Damping of torque speed oscillations in a vehicle transmission, including in the presence of disturbances

Abstract

A method is intended to dampen oscillations of a torsional velocity in a transmission of a vehicle driving drive wheels and designed to receive from the powertrain a primary torque corresponding to a primary rotational speed and to transmit this received primary torque to the drive wheels. This method includes a step (10-30) in which an estimator, having a physical and dynamic model of the transmission with parameters, is used to estimate the torsional velocity as a function of these parameters and this primary torque. A correction value is then determined based on this estimated torsional velocity, and the primary torque is modified by subtracting this correction value. Figure 5

Description

Title of the invention: DAMPING OF OSCILLATIONS OF THE TORSIONAL SPEED OF A TRANSMISSION OF A VEHICLE, INCLUDING IN THE PRESENCE OF DISTURBANCES Technical field of the invention

[0001] The invention relates to wheeled land vehicles, and more specifically to the damping of oscillations in the torsional speed of the transmission of such vehicles. State of the art

[0002] Wheeled land vehicles comprise a transmission chain comprising a powertrain (or GMP) and a transmission capable of receiving a primary torque from the GMP and transmitting this received primary torque to the drive wheels. It will be noted that the GMP comprises at least one prime mover providing the primary torque, and possibly electric or thermal.

[0003] The transmission, which transmits the torque between the GMP and a load, has a certain flexibility, in particular at the level of its transmission shaft. However, in the presence of the inertias of the GMP, the transmission and the load, this transmission has natural modes of torsional vibrations which can be excited and enter into resonance. Some of these resonances, and in particular the longitudinal ones, generate oscillations of the torsional speed which can be unpleasant for the passengers.

[0004] In order to reduce these oscillations it has been proposed to use an anti-oscillation controller capable of performing a first or a second action.

[0005] The first action is performed on the torsion speed (or regime) (between the primary shaft and the drive wheels). It consists of using the difference between the measurement of the primary rotation speed (of the primary shaft) and the measurement of the rotation speed of a drive wheel to determine a feedback value (or correction) which is then subtracted from the primary torque provided by the GMP.

[0006] This first action offers limited performance due to the delay required for transmitting the rotational speed of the drive wheel (generally via a multiplexed communication bus). Indeed, this delay does not allow the oscillations to be sufficiently attenuated, and therefore the feedback loop can be unstable.

[0007] The second action is performed on the primary rotation speed (of the primary shaft) by filtering. It consists of using only the measurement of the primary rotation speed (of the primary shaft) to determine a feedback value (or correction) which is then subtracted from the primary torque provided by the GMP.

[0008] This second action makes it possible to avoid measuring the rotational speed of a drive wheel thanks to the filter which estimates the torsion speed (or regime). However, it also has limited performance in the presence of parametric disturbances or uncertainties. Indeed, in the presence of an external torque received by the drive wheels or when, for example, the stiffness of the transmission varies significantly, undulations (or oscillations) appear in the torsion speed (or regime).

[0009] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0010] For this purpose, it proposes in particular a damping method intended to dampen oscillations of a torsional speed of a transmission of a vehicle driving drive wheels, capable of receiving from a powertrain of the vehicle a primary torque corresponding to a primary rotational speed, and capable of transmitting this received primary torque to the drive wheels.

[0011] This damping method is characterized by the fact that it comprises a step in which an estimator is used, having a physical and dynamic model of the transmission, comprising parameters, to estimate the torsion speed as a function of these parameters and the primary torque, then a correction value is determined as a function of this estimated torsion speed, then the primary torque is modified by subtracting this correction value from it.

[0012] Thanks to this estimator modeling the transmission, it is now possible to dampen, or even eliminate, all oscillations in the torsional speed of this transmission, including in the presence of internal and / or external disturbances, which makes it possible to improve the robustness of the anti-oscillation action with respect to parametric uncertainties and disturbances, and therefore to improve passenger comfort.

[0013] The damping method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0014] - in its stage, the physical and dynamic modeling can be representative of first and second masses, associated respectively with first and second inertias, and coupled by a spring, associated with a torsional stiffness parameter, and a damper, associated with a viscous friction parameter;

[0015] - in the presence of the first option, in its step, on the one hand, the first inertia may be equal to a sum of inertias of each driving machine of the powertrain, and of a gear change member and a reducer of the vehicle, and, on the other hand, the second inertia may be equal to a sum of inertias of the driving wheels and of a body of the vehicle;

[0016] - in the presence of the last sub-option, in its step, the physical modeling and dynamic may comprise as parameters, on the one hand, a torsion angle equal to a difference between a first displacement angle, representative of an inclination of a driving machine of the powertrain, and a second displacement angle, representative of an inclination of a driving wheel, on the other hand, a torsion speed equal to a difference between the primary rotation speed and a rotation speed of this driving wheel, and, on the other hand, a torsion torque equal to a sum of a first product of the torsion stiffness parameter by this torsion angle and a second product of the viscous friction parameter by the estimated torsion speed;

[0017] - in its step, we can use a proportional observer type estimator integral or observer type with unknown inputs.

