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Title:
METHOD AND SYSTEM FOR MEASURING THE TRUE SPEED OF A VEHICLE
Document Type and Number:
WIPO Patent Application WO/2019/197929
Kind Code:
A1
Abstract:
A method (100) for measuring a real advancing speed (V) on a deformable surface (S) of a vehicle (10). The vehicle (10) is equipped with an idle wheel (11) rolling on the deformable surface (S). The method comprises measuring (110) a height (H) of a rotation axis (O) of the idle wheel (11) with respect to an undeformed portion (S1) of the deformable surface (S) not deformed by the rolling of the idle wheel (11), and determining (120) the real advancing speed (V) of the vehicle based on the height (H) determined. The method comprises determining the angular speed and the effective rolling radius of the idle wheel. The effective rolling radius is calculated as a function of the maximum radius, corresponding to the radius of the undeformed idle wheel, the load radius, corresponding to the radius of the wheel deformed by a load, and the height (H).

Inventors:
BENASSI, Claudio (1/A Via Pezzetta, Mirandola, Mirandola, I-41037, IT)
Application Number:
IB2019/052439
Publication Date:
October 17, 2019
Filing Date:
March 26, 2019
Export Citation:
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Assignee:
ARBOS GROUP S.P.A. (3 Via Canale, Frazione: Migliarina, Carpi, 41012, IT)
International Classes:
G01P3/50
Domestic Patent References:
WO2004090473A12004-10-21
Foreign References:
US7428455B22008-09-23
Other References:
ROLAND JAKOBS ET AL: "Matlab/Simulink Module AS 2 TM User's Guide - UserGuide.pdf", AESCO SOFT SOIL TYRA MODEL, 14 July 2005 (2005-07-14), XP055100099, Retrieved from the Internet [retrieved on 20140204]
Attorney, Agent or Firm:
ING. C. CORRADINI & C. S.R.L. (4 Via Dante Alighieri, Reggio Emilia, Reggio Emilia, I-42121, IT)
Download PDF:
Claims:
CLAIMS

1. A method (100) for measuring a real advancing speed (V) on a deformable surface (S) of a vehicle (10) equipped with an idle wheel (11) rolling on the deformable surface (S), wherein the method comprises:

a) measuring (110) a height (H) of a rotation axis (O) of the idle wheel (11) with respect to an undeformed portion (Si) of the deformable surface not deformed by the rolling of the idle wheel (11), and

b) determining (120) the real advancing speed (V) of the vehicle

(10) based on the height (H) determined.

2. The method (100) according to claim 1, wherein determining b) the real advancing speed (V) comprises:

b1) measuring (130) a value of an angular speed (w) of the idle wheel

(11);

b2) determining (140) a value of an effective rolling radius (Reft) of the idle wheel (11); and

b3) calculating (150) the real advancing speed (V) as the product of a value of an effective rolling radius (Reft) of the idle wheel (11) and a value of an angular speed (w) of the idle wheel (11).

3. The method (100) according to claim 2, wherein the value of an effective rolling radius (Reft) of the idle wheel (11) is calculated as a function of a value of a maximum radius (Rw) of the idle wheel (11), corresponding to a value of the radius of the undeformed idle wheel (11), of a value of a load radius (Ri) of the idle wheel (11), corresponding to a value of the radius of the idle wheel (11) when deformed by means of a load bearing down on the idle wheel (11), and the height (H) determined.

4. The method (100) according to claim 3, wherein the value of the effective rolling radius (Reft) of the idle wheel (11) is calculated through the following formula:

¾ = 2a2 + 08 -ay,

wherein Reft is the effective rolling radius (Reft) of the idle wheel (11), a is calculated as:

and b is calculated as:

wherein Rw is the maximum radius (Rw) of the idle wheel (1 1 ), Ri is the load radius (Ri) of the idle wheel (1 1 ), and H is the height (H) determined.

5. The method (100) according to claim 3, wherein the value of the load radius (Ri) of the idle wheel (O) is determined as a function of the value of the maximum radius (Rw) of the idle wheel (O), of a value of a load (/.) bearing down on the idle wheel (O) and of a rigidity value (K) of the idle wheel (O).

