FR2933645A1 - Motor vehicle speed limiting method, involves calculating control force from reference speed and transmitting force for regulating real speed of vehicle, and calculating reference speed as function of setpoint speed and real speed - Google Patents

Abstract

The method involves setting a maximum setpoint speed (Vcons) to be not exceeded by a motor vehicle. Control force (Freg) is calculated from a reference speed (Vref) and is transmitted to an engine (1) of the motor vehicle for regulating a real speed (Vveh) of the motor vehicle. The reference speed as function of the setpoint speed and the real speed of the motor vehicle, is calculated based on a supervisor state. An independent claim is also included for a device for limiting a speed of a motor vehicle, comprising a regulation block.

Description

REN094FR PJ8803 deposit DA 1

The invention relates to a speed limitation device for a motor vehicle and a speed limitation method for a motor vehicle. It also relates to a motor vehicle as such incorporating such a speed limitation device.

There are currently systems for limiting the speed of a vehicle, intended to prevent a motor vehicle from exceeding a predetermined speed limit value, except by a voluntary operation of the driver. Any speed value below this maximum limit value is allowed.

Such a speed limiter system generally comprises as input the position information of the accelerator pedal, which is converted into an acceleration request signal from the driver. According to the result of the comparison between the actual speed of the vehicle and the set speed, the speed limiter system will define the acceleration control of the vehicle, which may for example be that requested by the driver or a lower value in the situation of the vehicle. near the set speed. Such devices are described in documents FR2755650 and FR2866281.

These existing solutions are unsatisfactory because they cause oscillations of the real speed around the maximum authorized value, this value being thus exceeded unacceptably, especially at the time of the rise and arrival at this speed value. In addition, regulating the rise of this speed towards the maximum value results in unusual and surprising behavior of the vehicle, which can baffle a driver. For example, the time to reach this limit value depends more than sometimes on certain parameters of the regulator and no longer on the amplitude between the real speed of the vehicle and the maximum speed.

Thus, a general object of the invention is to propose another solution for limiting the speed of a motor vehicle that does not have all or some of the preceding disadvantages.

For this purpose, the invention is based on a method for limiting the speed (VVén) of a motor vehicle comprising a step of setting a maximum target speed (Vcons) not to be exceeded by the vehicle, a step of speed regulation (Vvéh) of the vehicle comprising the calculation of a force requested by a servo (Frég) from a reference speed (Vref) and its transmission to the engine, characterized in that it comprises a step of calculation of the reference speed (Vref) as a function of the target speed (Vcons) and the real speed (VVén) of the vehicle.

The step of calculating the reference speed (Vref) may also be a function of the state of the supervisor. The step of calculating the reference speed (Vref) can compensate for one or more transmission zeros generated by the regulation step.

The step of calculating the reference speed (Vref) may comprise a filtering between the reference speed (Vcons) and the reference speed (Vref), which introduces a phase delay between these values which compensates the effect of the regulator.20 REN094EN PJ8803 DA 3 depot The speed regulation step (Vvéh) of the vehicle may be based on a Proportional Integral (PI) type correction defined by proportional (kp) and integral (k;) gains.

The step of calculating the reference speed (Vref) may comprise a filtering between the reference speed (Vcons) and the reference speed (Vref) determined by the transfer function F (s) defined by the following equation: F (s) = [(cf (to) kps) / k; +1] / [kps / k; +1] Where cf (t) is a function which depends on the variation of the velocity and cf (to) = cf (AVo) = Cf (Vcons - Vvéh (to)), to being the initial moment of the beginning of the operation of the closed-loop control method.

The filter function F (s) can be determined by the function cf at the value [cf (OVo)] that it has at the initial time (to) whose value is lower if the speed difference at the initial moment (OVo) is more important.

The limiting method may comprise three modes of operation, a first mode in which it is inactive, a second mode in which it is active but in which the motor is always controlled by the force demanded by the driver (u = Fcond) and a third mode in which it is active and in which the motor is controlled by the force requested by the servo (u = Frég).

