Brake clearance compensation method, device and equipment for electro-mechanical brake system

Abstract

The invention provides a brake clearance compensation method, device and equipment of an electronic mechanical brake system, and relates to the technical field of automobiles. The method comprises the following steps: acquiring driving state data of wheels after a vehicle is braked; determining whether the driving state data restores to a target value, the target value being associated with the driving state data of the wheel prior to braking; according to the control instruction of the vehicle, determining whether a brake disc of the vehicle has a voltage buildup demand or not; under the condition that the driving state data is not recovered to the target value and the brake disc does not have the pressure building requirement, estimated brake parameters of wheels are obtained; and under the condition that the estimated braking parameter is smaller than the second threshold value, the motor is controlled to drive the transmission mechanism to drive the piston, so that the piston drives the braking executing mechanism to release the braking disc. According to the scheme, under the condition that the estimated braking parameter of the wheel is smaller than the second threshold value due to errors of the sensor and the wheel still has the braking force, the residual braking force at the wheel end can be automatically released, and the braking performance is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of automobiles, and particularly relates to a braking gap compensation method, device and equipment for an electro-mechanical braking system. Background Art

[0002] The electro-mechanical braking system (EMB) is one of the research hotspots in the field of by-wire chassis at present. It uses an electronic controller and a mechanical actuator to directly apply braking force to the wheel end, significantly reducing system components. At the same time, it has a faster response speed and higher wheel-end execution flexibility, and is a highly integrated solution for the braking system.

[0003] Currently, the electro-mechanical braking system uses a force sensor to detect the magnitude of the braking force of the current wheel-end actuator.

[0004] However, affected by the accuracy and error of the sensor, the detected braking force does not match the estimated braking parameters, which further leads to poor braking performance. Summary of the Invention

[0005] Embodiments of the present invention provide a braking gap compensation method, device and equipment for an electro-mechanical braking system. By compensating for the braking gap, the influence brought by sensor accuracy and error can be solved, and the braking performance of the vehicle can be improved.

[0006] In a first aspect, embodiments of the present invention provide a braking gap compensation method for an electro-mechanical braking system. The electro-mechanical braking system includes a motor, a transmission mechanism, a piston and a braking execution mechanism. The motor is used to drive the transmission mechanism to drive the piston to move. The piston is used to drive the braking execution mechanism to clamp or release the brake disc of the wheel. The method includes:

[0007] Obtain the driving state data of the wheel after the vehicle brakes;

[0008] Determine whether the driving state data has returned to a target value, where the target value is associated with the driving state data of the wheel before braking;

[0009] Determine whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle;

[0010] When the driving state data has not returned to the target value and the brake disc has no pressure building requirement, obtain the estimated braking parameters of the wheel;

[0011] When the estimated braking parameter is less than a second threshold, control the motor to drive the transmission mechanism to drive the piston, so that the piston drives the braking execution mechanism to release the brake disc.

[0012] In an implementable embodiment, determining whether there is a pressure - building requirement for the brake disc of the vehicle according to the control instruction of the vehicle includes:

[0013] Obtaining a target braking force and / or a target torque of the motor according to the control instruction of the vehicle;

[0014] When the target braking force is less than a first threshold, determining that there is no pressure - building requirement for the brake disc, and / or when the target torque is less than a torque threshold, determining that there is no pressure - building requirement for the brake disc.

[0015] In an implementable embodiment, the estimated braking parameter is the braking force collected by a sensor of the wheel, and controlling the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake execution mechanism to release the brake disc includes:

[0016] When the estimated braking parameter is less than a second threshold, determining whether the position of the piston is greater than a third threshold;

[0017] When the position of the piston is greater than a third position, controlling the motor to drive the transmission mechanism to drive the piston to retract to a target position point at a target speed so that the piston drives the brake execution mechanism to release the brake disc.

[0018] In an implementable embodiment, it further includes:

[0019] Obtaining the contact point between the brake execution mechanism and the brake disc;

[0020] Determining whether the position of the piston is greater than the third threshold according to the position of the contact point and the position of the piston.

[0021] In an implementable embodiment, it further includes:

[0022] When any preset condition is met, continuing to maintain the brake execution mechanism to clamp the brake disc, and the preset conditions include that the driving state data returns to the target value, there is a pressure - building requirement, the estimated braking parameter is greater than or equal to the third threshold, and the position of the piston is less than or equal to the third position.