6. The method (100) according to claim 5, wherein the rigidity value (K) of the idle wheel (O) is calculated as a function of an inflation pressure (P) of the idle wheel (O).

7. A vehicle (10) comprising:

- an idle wheel (1 1 ) rolling on a deformable surface (S),

- a sensor (17) configured to measure a height (H) of a rotation axis (O) of the idle wheel (1 1 ) with respect to an undeformed portion (Si) of the deformable surface (S), not deformed by the rolling of the idle wheel (1 1 ), and

- an electronic control unit (13) operatively connected to the sensor (17) and configured to implement the method (100) according to one of the previous claims.

8. The vehicle (10) according to claim 7, wherein the sensor (17) is a distance sensor arranged in a position in front of the idle wheel (1 1 ) in an advancing direction (W) thereof on the deformable surface (S).

9. The vehicle (10) according to claim 8, wherein the sensor (17) comprises one among:

an ultrasound sensor;

a mechanical sensor, and

an optical sensor.

10. The vehicle (10) according to claim 9, further comprising an angular speed sensor (15) operatively coupled with the idle wheel (11 ).

11. The vehicle (10) according to claim 10, wherein the idle wheel (1 1 ) is connected to a support frame (19) hauled by a tractor (20).

Description:
METHOD AND SYSTEM FOR MEASURING THE TRUE SPEED OF A VEHICLE

TECHNICAL FIELD

The present invention concerns the field of vehicles, preferably farming vehicles. More specifically, embodiments of the present invention concern a method and a relative system for measuring the real speed of a vehicle.

PRIOR ART

In the field of vehicles there is a need to precisely determine the real speed thereof, both in the case of vehicles equipped with traction and in the case of driven vehicles, i.e. hauled/trailer or pushed vehicles. Such a requirement is particularly great in the field of work vehicles - like in the field of farming or construction vehicles.

For example, during the working of a field (for example during seeding, irrigation, fertilisation, watering or other work) by means of suitable machinery or equipment driven or hauled by a tractor - like a seeder or similar working/product dispensing device - it is very important to know the actual advancing speed of the driven machinery during the work to evaluate the work efficiency thereof and the accuracy/precision of work, for example of deposition of the seeds and of the dispensed product.

Indeed, the speed detected by the speedometer of the vehicle is not always accurate and suffers from an error due to the inevitable sliding of the wheels on the ground, which on slippery or deformable ground is far from negligible. In order to solve this problem, in the field apparatuses for detecting the speed based on satellite positioning systems, like the GPS or GLONASS system, and/or on radar, are implemented.

Apparatuses based on satellite positioning systems provide a very precise detection of the speed, but they are negatively impacted by sources of electromagnetic radiation like power lines, airports, hospitals, radio stations, etc., as well as atmospheric conditions with high humidity value like rain, fog, etc., and have areas not reached by the satellite service that, therefore, make the positioning system ineffective. Moreover, the apparatuses based on satellite positioning systems are distinguished by high complexity and production costs.

Apparatuses based on radar systems are capable of detecting the actual speed of the machinery with precision. However, radar detections can be offset by bodies projecting from the ground. For example, stalks and stumps of harvests can cause errors in the detection of distances through radar and, consequently, lead to incorrect evaluations of the actual speed.

A purpose of the present invention is to overcome the aforementioned drawbacks of the prior art, in a simple, rational and low-cost solution.

A further purpose of the present invention is to provide a reliable measurement of the real speed of an idle wheel of a vehicle, in particular, on deformable ground.

Such purposes are accomplished by the characteristics of the invention given in the independent claim. The dependent claims outline preferred and/or particularly advantageous aspects of the invention.

SUMMARY OF THE INVENTION

The invention, particularly, provides a method for measuring a real advancing speed on a deformable surface of a vehicle. The vehicle is equipped with an idle wheel rolling on the deformable surface. The method comprises measuring a height of a rotation axis of the idle wheel with respect to an undeformed portion of the deformable surface, not deformed by the rolling of the idle wheel, and determining the real advancing speed of the vehicle based on the height determined.

Thanks to such a solution, it is possible to determine the real speed of a vehicle in a simple but, at the same time accurate manner. Moreover, the measurement of the height of a rotation axis of the idle wheel with respect to an undeformed portion of the deformable surface makes it possible to measure the real speed of the vehicle accurately despite the variability introduced by the deformable surface.

