FR2874364A1 - METHOD AND DEVICE FOR INFORMATION ON THE RETURN OF FAULT CONDITIONS FROM A VEHICLE TO THE DRIVER - Google Patents

Abstract

Method for informing the driver of a vehicle equipped with a cable brake installation, characterized in that fault states of the brake installation in function and / or - operating states or systems of the vehicle related to the brake installation and / or - operating or fault conditions of vehicle infrastructure systems necessary for the correct functioning of the brake installation, - the operating behavior of at least one vehicle brake system so that the driver perceives this as limiting the comfort and / or operation of the vehicle.

Description

Field of the invention

  The present invention relates to a method of informing the driver of a vehicle equipped with a cable brake installation. The invention also relates to a device for informing the driver of a vehicle equipped with a brake system controlled by cable.

  State of the art The cable brake systems are distinguished by the absence of mechanical or hydraulic connection between the brake pedal and the wheel brakes. The purpose of the user interface of such a system is to allow the driver to properly measure the braking force by a perception if possible usual pedal. In addition, there are different embodiments of pedal simulators. There are both passive simulators and active simulators. Passive pedal simulators are characterized by a fixed characteristic curve connecting the force to the stroke and these simulators are realized in a purely mechanical and / or hydraulic way. Active pedal simulators, on the other hand, are made in a mechanical and electronic way. An actuator such as an electric motor or an electromagnet is thus controlled by an electric control unit. Active pedal simulators are characterized by the possibility of modifying during operation the force / stroke characteristic.

  DESCRIPTION AND ADVANTAGES OF THE INVENTION The present invention relates to a method for informing the driver of a vehicle equipped with a cable-controlled brake installation, characterized in that: - fault states of the brake installation according to and / or - operating states or defects of vehicle systems related to the brake installation and / or - operating or fault conditions of vehicle infrastructure systems necessary for the correct operation of the vehicle The brake installation modifies the operating behavior of at least one vehicle brake system so that the driver perceives this as a limitation of comfort and / or operation of the vehicle.

  Thus, in practice, it shortens the time during which the driver uses a faulty or defective system and which represents a clean potential risk and a risk for other drivers.

  According to an advantageous development of the invention.

  - the brake pedal generated brake pedal response is generated in whole or in part by an active pedal simulator, and - the pedal simulator pedal behavior varies so that the driver perceives this as a limitation comfort and / or possibility of operation of the brake system.

  According to another advantageous development of the invention, the active components of the active or partially active pedal simulator generate a pulsed reaction force (202) on the brake pedal.

  According to an advantageous development of the invention, the pulsed reaction has a variable amplitude and / or frequency.

  This avoids a habituation effect of the driver. The reaction or feedback of the pedal can be appropriately influenced to different critical fault scenarios.

  According to an advantageous development of the invention for modifying the pedal behavior, a characteristic curve is modified describing the relationship between the pedal reaction force and the pedal stroke.

  According to an advantageous development of the invention - with the aid of a first sensor, the pedal stroke or a magnitude representing the pedal stroke is determined, - from the characteristic curve, the determination value is determined. of the pedal reaction force, - using a second sensor, determining the actual value or a magnitude of the pedal reaction force representing the actual value, and - using a circuit of regulation, the actual value is enslaved to the setpoint.

  Another advantageous development of the invention is characterized in that the actual value or the magnitude of the pedal reaction force representing the actual value is determined as a function of a control variable of the actuator.

  According to another advantageous development of the invention the control variable is the intensity of the electric current passing through the actuator.

  This magnitude is particularly striking from the point of view of metrology.

  According to an advantageous development of the invention the variation of the pedal pedal simulator behavior is done according to at least two stages and the selected stage depends on the critical nature of the following elements: - the state of fault of the brake installation and / or the operating or defective condition of the vehicle systems related to the brake installation, and / or - the operating or defective condition of the vehicle infrastructure systems necessary for the proper functioning of the vehicle brake installation.

  According to another advantageous development of the invention the variation of pedal behavior of the pedal simulator depends on the recognized brake situation, and the variation remains forbidden in the case of a brake situation which is critical from the point of view of safety. and - in the case of comfort braking, a greater variation is made.