[0018] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a damping method of the type presented above for damping oscillations of a torsional speed of a transmission driving the drive wheels of a vehicle and comprising a transmission capable of receiving from a powertrain of the vehicle a primary torque corresponding to a primary rotational speed and capable of transmitting this received primary torque to the drive wheels.

[0019] The invention also provides a damping device intended to dampen oscillations of a torsional speed of a transmission of a vehicle driving drive wheels, capable of receiving from a powertrain of the vehicle a primary torque corresponding to a primary rotational speed, and capable of transmitting this received primary torque to the drive wheels.

[0020] This damping device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting of using an estimator, having a physical and dynamic model of the transmission, comprising parameters, to estimate the rotation speed as a function of these parameters and of the primary torque, then determining a correction value as a function of this estimated torsion speed, then triggering a modification of the primary torque by subtracting the latter from the correction value.

[0021] The invention also proposes a vehicle comprising, on the one hand, a powertrain, drive wheels, and a transmission suitable for receiving from the powertrain a primary torque corresponding to a primary rotation speed and suitable for transmitting this primary torque received to the drive wheels, and, on the other hand, a damping device of the type presented above.

[0022] For example, the powertrain may include at least one electric prime mover. Brief description of the figures

[0023] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0024] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a damping device according to the invention, an estimator, and a hybrid GMP associated with a supervision computer,

[0025] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a supervision computer comprising a damping device according to the invention,

[0026] [Fig.3] schematically and functionally illustrates an example of physical and dynamic modeling of the transmission of the vehicle of [Fig.l],

[0027] [Fig.4] schematically and functionally illustrates an exemplary embodiment of an estimator used in the vehicle of [Fig.l], and

[0028] [Fig.5] schematically illustrates an example of an algorithm implementing a damping method according to the invention. Detailed description of the invention

[0029] The invention aims in particular to propose a damping method, and an associated damping device DA, intended to allow the damping of oscillations in the torsional speed coT of a transmission AT driving the drive wheels of a vehicle V, including in the presence of disturbances.

[0030] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car, as illustrated in [Fig.l]. But the invention is not limited to this type of wheeled vehicle. It in fact relates to any type of wheeled vehicle and comprising a transmission chain capable of supplying torque to (driven) wheels. Thus, it relates in particular to utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, and agricultural machinery, for example.

[0031] Furthermore, it is considered in the following, by way of non-limiting example, that the transmission chain comprises a hybrid powertrain (or GMP) (and therefore comprising at least first and second respectively thermal and non-thermal driving machines). But the invention is not limited to this type of GMP. It in fact concerns any type of GMP, and in particular GMPs with purely thermal or purely non-thermal driving machine(s).

[0032] Finally, it is considered in the following, by way of non-limiting example, that the (each) non-thermal driving machine of the GMP is electric. But this is not obligatory.

[0033] [Fig.l] schematically shows a (land) vehicle V comprising a damping device DA according to the invention, a hybrid GMP transmission chain (and therefore comprising at least one first thermal motor machine MM1 and a second non-thermal MM2 prime mover (here electric)), a CS supervision calculator, and a main battery (or traction or even power) BP.

[0034] As illustrated, the transmission chain also comprises, here, a drive shaft AM, a coupling device DC1, a gear change member BV, and a transmission (comprising at least one transmission shaft AT).

[0035] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0036] The first (thermal) driving machine MM1 comprises a crankshaft (not shown) which is fixedly secured to the motor shaft AM in order to drive the latter (AM) in rotation. This first driving machine MM1 is capable of operating according to a first speed to provide a first torque which is a function of a first torque setpoint, for example determined by the supervision computer CS.

[0037] The control of the operation of this first driving machine MM1 is ensured by a machine computer (not shown).

[0038] Furthermore, the first driving machine MM1 is capable of being coupled to the gear change member BV, via at least the coupling device DC1. The latter (DC1) is capable of delivering a torque from the first torque, in particular for at least one train T1 of driving wheels, when it is in its coupled (or closed) position and therefore when it couples the first thermal driving machine MM1 to the gear change member BV.