In an embodiment, the undeformed portion of the deformable surface can be an area of the deformable surface arranged upstream of the idle wheel in an advancing direction of the idle wheel on the deformable surface itself, upstream of the groove caused by the idle wheel in rolling support on the deformable surface.

In this way, the height of the rotation axis of the idle wheel with respect to the undeformed portion is measured on a portion of deformable surface arranged on the path that the idle wheel must tackle. This makes it possible to obtain an even more accurate measurement of the real speed.

In an alternative embodiment, the undeformed portion of the deformable surface can be an area of the deformable surface arranged to the (right or left) side of the idle wheel with respect to the advancing direction of the idle wheel on the deformable surface itself, i.e. to the side of the groove caused by the idle wheel in rolling support on the deformable surface.

In an embodiment, determining the real advancing speed can comprise measuring a value of an angular speed of the idle wheel; determining a value of an effective rolling radius of the idle wheel, and calculating the real advancing speed as the product of a value of an effective rolling radius of the idle wheel and a value of an angular speed of the idle wheel.

Thanks to such a solution it is possible to measure the real speed of the vehicle in a particularly simple manner. In detail, the real speed can be determined accurately by acquiring only two physical magnitudes with simple and reliable detection systems operating with precision in any area of use of the vehicle.

In an embodiment, the value of an effective rolling radius of the idle wheel can be calculated as a function of a value of a maximum radius of the idle wheel, corresponding to a value of the radius of the undeformed idle wheel, of a value of a load radius of the idle wheel, corresponding to a value of the radius of the idle wheel when deformed by means of a load bearing down on the idle wheel, and the height determined.

In this way, the effective radius is measured in a simple and effective manner based on known or easy-to-determine physical magnitudes.

In an embodiment, the value of the effective rolling radius of the idle wheel can be calculated through the following formula:

R e „ = y Tw ~ sp

wherein Reft is the effective rolling radius of the idle wheel, a is calculated as:

where Rw is the maximum radius of the idle wheel, Ri is the load radius of the idle wheel, and H is the height determined, and b is calculated as:

Thanks to such a solution the effective radius is easy to calculate, in particular, through one or more automated procedures. Moreover, the calculation of the effective radius can be implemented by an electronic processor with an extremely low calculation power.

In an embodiment, the value of the load radius of the idle wheel can be determined as a function of the value of the maximum radius of the idle wheel, of a value of a load bearing down on the idle wheel and of a rigidity value of the idle wheel.

In this way, the value of the load radius can be determined simply based on known physical magnitudes and/or easily detectable parameters of the vehicle.

In an embodiment, the rigidity value of the idle wheel can be calculated as a function of an inflation pressure of the idle wheel.

Thanks to such a solution, the value of the load radius is obtained with greater accuracy, in particular, as a function of the configuration condition of the idle wheel of the vehicle.

A further aspect of the invention provides a vehicle comprising an idle wheel rolling on a deformable surface, a sensor configured to measure a height of a rotation axis of the idle wheel with respect to an undeformed portion of the deformable surface, not deformed by the rolling of the idle wheel, and an electronic control unit operatively connected to the sensor and configured to implement the method as described above.

Thanks to such a solution a vehicle is provided that is capable of accurately evaluating its real speed, even in the case in which it is hauled by another vehicle.

The sensor can be a distance sensor arranged in a position in front of the idle wheel in the advancing direction thereof on the deformable surface.

In this way, the vehicle is capable of measuring an operative distance from the ground to be tackled along the path of the vehicle.

In an embodiment, the sensor can comprise (or consist of) one among: an ultrasound sensor; a mechanical sensor; and an optical sensor.

Thanks to such a solution, the measurement of the distance can be implemented accurately and, at the same time, cost-effectively.

In an embodiment, the vehicle can further comprise an angular speed sensor operatively coupled with the idle wheel.

In this way it is easily possible to obtain a measurement of the angular speed of the idle wheel about its rotation axis. Moreover, it is possible to determine the real speed with an extremely small minimum number of sensors (two sensors).

In an embodiment, the idle wheel can be connected to a support frame hauled by a tractor (or hauling engine or vehicle).