[0023] In an implementable embodiment, the transmission mechanism includes a speed - reducing and torque - increasing mechanism, a ball screw, and a screw nut. The motor drives the speed - reducing and torque - increasing mechanism, the speed - reducing and torque - increasing mechanism drives the ball screw, and the ball screw drives the piston. The method further includes:

[0024] Obtain the mechanical angle of the motor rotation, the transmission ratio of the speed reduction and torque increase mechanism, the thread pitch and the pitch circle radius of the lead screw nut;

[0025] Determine the position of the piston according to the mechanical angle, the transmission ratio, the thread pitch and the pitch circle radius.

[0026] In an implementable embodiment, the driving state data includes wheel speed and / or slip ratio. Obtaining the driving state data of the wheel after the vehicle brakes includes:

[0027] After the vehicle brakes, obtain the angular velocity of the wheel, the wheel radius and the vehicle speed;

[0028] Determine the slip ratio according to the angular velocity, the wheel radius and the vehicle speed.

[0029] In an implementable embodiment, after controlling the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to release the brake disc, the method further includes:

[0030] When the driving state data returns to the target value, determine whether there is a pressure building requirement for the brake disc of the vehicle;

[0031] When there is the pressure building requirement, continue to control the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to clamp the brake disc.

[0032] In a second aspect, an embodiment of the present invention provides a brake clearance compensation device for an electro-mechanical braking system, including:

[0033] An acquisition module, configured to acquire the driving state data of the wheel after the vehicle brakes;

[0034] A data determination module, configured to determine whether the driving state data returns to a target value, where the target value is associated with the driving state data of the wheel before braking;

[0035] A requirement determination module, configured to determine whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle;

[0036] A parameter acquisition module, configured to acquire the estimated braking parameters of the wheel when the driving state data does not return to the target value and the brake disc has no pressure building requirement;

[0037] A control module, configured to control the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to release the brake disc when the estimated braking parameter is less than a second threshold.

[0038] In a third aspect, an embodiment of the present invention provides an electronic device, including: a processor and a memory storing computer program instructions; the processor reads and executes the computer program instructions to implement the method as described above.

[0039] The braking gap compensation method, device, and equipment of the electro-mechanical braking system provided by the embodiments of the present invention can automatically release the residual braking force at the wheel end through software when the estimated braking parameter of the wheel is less than a second threshold due to errors in the sensor, while there is still braking force on the wheel, improving braking performance. At the same time, this solution does not require additional redundant sensor mechanisms, which can save costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required to be used in the embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic structural diagram of the electro-mechanical braking system provided by the embodiments of the present application;

[0042] Figure 2 It is a schematic diagram of the braking process adopted by the embodiments of the present application;

[0043] Figure 3 It is a schematic diagram of the braking gap compensation method flow provided by the embodiments of the present application;

[0044] Figure 4 It is a schematic diagram of another braking gap compensation method flow provided by the embodiments of the present application;

[0045] Figure 5 It is a schematic structural diagram of the braking gap compensation device provided by the embodiments of the present application;

[0046] Figure 6 It is a schematic hardware structure diagram of the electronic device provided by the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] The following will describe in detail the features and exemplary embodiments of various aspects of the present invention. In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further describes the present invention in detail with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention, rather than limiting the present invention. For those skilled in the art, the present invention can be implemented without some of these specific details. The following description of the embodiments is only intended to provide a better understanding of the present invention by showing examples of the present invention.

[0048] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent in such process, method, article or device. Without further limitation, an element defined by the statement "comprising..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0049] The Electronic Mechanical Brake (EMB) is one of the research hotspots in the field of by-wire chassis. It uses an electronic controller and a mechanical actuator to directly apply braking force to the wheel end, significantly reducing system components. At the same time, it has a faster response speed and higher wheel-end execution flexibility, which is a highly integrated solution for the braking system. In the electronic mechanical braking system, it is necessary to constantly pay attention to the braking performance of the tire. Compared with the electronic hydraulic braking system, in which the oil pressure of the master cylinder is controlled and the current actual hydraulic pressure state is read through the master cylinder hydraulic pressure sensor, and then the wheel cylinder hydraulic pressure is adjusted to make the wheel braking performance better. The electronic mechanical braking system needs to be achieved by adjusting the pressing degree between the brake lining and the friction disc. At this time, the force sensor will display the magnitude of the braking force of the current wheel-end actuator. Affected by the accuracy and error of the sensor, when the force sensor shows a zero value of the wheel-end force, the wheel may actually be in a braking state, and the braking performance of the whole vehicle will have problems.