[0039] For example, the coupling device DC1 may be a hydraulic circuit clutch. But it could be of another type.

[0040] Also for example and as illustrated non-limitingly in [Fig. 1], the train T1 can be located in the front part PVV of the vehicle V. It is preferably, and as illustrated, coupled to the transmission shaft AT via a differential (here front) DV. But in a variant this train T1 could be that referenced T2 which is located in the rear part PRV of the vehicle V.

[0041] The second (non-thermal (here electric)) driving machine MM2 is capable of providing for the driving wheels of the vehicle V a second torque defined by a second torque setpoint, for example determined by the supervision computer CS.

[0042] The second prime mover MM2 is, here, installed between the coupling device DC1 and the gear change member BV, by way of example, and associated with a reducer RD. It therefore provides, here, a second torque for the train T1 when it is supplied with electrical energy by the main battery BP. But in a variant it could provide a second torque for the train T2. ​​More precisely, in the example illustrated non-limitingly in [Fig.l], the second prime mover MM2 is here connected to the output of the coupling device DC1 and to the primary shaft AP of the gear change member BV. It is therefore physically interposed between the coupling device DC1 and the primary input shaft AP of the gear change member BV, and therefore the first torque supplied by the first prime mover MM1 via the coupling device DC1 is transferred to the gear change member BV via the second prime mover MM2. But in an alternative embodiment (not shown) the transmission chain could comprise another coupling device physically interposed between the coupling device DC1 and the primary shaft of the gear change member BV and in this case the second prime mover MM2 is coupled via a mechanism between the output of the coupling device DC1 and this other coupling device.

[0043] For example, the main battery BP may be of the cellular type. In this case, it comprises electrical energy storage cells, possibly electrochemical (such as, for example, lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type cells). Also, for example, this main battery BP may be of the 450 V type. But this is not an obligation. Indeed, it could alternatively be of the 48 V or 600 V type, for example.

[0044] For example, the BV gear change unit may be a gearbox, preferably automated. In this case, the BV gearbox may be of the so-called “dual clutch (or DCT)” type. But this is not an obligation.

[0045] The vehicle V also comprises, here, an accelerator pedal PA (or similar) which allows the driver to signal his desire to accelerate, which then serves to define a torque demand (driver) cc. It is considered here that it is the percentage of depression of the accelerator pedal PA which makes it possible to determine the driver's desire to accelerate and therefore the torque demand cc.

[0046] The vehicle V also includes an EM estimator which has a physical and dynamic modeling of the AT transmission. This modeling includes parameters.

[0047] For example, and as illustrated non-limitingly in [Fig. 3], the modeling (physical and dynamic) can be representative of first and second masses, associated respectively with first Jp and second Jr inertias, and coupled by a spring RM, associated with a torsional stiffness parameter Kr, and a damper AM', associated with a viscous friction parameter Kv.

[0048] In the presence of the vehicle V illustrated in [Fig.l] and described above, the first inertia Jp can be equal to the sum of the inertias of each driving machine of the GMP (here MM1 and MM2), of the gear change member (here a gearbox) BV and of the reducer RD, and the second inertia Jr can be equal to the sum of the inertias of the driving wheels and of the body of the vehicle V.

[0049] When using the modeling (physical and dynamic) described above with reference to [Fig.3], this modeling can include as parameters a torsion angle 0T, the torsion speed (to be estimated) coT, and the torsion torque CT, in particular.

[0050] The torsion angle 0T is equal to the difference between a first displacement angle 0 p, representative of the inclination of a driving machine MM1 or MM2 of the GMP, and a second displacement angle 0r, representative of the inclination of a driving wheel, i.e. 0T = 0P - 0r.

[0051] The torsion speed coT is equal to the difference between the primary rotation speed (of the primary shaft AP) cop and the rotation speed cor of the drive wheel mentioned in the previous paragraph, i.e. coT = cop - cor.

[0052] The torsion torque CT is equal to the sum of a first product of the torsion stiffness parameter Kr by the torsion angle 0T and a second product of the viscous friction parameter Kv by the estimated torsion speed coT, i.e. CT = (Kr * 0T ) + (Kv * œT).