  According to another advantageous development of the invention the driver's reaction to a modified characteristic of the pedal is integrated in the formation of the set value.

  According to another advantageous development of the invention, the existing brake wish is briefly neutralized before the driver's reaction and this as a function of the driver's reaction.

  This compensates for the reaction of surprise or fear of the driver noting a change in the behavior of the pedal.

  According to another advantageous development of the invention, the fault states of the brake installation are as follows: - raising of the temperature of the brake disks and / or - failure of a brake circuit and / or - reduction of the dynamic or failure of a brake actuator and / or - uncompensated energy management of the brake energy.

  According to another advantageous development of the invention, the modified operating behavior is one of the following: a limitation of the maximum speed and / or a successive reduction of the power of the motor and / or a limitation to gear ratios. predetermined speeds for the gearbox, and / or - limitation to manual selection of gear ratios in the case of automated or automatic gearboxes and / or - failure of the adaptive behavior of the spring / damper and / or - reduction systems the air conditioning power of the passenger compartment.

  These means are perceived by the driver as reducing comfort but not as critical in terms of safety.

  The invention also relates to a device for informing the driver of a vehicle equipped with a cable controlled brake system comprising detection means for recognizing: - fault conditions of the brake system and / or - operating or fault conditions of the vehicle systems related to the brake installation and / or - operating or fault conditions of the vehicle infrastructure systems necessary for the correct operation of the brake system, and including influencing means which in case of opposition: - of the brake system fault states and / or operating or fault states of the vehicle systems connected to the brake system and / or - of operating states or deficiencies of vehicle infrastructure systems necessary for the correct functioning of the brake installation, modify the operating behavior of at least one vehicle system e for the driver to perceive a reduction in comfort and / or a limitation of the operation of the vehicle.

  The advantageous developments of the method of the invention are obviously also reflected in advantageous developments of the device of the invention and vice versa.

  Drawings The present invention will be described below in more detail with the aid of exemplary embodiments shown in the accompanying drawings in which: - Figure 1 shows different characteristics of the brake pedal, - Figure 2 shows the structure Principle of a brake pedal simulator and the corresponding forces, - Figure 3 shows the basic structure of a force control circuit.

  Description of embodiments

  The present invention makes it possible to combine the functional advantages of an active pedal simulator (for example the variation of the force / stroke characteristic, the haptic behavior) with the operating safety of a passive pedal simulator. The additional functions of the active pedal simulator can be used, for example, to provide feedback messages, which are effective concerning the fault state of the system towards the driver.

  For this purpose, a combination of passive and active elements generating an actuating counterforce in an actuating installation can be used. For example, it is possible to generate a basic characteristic (which indicates, for example, the response to actuation as a function of the actuating stroke) by passive mechanisms and thus to dispose of these means even in the event of failure of the active mechanisms and their control unit or their power supply. Thus, in the event of failure of the active mechanisms or of their control unit or of their power supply, the user will be able to actuate the brake in safety and with a control that assumes a sufficiently good manner.

  The active mechanisms make it possible to modify the characteristic of the pedal in the direction of an increase in comfort or as a feedback signal installation or reaction function for the operating states of the fault states of the brake or brake system. other systems (eg the vehicle system cooperating with the brake system or vehicle infrastructure systems necessary for the correct operation of the brake system.

  To increase comfort, it is possible to modify the behavior of the pedal according to the driving style of the driver, the settings of other vehicle systems such as, for example, the gearbox or the chassis, the environmental condition such as for example a wet pavement or the presence of snow, the vehicle parameter such as for example the state of charge or the speed of movement of the vehicle or any combination of such influence quantities.

  In addition, the active mechanisms make it possible to modify the characteristic curve of the pedal in the direction of information for the driver concerning the operating state or the incidents or the state of defect of the brakes.

  The modification is done for example according to the states of defects such as for example an increase in the temperature of the brake discs, the attenuation (the decrease of the coefficient of friction between the brake lining and the brake disc), the failure of a brake circuit, reduction of the dynamics of at least one brake actuator or unbalanced management of the external energy.