The step of calculating the reference speed (Vref) in the second mode of operation can be determined by the following equation: Vref (t) = Vvh (t) + cons' Vvh (t)] * Cf (t) where the filter parameter cf (t) is a function which depends on the variation of the speed and is expressed as cf (t) = Cf (AV (t)).

REN094FR PJ8803 DA 4 depot The filter parameter cf (t) can be constant during the implementation of the third mode or variable as a function of time.

The invention also relates to a device for limiting the speed (Vvéh) of a motor vehicle comprising a means of capturing a maximum target voltage (Vcons) not to be exceeded by the vehicle, a regulation block which calculates at its output a servo force value (Frég) intended for the engine of the motor vehicle from a reference speed (Vref), characterized in that it comprises at least one calculation block of a speed of reference (Vref) as a function of the target speed (Vcons) and the actual speed (Vvéh) of the vehicle, implementing the speed limiting method as described above.

The speed limiting device may comprise a supervision block, which comprises a first sub-block consisting in determining the activation or not of the device and a second sub-block consisting in determining the target force to be transmitted to the engine by arbitrating between the force demanded by the driver (Fcond) and that (Freg) calculated by the servo device.

The regulation block may consist of a Proportional-Integral (PI) type corrector, the dynamic of which introduces a transmission zero into the setpoint tracking and that the reference speed calculation block (Vref) comprises a filter that compensates for the time offset introduced by the regulation block.

Finally, the invention also relates to a motor vehicle characterized in that it comprises a device for limiting the speed as described above. These objects, features and advantages of the present invention will be described in detail. in the following description of a particular embodiment made in a non-limiting manner in relation to the appended figures among which: FIG. 1 represents a schematic view of a speed limiter servocontrol system according to a mode of execution of the invention; FIG. 2 represents a velocity curve of a vehicle comprising a speed limiter according to the embodiment of the invention as a function of time according to a first scenario; FIG. 3 represents a curve of the speed of a vehicle comprising a speed limiter according to the embodiment of the invention as a function of time according to a second scenario; FIG. 4 represents a velocity curve of a vehicle comprising a speed limiter according to the embodiment of the invention as a function of time according to a third scenario; Figure 5 shows a block diagram of the different modes of operation of the speed limiter device according to the embodiment of the invention; FIG. 6 represents a curve of the speed of a vehicle comprising a speed limiter according to a variant of the embodiment of the invention as a function of time according to a fourth scenario.

FIG. 1 diagrammatically represents the operating principle of the speed limiter device according to one embodiment of the invention. It is based on the control of the torque u transmitted to a motor 1 of a motor vehicle in order to obtain a speed of the motor vehicle Vv (h which does not exceed the maximum permissible speed entered as a speed of 30 set point V., s in the This set speed Vcons, which can be defined by the driver through a man-machine interface of the motor vehicle, is used as a basis for calculating a reference speed Vref, used as the basis of the engine. According to an essential element of the invention, this reference speed Vref is obtained as a function of the reference speed Vcons, of the actual speed Vref and possibly of the state of the device. different values pass through a block 2 of filtering logic before a filtering calculation block 3 to obtain the reference speed Vref A subtractor 4 allows the input of a value e representing the diff ence between the actual speed Vveh and the Vref reference speed in a control block 5 which calculates output a servo force value FREG for the motor 1 of the motor vehicle. This value is transmitted to a supervisor block 6 which finally defines the value u of the force setpoint to be transmitted to the engine 1. This supervisor 6 comprises a first block 7 which receives, on the one hand, the value of the force requested by the driver. , for example by means of the accelerator pedal or any other means, and a second block 8 for defining the state of the system.

