TEST OF MONITORING BRAKING INSTRUCTIONS IN A LAND VEHICLE INSTALLED ON A BENCH, BY A DRIVING ROBOT

Abstract

A test method is implemented in a driving robot comprising an actuator acting on a braking pressure of a land vehicle and installed on a roller test bench as a function of an actual position defined by a command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position.This method comprises a step (10-30) in which, during a test, when the vehicle speed is zero due to a chosen braking pressure, an actual braking pressure in the hydraulic braking system is determined, then a position correction value representative of a difference between the chosen braking pressure and the determined actual braking pressure, then, when the vehicle speed becomes non-zero, each command is determined by adding this determined position correction value to a theoretical actuator position corresponding to a required braking pressure. Figure 3.

Description

Title of the invention: TEST FOR MONITORING BRAKING INSTRUCTIONS IN AN INSTALLED LAND VEHICLE ON A BENCH, BY A DRIVING ROBOT Technical field of the invention

[0001] The invention relates to driving robots which are intended to partially drive land vehicles installed on roller test benches, and more precisely to tests by such driving robots of the monitoring of braking instructions intended for the braking systems of these vehicles. State of the art

[0002] Some driving robots comprise at least one actuator suitable for being mechanically coupled to a brake pedal of a land vehicle which controls the braking pressure of the hydraulic braking system. It will be noted that such driving robots may also sometimes comprise another actuator suitable for being mechanically coupled to the accelerator pedal of the (land) vehicle and / or another actuator suitable for being mechanically coupled to the gearshift lever of the vehicle.

[0003] For example, such driving robots, which are notably described in patent document FR-A1 3135942, can be arranged to test automobile-type vehicles installed on roller test benches.

[0004] When the actuator is mechanically coupled to a brake pedal, its action on the braking pressure of the hydraulic braking system is a function of the actual position in which it is placed, which defines the percentage of depression of the brake pedal and which is defined during a test by an actuator command determined according to a law (or a model) of evolution of the braking pressure as a function of the theoretical actuator position.

[0005] This law (or model), generally obtained during a prior learning phase, is very precise. However, due to the vibrations experienced by the driving robot, the position of the latter (and therefore of its braking actuator) may move very slightly in the vehicle during a test, and therefore the position in which its actuator is placed may no longer correspond precisely to the theoretical actuator position which corresponds in the law to the braking pressure required by a braking instruction. In other words, the law is no longer perfectly adapted to the vehicle tested. Consequently, current driving robots do not allow precise monitoring of braking instructions, in particular during phases of speed regulation of the vehicle tested. A fortiori, they can even less perform a optimal route tracking in the presence of significant deceleration gradients impacting the validation and energy optimization results.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] It proposes in particular for this purpose a test method intended to be implemented in a driving robot comprising an actuator capable of acting on a braking pressure of a hydraulic braking system of a land vehicle and installed on a roller test bench as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position.

[0008] This test method is characterized by the fact that it comprises a step in which, during a test, when the vehicle has a zero speed caused by a chosen braking pressure, an actual braking pressure is determined in the hydraulic braking system, then a position correction value representative of a difference between the chosen braking pressure and the determined actual braking pressure, then, when the speed of the vehicle becomes non-zero, each actuator command is determined by adding this determined position correction value to a theoretical actuator position corresponding in the law to a required braking pressure.

[0009] Thanks to the invention, it is now possible to recalibrate the law (or the model) in real time in order to adapt the braking control according to the vehicle tested, which allows the law (or model) to converge towards the actual response of the vehicle and therefore to ensure precise monitoring of the braking instructions.

[0010] The test method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0011] - in its step, when the difference between the chosen braking pressure and the actual brake pressure determined is negative, the position correction value to be used can be determined by subtracting a chosen increment from a previous position correction value;

[0012] - in its step, when the difference between the chosen braking pressure and the actual brake pressure determined is positive, the position correction value to be used can be determined by adding a chosen increment to a previous position correction value;

[0013] - in the presence of one of the two previous options, in its step, when the theoretical actuator position is a percentage of maximum displacement, the chosen increment can be between 0.01% and 0.05%.

[0014] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a test method of the type presented above, in a driving robot comprising an actuator capable of acting on a braking pressure of a hydraulic braking system of a land vehicle and installed on a roller test bench as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, to test the monitoring of braking instructions in the vehicle.

[0015] The invention also proposes a test device intended to equip a driving robot comprising an actuator capable of acting on a braking pressure of a hydraulic braking system of a land vehicle and installed on a roller test bench as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position.

[0016] This test 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, during a test, when the vehicle has a zero speed caused by a chosen braking pressure, in determining an actual braking pressure in the hydraulic braking system, then a position correction value representative of a difference between the chosen braking pressure and the determined actual braking pressure, then, when the speed of the vehicle becomes non-zero, in determining each actuator command by adding this determined position correction value to a theoretical actuator position corresponding in the law to a required braking pressure.

