Field of invention

The present invention relates to a method of a control system, as defined in the preamble of claim 1. The present invention also relates to a control system, as defined in the preamble of claim 15. The present invention also relates to a computer program and a computer-readable medium carrying out the method according to the invention.

Background of invention

The following background information is a description of the background of the present invention, which thus not

necessarily has to be a description of prior art. Vehicles, such as for example cars, buses and trucks, normally include a large number of actuators being arranged for

activating e.g. mechanical devices, components, parts or parameters in the vehicle. For example, actuators may be used for effecting a change in a clutch position, to activate a gear change in a gear box, to change an amount of air being input into an engine and/or to activate a spark ignition within an engine cylinder. Of course, actuators may be used for activating a number of other devices, components, parts or parameters than the ones being listed here, as is clear for a skilled person. The actuators are controlled by control units providing control signals to the actuators, thereby

instructing them how to act. In this document, the notation control unit includes essentially any device being

arranged/configured for controlling actuators, such as a controller, a regulator or the like. In some implementations, two or more of the actuators may be controlled based on one single reference value a and one single measured value η in order to minimize a control error ψ. This may be denoted a single input multiple output (SIMO) regulation system, i.e. a regulation system producing multiple control signals based on a single reference/measured value α/η .

It may sometime be difficult to determine, e.g. by use of models, specific/individual reference values a for some actuators, wherefore they by use of SIMO regulation instead may be commonly regulated together with one or more other actuators based on a reference value in some way being related to the actuator.

Further, it is sometimes not possible to measure all

parameters being regulated e.g. in a vehicle. It may then be advantageous to regulate such non-measurable parameters based on a related parameter which is possible to measure instead. This measurable parameter may then be used for regulation of the non-measurable parameter, and may also itself be

regulated, or may be used for regulation of other parameters.

In this document, SIMO regulation/control of an ignition spark timing in the engine cylinders and of an amount of air being input into the cylinders based on one single reference value a _r pm and on one single measured value _rpm for a number of revolutions for the engine is often used as a non-limiting example in order to explain the present invention. The

invention is, however, not restricted to this implementation, and may be generally used for essentially any SIMO regulation system in which two or more actuators are controlled based on one single reference value a and one single measured value η such that a control error ψ is minimized. If the control error ψ is equal to zero; ψ = 0; then each one of the two or more actuators are in a steady state condition.

As mentioned above, the two or more actuators are regulated such that the control error ψ is minimized. Then, the single reference value _r pm has been reached by the regulation of the two or more actuators being controlled based on one single reference value a and on one single measured value . A steady state condition for the two or more actuators, and thus for the devices, components, parts or parameters they activate, has commonly been reached when the control error ψ is

minimized, e.g. has the value zero; ψ = 0. Thus, each one of the two or more actuators are then at the same time in a steady state condition, since the single reference value _rp m has been commonly reached by the regulation of the two or more actuators.

SUMMARY OF INVENTION

It is, however, difficult to know the exact operational points for each respective actuator, and thus for each corresponding device, component, part or parameter being activated by that specific actuator, when SIMO regulation is used. Two or more actuators may commonly have been regulated such that they have commonly reached a minimized control error ψ, e.g. being equal to zero, and such that a steady state has been reached for the actuators. However, the separate/individual exact operating points, e.g. the separate/individual exact positions, for each one of the two or more actuators may still be undefined, and may also be undesired.

This uncertainty regarding the individual operating points for the two or more actuators may result in an undesired and/or non-optimal regulation of at least one of the two or more actuators . As a non-limiting example, an engine, e.g. in a vehicle, may work according to the so-called Otto cycle, for which a mixture of fuel and air in the engine cylinders is ignited by an electric spark, whereby a brake torque is created in the engine, which is used for driving e.g. driving wheels of the vehicle. The fuel may for an Otto cycle engine be e.g. petrol, ethanol, an/or natural gas.

For such an engine, one single reference value _r pm may be used for controlling both of an ignition spark timing in the engine cylinders and of an amount of air being input into the

cylinders. When the engine reaches the reference value, e.g. arpm = 600 rpm, the control error ψ is equal to zero; ψ _ΓΡ ιη = 0, and the regulation is completed. Then, in order to improve the efficiency of the engine, it might be needed to further adjust the ignition spark timing and/or the amount of air being input into the cylinders, since both of these have an impact on the combustion of the fuel and air mixture in the cylinders, and thus also have an impact on an engine efficiency.

However, such a further adjustment of one or more of the actuators controlling the ignition spark timing and the amount of air being input the cylinders is very difficult, often more or less impossible, to perform if the individual operation points for each one of the actuators are unknown/undefined, as is often the case in SIMO solutions known today. For an engine working according to the so-called Otto cycle, a specific ratio for the mixture of fuel and air in the engine cylinders is needed in order to achieve a wanted efficiency for the combustion of the mixture in the cylinders. Also, the electric spark used for ignition of the mixture should deliver the spark at the exact right time instant in order to provide the wanted combustion efficiency. In some situations, a lower combustion efficiency is wanted, for example when one or more catalysts in an exhaust treatment systems should be heated. In many situations, however, it is important to achieve an efficient combustion, in order to provide a minimized fuel consumption.

For example, when the number of revolutions for the engine is to be regulated, a suitable operation point may be defined, which is a compromise/balance between a performance of the regulation of the number of revolutions and the combustion efficiency. For differing cases, this compromise/balance may be adjusted in order to achieve a best possible regulation performance. If, for example, great/big increases of the provided brake torque should be possible to be quickly

performed, this results in a strategy for choosing an

operation point being different from a strategy for choosing an operation point making it possible to provide great/big and quick decreases of the provided brake torque. Correspondingly, if only smaller increases and/or decreases of the brake torque are to be expected, still further strategies for choosing operation points may be chosen.