The device may have different variants. It is implemented by a hardware device and / or software (hardware and / or software) of the motor vehicle, for example by means of the on-board computer. It finally implements the following three functions: it generates (blocks 2 and 3) a reference speed Vref used by the control loop as a reference value for the servocontrol of the system; it comprises a regulation (block 5) in order to be able to calculate a regulating force to be transmitted to the engine 1 if necessary, in replacement of the data transmitted by the driver; REN094FR PJ8803 depot DA 7 -ii includes a supervision logic of the device (block 6), which fulfills the two subfunctions consisting firstly to determine the activation (block 8) or not of the device and to determine on the other hand the reference force to be transmitted to the engine, by arbitrating (block 7) between the force requested by the driver Fcond and that Freg calculated by the servo device. For this, the device compares these two values, the device thus always calculating Ffég even in open loop, when it is not enslaved.

According to the embodiment of the invention, the regulation block 5 consists of a proportional-integral type corrector (PI), defined by gains kp and k; which respectively represent the proportional and integral gain of the PI type regulator. This corrector has a dynamic that introduces a transmission zero in the tracking of the setpoint which has the effect of exceeding the value of the speed of the setpoint. In a variant, this regulator could implement any other control law, continuous or discrete. This regulator generates one or more transmission zeros, whose characteristic frequency depends only on the parameters of the corrector, which are perfectly known.

Moreover, according to the embodiment of the invention, the system can occupy several different states represented by the combination of two parameters of Boolean type: first, the device uses an ACT flag which represents the state of activation of the device. In a first deactivated state (by ACT convention = 0), the driver has total control of the vehicle. When its state is activated (by ACT = 1 convention), the device intervenes to prevent the vehicle speed from exceeding the maximum speed. The device can be 'automatically in its deactivated state if the actual vehicle speed REN094FR PJ8803 depot DA 8 Vvét, is removed from the maximum speed Vcons authorized, beyond an activation threshold hACT, that is to say to say that the relationship Vcons - Vvéh> hACT. is checked. As a remark, the device can be activated in other situations, on a choice of the driver or following a request from another priority device of the motor vehicle;

then, a second flag aNM is used to determine whether or not the active servo control has the hand. It is said that the servo does not have the hand (by convention aNM = 1) if the two following conditions are simultaneously checked for a certain preset time taNM seconds: the servo is active (ACT = 1) and it has not not hand on the vehicle (u = Fcond) • In the opposite case, hand control (aNM = O).

These two flags distinguish three different states of the speed limiter device which operates in three different modes, shown schematically in Figure 5.

In a first mode (ACT = 0), the device is inactive and the engine is only managed by the driver (u = Fcond)

In a second mode (ACT = 1 and aNM = 1), the device is active but does not have the hand, the engine is always managed by the driver (u = Fcond).

In a third mode (ACT = 1 and aNM = 0), the device is active and has the hand, it manages the engine (u = Frég).

In each of these modes, a reference speed Vref is defined in an optimized manner. In the first mode where the device is inactive, this speed does not play an important role and is equal to that of the vehicle, according to the formula Vref = Vvéh In the second mode where the device is active, this speed reference is defined in the following way: Vref (t) = Vvh (t) + `nV cons - Vev (t)] * Cf (t) Where cf (t) depends on the variation of the speed and is expressed under the form: Cf (t) = Cf (AV (t)) Finally, in the third mode, the speed of reference is defined by: Vref (t) = Vvéh (t0) + 1-1 [F (s) (Vcons - Vvéh (t0)) / s Where 1-1 express the inverse transform of Laplace and Vvéh (to) the speed of the vehicle at the moment of entry into mode 3.

F (s) represents the transfer function of a filter, defined by the following equation: F (s) = [(SCf (to) kp) / k; +1 j / [kps / k; +1]

Where k.p represents the proportional gain of the PI type regulator, k; represents the integral gain of the PI type regulator, With cf (to) = cf (AVo) = Cf (Vcons - Vvéh (to))

The filter is inserted between the reference speed Vcor, s and the reference speed Vref, is in the Laplace domain and introduced as a phase delay between these values which compensates for the effect of the PI controller: the result obtained is a lower speed of the deposit. In addition, the convergence of the speed towards the target speed is carried out with a duration substantially identical to that obtained without filtering. The function F of the filter can also be written: F (s) = cf + (1 -cf) / [Skp / k; +1]

Thus, according to the main mode of execution of this third mode, the function F (s) does not change and its value is determined by the function cf at the value it has at the initial time to input into the mode # 3.

