further detail above, the control device 130 in the regulation system comprises the determination device 131, a comparing device 132, the estimation device 133 and the regulator 134.

As a person skilled in the art will realise, the control device may also be installed to control one or several further devices in the vehicle, such as for example the clutch 106 and/or the gearbox 103 {not displayed in the figure} .

The at least one control device 130 is drawn separately from the cruise control 120 in the figure. However, the control device 130 and the cruise control 120 may exchange information with each other. The cruise control 120 and the control device 130 may also be logically separate whilst being physically implemented in the same device, or may be both logically and. physically jointly

arranged/implemented .

The present invention is not limited to the above described

embodiments of the invention, but relates to and comprises all embodiments within the scope of the enclosed independent, claims.