  The feedback haptic information increases the perception of the fault by the driver. In practice, it can thus have a reduction in the time during which the driver uses a faulty system and which thus constitutes a clean potential risk and endangering other drivers.

  In the case of a cable brake installation, the application of a traction force on the brake jaws is no longer carried out directly by the brake pedal, but by means of one or more electrohydraulic actuators or electromechanical. In such a system, the brake pedal is no longer directly connected mechanically or hydraulically to the wheel brakes. Actuation of the brake pedal serves only as input to the electronic brake control units.

  To allow the user to operate the brakes safely in a well-dosed manner, a reaction is required when actuating. While passive pedal simulators have a fixed force / stroke characteristic, in the case of the active pedal simulator, the force / stroke characteristic can be changed during operation. However, in the case of a purely active pedal simulator, the mechanical-electronic actuator and the electronic control unit must be able to absorb fault tolerances in order to keep the system in operation after the occurrence of a fault. . This corresponds to an implementation of considerable technical and financial means.

  Therefore, for a pedal simulator, it is interesting to have in particular a combination of active and passive mechanisms to generate the response to the actuation.

  For this, Figure 1 shows different pedal characteristics. On the abscissa, the pedal stroke is shown and in order the force exerted on the pedal. The basic characteristic (for example the characteristic A in FIG. 1) generated by passive mechanisms is chosen to allow safety actuation sufficiently well dosed by the user. Additional active mechanisms make it possible to adjust the characteristic of the pedal in the direction of an increase of the comfort of service and of a user information (for example the characteristics B and C in FIG. 1) and this as a function of : - the actuator characteristic of the driver (adaptive brake pedal), - the driver settings (for example the selection of different characteristic curves such as for an automatic gearbox, air suspension, damping) ..., - the static and dynamic parameters of the vehicle (such as the load, the speed of movement, etc.), - the environmental conditions (eg wet pavement, snow, etc.), - the operating status of other systems which directly contribute to the deceleration of the vehicle such as, for example, a generator with recuperative delay, - the operating status of other systems which participate indirectly the deceleration of the vehicle such as, for example, a stepless automatic continuous transmission, making it possible to regulate the precise use of the engine traction torque.

  According to another embodiment, one can adapt the characteristic of the pedal so as to interpret as a function of the desired delay behavior of the vehicle.

  The method according to the invention provides for a modification of the characteristic of the pedal for information of the driver concerning the operating mode and the state of defect of the brake installation and that according to the following elements: - operating state of the brake system or brake system (eg attenuation by varying the coefficient of adhesion), - the condition of the assisted brake and the chassis dynamics control systems (eg ACC, ABS, ASR or regulation ESP), - fault state of the brake system (brake actuator failure, brake circuit failure), - operating and fault condition of vehicle infrastructure systems such as the network embedded electrical or communication systems.

  Firstly, defects in the vehicle infrastructure systems mentioned above have no direct effect on the perception function of the brake system by the driver because such systems are generally redundant for safety reasons . Failure of a channel of such a redundant system eliminates redundancy and thus increases the potential operational safety of the system, but in general there is no reduction in average braking effect. In this case, the driver may see the need to limit a repair shop due to a modified pedal behavior that is much less comfortable. Moreover, we are looking for a modification whose amplitude depends on the importance of the erroneous behavior of the system: the more the systematic and critical defect effect and the more dominant will be the modifications of the characteristic of the accelerator pedal. This makes it possible to force in the event of a very critical state of defect, a passage in the workshop, very quickly after the arrival of the fault of the error. On the one hand, it realizes the modification of the characteristic of the pedal not in a continuous but discontinuous manner (brutal way) to avoid a customary effect of the driver at the modified interface vis-à-vis the brake system. In addition, the modification of the characteristic of the pedal produces an additional safety risk such as that which could for example result from a reduction of the brake force from a certain incident characteristic. A preferred embodiment is to convert the characteristic of the brake pedal only during braking, with a desire for power, low (comfort braking) but to convert however not in case of emergency braking. As a result, an adaptive adaptation of the variation of the brake pedal with respect to the brake situation. A modification of the characteristic of the pedal can be done in the case of a static braking (for example as a result of a printing of a brake operating with difficulty) or dynamically by pulses comprising different forms of signals, opposite, for different frequencies and amplitudes.