[0053] To obtain the state representation of the AT transmission, we can start by using the equations of motion which result from the application of Newton's second law to the AT transmission modeled in [Fig.3], and, by carrying out the balance of the torques at the level of the primary shaft AP and at the level of the driving wheel concerned, we obtain:

[0054] [Math.l] JpWp = Cp-Cr (ij

[0055] [Math.2] Jrœr = Cr+CT (2)

[0056] Then, we can derive the equation giving CT with respect to time, then by replacing ^p and (Vr (derivatives with respect to time of cop and cor) by their expressions from equations (1 and 2), we can obtain the dynamic equation of the torsion torque CT:

[0057] [Math.3] CT = Krwp- Krwr- Cp +-çCp--p-Cr (3) where;

[0058] [Math.4] i _ / W \ jT \ JpL J

[0059] We can then combine equations (1), (2) and (3) to obtain the state representation of the AT transmission:

[0061] [Math.5] Wp Or (4) [Math.6] Wp y=[l 0 0] □ C T C LU

[0062] which can be presented in the form of standard equations of state:

[0063] [Math.7] ( X = Ax + Bu + Ev , (y-Cx

[0064] Here, the matrices A, B, C and E represent respectively state matrix, control matrix, output matrix and disturbance matrix, and the vectors x, u, y and v correspond respectively to the state vector, control vector, output vector and disturbance vector, for the EM estimator. It will be noted that the disturbance can have different origins, and in particular a passage of a driving wheel in a hole or on a bump, noise, parametric uncertainties, or an external torque received by a driving wheel. These disturbances are naturally present, whether due to the quality of the road or the dispersion of the physical parameters of the AT transmission from one vehicle to another.

[0065] To solve the state equations (5), one can, for example, use an EM estimator of the proportional integral observer (or OPI) type, possibly the so-called Luenberger one. It is recalled that this type of observer is an auxiliary dynamic system (model) which provides an estimate of the state taking into account the fact that the only accessible quantities of the system are the known input and measured output variables. Here, only the DC torque demand (or driver demand) is known, but the disturbance torque is not known.

[0066] An example of such an EM estimator of the Luenberger OPI type is illustrated schematically and functionally in [Fig.4]. In the presence of such an EM estimator, the following equations (6) are used, derived from the state equations (5):

[0067] [Math. 8] x = Ax + Bu + K p (yy) + Ev 1 v = Ki(yy) ( 6 )' ÿ-Cx

[0068] where the sign “A” represents an estimated variable, and Kp and K; represent the adjustment parameters of the convergence dynamics of the EM estimator.

[0069] The resolution of equations (6) by the EM estimator here makes it possible to estimate the torsion speed coT knowing only the torque demand cc (and therefore the primary torque Cp).

[0070] It should be noted that unlike a traditional estimator, an observer proportional integral (OPI) type estimator includes a correction that is proportional to the difference between the measured quantity and the estimated quantity, as well as an integral correction over a specific observation window. This combination gives it greater robustness in the face of uncertainties and disturbances.

[0071] It should also be noted that as a variant, an EM estimator of the observer type with unknown inputs (or OEI) could be used, for example.

[0072] It will also be noted that in the example illustrated non-limitingly in Figures 1 and 2, the estimator EM is part of the supervision computer CS. But it could be part of the damping device DA, in particular when the latter (DA) comprises a dedicated computer.

[0073] As mentioned above, the invention proposes in particular a damping method intended to allow the damping of oscillations of the torsion speed coT of the transmission (or transmission shaft) AT of the vehicle V, including in the presence of disturbances.

[0074] This (damping) method can be implemented at least partially by the damping device DA (illustrated in [Fig.2]) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one memory MD. This damping device DA can therefore be produced in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can be a microcontroller.

[0075] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the damping method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0076] In the example illustrated non-limitingly in Figures 1 and 2, the damping device DA is part of the supervision computer CS. But it could be part of another computer on board the vehicle V, or could include its own dedicated computer.

[0077] As illustrated non-limitingly in [Fig.2], the (damping) method, according to the invention, comprises a step 10-30 which is implemented each time the GMP of the vehicle V is in operation and must provide primary torque Cp to the primary shaft AP of the gearbox BV in order to drive the drive wheels (here of the front axle T1).

[0078] Step 10-30 of the method comprises a sub-step 10 in which, one (for example the damping device DA) begins by using the EM estimator to estimate the torsion speed coT as a function of the parameters of this EM estimator and of the primary torque Cp.

[0079] In addition, step 10-30 of the method also comprises a sub-step 20 in which, one (for example the damping device DA) determines a correction value vc as a function of the estimated torsion speed coT.

[0080] Finally, step 10-30 of the method also includes a sub-step 30 in which the (for example the damping device DA triggers a modification of the) primary torque Cp is modified by subtracting the correction value, i.e. Cp(t+1) = Cp(t) -vc.