[0050] In view of the above problems, the present application provides a braking gap compensation scheme based on the EMB system, which enables the electronic mechanical braking system to have wheel dynamic recognition and wheel braking recovery through a software control algorithm. When the force sensor value shows zero, the software automatically releases the residual braking force at the wheel end to achieve the compensation of the braking gap, avoiding the situation that the wheel is actually still in a braking state and improving the braking performance.

[0051] Exemplarily, Figure 1 is a schematic structural diagram of the electronic mechanical braking system provided by the embodiment of the present application, as Figure 1 shown, the motor drives a speed reduction and torque increase mechanism, and the speed reduction and torque increase mechanism drives a motion conversion mechanism (such as a ball screw), which converts the rotation output by the speed reduction and torque increase mechanism into linear motion through a lead screw nut, and the piston 11 pushes the friction lining 14 to press the brake disc 13.

[0052] Among them, an angle sensor is integrated in the motor to sense the current motor angle. A current sensor is integrated in the motor to sense the current motor current. A force sensor 12 is integrated in the motion conversion mechanism to sense the clamping force exerted by the friction lining 14 on the brake disc 13.

[0053] In this embodiment, when the motor controller receives a clamping instruction from the upper-layer controller, it drives the motor to rotate forward to complete clamping; when it receives a release instruction, it drives the motor to rotate backward to complete release. Specifically, during the operation of the electromechanical braking system, the upper-layer control system can send clamping / release instructions to the execution control system according to the braking intention of the driver or the intelligent driving system. The functional module responsible for calculation calculates the current piston position based on the motor angle and the actuator parameters. At the same time, the functional module responsible for contact point recognition can select to enable / disable the contact point recognition function according to the clamping / release instruction of the upper-layer control system. When the function is enabled, the contact point is refreshed according to the actuator clamping force, current, and piston position.

[0054] Among them, when the upper-layer control system issues a clamping instruction, the motor is driven to rotate forward according to the piston position and the actuator clamping force to complete the clamping of the actuator; when the upper-layer control system issues a release instruction, the motor is driven to rotate backward according to the piston position and the contact point, and the piston is rotated backward to a position that maintains a certain fixed distance from the contact point. In addition, through the clamping / release arbitration functional module, the motor torque for executing clamping control or release control can be determined according to the clamping / release instruction of the upper-layer control system.

[0055] Exemplarily, Figure 2 is a schematic diagram of the braking process adopted in the embodiment of the present application, as Figure 2 shown, which includes the following steps: Step S210: Upper-layer braking intention. Step S220: Vehicle four-wheel target braking force distribution. Step S230: Clamping / release control. Step S240: Control arbitration according to the release torque or clamping torque. Step S250: The actuator executes braking. Step S260: Wheel dynamic recovery.

[0056] Next, the technical solution of the present application will be described in detail through specific embodiments. It should be noted that these specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.

[0057] Figure 3Schematic flow diagram of the braking gap compensation method provided by an embodiment of this application. This method can be applied to a vehicle equipped with an electro-mechanical braking system. The electro-mechanical braking system includes a motor, a transmission mechanism, a piston, and a braking actuator. The motor is used to drive the transmission mechanism to drive the piston to move, and the piston is used to drive the braking actuator to clamp or release the brake disc of the wheel. Taking the electronic device in the vehicle as the main body for executing this method as an example, as Figure 3 shown, the method specifically includes the following steps:

[0058] Step S310: Obtain the driving state data of the wheel after the vehicle brakes.

[0059] In this embodiment, the driver or the intelligent driving system can trigger the braking of the vehicle. The upper control system of the vehicle sends a clamping / releasing instruction to the execution control system according to the braking intention of the driver or the intelligent driving system, and realizes braking by controlling the friction plate to clamp the brake disc.

[0060] In addition, in some special scenarios, if the vehicle has functions such as an Anti-lock Braking System (ABS), a Vehicle Dynamic Control (VDC), and a Traction Control System (TCS). Then the braking of the vehicle can be achieved through one of these functions.