The greater the depression of the accelerator pedal at this initial moment, the higher the AVo value, and the lower the value of cf (OVo). This makes it possible to implement a rise in the speed that is softer towards the set speed in this case and to avoid too much exceeding the setpoint speed Vcons. According to a variant of the embodiment, the filtering parameter cf can be variable in time during the third mode of the device, the filter then becoming non-stationary.

With this variant, it is possible to write the value V * ref (t) in the following manner, V * ref (t) = [1-Te / T] Vref (t-Te) + [Te / T] Vcons (t-Te) + cf (t) [Vcons (t) - Vcons (t-Te) Where Te is the sampling period and T = kp / k; As long as the setpoint speed Vcons remains constant, it appears that Vref (t) monotonically converges towards the target speed. The filter parameter cf (t) only occurs here when there is a variation of the value of the target speed. This variant thus implemented does not therefore disturb the behavior of the filter and provides the advantages which will be described later with reference to FIG.

As a variant, any other compensation than the filter described above, according to the embodiment or its variant, of one or more transmission zeros generated by the regulator could be implemented. This would be the case, for example, for a higher order regulator composed of a proportional-integral part, to which are added delay or phase advance terms introducing transmission zeros, the effect of which is to be masked in monitoring. deposit. Such a zero whose frequency is known, in order to be compensated, must have a negative real part.

FIG. 2 illustrates the operation of the device according to this embodiment of the invention, according to a first scenario. Curve 11 represents the variation of the real velocity V V e as a function of time, curve 12 represents the setpoint speed Vcons and curve 13 represents the value of the reference velocity Vref. At a point 15 of the speed curve 11, while the speed limiter device is inactive and in the first mode, the driver gives a strong throttle and causes a rapid increase in the actual speed of the vehicle. On arrival at a point 16 characterized by a speed difference 14 between the target speed and the actual speed equal to the activation threshold hACT, or for a real speed equal to the activation speed VACT, the device becomes active and goes into the third mode of operation. At this initial time of mode 3, the reference speed is then increased by a value 17 with respect to the actual speed according to the formula: Vfef = Cf (eons - VACT). Then, the actual speed increases to slightly exceed the set speed and stabilizes very quickly at the set speed. FIG. 18 represents, as an indication, the value of the actual speed that would be obtained under the same conditions in the absence of reference speed filtering. This speed would far exceed the set speed and would require a longer time to stabilize at that speed.

Figure 3 represents another scenario as an illustration of the operation of the device. The curve 21 represents the variation of the real speed Väh of the vehicle as a function of time, the curve 22 represents the setpoint speed Vcons and the curve 23 represents the value of the reference speed Vref. At a point 25 of the curve 21, while the speed limiter device is inactive and in the first mode, the driver gives a slight boost and causes a slight increase in the actual speed of the vehicle. On arrival at a point 26 characterized by an actual speed equal to the activation speed VACT, a difference with respect to the set speed equal to the activation threshold hACT, the device becomes active and switches to the third mode Operating. The reference speed is then increased to a level 27 with respect to the actual speed according to the formula: Vref = Cf (Vcons VACT). This mode 3 is extended for a period 24 equal to a predetermined time taNM. At the end of this period during which the engine is constantly managed by the driver (u = Fcond), the device goes into mode 2 and the reference speed decreases to a value 28. At a point 29, the driver gives a strong accelerator and causes a rapid increase in the actual speed of the vehicle. The device then enters the third mode and the actual speed increases in a controlled manner until it stabilizes at the set speed.