[0081] Thanks to the use of this EM estimator which models the AT transmission, it is now possible to dampen, or even eliminate, all oscillations of the torsional speed coT of this AT transmission, including in the presence of internal and / or external disturbances. This results in an improvement in the robustness of the anti-oscillation action with respect to parametric uncertainties and disturbances (in particular from the road), and therefore an improvement in the comfort (or driving pleasure) of the passengers of the vehicle V, but also an increase in the service life of the transmission chain (and in particular of the AT transmission). In addition, the invention allows an improvement in the robustness to the dispersion linked to the large-scale production of the vehicles.

[0082] It will be noted, as illustrated non-limitingly in [Fig.l], that the supervision computer CS (or the damping device computer DA) can also comprise a mass memory MM1, in particular for storing the primary torque Cp (or the torque request cc), as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision computer CS (or the damping device computer DA) can also comprise an input interface IE for receiving at least the primary torque Cp, (or the torque request cc), to use it in calculations or processing, possibly after having shaped and / or demodulated and / or amplified it, in a manner known per se, at by means of a PR2 digital signal processor. In addition, this CS supervision calculator (or the DA damping device calculator) can also include an IS output interface, in particular to deliver each message containing the modified primary torque Cp(t+1) or the correction value vc of the latter (Cp(t+1)).

[0083] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the damping method described above to damp the oscillations of the torsion speed coT of the transmission AT of the vehicle V.

Claims

Claims

1. Method for damping oscillations of a torsional speed of a transmission (AT) of a vehicle (V) driving drive wheels, suitable for receiving from a powertrain of said vehicle (V) a primary torque corresponding to a primary rotational speed, and suitable for transmitting this received primary torque to said drive wheels, characterized in that it comprises a step (10-30) in which an estimator (EM) is used, having a physical and dynamic modeling of said transmission, comprising parameters, to estimate said torsional speed as a function of said parameters and said primary torque, then a correction value is determined as a function of said estimated torsional speed, then said primary torque is modified by subtracting said correction value from it.

2. Method according to claim 1, characterized in that in said step (10-30) said physical and dynamic modeling is representative of first and second masses, associated respectively with first and second inertias, and coupled by a spring, associated with a torsional stiffness parameter, and a damper, associated with a viscous friction parameter.

3. Method according to claim 2, characterized in that in said step (10-30) i) said first inertia is equal to a sum of inertias of each driving machine (MM1, MM2) of said powertrain, and of a gear change member (BV) and of a reducer (RD) of said vehicle (V), and ii) said second inertia is equal to a sum of inertias of said driving wheels and of a body of said vehicle (V).

4. Method according to claim 3, characterized in that in said step (10-30) said physical and dynamic modeling comprises as parameters i) a torsion angle equal to a difference between a first displacement angle, representative of an inclination of a prime mover (MM1, MM2) of said powertrain, and a second displacement angle, representative of an inclination of a drive wheel, ii) a torsion speed equal to a difference between said primary rotation speed and a rotation speed of this drive wheel, and iii) a torsion torque equal to a sum of a first product of said torsion stiffness parameter by said torsion angle and a second product of said viscous friction parameter by said estimated torsion speed.

5. Method according to one of claims 1 to 4, characterized in that in said step (10-30) an estimator (EM) of the proportional integral observer type is used.

6. Method according to one of claims 1 to 4, characterized in that in said step (10-30) an estimator (EM) of observer type with unknown inputs is used.

7. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the damping method according to one of claims 1 to 6 for damping oscillations of a torsional speed of a transmission (AT) of a vehicle (V) driving drive wheels, capable of receiving from a powertrain of said vehicle (V) a primary torque corresponding to a primary rotational speed, and capable of transmitting this received primary torque to said drive wheels.

8. Damping device (DA) for damping oscillations of a torsional speed of a transmission (AT) of a vehicle (V) driving drive wheels, suitable for receiving from a powertrain of said vehicle (V) a primary torque corresponding to a primary rotational speed, and suitable for transmitting this received primary torque to said drive wheels, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of using an estimator (EM), having a physical and dynamic modeling of said transmission, comprising parameters, to estimate said rotational speed as a function of said parameters and said primary torque, then determining a correction value as a function of said estimated torsional speed, then triggering a modification of said primary torque by subtracting the latter from said correction value.

9. Vehicle (V) comprising a powertrain, drive wheels, and a transmission (AT) capable of receiving from said powertrain a primary torque corresponding to a primary rotation speed and capable of transmitting this received primary torque to said drive wheels, characterized in that it further comprises a damping device (DA) according to claim 8.

10. Vehicle according to claim 9, characterized in that said powertrain comprises at least one electric motor (MM2).

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