FR2850069A1 - DEVICE AND METHOD FOR CONTROLLING BRAKING DURING THE STOPPING AND MOVING PHASES OF A MOTOR VEHICLE EQUIPPED WITH DECOUPLED BRAKING. - Google Patents

Abstract

The device comprises at least one sensor measuring the force applied to the wheels of the vehicle, an environmental gradient sensor, one or more means measuring the driver's braking request, an electronic control unit, setpoint calculation means of holding braking when the vehicle is stationary regardless of the gradient of the environment, means for calculating the braking setpoint when starting on a hill desired by the driver, means for calculating the braking setpoint during a downhill start desired by the driver, and braking setpoint calculation means limiting the acceleration of the vehicle, during maneuvers on a slope, possibly with the drive motor decoupled from the transmission. The electronic control unit is capable of activating each of said braking reference calculation means successively or independently of one another.

Description

i

  The present invention relates to a device and a method for controlling braking during the stopping phases. and the setting in motion of a motor vehicle equipped with decoupled braking.

  Several systems are known for managing the stopping of a vehicle by actuating a control other than that of the brake pedal. The most widespread system today is the manual parking brake or hand brake which is mechanically actuated by the driver and which comes to mechanically tighten and lock one or both rear wheels. On vehicles fitted with a conventional parking brake system, the driver is obliged, when his stop is prolonged, to manually pull his hand brake so as not to have to keep his foot continuously on the brake pedal.

  In the starting phase, in particular when the vehicle is on a slope, the driver is required to manage the setting in motion of the vehicle with the hand brake or with the vehicle service brake, if he does not want to slip too much into the slope before starting.

  During the maneuvering phase, the driver may wish to let his vehicle slide freely on a slope, but must then manage the acceleration and speed of the vehicle with the hand brake or by acting on the brake pedal. When it wants to restart, it must not only overcome the effort due to gravity, but also that due to the inertia of the moving vehicle. This brings about a management of the motor skills of the vehicle which is delicate enough to succeed in not stalling.

  Recently, more advanced parking braking systems have appeared, which replace mechanical control with electrical control. They use the same architecture as conventional parking brakes, but the mechanical action of the driver is ensured using an electric motor.

  These systems do not have automated management and the fact that they use the classic parking brake architecture limits their performance in terms of response time, maximum effort that can be achieved, and possibility of management. If they can help when starting on a slope, the management of the relaxation of the clamping forces is often done in an all or nothing manner or in any case with very little progressiveness and is often irreversible (when one begins to release, one can no longer tighten until you have finished loosening).

  Various solutions have already been devised to help the driver control his braking.

  Patent applications WO 99/39951, WO 0076818A1, and WO 10 99/38738 relate only to assistance during the vehicle standstill phases. Patent application WO 99/29531 only relates to assistance during maneuvering assistance phases. Patent applications WO 99/20921 and WO 01 / 58714A1 only relate to assistance during start-up assistance phases.

  These documents therefore only allow ad hoc assistance in specific strategies.

  The object of the invention is to improve the braking control of a vehicle by providing the driver with complete assistance for all of the stopping and setting in motion phases of the vehicle, whatever the gradient of the environment.

  The subject of the invention is also a device and a method which can be implemented not only for any succession of several phases of stopping, starting and setting in motion of the vehicle, but also for any individual phase of stopping, of starting or setting in motion of the vehicle.

  Another object of the invention is to bring together all of these functions in a single system capable of managing their interaction and their coexistence, while maintaining each function completely independent.

  The device of the invention makes it possible to control the braking of a motor vehicle during the stopping and setting in motion phases of the vehicle. The device comprises a drive motor and a transmission, an electronically controlled decoupled braking system, at least one sensor for measuring or estimating the longitudinal speed of the vehicle, at least one sensor measuring the driving force applied to the wheels of the vehicle , an environmental gradient sensor, a sensor measuring the braking request of the driver, an interface between the driver 5 and the device, and an electronic control unit. The device also includes means for calculating the braking setpoint for keeping the vehicle stationary, whatever the slope of the environment, means for calculating the braking setpoint during a hill start desired by the driver, means for calculating the braking setpoint when starting downhill desired by the driver, and means for calculating the braking setpoint limiting the acceleration of the vehicle, when maneuvering on a slope, possibly with the drive motor decoupled from the transmission. The electronic control unit is capable of activating each of said braking setpoint calculation means successively or independently of each other.