A so-called torque reserve may be provided by intentionally reducing the combustion efficiency of the engine. Hereby, a torque reserve is created, which may be used for responding to a request for a fast increase in provided brake torque. Thus, the wanted combustion efficiency is here chosen to be lower, such that there is a sufficient torque reserve/buffer which may be used for quickly increase the provided brake torque. If major torque increases are expected to be requested, the torque reserve may be set to have a larger size, e.g. having a size corresponding to these expected increases. This larger sized torque reserve is then achieved at the cost of a less efficient combustion. For example, in an operation point corresponding to a specific mixture of air and fuel in the cylinders, a minimal torque being provided for a worst possible ignition timing, i.e. for a least efficient combustion at the top dead centre (TDC) ignition timing angle, is 800 Nm, and a maximal torque being provided for a maximum brake torque (MBT) ignition timing angel, i.e. for a most efficient combustion, is 1000 Nm.

Then, a brake torque of 960 Nm may for example be requested if only smaller changes of the brake torque are to be expected, and if the regulation focusses on a number of revolution regulation stability and on the fuel consumption. Hereby, the torque reserve is 40 Nm, which is sufficient for responding to the probably upcoming smaller adjustments of the brake torque.

However, if e.g. one or more catalysts initially are going to be heated by the combustion, a brake torque of 840 may be requested, which means that there is a torque reserve of 160 Nm, which may be used for responding to a probably upcoming request for a quick increase of the brake torque.

However, as mentioned above, adjustment of one or more of the actuators controlling the ignition spark timing and the amount of air being input into the cylinders may be very difficult to perform since the individual operation points for the

actuators are often unknown/undefined in SIMO control systems.

This may also be described as the torque reserve for the engine not being easily used for known solutions of today, since it will for example be unknown for the ignition control unit exact in which time instant the ignition spark will ignite the fuel/air mixture. Thus, the exact ignition timing will be unknown, which may cause regulation problems, such as regulation instability, and/or problems to reach a wanted engine efficiency. Correspondingly, the unknown/undefined position for the actuator controlling the amount of air being input into the cylinders may result in a non-optimal mixture of fuel and air in the cylinders, which also makes it very difficult to reach the wanted engine efficiency. Devices, components, part and/or parameters may thus be regulated in a way which result in non-optimal combustion efficiency, causing an unnecessary high fuel consumption and/or a non-optimal torque reserve, for an engine being regulated in accordance with known principles. It is therefore an object to solve at least some of the above mentioned disadvantages.

The object is achieved by the above mentioned method of a control system according to the characterizing portion of claim 1. The control system includes means, e.g. at least two control units, arranged for controlling at least two actuators based on one reference value a and one measured value η such that a control error ψ is minimized. The method includes:

- determining if the at least two actuators are in a steady state condition; and

- if the at least two actuators are in the steady state condition :

- identifying a first actuator of the at least two actuators which has a shortest response time β;

- determining at least one difference μι _< between a first control signal Ui used for controlling the first actuator and at least one second control signal Uk used for controlling at least one second actuator of the at least two actuators, respectively;

- adjusting the at least one second control signal Uk by adding the determined at least one difference i to the at least one second control signal Uk, respectively; Uk = Uk + k,- such that the at least one adjusted second control signal Uk converges with the first control signal Ui, respectively; and - utilizing the first control signal Ui for controlling the first actuator, and the at least one second adjusted control signal Uk for controlling the at least one second actuator, respectively.

According to an embodiment of the present invention, the at least one difference i is at least one amplitude difference μι, whereby the at least one adjusted second control signal Uk converges in amplitude with the first control signal Ui when being adjusted.

According to an embodiment of the present invention, at least one offset Ui_ _op , Uk_op related to at least one operating point is added to one or more of the first control signal Ui and the at least one second adjusted control signal Uk, thereby creating one or more of a first offset control signal; Ui_ ₀ ffset = Ui + Ui_ ₀ p ; and at least one second offset control signal; Uk_offset = Uk + Uk_op ; and

- utilizing one or more of the first offset control signal

Ui_ ₀ ffset for controlling the first actuator, and the at least one second offset control signal Uk_offset for controlling the at least one second actuator, respectively.

According to an embodiment of the present invention, the at least one difference k is scaled by a scaling factor cpk before adjusting the at least one second control signal Uk by adding the at least one difference to the at least one second control signal Uk, respectively; Uk = Uk + k*pk," the scaling factor cpk defining how fast the at least one adjusted second control signal Uk converges with the first control signal Ui .

According to an embodiment of the present invention, the determined at least one difference i is added to at least one second integral term signal Uk_i used by the at least one second control unit arranged for controlling the at least one second actuator, respectively, thereby creating at least one second adjusted integral term signal Uk_i; Uk_i = Uk_i + k to be used for controlling the at least one second actuator in order to provide the converging of the at least one adjusted second control signal Uk with the first control signal Ui .

According to an embodiment of the present invention, the at least one difference k is scaled by a scaling factor cpk before creating the at least one second integral term signal Uk_i by adding the at least one difference to the at least one second integral term signal Uk_i, respectively; Uk_i = Uk_i + k*pk,- the scaling factor cpk defining how fast the at least one adjusted second control signal Uk converges with the first control signal Ui . According to an embodiment of the present invention, the determination of if the at least two actuators are in steady state condition includes:

- determining if the control error ψ is smaller than an absolute threshold value | I ; ψ ≤ | I ;

- determining if the first control signal Ui is within a controllable interval for the first actuator; Ui ≤ I θι | ; and

- determining if the at least one second control signal Uk is within at least one second controllable interval for the at least one second actuator, respectively; Uk ≤ I 6k I . According to an embodiment of the present invention, the determination of if the at least two actuators are in steady state condition includes:

- starting a timer ω when:

- the control error ψ is smaller than the absolute threshold value | I ; ψ ≤ I | ;

- the first control signal Ui is within the controllable interval for the first actuator; Ui ≤ I θι | ; and

- the at least one second control signal Uk is within the at least one second controllable interval for the at least one second actuator, respectively; Uk ≤ I 6k I ; and

- determining that the at least two actuators are in steady state condition when the timer ω reaches a timer threshold value λ; ω ≥ λ.

According to an embodiment of the present invention, the determination of the at least one difference k includes filtering of one or more of the first control signal Ui and the at least one second control signal Uk before the at least one difference k is determined.

