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

Abstract

A test procedure 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 a real position defined by a command determined according to a law of evolution of a braking pressure as a function of a theoretical actuator position.This process includes 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 is determined in the hydraulic braking system, then a position correction value is determined representing the difference between the chosen braking pressure and the determined actual braking pressure, and 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 FOLLOWING BRAKE 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 intended to partially drive land vehicles installed on roller test benches, and more specifically to tests by such driving robots of the following of braking instructions intended for the braking systems of these vehicles. State of the art

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

[0003] For example, such driving robots, which are described in particular 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 depressment 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 preliminary learning phase, is very precise. However, due to the vibrations experienced by the driving robot, its position (and therefore that of its braking actuator) may shift very slightly within the vehicle during a test. Consequently, the position of its actuator may no longer precisely correspond to the theoretical actuator position that, according to the law, corresponds to the braking pressure required by a braking command. In other words, the law is no longer perfectly adapted to the vehicle being tested. As a result, current driving robots cannot accurately track braking commands, particularly during speed regulation phases of the vehicle being tested. A fortiori, they are even less able to perform a optimal path tracking in the presence of significant deceleration gradients impacting validation and energy optimization results.

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

[0007] In particular, it proposes for this purpose a test method intended to be implemented in a driving robot comprising an actuator suitable for 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 a real position defined during a test by an actuator command determined according to 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 includes 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 vehicle speed becomes non-zero, each actuator command is determined by adding this determined position correction value to a theoretical actuator position corresponding in law to a required braking pressure.

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

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

[0011] - in its stage, when the difference between the chosen braking pressure and the if the actual braking 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 stage, when the difference between the chosen braking pressure and the if the actual braking 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 The theoretical actuator position is a percentage of a maximum displacement; the chosen increment can be between 0.01% and 0.05%.

[0014] The invention also proposes a computer program product comprising a instruction set which, when executed by processing means, is suitable for implementing a test method of the type presented above, in a driving robot comprising an actuator suitable for 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 according to a law of evolution of a braking pressure as a function of a theoretical actuator position, to test the following of braking instructions in the vehicle.

[0015] The invention also proposes a test device intended to equip a driving robot comprising an actuator suitable for 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 a real position defined during a test by an actuator command determined according to a law of evolution of a braking pressure as a function of a theoretical actuator position.

[0016] This test device is characterized in that it comprises at least one processor and at least one memory arranged to perform the operations consisting, during a test, when the vehicle has a zero speed caused by a chosen braking pressure, of 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 vehicle speed becomes non-zero, of determining each actuator command by adding this determined position correction value to a theoretical actuator position corresponding in 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 a real position defined during a test by an actuator command determined according to a law of evolution of a braking pressure as a function of a theoretical actuator position, and a test device of the type of that presented above.

[0018] For example, this actuator may be designed to be mechanically coupled to a vehicle brake pedal that controls the braking pressure of the hydraulic braking system. In this case, this actuator may include an electrically controlled cylinder.

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

[0020] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0021] [Fig-1] schematically and functionally illustrates an example of the realization 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 example of an embodiment of a robot computer comprising an example of an 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 an RC driving robot installed in a land vehicle V, itself installed on a roller test bench BE, of the following of braking instructions cf intended for the braking system SF of this land vehicle V.

[0025] In what follows, the land vehicle V is considered, by way of non-limiting example, to be of the automobile type. For example, it is a car. However, the invention is not limited to this type of land vehicle. It relates 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 commercial vehicles, motorhomes, minibuses, coaches, trucks, motorcycles, road maintenance vehicles, construction equipment, agricultural machinery, recreational vehicles (snowmobiles, go-karts), tracked vehicles, trains, and trams, for example.

[0026] Furthermore, in what follows, by way of non-limiting example, the (land) vehicle V comprises a powertrain with an all-electric drive unit (or PDU) (and therefore whose propulsion is provided exclusively by at least one electric motor). However, the PDU could be of the hybrid (thermal and electric) type or purely thermal.

[0027] A roller test bench BE is very schematically represented on [Fig. 1] on which is installed a (terrestrial) vehicle V comprising a braking system SF and in which is installed a driving robot RC according to the invention comprising a test device DT according to the invention and charged with testing the following 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 vehicle V which is intended to accommodate a driver.

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

[0030] It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the AF actuator is coupled, via a coupling means MC (such as a flange), to the vehicle V's brake pedal PF, 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 depressment) constitutes a braking command cf for the hydraulic braking system SF, representing the braking pressure pfs that it must internally establish. In this case, the actual position pafr of the AF actuator defines the percentage of depressment of the brake pedal PF.