  In a preferred embodiment, the device comprises at least one longitudinal acceleration sensor.

  In an advantageous embodiment, the device comprises at least one auxiliary deceleration device.

  In a preferred embodiment, the electronic control unit manages the activation or deactivation of the various calculation means as a function of the state of the vehicle communicated by the information from the various sensors.

  The method of the invention for braking control during the stopping and setting in motion phases of a motor vehicle comprising a drive motor and a transmission, and equipped with an electronically controlled decoupled braking consists in performing successively or independently one or more of the following 30 steps: - calculating a braking setpoint for keeping the vehicle stationary; - calculate a braking instruction when the driver wishes to start uphill; calculate a braking setpoint to limit the acceleration of the vehicle during slope maneuvers, possibly with the drive motor decoupled from the transmission - calculate a braking setpoint to limit the vehicle acceleration during slope maneuvers.

  The choice of the succession of steps or of the individual step is made according to an interpretation of what the driver wants to do by processing data from sensors.

  In a preferred embodiment, the calculation of the vehicle holding braking setpoint 10 is done by respecting: Fserrage = Fpente o Fserrage Longitudinal force requested from the brake, in Newton Fpente: Longitudinal force exerted by the slope on the vehicle, in Newton In an advantageous mode of implementation, the calculation of the braking setpoint during a hill start avoiding the vehicle rolling back is done by respecting: Fserrage = Fpente- Froue o: Froue: Longitudinal driving force , in Newton Fserrage Longitudinal force requested from the brake, in Newton Fslope: Longitudinal force exerted by the slope on the vehicle, in Newton In a preferred embodiment, the calculation of the braking setpoint during a start in descent limiting the acceleration of the vehicle as a function of the slope is made by respecting: Fserrage = Fpente- kt o Fserrage Longitudinal force requested from the brake, in Newton Fpente Longitudinal force exerted by the pent e on the vehicle, in Newton k Constant coefficient, in Newton / st time elapsed since the start of the torque shift at the wheel, in s Advantageously, the constant coefficient k can be chosen equal to 0.5 In a setting mode advantageous work, the braking setpoint calculation during a slope maneuver is done by respecting: Fserrage = max [(Slope - Frou), min (Fcond, Fpente o: Fpente: Longitudinal force exerted by the slope on the vehicle, 20 in Newton Froue Longitudinal driving force, in Newton Fcond Longitudinal force requested from the driver by the brake, in Newton Other objects, characteristics and advantages of the invention will become apparent on reading the following description, given solely by way of non-limiting example, and made with reference to the accompanying drawings in which: - Figure 1 is a block diagram of a braking control device during the stopping and setting in motion phases of a motor vehicle, is lon the invention.

  - Figure 2 is a block diagram of the integration of the invention within the electronic control unit of the motor vehicle.

  - Figure 3 is a states / transitions diagram of the automaton which manages the activation or deactivation of the calculation functions.

  FIG. 1 shows the general architecture of a brake control device during the stopping and setting in motion phases of a motor vehicle. The device comprises an electronic control unit UCE 1, a decoupled braking system comprising two rear brake actuators 2 and 3, and two front brake actuators 4 and 5. The two rear brake actuators 2 and 3 are mounted on the rear wheels 6 and 7, and the two front brake actuators 4 and 5 are mounted on the front wheels 8 and 9. The device also includes a set of sensors. In the nonlimiting example shown, the device comprises two longitudinal speed sensors 10 and 11 mounted on the rear wheels 20 and 7, and two longitudinal speed sensors 12 and 13 mounted on the front wheels 8 and 9. In addition, the device comprises a gradient sensor 15 of the environment, a sensor 16 for measuring the position of the brake pedal 14, and a sensor 16a for measuring the driving force applied to the wheels of the vehicle.