[0061] Taking the anti-lock braking system as an example, the ABS system continuously monitors the rotational speed and slip of the wheel. During the entire braking process, there will be multiple clampings and releases, that is, the braking actuator will clamp and release the brake disc back and forth multiple times. This requires precise control of the reciprocating motion of the braking actuator, retreating in time when braking is not required to release the brake disc, and advancing in time when braking is required to clamp the brake disc.

[0062] Step S320: Determine whether the driving state data has returned to the target value.

[0063] Among them, the target value is associated with the driving state data of the wheel before braking.

[0064] In this embodiment, the target value may refer to the driving state data when the wheel is driving normally before the vehicle brakes. Exemplarily, the driving state data may include the slip ratio and wheel speed of the wheel.

[0065] It should be noted that the vehicle has multiple wheels (for example, a car has 4 wheels). The wheel mentioned in this embodiment refers to the same wheel. For example, if the vehicle includes wheel A and wheel B, then the wheel mentioned in this embodiment can generally refer to wheel A.

[0066] In this embodiment, the driving state data can be collected by sensors. For example, the wheel speed of the wheel can be collected by a wheel speed sensor.

[0067] Step S330: Determine whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle.

[0068] In this embodiment, the pressure building requirement can be used to indicate whether the wheel needs to be braked. If there is a pressure building requirement, it means that the driver or the intelligent driving system hopes to brake the wheel, that is, the brake actuator needs to move forward to clamp the brake disc.

[0069] Exemplarily, in some embodiments, the control instruction of the upper control system can be obtained, and the control instruction can include the target braking force. When the target braking force is less than the first threshold, it is determined that there is no pressure building requirement for the brake disc. Exemplarily, the first threshold can be set to 0.

[0070] Furthermore, in some other embodiments, the target torque of the motor can also be obtained. When the target torque is less than the torque threshold, it is determined that there is no pressure building requirement for the brake disc.

[0071] Among them, by determining whether there is a pressure building requirement for the vehicle, it can be further determined whether the wheel needs to be braked again after braking, which is convenient for more accurate control of the piston movement. For example, if braking is required again, the piston does not need to retract too far during the retraction process, so that when braking is required again, the piston can quickly drive the brake actuator to clamp the brake disc of the wheel. When the piston retracts, it will drive the brake actuator to release the brake disc, that is, there will be a gap between the brake actuator and the brake disc. The larger the piston retraction distance, the larger the gap. When the piston moves forward, it will drive the brake actuator to clamp the brake disc. The larger the piston forward distance, the greater the clamping force of the brake actuator on the brake disc and the greater the braking force.

[0072] Step S340: When the driving state data has not recovered to the target value and there is no pressure building requirement for the brake disc, obtain the estimated braking parameters of the wheel.

[0073] Exemplarily, the estimated braking parameters can refer to the braking force or the braking torque. The braking force can be collected by the sensors of the wheel or calculated by the wheel-end braking force estimation scheme.

[0074] In this embodiment, the force sensor on the wheel is affected by accuracy and error, resulting in the following situation: the estimated braking parameter collected by the force sensor is zero, but the braking actuator still clamps the brake disc at this time, that is, there is still braking force on the wheel. This will cause misjudgment in the electromechanical braking system because when the estimated braking parameter collected by the force sensor is zero, the electromechanical braking system may not control the piston to retract anymore, which results in the fact that there is still braking force on the wheel and the driving state data of the wheel cannot be restored to the target value.

[0075] Step S350: When the estimated braking parameter is less than the second threshold, control the motor to drive the transmission mechanism to drive the piston, so that the piston drives the braking actuator to release the brake disc.

[0076] In this embodiment, the piston can move forward or backward. When the piston moves forward, it drives the braking actuator to clamp the brake disc, and the braking force gradually increases. When the piston retracts, it drives the braking actuator to release the brake disc, and the braking force gradually decreases. Among them, the second threshold can be preset.

[0077] In this embodiment, when the estimated braking parameter is less than the second threshold and the driving state data of the wheel has not been restored to the target value, it means that there is still braking force on the wheel, that is, the braking actuator still clamps the brake disc and there is no gap between them. When the piston drives the braking actuator to release the brake disc, a gap will gradually appear between the braking actuator and the brake disc, and the braking force will also gradually decrease, thereby realizing brake clearance compensation.

[0078] In the embodiment of the present application, when there is an error in the sensor, resulting in the situation that the estimated braking parameter of the wheel is less than the second threshold while there is still braking force on the wheel, the residual braking force at the wheel end can be automatically released by software to improve the braking performance. At the same time, this solution does not require additional redundant sensor mechanisms, which can save costs.