In this way the idle wheel supports a vehicle of the driven type, and it is thus possible to measure the real speed of the driven vehicle (and consequently of the hauling vehicle) regardless of the tractor to which it is connected.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will become clear from reading the following description provided as an example and not for limiting purposes, with the help of the figures illustrated in the attached tables.

Figure 1 is a schematised view of a work group comprising a first vehicle hauled by a second vehicle according to an embodiment of the present invention.

Figures 2A and 2B are schematised views of a portion of the first vehicle of Figure 1 in which the position of a distance sensor is highlighted.

Figure 3 is a schematised view of an idle wheel of the first vehicle of figure 1 rolling on a deformable surface.

Figure 4 is a basic block diagram of a method for measuring the real speed of the first vehicle of Figure 1. BEST EMBODIMENT OF THE INVENTION

With particular reference to such figures, reference numeral 1 globally indicates a work group comprising a first vehicle, for example a machine 10 (or tool), for example for farming, which is for example driven (i.e. not motorised), and a second vehicle (motorised), for example a tractor 20, connected to one another (rigidly or in any case advancing as a unit). For example, the machine 10 comprises a plough, a harrow, a seeder, a sprayer of liquid or solid substances (like a muck-spreading apparatus or a herbicide/insecticide spreading apparatus or similar), an irrigator or another similar machine. The tractor 20 and the machine 10 are connected together by a connection element 30 (inextensible, i.e. such that the advancing speed of the tractor 20 is equal to the advancing speed of the machine 10).

In the embodiment considered, the machine 10 is hauled by the tractor 20 (and has the same advancing speed of the tractor itself, in practice the machine 10 and the tractor 20 translation as a unit with each other).

The machine 10 comprises an idle wheel 1 1 for resting on the ground (or more generically a deformable surface S on which the idle wheel 1 1 rests, rolling without sliding).

The term deformable surface S is meant to indicate any support surface, like the ground, which has a certain deformability (by compression) in the vertical direction, wherein for example the idle wheel 1 1 , in the weight form of a load bearing down on it, sinks deforming the deformable surface S itself and creating, therefore, a groove that receives (in a close-fitting manner) the idle wheel 1 1 itself.

The groove made by the idle wheel 1 1 on the deformable surface S, for example, extends axially along an advancing direction W of the machine 10 (as imparted by the tractor 20) on the deformable surface S itself.

The deformable surface S can for example be a field for farming use, for example but not for limiting purpose previously ploughed or worked.

The term idle wheel 1 1 is meant to indicate a wheel free to rotate (idly) around a central axis thereof without any drive torque or any brake torque being applied to it. The idle wheel 1 1 is rotatably connected (freely) to a support frame 19 of the machine 10 about a rotation axis O. The idle wheel 1 1 comprises, preferably, a rim and a tyre (inflatable and, therefore, also deformable).

In the embodiments of the present invention, the machine 10 also comprises a sensor suitable for providing an indication of a distance between the rotation axis O of the idle wheel 1 1 and a deformable surface S (ground) on which the idle wheel 1 1 rests. For example, the machine 10 comprises a distance sensor 17 suitable for providing an electric signal corresponding to the measurement of a distance from the ground S.

In addition, the machine 10 (or the tractor 20) can comprise an electronic control unit, or ECU 13. The machine 10 can comprise an angular speed sensor 15 operatively coupled with the idle wheel 1 1. For example, the angular speed sensor 15 comprises an encoder, like a phonic wheel encoder.

Optionally, the machine 10 can comprise one or more additional sensors, like for example a tyre pressure sensor, suitable for providing an indication of a pressure value of the tyre of the idle wheel 11 , and/or a load sensor, suitable for providing an indication of a weight value that bears down on the idle wheel 1 1.

The angular speed sensor 15 and the distance sensor 17, as well as possible other sensors with which the machine is equipped, are operatively connected to the ECU 13.

Advantageously, the distance sensor 17 is mounted on the machine 10 close to the idle wheel 1 1. Preferably, the distance sensor 17 is arranged aligned with the idle wheel 1 1 along the advancing direction W (or more generically movement direction) of the machine 10. Even more preferably, the distance sensor 17 is arranged in a position in front of the idle wheel 1 1 in the advancing direction W thereof on the deformable surface S. In other words, the distance sensor 17 is arranged upstream of the idle wheel 1 1 in an advancing direction of the idle wheel 1 1 along the advancing direction W on the deformable surface S.