  The electronic control unit UCE 1 is connected to the brake actuator 2 and to the speed sensor 10 by a data transmission cable 17, and to the brake actuator 3 and to the speed sensor 11 by a data cable data transmission 18. The electronic control unit UCE 1 is also connected to the brake actuator 4 and to the speed sensor 12 by a data transmission cable 19, and to the brake actuator 5 and to the sensor speed 13 by a data transmission cable 20. In addition, the electronic control unit UCE 1 is connected to the gradient sensor 15 by a data transmission cable 21, to the sensor 14 by a data transmission cable 22 , and to the measurement sensor 16 by a data transmission cable 23.

  FIG. 2 represents the main elements of a device of the invention integrated into the electronic control unit UCE 1. 5 input signals, emitted by all of the aforementioned sensors, are received, processed and conditioned by a processing and conditioning block 30. A controller 31 controls the activation or deactivation of the braking setpoint calculation functions. These different braking setpoint calculation functions can be implemented successively or independently. A first block 32 calculates a braking instruction for keeping the vehicle stationary, a second block 33 calculates a braking instruction for a hill start. A third block 34 calculates a braking setpoint for starting downhill, and finally, a fourth block 15 35 calculates a braking setpoint for a maneuver on a slope. Block 36 receives the outputs of blocks 32, 33, 34 and 35, as well as the activation signal from the controller 31, and calculates the braking setpoint to be applied to the vehicle. In all cases, when the driver presses the brake pedal, his request is taken into account from the moment it is greater than what the device applies.

  For the automatic maintenance, calculated by block 32, when the driver immobilizes his vehicle and that one detects his desire to keep it stationary, a brake application force is applied which allows the vehicle to remain maintained on the slope without any driver action 25. This will allow the driver to avoid any action on the brake pedal during this immobility phase. The longitudinal tightening force calculated by the block 32 will be the force necessary to compensate for the longitudinal force exerted by the slope on the vehicle, which depends on the instantaneous mass of the vehicle and the angle of the slope. Block 32 therefore calculates the clamping force using the equation: Fserrage = Fpente o: Fserrage Longitudinal force requested from the brake, in Newton Fpente: Longitudinal force exerted by the slope on the vehicle, in Newton For starting on a hill, block 33 will help the driver by acting on the brakes during the setting in motion of the vehicle. This calculation is carried out using the equation: Fserrage = Fpente- Froue o: Froue: Longitudinal driving force, in Newton Fserrage Longitudinal force requested at the brake, in Newton Fpente: Longitudinal force exerted by the slope on the vehicle, in Newton Le The aim is to gradually and linearly support the engine forces applied to the wheel in response to the driver's action on the clutch and accelerator pedals. This facilitates starting and prevents the vehicle from rolling back during this phase. This makes it possible to apply the braking forces just necessary with respect to the engine torque applied to the wheel. This avoids any feeling of restraint or premature relaxation. Indeed, the tightening instruction becomes zero when the force exerted by the slope is compensated by the driving force requested by the driver, and there is then no longer any need to apply braking, the vehicle being able to move forward. coast without retreating.

  For starting downhill, block 34 makes it possible to avoid excessively abrupt transitions, as well as the feeling that the vehicle is completely released on the descent. The calculation of the tightening setpoint is such that the braking forces are managed gradually and linearly as a function of the slope and of the motor forces applied by the driver, and carried out by means of the equation: F tightening = Slope - kt o: Fserrage Longitudinal force requested from the brake, in Newton Fslope Longitudinal force exerted by the slope on the vehicle, in Newton k: Constant coefficient, in Newton / st: time elapsed since the start of the torque shift at the wheel, in s La braking force is thus gradually eliminated as a function of time, as soon as the driver begins to pass from torque to the wheel.