[0079] Figure 4 Another schematic flow chart of the brake clearance compensation method provided by the embodiment of the present application is as Figure 4 shown, which includes the following steps:

[0080] Step S410: Upper-layer target braking force control. Step S420: Vehicle wheel dynamic recognition. Step S430: The wheel speed / slip ratio of a certain wheel has not been able to be restored. Step S440: The target force is less than threshold A. Step S450: The braking force of the wheel collected by the sensor is less than threshold B. Step S460: Whether the piston position is greater than threshold C. Step S470: Output the retraction speed D of a certain piston. Step S480: The actuator performs a clamping action or a release action. Step S490: Whether the wheel speed / slip ratio of this wheel is restored.

[0081] In this embodiment, the driving state data may refer to the wheel speed and / or the slip ratio. The estimated braking parameter may refer to the braking force of the wheel collected by the sensor.

[0082] In this embodiment, when the estimated braking parameter is less than the second threshold, it is necessary to determine whether the position of the piston is greater than the third threshold (i.e., threshold C mentioned in this embodiment). Among them, when the position of the piston is greater than the third position, the control motor drives the transmission mechanism to drive the piston to retract to the target position point at the target speed, so that the piston drives the brake actuator to release the brake disc.

[0083] Among them, the target position point may be a pre-set position point. When the piston is at this target position point, it drives the brake actuator to no longer clamp the brake disc. If the piston continues to move forward, the brake actuator will clamp the brake disc again.

[0084] In this embodiment, the target speed can be pre-set. The greater the target speed, the faster the brake actuator releases the brake disc, and the faster the braking force decreases. This can make the driving state data of the wheel return to the target value as soon as possible. In the anti-lock scenario, this can make the friction between the wheel and the ground greater, improving the braking performance and driving safety of the vehicle.

[0085] In some other embodiments, a reference point may be set to determine whether the position of the piston is greater than the third threshold. Specifically, the contact point between the brake actuator and the brake disc can be obtained. Exemplarily, the piston can move forward or retract backward. When the piston moves forward to the front of the contact point, the position of the piston is greater than the third threshold. When the piston retracts backward to the rear of the contact point, the position of the piston is less than the third threshold.

[0086] In this embodiment, the contact point may refer to the actual contact or close position between the brake actuator (such as a brake caliper, a friction pad, etc.) and the object to be braked (such as a brake disc).

[0087] Among them, the contact point can be a position point comprehensively judged and refreshed by the system based on parameters such as sensors, clamping force of the braking actuator, current, and piston position. During the clamping process, after the upper control system issues a clamping instruction, the motor can be driven to rotate forward according to the piston position and the clamping force of the braking actuator, so that the braking actuator moves towards the object to be braked and gradually clamps it. At this time, the contact point is the position where the braking actuator starts to contact the object to be braked and performs the clamping operation. During the release process, after the upper control system issues a release instruction, the motor can be driven to rotate in reverse according to the piston position and the contact point, so that the braking actuator moves away from the object to be braked to a safe or preset position. Here, the contact point is used as a reference point to ensure that the piston rotates in reverse to a position maintaining a certain fixed distance from the contact point, avoiding excessive separation between the braking actuator and the object to be braked or unnecessary impacts.

[0088] Furthermore, in some other embodiments, the piston displacement can be calculated through the position sensor of the motor, and the measured values of the force sensor can be used as different-source values for mutual verification, enabling the EMB function safety.

[0089] In the embodiments of the present application, by setting the contact point, the retraction of the piston can be controlled more accurately, avoiding excessive separation between the braking actuator and the brake disc and a large gap between them, and improving the timeliness of the braking response during subsequent braking.

[0090] Furthermore, on the basis of the above embodiments, when any of the following preset conditions is met, the braking actuator can continue to clamp the brake disc. The preset conditions include at least one of the driving state data returning to the target value, the presence of a pressure building requirement, the estimated braking parameter being greater than or equal to the third threshold, and the position of the piston being less than or equal to the third position.

[0091] Exemplarily, continue to refer to the above Figure 4 , it is judged whether there is a pressure building requirement in the current upper layer instruction through the target force threshold A. It is determined whether the wheel has been depressurized completely under the braking force collected by the sensor based on the actual force threshold B, and it can be determined whether the piston needs to retract during this process through the piston position threshold C.