In the non-limiting embodiments considered, the distance sensor 17 is fixed to the frame 19 in a frontal position of the machine 10 with respect to a position of the idle wheel 1 1 in the advancing direction W of the group 1. Advantageously, the distance sensor 17 comprises at least one among an ultrasound sensor, a mechanical sensor and an optical sensor (for example a rangefinder). The ultrasound or optical sensor (schematically illustrated in Figure 2A) generates an ultrasound signal or an electromagnetic radiation (for example a laser), respectively, and detects a time passed between the emission of the signal and the reception of a corresponding reflected signal. The signal detected by the distance sensor 17, in this case, is measured as a function of the time detected.

The mechanical sensor (schematically illustrated in Figure 2B) comprises a feeler arm equipped with a first end constrained to the frame 19 and an opposite second free end that is adapted for making contact with the undeformed portion of the deformable surface S (without deforming it).

For example, the arm (of known length) is hinged to the frame 19 at the first end and, for example, the second end is equipped with a rolling element like a wheel or an idle roller. In this case, the distance detected by the distance sensor 17 is measured as a function of an angle Q of inclination between the arm and the vertical.

This does not exclude the possibility that the arm can be of the elongatable type and the first end can be rigidly connected to the frame 19. In this case, the distance detected by the distance sensor 17 is measured as a function of a length of the arm.

In the embodiments of the present invention, the ECU 13 of the machine 10 is configured to implement a method 100 for measuring the real speed V of the machine 10. Advantageously, the method 100 is suitable for measuring the real speed V of the machine 10 when it is in motion with the idle wheel 11 resting and rolling on a deformable surface S, like for example the ground of a field.

In practice, such a method 100 makes it possible to measure the real advancing speed V of the machine 10 along the advancing direction W, when the machine 10 rests on the deformable surface S by means of the idle wheel 11 and, by means of its load bearing down on the deformable surface S locally deforms the deformable surface S creating a groove at the resting area of the deformable surface S that has come into contact with the idle wheel 1 1.

In detail, the ECU 13 is configured to measure (block 1 10) a height H of the rotation axis O of the idle wheel 11 with respect to an undeformed portion Si of the deformable surface S. In the present document the term‘undeformed portion’ is meant to indicate a portion of the deformable surface S that has not (yet) come into contact with the idle wheel 1 1 at the moment of the measurement of the height H. In other words, the measurement of the height H is carried out from a portion of ground not deformed (not compressed) by the passage (rolling) of the idle wheel 11.

In the embodiment considered, the ECU 13 is configured to identify the height H based on the indication of the distance detected and provided by the distance sensor 17. As described above, the distance sensor 17 is, preferably, arranged upstream of the idle wheel 1 1 with respect to the direction of movement thereof. Consequently, the undeformed portion Si used to measure the height H is also arranged upstream of the idle wheel 11 in the advancing direction thereof on the deformable surface S.

Advantageously, the ECU 13 is configured to calculate the height H as the difference (or the sum) of a first distance D + H detected by the distance sensor 17 (which corresponds to the vertical distance between the first end and the second end of the arm or, in any case, the vertical distance between the distance sensor 17 and the undeformed portion Si) and a second vertical distance D between (the height of) the distance sensor 17 and the rotation axis O of the idle wheel 1 1 (which corresponds to the vertical distance between the first end of the arm and the rotation axis O of the idle wheel 1 1 or, in any case, the vertical distance between the distance sensor 17 and the rotation axis O of the idle wheel 1 1 ). Advantageously, the second distance D is a constant value that is stored in the ECU 13, for example, in a non-volatile memory unit thereof.

Once the height H has been identified, the ECU 13 is configured to determine (set of blocks 120) the real advancing speed V of the machine 10 based on the height H determined.

In greater detail, the real advancing speed V of the machine 10 can be determined in the following way.

A value of an angular speed w of the idle wheel 1 1 is measured (block 130). For example, the ECU 13 is configured to determine the value of the angular speed w of the wheel 1 1 through an indication of the angular speed provided by the angular speed sensor 15.

Subsequently or simultaneously, a value of an effective rolling radius Reft of the idle wheel 1 1 is determined (block 140).