  For slope maneuvers, the block 35 makes the vehicle as easy to drive on a steep slope as on a slight slope. Calculation 15 of the braking setpoint is carried out using the equation F srrage = max [(Slope - Frow), min (Fcond, Fslope o: Slope Longitudinal force exerted by the slope on the vehicle, in Newton Froue Force longitudinal drive, in Newton FcOfld Longitudinal force required by the driver to brake, In Newton On a slope, the vehicle is subjected, apart from any action by the driver, to the acceleration due to gravity. the higher this acceleration, which results in faster and faster speed gain and requires the driver to take faster and faster actions. To guarantee a sufficient level of safety, a braking force calculated according to the slope will therefore be applied to maintain a level of acceleration of the vehicle lower than that of gravity, in order to limit the speed gain thereof. The level of acceleration then changes to gradually catch up with the accelerated natural ration of the vehicle in order, for example, to authorize coasting starts. The goal is to modulate the actions of the driver without however going against his will. This makes it possible to control the braking as a function of the engine forces applied to the wheel, without going against the will of the driver, and always seeking to assist him.

  The braking forces always depend linearly on the engine forces, which ensures great progressiveness in the acceleration of the vehicle. This ensures progressive and comfortable consideration of the driver's wishes.

  FIG. 3 is a state / transition diagram of the automaton which manages the activation or deactivation of the calculation functions, in particular for a successive implementation of several steps.

  The transition a1 represents the passage from the immobile hold to the hill start and the transition a2 represents the change from the start from the hill to the stationary hold. The transition b represents the transition from starting up ascent to maneuvering on a slope. The transition ci represents the passage from the immobile hold to the start downhill, and the transition c2 represents the passage from the start downhill to the immobile hold. The transition d represents the passage 20 from holding to the maneuver on a slope. The transition e represents the passage from the sloping maneuver to the immobile hold. The transition f represents the transition from starting downhill to maneuvering on a slope. In each case, the device of the invention therefore successively activates two or more blocks 32 to 35. It is for example possible to implement the transition al then the transition b and finally the transition e so as to pass from the immobile holding 32 of the vehicle , on a hill start 33, then on a slope maneuver 35, to finally keep the vehicle stationary 32.

  The transition al makes it possible to pass from the block 32 for holding stationary 30 to the block 33 for starting on a quarid hill the driver's desire to set his vehicle in motion is detected by means of the input signals. It will ensure a transition from keeping the vehicle stationary on a slope to assistance by braking during a movement which goes up the slope (in forward or reverse). The transition a2 makes it possible to pass from the hill starting block 33 to the stationary holding block 32, when the driver stops his vehicle by applying the brake and keeps it stationary.

  During the transition b, the block 33 for starting assistance on a hill 5 ends when the driver has completely overcome the slope with the help of the engine forces which he passes to the wheels, that is to say when all the braking efforts which initially made it possible to maintain the vehicle and avoid its reversing have disappeared. This transition has a safety aspect and allows the driver who misses his start not to be surprised and taken aback. He has time, knowing that the acceleration of the vehicle is limited by a braking action, either to brake and stop his vehicle, or to re-engage and accelerate to start again. The urgent and delicate nature of these situations on steep slopes is thus considerably reduced by the actions produced by the two blocks 33 and 35, as well as the possibility of switching from one to the other.

  The transition cl makes it possible to pass from the block 32 for immobile maintenance to the block 34 for assistance in starting downhill by detecting the will of the driver to set the vehicle in motion in this direction by means of the input signals. The vehicle start-up management is then done in the most comfortable way possible. During the transition c2, for the passage of the starting aid block 34 when going downhill to the stationary holding block 32, the driver need only act on the brake pedal.

  The transition d represents the passage from the immobile holding block 32 to the sloping maneuvering aid block 35 so that the maneuvers are as easy on steep slopes as on slight slopes. If the driver wishes to allow the vehicle to slide freely, this offers him the means of releasing the vehicle from the support, for example, by a button or a switch not shown in the figures.

  The transition e is ensured when the device detects the immobilization of the vehicle and the will of the driver to maintain it in this state using the input signals.

  The transition f is essentially based on the observation of the vehicle speed.

  The invention thus makes it possible to assist the driver during the 5 phases of stopping the vehicle by guaranteeing the immobilization of the latter without requiring the action of the driver (maintenance of a support on the brake, or actuation of the brake hand or any other system). The minimum tightening is applied here to keep the vehicle on the slope, for the sake of responsiveness and transparency of the system.