According to an embodiment of the present invention, the first control signal Ui and the at least one second control signal Uk initially have the same quantity.

According to an embodiment of the present invention, one or more of the first control signal Ui and the at least one second adjusted control signal Uk are transformed by a quantity transformation Ω± before being used for controlling the first actuator and the at least one second actuator.

According to an embodiment of the present invention,

- the first control signal Ui and the at least one second control signal Uk initially have differing quantities; and

- one or more of the first control signal Ui and the at least one second control signal Uk are transformed by a quantity transformation Ω± before the determination of the at least one difference μ± between the first control signal Ui and the at least one second control signal Uk.

According to an embodiment of the present invention, one or more of the first control signal Ui and the at least one second adjusted control signal Uk are retransformed by a quantity retrans formation Qi_ _re before being used for controlling the first actuator and the at least one second actuator,

respectively . The object is also achieved by the above mentioned control system according to the characterizing portion of claim 15. The control system includes:

- means, such as e.g. a first determination unit, arranged for determining if the at least two actuators are in a steady state condition; and

- if the at least two actuators are in the steady state condition, the control system is arranged for activating:

- means, such as e.g. an identification unit, arranged for identifying a first actuator of the at least two actuators which has a shortest response time β;

- means, such as e.g. a second determination unit, arranged for determining at least one difference μι _< between a first control signal Ui used for controlling the first actuator and at least one second control signal Uk used for controlling at least one second actuator of the at least two actuators, respectively;

- means, such as e.g. an adjustment unit, arranged for adjusting the at least one second control signal Uk by adding the determined at least one difference i to the at least one second control signal Uk , respectively; Uk = Uk + k ,- such that the at least one adjusted second control signal Uk converges with the first control signal Ui , respectively; and

- means, such as e.g. a utilization unit, arranged for utilizing the first control signal Ui for controlling the first actuator, and the at least one second adjusted control signal Uk for controlling the at least one second actuator,

respectively . According to an embodiment of the present invention,

- the adjustment unit/means is arranged for adding at least one offset Ui_ _op , Uk_op related to at least one operating point to one or more of the first control signal Ui and the at least one second adjusted control signal Uk, thereby creating one or more of a first offset control signal; Ui_ ₀ ffset = Ui + Ui_ ₀ p; and at least one second offset control signal; Uk_offset = Uk + Uk_op," and

- the utilization unit/means is arranged for utilizing one or more of the first offset control signal Ui_ ₀ ffset for controlling the first actuator, and the at least one second offset control signal Uk_offset for controlling the at least one second

actuator, respectively.

According to an embodiment of the present invention, the adjustment unit/means is arranged for scaling the at least one difference k by a scaling factor cpk before adjusting the at least one second control signal Uk by adding the at least one difference to the at least one second control signal Uk, respectively; Uk = Uk + k*pk," the scaling factor cpk defining how fast the at least one adjusted second control signal Uk converges with the first control signal Ui .

According to an embodiment of the present invention, the adjustment unit/means is arranged for adding the determined at least one difference i to at least one second integral term signal Uk_i used by the at least one second control unit/means arranged for controlling the at least one second actuator, respectively, thereby creating at least one second adjusted integral term signal Uk_i; Uk_i = Uk_i + k to be used for controlling the at least one second actuator in order to provide the converging of the at least one adjusted second control signal Uk with the first control signal Ui . According to an embodiment of the present invention, the adjustment unit/means is arranged for scaling the at least one difference μι _< by a scaling factor cpk before creating the at least one second integral term signal Uk_i by adding the at least one difference to the at least one second integral term signal Uk_i, respectively; Uk_i = Uk_i + k*pk,- the scaling factor cpk defining how fast the at least one adjusted second control signal Uk converges with the first control signal Ui .

According to an embodiment of the present invention, the first determination unit/means is arranged for determining if the at least two actuators are in steady state condition by:

- determining if the control error ψ is smaller than an absolute threshold value | I ; ψ ≤ | I ;

- determining if the first control signal Ui is within a controllable interval for the first actuator; Ui ≤ I θι | ; and

- determining if the at least one second control signal Uk is within at least one second controllable interval for the at least one second actuator, respectively; Uk ≤ I 6k I .

According to an embodiment of the present invention, the first determination unit/means is arranged for determining if the at least two actuators are in steady state condition by:

- starting a timer ω when:

- the control error ψ is smaller than the absolute threshold value | I ; ψ ≤ I | ;

- the first control signal Ui is within the controllable interval for the first actuator; Ui ≤ I θι | ; and

- the at least one second control signal Uk is within the at least one second controllable interval for the at least one second actuator, respectively; Uk ≤ I 6k I ; and

- determining that the at least two actuators are in steady state condition when the timer ω reaches a timer threshold value λ; ω ≥ λ. According to an embodiment of the present invention, the second determination unit/means is arranged for determining the at least one difference μι _< by including filtering of one or more of the first control signal Ui and the at least one second control signal Uk before the at least one difference k is determined .

According to an embodiment of the present invention, the first control signal Ui and the at least one second control signal Uk initially have the same quantity. According to an embodiment of the present invention, a

transformation unit/means is arranged for transforming one or more of the first control signal Ui and the at least one second adjusted control signal Uk by use of a quantity transformation Ωι before being used for controlling the first actuator and the at least one second actuator.

According to an embodiment of the present invention,

- the first control signal Ui and the at least one second control signal Uk initially have differing quantities; and

- a transformation unit/means is arranged for transforming one or more of the first control signal Ui and the at least one second control signal Uk by use of a quantity transformation Ω± before the determination of the at least one difference μ± between the first control signal Ui and the at least one second control signal Uk . According to an embodiment of the present invention, a

transformation unit/means is arranged for retransforming one or more of the first control signal Ui and the at least one second adjusted control signal Uk by use of a quantity

retrans formation Qi_ _re before being used for controlling the first actuator and the at least one second actuator,

respectively . The object is also achieved by the above mentioned computer program and computer-readable medium.

By usage of the present invention, a structured method for achieving a wanted/required behaviour for the SIMO-regulated systems and/or actuators is provided, including well defined operational points for the regulated systems and/or actuators.