In the embodiments of the present invention, the ECU 13 is configured to calculate the effective radius Reft (at block 140) as a function of a value of a maximum radius Rw of the idle wheel 1 1 , of a value of a load radius Ri of the idle wheel 1 1 , and of the height H previously determined.

The maximum radius Rw corresponds to a value of the radius of the undeformed idle wheel 1 1 , i.e. a predetermined (known) value that depends on the model of idle wheel 1 1 used in the machine 10. Advantageously, the value of the maximum radius Rw is (for example provided by the supplier of the idle wheel itself or measured through suitable calibration activities and) stored in the ECU 13.

Differently, the load radius Ri of the idle wheel 1 1 corresponds to a value of the radius of the idle wheel 1 1 when this is deformed by means of a (static) load bearing down on it (for example on the machine 10 that it supports). In particular, the value of the load radius Ri of the idle wheel 1 1 is a function of the value of the maximum radius Rw of the idle wheel 1 1 , of a rigidity value K thereof and of a value of a load L - or weight force - bearing down on the idle wheel 1 1.

The load radius Ri can be a value that is substantially constant or variable over time depending on whether the load L and/or an inflation pressure P of the tyre of the idle wheel 1 1 is constant or variable - which influences the rigidity value K of the idle wheel.

For example, in the case in which the machine 10 is a seeder, the load L bearing down on the idle wheel 10 varies over time, in particular it decreases as the seeds planted in the ground, i.e. that are unloaded from the machine 10, increases. In addition, the value of the pressure P of the tyre can vary (for example reduce or increase) during the operation of the machine 10.

For example, the load radius Ri of the idle wheel 1 1 can be calculated based on the following formula:

wherein R w is the value of the maximum radius, L is the value of the load bearing down on the idle wheel 1 1 and K(P) is the value of the rigidity (of the tyre) of the idle wheel 1 1 as a function of the inflation pressure P thereof.

For example, the value of the load radius Ri is (for example provided by the supplier of the idle wheel itself or measured through suitable calibration activities and) stored in the ECU 13.

Alternatively, the ECU 13 can be configured to calculate the value of the load radius Ri from the indications supplied by the pressure sensor and/or by the load sensor (when present), i.e. to calculate , with the formula (1 ), the value of the load radius Ri based on the value of the maximum radius Rw, the value of the load L bearing down on the idle wheel 1 1 and the value of the rigidity K(P) (of the tyre) of the idle wheel 1 1 as a function of the inflation pressure P thereof, for example previously measured or pre-stored in the non-volatile memory unit of the ECU 13.

In the preferred embodiment, the ECU 13 is configured to calculate (at block 140) the value of the effective rolling radius Reft of the idle wheel 1 1 based on the following formula:

wherein a is calculated according to the following formula:

and b is calculated according to the following formula:

wherein - as stated above - Rw is the value of the maximum radius (as determined above), Ri is the value of the load radius and H is (the value) of the height (vertical distance) of the rotation axis O of the idle wheel 1 1 with respect to the undeformed portion S1 of the deformable surface S.

Finally, the ECU 13 is configured to calculate (block 150) real advancing speed V of the machine 10 (i.e. corresponding to the real advancing speed of the tractor 20) as a function of the determined value of the effective rolling radius Reft of the idle wheel 1 1 and the measured angular speed value w thereof.

In particular, the real advancing speed V is calculated by the ECU 13 by means of a combination, for example through the product, between the value of the effective rolling radius Reft of the idle wheel 1 1 and the angular speed value w thereof.

In practice, the real advancing speed V (i.e. the modulus of the advancing speed of the rotation axis O along the advancing direction W) is calculated through the following formula:

V = w x R eff , (5)

wherein w is the angular speed value (measured, as described above, at block 130) and Reff is the value of the effective radius (determined at block 140).

The ECU 13 can be configured to carry out the method 100 continuously or periodically.

The aforementioned method 100 stems from the following mathematical observations illustrated hereinafter with particular reference to Figure 3.

Firstly, it should be observed that the idle wheel 1 1 hauled on the deformable surface S compresses it as it passes. In particular, it is possible to define an undeformed portion Si of deformable surface S arranged (for example) upstream of the idle wheel 1 1 in the advancing direction W thereof and a deformed portion S2 (groove) arranged downstream of the idle wheel 1 1 in the advancing direction W.