[0017] The invention also proposes a driving robot, on the one hand, suitable for being temporarily installed in a land vehicle, installed on a roller test bench and comprising a hydraulic braking system, and, on the other hand, comprising an actuator suitable for acting on a braking pressure of the hydraulic braking system as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, and a test device of the type presented above.

[0018] For example, this actuator may be capable of being mechanically coupled to a brake pedal of the vehicle controlling the braking pressure of the hydraulic braking system. In this case, this actuator may comprise an electrically controlled cylinder.

[0019] Also for example, this driving robot can be arranged to test a vehicle of the automobile type. Brief description of the figures

[0020] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0021] [Fig-1] schematically and functionally illustrates an example of the embodiment of a land vehicle, installed on a roller test bench and comprising a hydraulic braking system associated with a brake pedal to which is coupled an actuator of an example of a driving robot comprising a robot computer and a test device according to the invention,

[0022] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a robot calculator comprising an exemplary embodiment of a test device according to the invention, and

[0023] [Fig.3] schematically illustrates an example of an algorithm implementing a test method according to the invention. Detailed description of the invention

[0024] The invention aims in particular to propose a test method, and an associated test device DT, intended to allow a test by a driving robot RC installed in a land vehicle V, itself installed on a roller test bench BE, of the monitoring of braking instructions cf intended for the braking system SF of this land vehicle V.

[0025] In the following, it is considered, by way of non-limiting example, that the land vehicle V is of the automobile type. This is for example a car. But the invention is not limited to this type of land vehicle. It relates in fact to any type of land vehicle comprising a braking system whose braking pressure can be controlled by a brake pedal (or lever). Thus, it also relates to utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), tracked vehicles, trains and trams, for example.

[0026] Furthermore, it is considered in the following, by way of non-limiting example, that the (land) vehicle V comprises a transmission chain with a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by at least one electric motor). But the GMP could be of the hybrid (thermal and electric) or purely thermal type.

[0027] [Fig. 1] shows very schematically a roller test bench BE on which a (land) vehicle V is installed comprising a braking system SF and in which a driving robot RC according to the invention is installed comprising a test device DT according to the invention and responsible for testing the monitoring of braking instructions cf intended for the braking system SF.

[0028] For example, this RC driving robot can be fixedly and temporarily attached to the driver's seat of the vehicle V which is intended to accommodate a driver.

[0029] As illustrated, the driving robot RC comprises at least one actuator AF which is arranged during a test of the vehicle V so as to act on a (real) braking pressure pfr of the hydraulic braking system SF as a function of the real position pafr in which it is placed. This real position pafr is defined by an actuator command ca which is determined as a function of a law (or a model) of evolution of the braking pressure as a function of a theoretical actuator position. This actuator command ca is representative of a braking setpoint cf which is to be monitored by means of the test.

[0030] It will be noted that in the example illustrated non-limitingly in [Fig. 1] the actuator AF is coupled, via a coupling means MC (such as for example a flange), to the brake pedal PF of the vehicle V, which is itself coupled to the hydraulic braking system SF. It will be understood that the actual position of this brake pedal PF (for example defined by its percentage of depression) constitutes for the hydraulic braking system SF a braking setpoint cf which represents the braking pressure pfs that it must establish internally. In this case, the actual position pafr of the actuator AF defines the percentage of depression of the brake pedal PF.

[0031] In an alternative embodiment, the actuator AF could be coupled, via a coupling means, to a brake lever of the vehicle to be tested, which is itself coupled to the hydraulic braking system SF.

[0032] For example, and as illustrated non-limitingly in [Fig.l], the actuator AF may comprise an electrically controlled cylinder. In this case, the piston of the cylinder acts on the brake pedal PF, and it is the position of this piston (defined by its current movement) which represents the actual position pafr of the actuator AF (and therefore defines the braking setpoint cf).

[0033] Also for example, and as illustrated in [Fig.l], the hydraulic braking system SF comprises a pressure sensor CP responsible for measuring, for example periodically, its actual braking pressure pfr.

[0034] As mentioned above, the invention proposes in particular a test method intended to allow the RC driving robot to test the monitoring of the braking instructions cf intended for the SF braking system of the vehicle V.

[0035] This (test) method can be implemented at least partially by the test device DT (illustrated at least partially in Figures 1 and 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 test device DT 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 could be a microcontroller.

[0036] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the test 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.

[0037] In the example illustrated non-limitingly in Figures 1 and 2, the test device DT is part of the robot computer CR. But this is not obligatory. Indeed, the test device DT could comprise its own dedicated computer, which is then coupled to the robot computer CR, for example.