[0092] Among them, due to the influence of the accuracy and error of the sensor, the braking force collected by it may be incorrect. For example, the braking force collected by it is zero, but the wheel actually still has braking force, which may cause the electronic mechanical braking system to misjudge that the wheel has been depressurized completely.

[0093] Exemplarily, when the vehicle is in a special working condition, such as when functions like ABS, VDC, and TCS are activated, it is necessary to quickly reduce the braking force on the wheel to restore the wheel dynamics. However, when the target force collected by the sensor is zero, in order to achieve subsequent pressure building response, the wheel cannot continue to retract back to the braking gap. But in fact, there is still braking force on the wheel at this time, which results in a slower recovery of the wheel speed / slip ratio of a certain wheel even though the force sensor shows that the actual force value is 0 at this moment. That is, it is determined that the display of the force sensor does not match the actual braking force at the wheel end.

[0094] In this embodiment, by setting the above preset conditions, it can be accurately determined whether the display of the force sensor matches the actual braking force at the wheel end. When the above preset conditions are met, the braking actuator is continued to clamp the brake disc.

[0095] In the embodiment of the present application, by determining whether the display of the force sensor matches the actual braking force at the wheel end, the influence caused by sensor errors can be solved, and the braking performance of the vehicle can be improved.

[0096] Further, on the basis of the above embodiment, in some other embodiments, the transmission mechanism includes a speed reduction and torque increase mechanism, a ball screw, and a lead screw nut. The motor drives the speed reduction and torque increase mechanism, the speed reduction and torque increase mechanism drives the ball screw, and the ball screw drives the piston. The position of the piston can be calculated through the following steps:

[0097] Step (1): Obtain the mechanical angle of the motor rotation, the transmission ratio of the speed reduction and torque increase mechanism, the thread pitch of the lead screw nut, and the pitch circle radius.

[0098] Step (2): Determine the position of the piston according to the mechanical angle, the transmission ratio, the thread pitch, and the pitch circle radius.

[0099] In this embodiment, since the motor position sensor can sense the motor angle in real time, the piston position can be obtained by integrating according to the actuator parameters:

[0100]

[0101] In the above formula, A is the piston position, φ is the mechanical angle of the motor rotation, K is the transmission ratio of the speed reduction and torque increase mechanism, p is the thread pitch, and r is the pitch circle radius.

[0102] Further, in some embodiments, the slip ratio of the wheel can be determined through the following steps:

[0103] Step ①: After the vehicle brakes, obtain the angular velocity of the wheel, the wheel radius, and the vehicle speed. Step ②: Determine the slip ratio according to the angular velocity, the wheel radius, and the vehicle speed.

[0104] In this embodiment, when the driver steps on the brake pedal, the wheel speed will decrease. However, due to the inertia of the vehicle itself, the actual vehicle speed is no longer equal to the wheel speed, thus generating a slip ratio. Different values of the slip ratio result in different adhesion forces between the wheel and the road surface. For example, when the slip ratio is approximately around 20%, the adhesion force between the wheel and the road surface is the largest, and the ground braking force is also the largest at this time, achieving the best braking effect.

[0105] In this embodiment, as the output force of the vehicle brake pedal changes, the degree of slip between the wheel and the ground also changes. Among them, the calculation formula for the slip ratio of the wheel is specifically as follows:

[0106] S = (V - w * r) / V

[0107] In the above formula, S is the slip ratio, V is the vehicle speed, w is the angular velocity of the wheel, and r is the wheel radius.

[0108] In some embodiments, when the piston drives the brake actuator to release the brake disc, the braking force gradually decreases to zero. When the braking force becomes zero, the driving state data of the vehicle returns to the target value. At this time, it is possible to further determine whether there is a need to build pressure on the vehicle's brake disc;

[0109] In the case of a need to build pressure, continue to control the motor to drive the transmission mechanism to drive the piston, so that the piston drives the brake actuator to clamp the brake disc.

[0110] Exemplarily, continue to refer to the above Figure 4 , determine whether the current target force is less than the set threshold A, whether the braking force collected by the sensor is less than the set threshold B, and whether the current piston position is greater than the threshold C. When the above conditions are met, by outputting a reverse speed D, the piston starts to retract from the current position at this time, and the actual braking force at the wheel end decreases. When the piston position is less than C, the reverse scheme ends at this time, and the braking force at the wheel end enters the subsequent upper-level control process.