Moreover, it has been observed that the idle wheel 1 1 is also subject to deformation, i.e. it deforms both by means of the load L and by means of the interaction between the idle wheel 1 1 and (the undeformed portion Si of) the deformable surface S.

Therefore, it has been observed that a deformable idle wheel 1 1 (not subjected to braking or drive torques) resting on a deformable surface S has the movement of the centre of instantaneous rolling with respect to the case in which the (deformable) idle wheel 1 1 rests on an undeformable surface.

In particular, it can be hypothesised that the deformed portion S2 of the deformable surface S is actually rigid and, therefore, defining an undeformable support plane for the idle wheel 1 1 (deformable).

In this case, it should be observed that the idle wheel 1 1 , by means of its deformation, rests on a rope DD’ distant from the rotation axis O by a (vertical) distance equal to the value of the load radius Ri.

Another important point is defined by the point indicated with B in figure 3, in which the deformation of the idle wheel 1 1 by means of the load L is substantially zero and also the deformation of the deformable surface S is also zero (i.e. the intersection point between the undeformed portion Si and the circumference centred in the rotation axis O and having a radius equal to the maximum radius Rw).

For the calculation of the value of the effective radius Reft, which the value of the radius of the idle wheel 1 1 in the centre of instantaneous rolling C (in the case in which the idle wheel 1 1 is deformable and resting on the deformable surface S), the following hypotheses are formulated, corroborated by experimental data:

a) the centre of instantaneous rolling C lies on a segment (rope) that joins the ideal point of instantaneous rolling A (corresponding to the point arranged on the circumference centred in the rotation axis O and with radius equal to the maximum radius Rw and aligned vertically below the rotation axis O) and the aforementioned point B;

b) the centre of instantaneous rolling C lies on a segment (radius) that joins the rotation axis O at point D (extremity of the rope DD’ arranged between point A and point B along the advancing direction W.

In particular, the point D is a point that is arranged on the circumference centred in the rotation axis O and with radius equal to the maximum radius Rw.

Based on the above, the effective radius Reft will extend from the rotation axis O of the idle wheel 11 up to the centre of instantaneous rolling C, i.e. it is equal to the segment that joins the rotation axis O with the centre of instantaneous rolling C.

Consequently, the centre of instantaneous rolling C can be defined as the intersection point between a first segment AB passing through the points A and B and a second segment OD passing through the points O and D.

Considering a Cartesian coordinate system , / centred in the rotation axis O of the idle wheel 1 1 and with axis x directed parallel to the advancing direction W (horizontal), the calculation of the effective radius Reft can be expressed as follows.

Points A, B, D, and the rotation axis O are known and have the following coordinates:

The first segment AB and the second segment OD lie on a first and a second line defined by the functions:

y = m AB x + q

The coordinates of the third point C correspond to the intersection of the first and the second line:

I c _ QAB ~ QQD

C ™ OD ~ m AB (7) y c = m oD X c + q OD

The effective radius Reft is, finally, calculated - as the distance between the rotation axis O and the third point C - through the following formula:

which substantially corresponds to formula (2).

The invention thus conceived can undergo numerous modifications and variants all of which are encompassed by the inventive concept.

For example, the ECU of the machine can comprise a communication module configured to exchange data with a further ECU of the tractor by which the machine is hauled through a wired or radio frequency connection. Alternatively or additionally, the communication module can be configured to exchange data with a remote data processing unit through a radio frequency connection.

Furthermore, the undeformed portion Si of the deformable surface S could be an area of the deformable surface arranged at the (right or left) side of the idle wheel with respect to the advancing direction of the idle wheel on the deformable surface itself, i.e. at the side of the groove caused by the idle wheel supported rolling on the deformable surface.

Moreover, the idle wheel could be an idle wheel (driven) of the tractor, for example an idle wheel rotatably connected to the frame of the tractor (or engine) or in any case of the second motorised vehicle.

Moreover, all of the details can be replaced by other technically equivalent elements.

In practice, the materials used, as well as the contingent shapes and sizes, can be whatever according to the requirements without for this reason departing from the scope of protection of the following claims.