It is hereby possible to provide, and also to over time maintain, a specified/wanted ratio between regulators of a SIMO control system. A well-defined torque reserve may thus be determined, which may be used for providing a wanted/suitable compromise/trade-off between different parameters, such as between e.g. the fuel consumption and regulation possibilities for the number of revolutions for an engine.

The adjustments of the control signals Ui , Uk used for

controlling the at least two actuators are, according to the present invention, only performed if the regulation goal has been reached, i.e. if the regulation error ψ is smaller than an absolute threshold value | I , and if the at least two actuators are in a steady state condition. It is hereby secured that the regulation of the actuators is stable before the control signals are adjusted, which reduces the risk for regulation instability for the control system. It may be noted that before steady state has been reached, the at least two regulators for the at least two actuators individually and separately try to reach the regulation goal. Thus, the

regulation of the two or more actuators can then not be related to each other.

However, according to the present invention, when all the actuators have reached a steady state condition, the total regulation process is led by the regulation of the first actuator having the shortest response time β. In other words, when the steady state condition has been reached for the at least two actuators, the regulation of all of the first and at least one second actuators being commonly regulated is related to the regulation of the first actuator having the shortest response time β, such that the control signals Uk for all of the at least one second actuator are moved closer to the first control signal Ui of the first actuator.

When the first Ui and at least one second Uk control signals are closer together, e.g. closer toghether in amplitude, it is much easier to thereafter control the individual points of operation for the first and at least one second systems at the same time as the regulation goal is still fulfilled. Thus, the present invention creates possibilities for controlling the individual actuators to suitable/wanted operational points. Detailed exemplary embodiments and advantages of the method, control system, computer program and computer-readable medium according to the invention will now be described with

reference to the appended drawings illustrating some preferred embodiments . BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described in more detail with reference to attached drawings illustrating examples of embodiments of the invention in which:

Figure 1 schematically shows an exemplary vehicle in which the present invention may be implemented,

Figures 2a-b show flow chart diagrams for methods according to some embodiments of the present invention,

Figure 3 is a schematic block illustration of a control system according to some embodiments of the present invention, Figure 4 schematically illustrates a control unit/device according to some embodiments of the present invention, and

Figure 5 is an illustration of a non-limiting example of a use of an embodiment of the present invention. DETAILED DESCRIPTION OF INVENTION

Figure 1 schematically shows a heavy example vehicle 100, such as a truck, a bus or similar, which will be used to explain the present invention. The present invention is, however, not limited to use in heavy goods vehicles as the one shown in figure 1, but may also be used in lighter vehicles such as passenger cars, or even in non-vehicle implementations.

The vehicle 100, shown schematically in figure 1, comprises a pair of driving wheels 110, 111. The vehicle furthermore comprises a powertrain 130 with an engine 101, which may be a combustion engine working according to the Otto cycle, according to which an electric spark ignites a fuel and air mixture in the engine cylinders 134. The engine 101 may include an air input system 142 including at least one air actuator 132 controlled by an air control unit/means 122, an ignition system 141 including at least one ignition actuator 131 controlled by at least one ignition control unit/means 121, and a fuel system 143 including at least one fuel actuator 133 controlled by a fuel control unit/means 123 as described more in detail below. The air input system 142, the ignition system 141, and the fuel system 143 are schematically illustrated in figure 1.

Generally, the ignition system 141 has a relatively short response time βί ₉ η, which means that a change in an ignition control signal relatively quickly causes a change in the actual ignition of the mixture of fuel and air in the

cylinders of the engine. I.e., the time instant when the ignition spark occurs may be adjusted essentially instantaneously due to the short response time βign.

The air input system 142, however, has a relatively long response time β which is often considerably longer than the ignition response time βign. The air input system has to take into consideration how fast the fuel is injected into the cylinders 134 by the fuel system 143, which makes the response time β even longer since the injection of fuel may be slow in some applications, such as for port fuel injection (PFI) applications and/or for single point injection (SPI)

applications. Thus, the fuel injection may include delays caused by physical limitations and/or control system

construction limitations, and these delays add to the air response time β For engines having direct injection (DI) systems, the fuel related delays are often considerably shorter, but the air response time β is normally

considerably longer than the air response time β anyway.

Also, the air response time β may dynamically change due to a current point of operation for the vehicle, since the air response time β may depend on e.g. a number of revolutions for the engine, an ambient temperature and/or an ambient pressure. Thus, the air response time β is relatively long and may also vary considerably over time.

The engine 101 may, for example, in a customary fashion, via an output shaft 102 of the engine 101, be connected with a gearbox 103, via a clutch 106 and an input shaft 109 connected to the gearbox 103. An output shaft 107 from the gearbox 103, also known as a propeller shaft, drives the driving wheels 110, 111 via a final gear 108, such as e.g. a customary differential, and drive shafts 104, 105 connected with the final gear 108. The components of the powertrain have differing response times β. For example, the clutch system has a response time β οΐ^οΐι , the fuel system has another response time β the air

providing system has the above mentioned response time β ₃ ίΓ, and the ignition system has the above mentioned response time There may further be a large number of other response times β for other powertrain components and/or for other devices, components, parts or parameters in e.g. a vehicle, as is understood by a skilled person. First 120 and second 150 control devices are in figure 1 schematically illustrated as receiving signals and/or

providing control signals from and/or to the engine 101, the clutch 106, the gearbox 103, the ignition system/actuator 141/131, the air input system/actuator 142/132 and/or the fuel system/actuator 143/133. The first 120 and second 150 control devices may of course also be connected to more and/or other components of the vehicle. As described above and below, the second control device 150 may comprise means arranged for determining 151, i.e. a first determination unit 151, means arranged for identifying 152, i.e. an identification unit 152, means arranged for determining 153, i.e. a second

determination unit 153, means arranged for adjusting 154, i.e. an adjustment unit 154, and means arranged for utilizing 155, i.e. a utilization unit 155. The herein described control means/units/devices 120, 121, 122, 123, 150, 151, 152, 153, 154, 155 may be divided physically into more control

means/units/devices than the herein described second control means/units/devices/systems 120, 150.