Finally, FIG. 4 represents another scenario as an illustration of the operation of the device. Curve 31 represents the variation of the real speed Väéh of the vehicle as a function of time, the curve 32 represents the set speed Vcons fixed at the speed of 50 krn / h and the depot 33 represents the value of the reference speed Vref. At a point 35 of the curve, while the speed limiter device is inactive and in the first mode, the driver gives a great boost and causes a sharp increase in the actual speed of the vehicle. On arrival at a point 36 characterized by a real speed equal to the activation speed VACT, the device becomes active and goes into the third mode of operation. The speed of the vehicle stabilizes at the set speed. At a point 37, the driver releases the foot and the speed goes down, the device then going into mode 2 after the preset time taNM. At a point 38, the driver gives a new throttle and the speed rises to the set speed, the device being found in mode 3, until a new release of the acceleration at a point 39. In this For example, the following values are used: hACT = 10 km / h, VACT = 41 km / h; cf (10) = 0.25; cf (3) = 0.6 This scenario illustrates the behavior of the device in the case of oscillation of the speed near the set speed.

FIG. 6 illustrates the behavior of the device according to a particular scenario in the case of the variant embodiment in the filtering parameter cf is variable in time. The curve 41 represents the variation of the real speed VVh of the vehicle as a function of time, the curve 42 represents the reference speed V, and the curve 43 represents the value of the reference speed Vref. At a point 45 of the curve, while the speed limiter device is inactive and in the first mode, the driver gives a great boost and causes a sharp increase in the actual speed of the vehicle. On arrival at a point 46 at the initial time to characterized by a real speed equal to the activation speed VACT, the device becomes active and goes into the third mode of operation. At this initial time to, the actual speed of the vehicle Vvéh is away from the set speed Vcons. To avoid the excessively high speed of this set speed, a filter parameter cf (to) small is chosen. The speed of the vehicle stabilizes at the set speed. At a point 47 at a moment the driver, without having lifted the foot of the accelerator, accelerates slightly and the target speed increases by 2 km / h. In this situation, if the filtering parameter cf is maintained at the same value as above, the device will be unreactive and the convergence of the speed towards this new set speed will be slow and the device will be perceived as soft. Thus, in this situation, it is chosen to increase the value of Cf (tl). Finalerent, in this example shown, the following values are used: hAcr = 10 km / h; VACT = 40 km / h; cf (to) = 0.2; cf ()) = 0.7; Vcor, s (to) = 50; Vcons (ti) = 52;

Finally, the solution achieves the desired objects and has the following advantages: the same regulator is used for the calculation of the force required by the open-loop and closed-loop servocontrol, implementing the same management of the non-linearities in both situations, making it possible to better manage the saturations and the asymmetric and non-stationary nature of the engine, the calculation of the force required by the servo control takes account of the state of the supervisor and the proximity to the limit speed. , which allows a better grip by the regulator and a more intuitive response thereof vis-à-vis the felt of the driver, 25 -suite acceleration of the driver by pressing the accelerator pedal, the solution allows the arrival at the set speed by reducing the overtaking without modifying the parameters of the corrector or the response of the vehicle vis-à-vis external disturbances eures (gale, change of slope ...), REN094FR PJ8803 depot DA 15 - in the case of the variant embodiment with a time-dependent filtering parameter, the filter can adapt permanently to the requested setpoint changes by the driver, while ensuring the convergence and monotony of the reference speed; it allows a perfect continuity of the control when closing the control loop, it adapts very well to structures of proportional-integral type (PI), common in speed limiters.

Claims (14)