  According to another embodiment, the driver's reaction related to the variation of the characteristic of the pedal (for example the reduction of the force applied to the pedal or the pedal stroke) can be integrated into the determination of the braking effect actually desired. If, for example, because of a fault signal the driver is frightened and reduces or increases (unconsciously) his actual desired behavior, the system will compensate for this influence for example by a brief neutralization of the brake demand existing before this shock situation. This is done using a driver model obtained by analyzing the man / machine interface at the brake pedal.

  If already in a faultless operating state of the brake system, the reaction of the pedal generated by passive mechanisms is completed by a reaction generated by active mechanisms, in case of failure of the active mechanisms and / or their system energy supply or supply of information, the pedestal will automatically have for the driver a perceptible reaction unequivocal.

  The mechanical-electronic actuator and the electronic control unit do not have to be designed to tolerate faults, because in the event of failure of the active mechanisms, there will always be a sufficient actuation reaction. Will then be valid the basic characteristic generated by the passive mechanisms. However, it must be ensured that in the event of a fault in the mechanical-electronic actuator or in the electronic control unit, the basic passive characteristic curve will not be influenced by corresponding alternating effects. The mechanical-electronic actuator and the electronic control unit must thus be designed to allow the safe recognition of a fault for which the actuator will be cut and thus the basic characteristic curve realized in a passive way of the pedal simulator. will not be influenced.

  Regardless of the nature of application of an actuation reaction, at least two sensors are required to unequivocally and correctly determine the intensity of the actuation. In case of significant deviation between the two sensor signals, the operation of the active pedal simulator can be cut off.

  The pedal simulator according to the invention is characterized in that at least one sensor detects the actuating stroke or a magnitude representing the actuating stroke and in that at least one sensor detects the actuating force or an actuating force. magnitude representing the actuating force. The force measurement may alternatively include the total force resulting from the active and passive return or only the partial force of the active return. If the measurement of the force is limited to that of the reaction of the active return, it is necessary to determine the total force, add the passive restoring force determined according to the force-stroke characteristic of the passive return mechanism. If the active reaction is applied by an electric motor it is not necessary to directly measure the counterforce but it can be calculated from the resulting motor current. The electronic control unit can thus determine the actual value of the active force of the pedal. By integrating other current information, characteristic variables and operating parameters of the brakes, as well as the vehicle and the environment, the control unit can determine in a function block called setpoint generator a current setpoint value. the actuating force. In the basic structure shown in FIG. 3, the force regulation circuit is characterized by the following means: 300 = setpoint generator, 301 = regulator, 302 = actuator or regulation path.

  As input variables, there is the travel of the pedal 303, the driving situation and the state of the vehicle 304. The difference generator 305 forms the difference between: the set value supplied by the block 300 for the counter-access to the pedal, and - the reaction of the active pedal, obtained at the output of the block 302 and available as an antagonistic pedal force, active or measured.

  The expression, pedal reaction, refers to the force applied by the actuator and opposes the force exerted by the driver's foot on the brake pedal.

  So that in case of difference between the setpoint and the actual value, this difference can be compensated by at least one actuator. The actuator may be of electromechanical, electromagnetic, electrohydraulic or electropneumatic form.

  According to another embodiment, depending on the defects of the brake system or other systems such as for example vehicle systems related to the installation of brake or vehicle infrastructure systems necessary for the proper functioning of the system. brake system, the behavior of other vehicle systems such as engine or transmission control or comfort systems can be changed. Measurements can be envisaged such as limitation of the maximum speed, successive reduction of the power of the engine, limitation to a certain level of operation of the gearbox, limitation to the manual selection of the driving level ( in automated or automatic gearboxes), the adaptive behavior of the suspension and damping systems or a reduction of the power of the indoor air-conditioning system.

  Such possibilities of intervention may be in combination with a modification of the pedal characteristic while also presenting for pedal sensing vehicles a good possibility for additional driving information concerning the signal lights required by the pedal. legislation.