Figure 2a shows a flow chart diagram for a method according to an embodiment of the present invention. The method relates to a control system 300 including means 121, 122 arranged for controlling at least two actuators 131, 132, activating at least two systems 141, 142 based on one reference value a and one measured value η such that a control error ψ is minimized. The means may here be control units, such that the system includes at least two control units 121, 122 arranged for controlling at least two actuators 131, 132, respectively, based on one reference value a and one measured value η such that a control error ψ is minimized. The at least two systems 141, 142 may have differing response times. An embodiment of the control system 300 is schematically illustrated in figure 3.

In a first step 210 of the method, it is determined if the at least two actuators 131, 132 are in a steady state condition, e.g. by use a herein described determination means/unit. This determination is described more in detail below. If the at least two actuators 131, 132 are not in a steady state condition, the method starts over again with the first step 210. If the at least two actuators 131, 132 are

determined to be in a steady state condition, a first actuator 131 of the at least two actuators 131, 132 is identified in a second step 220 of the method as having a shortest response time β of the at least two actuators 131, 132. The response time is in this document defined as the time period from a change being made in a control signal for a system 141, 142 until the change is effected in the system 141, 142. For the non-limiting example mentioned above, in which the ignition timing and the engine air input are commonly

controlled based on the single reference value, the ignition system 141 often has a much shorter response time β ign than the response time for engine air input system 142. Thus, the ignition actuator 131 would then in the second step 220 be identified as having a shortest response time β ign of the two response times β ign , β ₃ ίΓ.

Then, it is determined in a third step 230 of the method at least one difference i between a first control signal Ui used for controlling the first actuator 131 and at least one second control signal Uk used for controlling at least one second actuator 132 of the at least two actuators, respectively.

Thus, one or more of the differences i are here determined between the control signal Ui, of the fastest control

system/actuator 141/131 and the control signals Uk of the rest of the control systems /actuators 142/132 being commonly regulated .

Hereafter, and in this document, the at least one difference k is for pedagogical reasons often described as at least one amplitude difference μι . However, the at least one differencei may of course be essentially any other suitable difference value, such as e.g. a mean value difference, a top value difference, or another difference value.

In the example of figure 3, a second amplitude differences μ2 is determined between the control signal Ui of the fastest control system/actuator 141/131 and the control signals U2 of the second control system/actuator 142/132. According to an embodiment of the present invention, the determination 230 of the at least one amplitude difference i includes filtering, such as lowpass filtering, of one or more of the first control signal Ui and the at least one second control signal Uk before the at least one amplitude difference i is determined, which is advantageous since it reduces the risk for instability caused by possible regulation of a slow control

system/actuator with a fast changing control signal. In a fourth step 240 of the method, amplitude differences μι _< determined in the third step 230 for each one of the one or more second actuators 132 are added to the at least one second control signal Uk , respectively. Hereby, the at least one second control signal Uk is adjusted in amplitude; Uk = Uk + k . In the example illustrated in figure 3, this results in U2 = U2 + μ2. The at least one adjusted second control signal Uk is hereby moved closer in amplitude to the first control signal Ui , such that the at least one adjusted second control signal Uk is tilted in amplitude towards the first control signal Ui , respectively .

In a fifth step 250 of the method, the first 131 and at least one second 132 actuators are controlled by utilizing the first control signal Ui for controlling the first actuator 131, and by utilizing the at least one second adjusted control signal Uk for controlling the at least one second actuator 132,

respectively .

By usage of the present invention, a structured method for achieving a wanted/required behaviour for the regulated

systems 141, 142 and/or actuators 131, 132 is provided. Also, well defined operational points for the regulated systems 141, 142 and/or actuators 131, 132 are provided by the method. This is very advantageous for a SIMO regulation system, in which a specified ratio between regulators should preferably be provided and maintained over time.

For example, a regulation of the revolutions per minute for an engine 101 working according to the Otto-cycle may, when the present invention is utilized, have a well defined torque reserve, such that a wanted/suitable compromise/trade-off between fuel consumption and a regulation range for the number of revolutions is achieved. According to an embodiment of the present invention, also schematically illustrated in figure 3, at least one offset Ui_ _op , Uk_op related to at least one operating point is added to one or more of the first control signal Ui and the at least one second adjusted control signal Uk. Hereby, one or more of a first offset control signal; Ui_ ₀ ffset = Ui + Ui_ ₀ p; and at least one second offset control signal; Uk_offset = Uk + Uk_op," are created. In the example illustrated in figure 3, a first offset control signal is created; Ui_ ₀ ffset = Ui + Ui_ ₀ p in a first offset adding circuit 311; and a second offset control signal is created; U2_offset = U2 + U2_op in a second offset adding circuit 312. The offset Ui_ _op added to the first control signal Ui is, according to an embodiment, equal to zero, i.e. Ui_ ₀ ffset = Ui. Then, the created first offset control signal Ui_ ₀ ffset is used for controlling the first actuator 131, and/or the at least one second offset control signal Uk is used for controlling the at least one second actuator 132, respectively, as illustrated in figure 3. Hereby, a required/wanted ratio between the first 121 and at least one second 122 control units/regulators, and thus also between their corresponding actuators 131, 132, is created, which also means that a torque reserve is well defined. The ratio/torque reserve may, when the embodiment is utilised, be well defined in essentially each relevant

operational point for the first 141 and at least one second 142 systems. As a non-limiting example, a first offset Ui_ _op and/or the at least one second offset U2_op may be approximately 5% of a maximal torque, i.e. the MBT-ignition torque, e.g. 50 Nm at a maximal torque of 1000 Nm, for achieving a number of revolution regulation stability and wanted fuel consumption.

Correspondingly, the first offset Ui_ ₀ p and/or the at least one second offset U2_op may be approximately 15% of a maximal torque, e.g. 150 Nm at a maximal torque of 1000 Nm, for

heating one or more catalysts.