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

[0032] For example, and as illustrated non-limitingly in [Fig. 1], the AF actuator may include 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) that represents the actual position pafr of the AF actuator (and therefore defines the braking setpoint cf).

[0033] Also, for example, and as illustrated in [Fig.1], the hydraulic braking system SF includes 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 following of the braking instructions cf intended for the braking system SF 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 PR1 processor, for example a digital signal processor (or DSP), and at least one MD memory. This test device DT can therefore be implemented 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 MD memory is random access memory (RAM) to store instructions for the implementation by the PR1 processor of at least part of the test procedure. The PR1 processor may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is defined as any type of device capable of performing at least one electrical or electronic operation.

[0037] In the example illustrated, but not limited to, Figures 1 and 2, the DT test device is part of the CR robot computer. However, this is not mandatory. Indeed, the DT test device could comprise its own dedicated computer, which is then coupled to the CR robot computer, for example.

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

[0039] Step 10-30 of the method includes a substep 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 by the test device DT), for example by the pressure sensor CP.

[0040] It will be noted that during a test, the detection of the beginning 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 should also be noted that, when the duration of the stopping phase during which the vehicle speed 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 that 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 selected braking pressure pfc (which is applied constantly and temporarily to immobilize the vehicle V on the roller test bench BE) can be between 8 bar and 15 bar. As an example, this selected braking pressure pfc can be equal to 10 bar.

[0043] Step 10-30 of the process also includes a substep 20 in which a position correction value vcp is determined (for example, by the test device DT), which is representative of the difference dp between (always when the velocity vv is zero). the chosen 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 includes a substep 30 in which, when the vehicle speed vv of V becomes non-zero, each actuator command ca for the AF actuator is determined (for example, by the test device DT) by adding the determined position correction value vcp to the theoretical actuator position pat that corresponds in the law (or model) to the required braking pressure pfs, i.e., ca = pat + vcp. This required braking pressure pfs is the one that 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 tracking is to be tested.

[0045] If during the test the speed vv returns to zero, it means that a new stopping phase occurs 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 vehicle V, it is now possible to calibrate in real time the law (or model) governing the evolution of braking pressure as a function of the theoretical actuator position in order to adapt the braking control cf according to the vehicle V under test. This allows the law (or model) to converge towards the actual response of vehicle V. This ensures precise monitoring of the braking commands cf, particularly during vehicle V homologation cycles, without error, wheel lock-up, or overshoot during these real-world situations, even in the presence of very slight movements of the RC driving robot within vehicle V. In other words, the invention optimizes the regulation of the monitoring of the braking commands cf performed by the RC driving robot, especially during the deceleration phases of vehicle V.

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

[0048] It should be noted that the invention has other advantages as well:

[0049] - transparency for the user of the RC driving robot, due to its high speed of execution that does not significantly increase the test duration and has no impact on the user,

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

[0051] - an absence of parameterization which facilitates a rapid implementation time, for to achieve an improvement in the quality of monitoring speed instructions,

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

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

[0054] For example, in substep 20 of step 10-30, when the difference dp between the selected brake pressure pfc and the determined actual brake pressure pfr is negative (i.e., (pfc - pfr) < 0), one (for example, 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 brake pedal displacement PF by the AF actuator will be greater and consequently the brake pressure pf will be increased.

[0055] Also, for example, in substep 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 (for example, 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 movement of the brake pedal PF by the AF actuator will be less and consequently the braking pressure pf will be reduced.

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

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

[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 type of electronic circuits (or hardware), such as for example the PR1 processor, is suitable for implementing the test method described above to test the following of the braking instructions cf in the vehicle V (installed on the BE roller test bench), by means of the RC driving robot.

Claims

Demands

1. A test method for a driving robot (RC) comprising an actuator (AF) adapted to act 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 according to 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 zero velocity caused by a chosen braking pressure, an actual braking pressure is determined 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 (V) velocity becomes non-zero,Each actuator command is determined by adding the specified position correction value to a theoretical actuator position corresponding, in the specified 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 chosen braking pressure and the determined actual braking pressure is negative, said position correction value to be used is determined by subtracting a chosen increment from a previous position correction value.

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

4. 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 selected increment is between 0.01% and 0.05%.

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

6. Test device (TD) for a driving robot (RC) comprising an actuator (AF) adapted to act 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 according to 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 perform the operations consisting, during a test, when said vehicle (V) has zero speed caused by a chosen braking pressure, of 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 temporary installation 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 according to 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 adapted to be 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 any 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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