The invention also makes it possible to guarantee easy starting of the vehicle in any slope condition and to assist the driver in maneuvers on a slope, while maintaining a level of acceleration of the vehicle always lower than the level of acceleration d to gravity. , which ensures movement as easy to manage on a slope as on the flat. Finally, the invention makes it possible to combine these different assistance phases, thus providing assistance to the driver for example during a hill restart following a coasting maneuvering phase, or any other combination of assistance phases. .

Claims (10)

  1. Braking control device during the stopping and setting in motion phases of a motor vehicle comprising a drive motor and a transmission, an electronically controlled decoupled braking system, at least one sensor (10, 11,12,13) for measuring or estimating the longitudinal speed of the vehicle, at least one sensor (16a) 10 measuring the driving force applied to the wheels of the vehicle, a gradient sensor (15) for the environment, a sensor (16) measuring the braking request of the driver, an interface between the driver and the device, and an electronic control unit (ECU) (1), characterized in that it comprises: calculation means (32) of braking setpoint to keep the vehicle stationary regardless of the gradient of the environment; means for calculating (33) braking setpoint during a hill start desired by the driver; means for calculating (34) braking setpoint during a downhill start desired by the driver; and braking setpoint calculating means (35) limiting the acceleration of the vehicle, during incline maneuvers, possibly with the drive motor decoupled from the transmission; the electronic control unit (1) being capable of activating each of said means for calculating (32, 33, 34, 35) braking setpoint successively or independently of each other.   2. Control device according to claim 1, 30 characterized in that it comprises at least one sensor (10,11,12,13) of longitudinal acceleration.   3. Control device according to claims 1 or 2, characterized in that it comprises at least one auxiliary slowing device.   4. Control device according to any one of claims 5 to 3, characterized in that the electronic control unit (1) is capable of managing the activation or deactivation of the various calculation means (32,33, 34.35) depending on the state of the vehicle communicated by the information from the various sensors.   5. Method for controlling braking during the stopping and setting in motion phases of a motor vehicle comprising a drive motor and a transmission, and equipped with an electronically controlled decoupled braking, characterized in that it consists in carrying out successively or independently one or more of the following steps: - calculating a braking setpoint for keeping the vehicle stationary; - calculate a braking instruction when the driver wishes to start uphill; - calculate a braking instruction when the driver wishes to start downhill; - calculate a braking instruction to limit the acceleration of the vehicle during maneuvers on slopes, possibly with the drive motor decoupled from the transmission; based on an interpretation of the driver's wishes, the condition of the vehicle, and the gradient of the environment.   6. Control method according to claim 5, characterized in that the calculation (32) of the braking setpoint for maintaining the vehicle immobile is done by respecting 30 Fserrage = Fpente o: Fserrage Longitudinal force requested from the brake, in Newton Fpente Force longitudinal exerted by the slope on the vehicle, in Newton 7. Control method according to claims 5 or 6, characterized in that the calculation (33) of the braking setpoint during a hill start preventing the vehicle from rolling back is done by respecting: Fserrage = Fpente- Froue o: Froue: Longitudinal driving force, in Newton Fserrage Longitudinal force required to brake, in Newton Fslope Longitudinal force exerted by the slope on the vehicle, 10 in Newton 8. Control method according to any one of claims 5 to 7, characterized in that the calculation (34) of the braking setpoint during a downhill start limiting the acceleration of the vehicle as a function of the slope is done by respecting 15 Fserrage = Fpente - kt o Fserrage Longitudinal force requested from the brake, in Newton Fpente: Longitudinal force exerted by the slope on the vehicle, in Newton k Constant coefficient, in Newton / st time elapsed since the start of the torque shift at the wheel in s 9. Control method according to claim 8, characterized in that the constant coefficient k is chosen to be equal to 0.5. 25 10. Control method according to any one of claims 5 to 9, characterized in that the calculation (35) of the braking setpoint during a maneuver on a slope is done while respecting Fserrage = max [(Slope - Frou), min (Fcond, Fpente o: Fpente: Longitudinal force exerted by the slope on the vehicle, in Newton Froue: Longitudinal driving force, in Newton Fcond: Longitudinal force requested to the brake by the driver, in Newton