According to an embodiment of the present invention, the at least one amplitude difference i is scaled by a scaling factor cpk before being used for adjusting the at least one second control signal Uk 240. The scaling factor cpk may have a chosen calibration value, for example 0.1-1%, depending e.g. on a time resolution of the control system, which system being regulated, and how fast a desired operation point should be reached. The creation of the at least one second adjusted control signal Uk is then achieved by adding the scaled at least one amplitude difference to the at least one second control signal Uk , respectively; Uk = Uk + k* pk . In the example of figure 3, the second control signal U2 is adjusted by adding a scaled second amplitude difference to it; U2 = U2 + 2 * ψ2 . The scaling factor cpk defines how fast the at least one adjusted second control signal Uk converges with the first control signal Ui .

Thus, the scaling factor cpk indicates a percentage of the amplitude difference k which is to be transferred to the slower regulator 122. Hereby, the amplitude difference i

transfer to the slower regulator 122 is ramped in such that a larger transferred amplitude step in the at least one second control signal U2 is prevented, which secures regulation stability. The fastest regulator 121 is continuously

regulating, also when the regulation goal and the steady state has been reached. To ramp the difference i being transferred to the slower regulator 122 reduces the risk for instability for the slower regulator 122, since the transfer of the

possibly fast altering amplitude of the first control signal Ui is ramped/slowed down. According to an embodiment of the present invention, the first 121 and at least one second 122 control units include a first and at least one second PID-regulator , respectively. Here, the determined at least one amplitude difference i is added to at least one second integral term signal Uk_i used by the at least one second PID-regulator of the at least one second control unit 122 arranged for controlling the at least one second actuator 132. At least one second adjusted integral term signal Uk_i; Uk_i = Uk_i + k is then created to be used by the second PID-regulator 122 for controlling the at least one second actuator 132. Hereby, the at least one adjusted second control signal Uk is forced to converge with the first control signal Ui . Thus, the least one adjusted second control signal Uk and the first control signal Ui are moved closer together in amplitude by the altered/adjusted integral term.

A PID-regulator may be described as generating the control signal Uk as Uk = Uk_p + Uk_i + Uk_d, where Uk_p is a control signal related to present error values, Uk_i is a control signal related to past /integrated values and Uk_d is a control signal related to possible future trends. An adjustment of the integral term signal Uk_i thus results in an adjustment of the at least one second control signal Uk. The integral term signal Uk_i may include an integral term Ik and an amplification factor Pk_i; Uk_i = Pk_i * Ik,- wherefore the adjustment of the integral term signal Uk_i may also be written as: Uk_i = Pk_i * Ik.

As mentioned above, according to an embodiment, the at least one amplitude difference i may be scaled by a scaling factor cpk before adjusting the at least one second integral term signal Uk_i . Thus, the at least one scaled amplitude difference is here added to the at least one second integral term signal Uk_i, respectively; Uk_i = Uk_i + k*pk. The scaling factor cpk sets how fast the at least one adjusted second control signal Uk and the first control signal Ui converge. As stated above, the second 220, the third 230, the fourth 240 and the fifth 250 steps of the method shown in figure 2a are only performed if the at least two actuators 131, 132 are in a steady state condition, i.e. if all of the at least two actuators 131, 132 are in a steady state condition at the same time. According to an embodiment of the present invention, illustrated in figure 2b, the determination 210 of if a steady state condition is present includes the first step 211 of determining if the control error ψ is smaller than an absolute threshold value | | ; ψ ≤ | I ; where the absolute threshold value | ε| may depend on the one or more systems and/or

processes being regulated. The control error ψ may e.g. be determined in a difference circuit 310 illustrated in figure 3 as a difference between the reference value a and the

measured/output value . As a non-limiting example, the absolute threshold value | ε I may be 3% of the reference value a, i.e. the control error ψ is smaller than 3% of the

reference value a.

In a second step 212, it is determined if the first control signal Ui is within a controllable interval for the first actuator 131; Ui ≤ | θι | . The controllable first interval | θι | may here be related to saturation points/intervals for the first actuator 131 and/or for the first control unit 121. The first actuator 131 may here at least partly continuously monitor and/or adapt its controllable first interval | θι | such that a risk for wind-up of the first regulator/control unit 121 is reduced. Then, in a third step 213, it is determined if the at least one second control signal Uk is within at least one second controllable interval for the at least one second actuator 132, respectively; Uk ≤ 6k . The at least one second

controllable interval | 6k may here be related to saturation points/intervals for the at least one second actuator 132 and/or for the at least one second control unit 122. The at least one second actuator 132 may here at least partly

continuously monitor and/or adapt its controllable at least one second controllable interval | 6k such that a risk for wind-up of the second regulator /control unit 122 is reduced.

Further, according to an embodiment, the determination 210 of if all of the at least two actuators 131, 132 are in a steady state condition at the same time also includes starting 214 a timer ω in a fourth step when:

- the control error ψ is smaller than the absolute threshold value |

- the first control signal Ui is within the controllable interval for the first actuator 131; Ui ≤ | ; and

- the at least one second control signal Uk is within the at least one second controllable interval for the at least one second actuator 132, respectively; Uk ≤ 6k

Then, it is in a fifth step 215 determined that the at least two actuators 131, 132 are in a steady state condition when the timer ω reaches a timer threshold value λ; ω ≥ λ. The stability time period defined by the timer threshold value λ may depend of the one or more systems and/or processes to be regulated. As a non-limiting example, the timer threshold value λ may have a value of 1 second. The first control signal Ui and the at least one second control signal Uk may initially have the same quantity, for example a number of revolutions rpm signal or a current value. If differing actuators / systems are to be controlled, i.e. if the actuators / systems are controlled using control signals of differing quantities, the first control signal Ui and/or the at least one second adjusted control signal Uk may, according to an embodiment, be transformed by a quantity transformation Ω± before being used for controlling the first actuator 131 and the at least one second actuator 132. Often, both of the first control signal Ui and the at least one second adjusted control signal Uk are transformed by a quantity transformation Ω± before being used for controlling the first actuator 131 and the at least one second actuator 132. Hereby, the actually used control signals have a quantity matching each respective actuator/system . For the embodiments described above where a first offset control signal; Ui_ ₀ ffset = Ui + Ui_ _op ; and at least one second offset control signal; Uk_offset = Uk + Uk_op ," are used for controlling the first 131 and/or the at least one second 132 actuator, the first offset control signal Ui_ ₀ ffset and/or the at least one second offset control signal Uk_offset may be transformed by the quantity transformation Ω± correspondingly, as schematically illustrated in figure 3 for two actuators 131, 132. According to an embodiment of the present invention, the first and second quantity transformations Ω± used for controlling the first actuator 131 and the at least one second actuator 132 are identical.