Revendications1. A method for limiting the speed (VVéh) of a motor vehicle comprising a step of setting a maximum speed setpoint (\ lems) not to be exceeded by the vehicle, a step of regulating the speed (VVén) of the vehicle comprising calculating a force demanded by servocontrol (Ffeg) from a reference speed (Vref) and then transmitting it to the engine (1), characterized in that it comprises a step of calculating the reference speed (Vref) as a function of the set speed (V0or, $) and the actual speed (VVh) of the vehicle. 2. Method of limiting the speed (Vvéh) of a motor vehicle according to claim 1, characterized in that the step of calculating the reference speed (Vref) is furthermore function of the state of the supervisor. 3. A method for limiting the speed (Vvéh) of a motor vehicle according to claim 1 or 2, characterized in that the step of calculating the reference speed (Vref) compensates for one or more transmission zeros generated (s). ) by the regulation step. 20 4. Method for limiting the speed (Vvéh) of a motor vehicle according to claim 3, characterized in that the step of calculating the reference speed (Vref) comprises a filtering between the set speed (Veens) and the reference velocity (Vref), which introduces as a phase delay between these values which offsets the effect of the regulator. 5. A method for limiting the speed (Vvéh) of a motor vehicle according to one of the preceding claims, characterized in that the step of regulating the speed (Vvéh) of the vehicle is based on a correction of 15REN094FR PJ8803 depot DA 17 Proportional Integral (PI) type defined by proportional (kp) and integral (k;) gains. 6. A method for limiting the speed (Vvéh) of a motor vehicle according to claims 4 and 5, characterized in that the step of calculating the reference speed (Vref) comprises a filtering between the set speed (V .) and the reference velocity (Vref) determined by the transfer function F (s) defined by the following equation: F (s) = [(cf (to) kps) / k; +1] / [kps / k; +1] where cf (t) is a function which depends on the variation of the velocity and cf (to) = Cf (IVO) = Cf (Vcons - Vvéh (to)), to being the initial moment of the beginning operation of the closed-loop control process. 7. Process for limiting the speed (Vvéh) of a motor vehicle according to the preceding claim, characterized in that the filtering function F (s) is determined by the function cf at the value [cf (OVo)] that it has at initial time (to) whose value is lower if the difference in speed at the initial time (AV0) is greater. 8. A method for limiting the speed (Vvéh) of a motor vehicle according to one of the preceding claims, characterized in that the limiting method comprises three modes of operation, a first mode in which it is inactive, a second mode in which it is active but in which the motor is always controlled by the force demanded by the driver (u = Fcond) and a third mode in which it is active and in which the motor is controlled by the force required by the servocontrol ( u = Freg). 9. A method for limiting the speed (Vvéh) of a motor vehicle according to the preceding claim, characterized in that the step of calculating the PJ8803 deposition DA 18 reference speed (Vref) in the second operating mode is determined by the following equation: Vref (t) = Vvh (t) + [Vcons - Vvh (t)] 'r cf (t) where the filter parameter cf (t) is a function which depends on the variation of the velocity and is expressed as cf (t) = cf (OV (t)). 10. A method for limiting the speed (VVéh) of a motor vehicle according to the preceding claim, characterized in that the filter parameter cf (t) can be constant during the implementation of the third mode or variable depending time. 10 11. Apparatus for limiting the speed (Vvéh) of a motor vehicle comprising a means of capturing a maximum target speed (Voons) not to be exceeded by the vehicle, a regulating block (5) which calculates as an output a servo force value (Freg) for the motor (1) of the motor vehicle from a reference speed (Vref), characterized in that it comprises at least one calculation block (2, 3) a reference speed (Vref) as a function of the target speed (Vcons) and the actual speed (Vvéh) of the vehicle, implementing the method of speed limitation according to one of the preceding claims. 12. Device for limiting the speed (Vvéh) of a motor vehicle according to the preceding claim, characterized in that it comprises a supervision block (6), which comprises a first sub-block (8) consisting in determining the activation or not of the device and a second sub-block (7) of determining the target force to be transmitted to the engine (1) by arbitrating between the force requested by the driver (Foond) and that (Ffeg) calculated by the servo device.5REN094EN PJ8803 deposit DA 19 13. Apparatus for limiting the speed (Väéh) of a motor vehicle according to claim 11 or 12, characterized in that the regulating block (5) consists of a Proportional-Integral (PI) corrector, whose dynamics introduces a transmission zero in the setpoint tracking and in that the reference velocity calculation block (2, 3) (Vfef) includes a filter which compensates for the time offset introduced by the control block (5). 14. Motor vehicle characterized in that it comprises a speed limitation device according to one of claims 11 to 13.