[0038] As illustrated non-limitingly in [Fig. 3], the (test) method, according to the invention, comprises a step 10-30 which is implemented each time that a test of the monitoring of the braking instructions cf in the vehicle V (installed on the roller test bench BE) must be carried out by means of the driving robot RC (installed in this vehicle V).

[0039] Step 10-30 of the method comprises a sub-step 10 in which, during a test, when the vehicle V has a zero speed vv caused by a chosen braking pressure pfc, the actual braking pressure pfr in the hydraulic braking system SF is determined (for example the test device DT), for example from the pressure sensor CP.

[0040] It will be noted that during a test, the detection of the start and end of a stopping phase (during which the speed vv is zero), can either be determined (for example by the test device DT by analysis of the speed vv (for example in sub-step 10), or signaled by a computer of the vehicle V.

[0041] It will also be noted that, when the duration of the stopping phase during which the speed vv of the vehicle V remains zero during a test, several actual braking pressures pfr can be measured successively by the pressure sensor CP. In this case, the actual braking pressure pfr which is determined can, for example, be equal to the average value of the actual braking pressures pfr measured successively during the stopping phase.

[0042] For example, the chosen braking pressure pfc (which is applied constantly and temporarily to immobilize the vehicle V on the roller test bench BE) can be between 8 bars and 15 bars. For example, this chosen braking pressure pfc can be equal to 10 bars.

[0043] Step 10-30 of the method also comprises a sub-step 20 in which one (for example the test device DT) determines (always when the speed vv is zero) a position correction value vcp which is representative of the difference dp between the selected braking pressure pfc and the actual braking pressure pfr determined in sub-step 10 (i.e. dp = pfc - pfr).

[0044] Step 10-30 of the method also comprises a sub-step 30 in which, when the speed vv of the vehicle V becomes non-zero, one (for example the test device DT) determines each actuator command ca for the actuator AF by adding the determined position correction value vcp to the theoretical actuator position pat which corresponds in the law (or the model) to the braking pressure pfs which is required, i.e. ca = pat + vcp. This required braking pressure pfs is that which must be temporarily established during at least part of the test in the hydraulic braking system SF, and which is representative of the braking setpoint cf whose monitoring is to be tested.

[0045] If during the test the speed vv becomes zero again, this means that a new stopping phase is occurring and therefore a new position correction value vcp is determined which will then be used to determine each new actuator command ca as soon as this stopping phase ends.

[0046] Thanks to this determination of a position correction value vcp updated during each stopping phase (vv = 0) of the vehicle V, it is now possible to recalibrate in real time the law (or the model) of evolution of the braking pressure as a function of the theoretical actuator position in order to adapt the braking command cf as a function of the vehicle V tested, which allows the law (or model) to converge towards the real response of the vehicle V. This makes it possible to ensure precise monitoring of the braking instructions cf, in particular of the homologation cycles of the vehicle V, without error, without locking of the wheels or overshoot during these life situations, including in the presence of very slight movements of the driving robot RC in the vehicle V. In other words, the invention makes it possible to optimize the regulation of the monitoring of the braking instructions cf carried out by the driving robot RC, in particular during the deceleration phases of the vehicle V.

[0047] Furthermore, thanks to the invention, the evolution of the test conditions and the evolution of the behavior of the vehicle V tested, not taken into account by the law (or model) obtained during a learning phase before the test, no longer risk inducing degradations in the monitoring of the braking instructions cf, in particular during the deceleration phases of the vehicle V.

[0048] It will be noted that the invention also has other advantages:

[0049] - transparency for the user of the RC driving robot, due to its high speed of execution which does not lead to a significant increase in the duration of the test and the absence of impact for this user,

[0050] - a lack of management of the diversity of settings depending on the vehicle's GMP tested, due to automatic pressure response detection for the vehicle tested and adapted to GMP characteristics,

[0051] - an absence of configuration which favors a rapid implementation time, for obtain a gain in quality of monitoring of speed instructions,

[0052] - robustness of the process regardless of the types of GMPs (thermal, hybrid or electric),

[0053] - use of data from GMP control synchronized on the physical placements of the PF brake pedal to identify the law (or model) to use.

[0054] For example, in sub-step 20 of step 10-30, when the difference dp between the selected braking pressure pfc and the determined actual braking pressure pfr is negative (i.e. (pfc - pfr) < 0), one (e.g. the test device DT) can determine the next position correction value to be used vcp(t+l) by subtracting a selected increment ic from the previous position correction value vcp(t), i.e. vcp(t+l) = vcp(t) + ic. Thus, the displacement of the brake pedal PF by the actuator AF will be greater and consequently the braking pressure pf will be increased.