Sometimes, however, the first control signal Ui and the at least one second control signal Uk may initially have differing quantities, i.e. the input signals Ui , Uk may have differing quantities. According to an embodiment, the first control signal Ui and/or the at least one second control signal Uk may then be transformed by a quantity transformation Ω± before the determination 230 of the at least one amplitude difference μ± between the first control signal Ui the at least one second control signal Uk, such that the same quantities are compared when the at least one amplitude difference μ± is determined.

Then, the first control signal Ui and/or the at least one second adjusted control signal Uk may be retransformed by a quantity retransformation Qi_ _re before being used for

controlling the first actuator 131 and the at least one second actuator 132, respectively. Hereby, the actually used control signals have a quantity matching the respective actuator. For the embodiments described above where a first offset control signal; Ui_ ₀ ffset = Ui + Ui_ ₀ p; and at least one second offset control signal; Uk_offset = Uk + Uk_op," are used for controlling the first 131 and/or the at least one second 132 actuator, the first offset control signal Ui_ ₀ ffset and/or the at least one second offset control signal Uk_offset may be retransformed by the quantity retransformation Qi_ _re correspondingly.

The person skilled in the art will appreciate that a method for a control system according to the present invention can also be implemented in a computer program, which, when it is executed in a computer, instructs the computer to execute the method. The computer program is usually constituted by a computer program product 403 stored on a non-transitory/nonvolatile digital storage medium, in which the computer program is incorporated in the computer-readable medium of the

computer program product. The computer-readable medium

comprises a suitable memory, such as, for example: ROM (Read- Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable PROM) , Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc. Figure 4 shows in schematic representation a control

unit/system 400/120/150/300. The control unit/system 400/120/150/300 comprises a computing unit 401, which may be constituted by essentially any suitable type of processor or microcomputer, for example a circuit for digital signal processing (Digital Signal Processor, DSP), or a circuit having a predetermined specific function (Application Specific Integrated Circuit, ASIC) . The computing unit 401 is connected to a memory unit 402 arranged in the control unit/system

400/120/150/300, which memory unit provides the computing unit 401 with, for example, the stored program code and/or the stored data which the computing unit 401 requires to be able to perform computations. The computing unit 401 is also arranged to store partial or final results of computations in the memory unit 402.

In addition, the control unit/system 400/120/150/300 is provided with devices 411, 412, 413, 414 for receiving and transmitting input and output signals. These input and output signals can contain waveforms, impulses, or other attributes which, by the devices 411, 413 for the reception of input signals, can be detected as information and can be converted into signals which can be processed by the computing unit 401. These signals are then made available to the computing unit 401. The devices 412, 414 for the transmission of output signals are arranged to convert signals received from the computing unit 401 in order to create output signals by, for example, modulating the signals, which can be transmitted to other parts of and/or systems in the vehicle.

Each of the herein described/ shown connections to the devices for receiving and transmitting input and output signals can be constituted by one or more of a cable; a data bus, such as a CAN bus

(Controller Area Network bus), a MOST bus (Media Orientated Systems Transport bus), or some other bus configuration; or by a wireless connection. A person skilled in the art will appreciate that the above-stated computer can be constituted by the computing unit 401 and that the above- stated memory can be constituted by the memory unit 402. Control systems in modern vehicles commonly comprise

communication bus systems including one or more

communication buses for linking a number of electronic control units (ECU's), or controllers, and various components located on the vehicle. Such a control system may comprise a large number of control units and the responsibility for a specific function can be divided amongst more than one control unit. Vehicles of the shown type thus often comprise significantly more control units than are shown in figures 1, 3 and 4, which is well known to the person skilled in the art within this technical field.

In the shown embodiment, the present invention and the control devices /units /means 120, 150 may be implemented in the control unit/system 400/300. The invention can also, however, be implemented wholly or partially in one or more other control units already present in the vehicle, or in some control unit dedicated to the present invention.

Here and in this document, units are often described as being arranged for performing steps of the method according to the invention. This also includes that the units are designed to and/or configured to perform these method steps.

The at least one control device/system 150 is in figure 1 illustrated as including separately illustrated units/means 151, 152, 153, 154, 155. Also, control system 300 may include the engine control device/system 120, which may include a number of units 121, 122, 123, as described above. The control system 300. These means/units/devices/systems 150, 151, 152, 153, 154, 155, 120, 121, 122, 123, 130 may, however be at least to some extent logically separated but implemented in the same physical unit/device. These

means/units/devices/systems 150, 151, 152, 153, 154, 155, 120, 121, 122, 123, 130 may also be part of a single logic unit which is implemented in at least two different physical units/devices. These means/units/devices 150, 151, 152, 153,

154, 155, 120, 121, 122, 123, 130 may also be at least to some extent logically separated and implemented in at least two different physical means/units/devices. Further, these

means/units/devices 150, 151, 152, 153, 154, 155, 120, 121, 122, 123, 130 may be both logically and physically arranged together, i.e. be part of a single logic unit which is

implemented in a single physical means/unit /device . These means/units/devices/systems 150, 151, 152, 153, 154, 155, 120, 121, 122, 123, 300 may for example correspond to groups of instructions, which can be in the form of programming code, that are input into, and are utilized by at least one

processor when the units are active and/or are utilized for performing its method step, respectively.

It should be noted that the control system 300 may be

implemented at least partly within the vehicle 100 and/or at least partly outside of the vehicle 100, e.g. in a server, computer, processor or the like located separately from the vehicle 100.