  The structure of the pedal simulator of FIG. 2 corresponds to the following characteristics: = actuating force, 201 = passive reaction, and 202 = active reaction, 203 = characterizing the actuator, which can be, for example, an electromagnetic actuator.

Claims (15)

  1) A method for informing the driver of a vehicle equipped with a cable brake system, characterized in that - fault states of the brake installation in function and / or - operating states or systems of the vehicle related to the brake installation and / or - operating or fault conditions of vehicle infrastructure systems necessary for the correct functioning of the brake system, - the operating behavior of at least a vehicle brake system so that the driver perceives this as a limitation of comfort and / or operation of the vehicle.   2) Method according to claim 1, characterized in that - the reaction (201, 202) generated by the brake cable system on the brake pedal is generated in whole or in part by an active pedal simulator (203), and - the pedal behavior of the pedal simulator (203) varies so that the driver perceives this as a limitation of comfort and / or possibility of operation of the brake installation.   3) Method according to claim 2, characterized in that the active components (203) of the active or partially active pedal simulator generate a pulsed reaction force (202) on the brake pedal.   4) Method according to claim 3, characterized in that the pulsed reaction (202) has a variable amplitude and / or frequency.   5) Method according to claim 2, characterized in that to modify the pedal behavior, modifying a characteristic curve describing the relationship between the reaction force of the pedal and the pedal stroke.   6) Method according to claim 5, characterized in that - with the aid of a first sensor, the pedal stroke or a magnitude representing the pedal stroke is determined, - from the characteristic curve, the a reference value of the pedal reaction force, using a second sensor, determining the actual value or a magnitude of the pedal reaction force representing the actual value, and - using a control circuit, the actual value is enslaved to the setpoint value.   7) Method according to claim 6, characterized in that one determines the actual value or the magnitude of the pedal reaction force representing the actual value as a function of a control variable of the actuator.   8) Method according to claim 7, characterized in that the control variable is the intensity of the electric current flowing in the actuator.   9) Method according to claim 2, characterized in that the variation of the pedal pedal simulator behavior is made according to at least two stages and the selected stage depends on the critical nature of the following elements: - the state of defect of the brake installation and / or, the operating or defective condition of the vehicle systems related to the brake installation, and / or - the operating or defective condition of the vehicle infrastructure systems required for operation correct brake installation.   10) Method according to claim 2, characterized in that the variation of the pedal behavior of the pedal simulator depends on the recognized brake situation, and - the variation remains prohibited in the case of a critical brake situation from the point of view safety, and - in the case of comfort braking, a greater variation is made.   11) Method according to claim 6, characterized in that the driver reaction to a modified characteristic of the pedal is integrated in the formation of the set value.   12) A method according to claim 11, characterized in that one briefly cancels the existing brake wish before the reaction of the driver and that depending on the reaction of the driver.   13) Method according to claim 1, characterized in that the fault states of the brake system are as follows: - raising of the temperature of the brake disks and / or - failure of a brake circuit and / or - reducing the dynamics or failure of a brake actuator and / or - uncompensated energy management of the brake energy.   14) Method according to claim 1, characterized in that the modified operating behavior is one of the following: - a limitation of the maximum speed and / or - a successive reduction of the engine power and / or - a limitation to predetermined speed ratios for the gearbox, and / or - limitation to manual gear selection in the case of automatic or automatic gearboxes and / or - failure of the adaptive behavior of the spring / damper systems and / or - reduction of the air conditioning power of the passenger compartment.   15) Device for informing the driver of a vehicle equipped with a cable-controlled brake system comprising detection means making it possible to recognize: - fault states of the brake system and / or - operating states or fault of the vehicle systems connected to the brake system and / or - the operating or fault conditions of the vehicle infrastructure systems necessary for the correct operation of the brake system, as well as the means of influence which in case of opposition: - of the brake system fault states and / or - of the operating or fault conditions of the vehicle systems related to the brake installation and / or operating conditions operation or failure of vehicle infrastructure systems necessary for the correct operation of the brake installation, modify the operating behavior of at least one vehicle system for the driver to perceive oive a reduction of comfort and / or a limitation of the operation of the vehicle.