[0055] Also for example, in sub-step 20 of step 10-30, when the difference dp between the chosen braking pressure pfc and the determined actual braking pressure pfr is positive (i.e. (pfc - pfr) > 0), one (e.g. the test device DT) can determine the next position correction value to be used vcp(t+l) by adding a chosen increment ic to the previous position correction value vcp(t), i.e. vcp(t+l) = vcp(t) - ic. Thus, the displacement of the brake pedal PF by the actuator AF will be less and consequently the braking pressure pf will be reduced.

[0056] Also for example, in sub-step 20 of step 10-30, when the theoretical actuator position pat is a percentage of a maximum displacement of the actuator AF (and therefore of the brake pedal PF), the chosen increment ic can be between 0.01% and 0.05%. For example, the chosen increment ic can be equal to 0.03%.

[0057] It will also be noted, as illustrated non-limitingly in [Fig. 2], that the robot computer CR (or the computer of the test device DT) can also comprise a mass memory MM1, in particular for storing each actual braking pressure pfr, the chosen braking pressure pfc and each required braking pressure pfs, as well as any intermediate data involved in all its calculations and processing. Furthermore, this robot computer CR (or the computer of the test device DT) can also comprise an input interface IE for receiving at least each speed vv or each possible signal of zero speed vv during a test, each possible signal of non-zero speed vv during a test, each actual braking pressure pfr, the chosen braking pressure pfc and each required braking pressure required pfs, to use them in calculations or processing, possibly after having formatted and / or demodulated and / or amplified them, in a manner known per se, by means of a PR2 digital signal processor. In addition, this robot computer CR (or the computer of the test device DT) can also include an output interface IS, in particular to deliver a message (or order) containing each actuator command ca.

[0058] 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 test method described above to test the monitoring of the braking instructions cf in the vehicle V (installed on the roller test bench BE), by means of the driving robot RC.

Claims

Claims

1. Test method for a driving robot (RC) comprising an actuator (AF) capable of acting on a braking pressure of a hydraulic braking system (SF) of a land vehicle (V) and installed on a roller test bench (BE) as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, characterized in that it comprises a step (10-30) in which, during a test, when said vehicle (V) has a zero speed caused by a chosen braking pressure, an actual braking pressure in said hydraulic braking system (SF) is determined, then a position correction value representative of a difference between said chosen braking pressure and determined actual braking pressure, then, when said vehicle speed (V) becomes non-zero,each actuator command is determined by adding said determined position correction value to a theoretical actuator position corresponding in said law to a required braking pressure.

2. A method according to claim 1, characterized in that in said step (10-30), when said difference between the selected braking pressure and the determined actual braking pressure is negative, said position correction value to be used is determined by subtracting a selected increment from a previous position correction value.

3. A method according to claim 1, characterized in that in said step (10-30), when said difference between the selected braking pressure and the determined actual braking pressure is positive, said position correction value to be used is determined by adding a selected increment to a previous position correction value.

4. A method according to claim 2 or 3, characterized in that in said step (10-30), when said theoretical actuator position is a percentage of a maximum displacement, said chosen increment is between 0.01% and 0.05%.

5. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the test method according to one of claims 1 to 4, in a driving robot (RC) comprising an actuator (AF) capable of acting on a braking pressure of a hydraulic braking system (SF) of a land vehicle (V) and installed on a roller test bench (BE) as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, to test the monitoring of braking instructions in said vehicle (V).

6. Test device (DT) for a driving robot (RC) comprising an actuator (AF) capable of acting on a braking pressure of a hydraulic braking system (SF) of a land vehicle (V) and installed on a roller test bench (BE) as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting, during a test, when said vehicle (V) has a zero speed caused by a chosen braking pressure, in determining an actual braking pressure in said hydraulic braking system (SF), then a position correction value representative of a difference between said chosen braking pressure and determined actual braking pressure, then,when said vehicle speed (V) becomes non-zero, to determine each actuator command by adding said determined position correction value to a theoretical actuator position corresponding in said law to a required braking pressure.,

7. Driving robot (RC) suitable for being temporarily installed in a land vehicle (V) and installed on a roller test bench (BE) and comprising a hydraulic braking system (SF), said driving robot (RC) comprising an actuator (AF) suitable for acting on a braking pressure of said hydraulic braking system (SF) as a function of an actual position defined during a test by an actuator command determined as a function of a law of evolution of a braking pressure as a function of a theoretical actuator position, characterized in that it further comprises a test device (DT) according to claim 6.

8. Driving robot according to claim 7, characterized in that said actuator (AF) is suitable for being mechanically coupled to a brake pedal (PF) of said vehicle (V) controlling said braking pressure of said hydraulic braking system (SF).

9.

10. Driving robot according to claim 8, characterized in that said actuator (AF) comprises an electrically controlled cylinder. Driving robot according to one of claims 7 to 9, characterized in that it is arranged to test a vehicle (V) of the automobile type.

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