As mentioned above, the means/units 151, 152, 153, 154, 155 described above correspond to the claimed means 151, 152, 153, 154, 155 arranged for performing the embodiments of the present invention, and the present invention as such. According to an aspect of the present invention, a control system 300 is presented. The control system 300 includes, as described above, means, e.g. at least two control means/units 121, 122, arranged for controlling at least two actuators 131, 132, respectively, based on one single reference value a and one single measured value η such that a control error ψ is minimized.

The control system 300 includes a first determination

unit/means 151, arranged for determining 210 if the at least two actuators 131, 132 are in a steady state condition. The first determination unit/means 151 is here arranged for performing the above described embodiments related to the determination e.g. of if a steady state condition is reached or not for all of the at least two actuators 131, 132 at one time instant .

If the at least two actuators 131, 132 are determined to be in the steady state condition, the control system 300 is arranged for activating:

- an identification unit/means 152, arranged for identifying 220 a first actuator 131 included in the at least two actuators 131, 132, the first actuator having a shortest response time β;

- a second determination unit/means 153, arranged for determining 230 at least one difference μι _< between a first control signal Ui used for controlling the identified first actuator 131 and at least one second control signal Uk used for controlling at least one second actuator 132 of the at least two actuators 131, 132, respectively;

- an adjustment unit/means 154, arranged for adjusting 240 the at least one second adjusted control signal Uk by adding the determined at least one difference i to the at least one second control signal Uk , respectively, Uk = Uk + μι; such that the at least one adjusted second control signal Uk converges in with the first control signal Ui , respectively; and

- a utilization unit/means 155, arranged for utilizing 250 the first control signal Ui for controlling the first actuator 131, and the at least one second adjusted control signal Uk for controlling the at least one second actuator 132, respectively.

The system according to the present invention can be arranged for performing all of the above, in the claims, and in the herein described embodiments method steps. The system is hereby provided with the above described advantages for each respective embodiment.

A skilled person also realizes that the above described system may be modified according to the different embodiments of the method of the present invention. The present invention is also related to a vehicle 100, such as a truck, a bus or a car, including the herein described control system.

Figures 5a-d shows the principles of the present invention by illustrations of a non-limiting example according to an embodiment of the present invention. Figure 5a shows a non-limiting example of a first control signal Ui (dashed line) used for controlling the identified first faster actuator 131 and a second control signal U2 (dot- dashed line) used for controlling a slower second actuator 132. Both the first Ui and second U2 control signals are determined based on one single reference value a and one single measured value η such that a control error ψ

(determined in the difference circuit 310) is minimized, as explained above. Figure 5a also shows the control error signal ψ ( solid line ) . It is in this example assumed that the first control signal Ui is within the controllable interval for the first actuator 131; Ui ≤ ; and that the second control signal Uk is within the second controllable interval for the second actuator 132; Uk ≤ 6k , as explained above.

The control system 300 is then arranged for determining 210 if the first 131 and second 132 actuators are in a steady state condition. A timer ω is for this reason started 214 when the control error ψ is smaller than the absolute threshold value ; ψ ≤ |ε|, i.e. when the control error ψ is within the interval -ε < ψ < ε, as illustrated in figures 5a and 5b. At the first ti point in time, the control error is within the interval; ψ ≤ |ε|; and the timer starts to run/increment. But in the second time point t2, the control error fall out of the interval; ψ > |ε|; and the timer ω stops and resets. At the third time instant t _3f the control error is within the interval again; ψ < |ε|; and the timer ω starts to run/increment once more. At the fourth time point t , the timer ω reaches the timer threshold value λ; ω ≥ λ, and the it is determined that a steady state condition has been reached.

Therefore, i.e. since the steady state condition has been reached, the first actuator 131 is identified as having a shortest response time β. Then, a second amplitude difference μ2 is determined between the first control signal Ui and the second control signal U2, which is illustrated in figure 5c.

Figure 5d illustrates the above mentioned scaled second amplitude difference μ2*ψ2, which is added to the second control signal in order to create the second adjusted control signal U2 shown in figure 5a; U2 = U2 + 2*ψ2. The second adjusted control signal U2 (dot-dashed line) is thus during steady state conditions, i.e. after the fourth time point t4, constantly updated/adjusted by the addition of the scaled second amplitude difference μ2*φ2,- U2 = U2 + μ2*φ2. After the fourth time point t4, and due to this update/adjustment of the second control signal U2, the second adjusted control signal U2 is converged/tilted towards the first control signal Ui by use of the scaled second amplitude difference μ2*φ2,- U2 = U2 + μ2*φ2. The second scaling factor φ2 smooths the converging of the first control signal Ui and the second adjusted control signal U2. The first control signal Ui and the second adjusted control signal U2 meet / intersect in a fifth time point ts.

A second offset control signal; U2_ _. offset ^— u ₂ + u ₂ __adj_op (dubble- dot-dashed) is then created by adding a second offset U2_op to the second adjusted control signal U2.

The first control signal Ui is then used for controlling the first actuator 131, and the second offset control signal

U2_offset is used for controlling the second actuator 132.

As at mentioned above, the inventive method, and embodiments thereof, as described above, may at least in part be performed with/using/by at least one device. The inventive method, and embodiments thereof, as described above, may be performed at least in part with/using/by at least one device that is suitable and/or adapted for performing at least parts of the inventive method and/or embodiments thereof. A device that is suitable and/or adapted for performing at least parts of the inventive method and/or embodiments thereof may be one, or several, of a control unit, an electronic control unit (ECU) , an electronic circuit, a computer, a computing unit and/or a processing unit.

With reference to the above, the inventive method, and

embodiments thereof, as described above, may be referred to as an, at least in part, computerised method. Said method being, at least in part, computerised meaning that it is performed at least in part with/using/by said at least one device that is suitable and/or adapted for performing at least parts of the inventive method and/or embodiments thereof.

With reference to the above, the inventive method, and

embodiments thereof, as described above, may be referred to as an, at least in part, automated method. Said method being, at least in part, automated meaning that it is performed

with/using/by said at least one device that is suitable and/or adapted for performing at least parts of the inventive method and/or embodiments thereof.

The present invention is not limited to the above described embodiments. Instead, the present invention relates to, and encompasses all different embodiments being included within the scope of the independent claims.