[0111] Specifically, taking the anti-lock scenario as an example, after the first braking, the brake actuator needs to release the brake disc as soon as possible to prevent locking and let the wheel return to a dynamic state. Immediately afterwards, the brake actuator needs to clamp the brake disc as soon as possible to continue providing braking force. Only by repeating this process can the vehicle achieve safe braking in a short time. And in this process, it is necessary to control the motor to drive the transmission mechanism to drive the piston, so that the piston drives the brake actuator to quickly switch between the two states of clamping the brake disc and releasing the brake disc.

[0112] The following is an embodiment of the device of the present application, which can be used to execute the method embodiment of the present application. For the details not disclosed in the device embodiment of the present application, please refer to the method embodiment of the present application.

[0113] Figure 5The structural schematic diagram of the brake clearance compensation device provided by the embodiment of the present application is as follows. Figure 5 As shown in the figure, the brake clearance compensation device 500 may include an acquisition module 510, a data determination module 520, a demand determination module 530, a parameter acquisition module 540, and a control module 550.

[0114] Among them, the acquisition module 510 is used to acquire the driving state data of the wheel after the vehicle brakes. The data determination module 520 is used to determine whether the driving state data has returned to the target value, and the target value is associated with the driving state data of the wheel before braking. The demand determination module 530 is used to determine whether there is a pressure building demand for the brake disc of the vehicle according to the control instruction of the vehicle. The parameter acquisition module 540 is used to acquire the estimated braking parameters of the wheel when the driving state data has not returned to the target value and there is no pressure building demand for the brake disc. The control module 550 is used to control the motor to drive the transmission mechanism to drive the piston when the estimated braking parameter is less than the second threshold, so that the piston drives the brake actuator to release the brake disc.

[0115] Optionally, the demand determination module may specifically be used to: acquire the target braking force and / or the target torque of the motor according to the control instruction of the vehicle; determine that there is no pressure building demand for the brake disc when the target braking force is less than the first threshold, and / or determine that there is no pressure building demand for the brake disc when the target torque is less than the torque threshold.

[0116] Optionally, the estimated braking parameter is the braking force collected by the sensor of the wheel. The control module may specifically be used to: determine whether the position of the piston is greater than the third threshold when the estimated braking parameter is less than the second threshold; when the position of the piston is greater than the third position, control the motor to drive the transmission mechanism to drive the piston to retract to the target position point at the target speed, so that the piston drives the brake actuator to release the brake disc.

[0117] Optionally, it further includes a position determination module, which is used to acquire the contact point between the brake actuator and the brake disc; determine whether the position of the piston is greater than the third threshold according to the position of the contact point and the position of the piston.

[0118] Optionally, it further includes a brake maintenance module, which is used to continue to maintain the brake actuator to clamp the brake disc when any preset condition is met. The preset conditions include that the driving state data has returned to the target value, there is a pressure building demand, the estimated braking parameter is greater than or equal to the third threshold, and the position of the piston is less than or equal to the third position.

[0119] Optionally, the transmission mechanism includes a speed reduction and torque increase mechanism, a ball screw, and a lead screw nut. The motor drives the speed reduction and torque increase mechanism, which drives the ball screw, and the ball screw drives the piston. A position determination module is further included, which is configured to obtain the mechanical angle of the motor rotation, the transmission ratio of the speed reduction and torque increase mechanism, the pitch of the lead screw nut, and the pitch circle radius; and determine the position of the piston according to the mechanical angle, the transmission ratio, the pitch, and the pitch circle radius.

[0120] Optionally, the driving state data includes wheel speed and / or slip ratio. The data determination module can specifically be configured to: after the vehicle brakes, obtain the angular velocity of the wheel, the wheel radius, and the vehicle speed; and determine the slip ratio according to the angular velocity, the wheel radius, and the vehicle speed.

[0121] Optionally, a clamping control module is further included, which is configured to determine whether there is a pressure building requirement for the vehicle's brake disc when the driving state data returns to the target value; and when there is a pressure building requirement, continue to control the motor to drive the transmission mechanism to drive the piston, so that the piston drives the brake actuator to clamp the brake disc.

[0122] The device provided in the embodiments of the present application can be used to execute the methods in the above embodiments. The implementation principles and technical effects are similar and will not be elaborated here.

[0123] It should be noted that it should be understood that the division of each module of the above device is only a division of logical functions. In actual implementation, it can be fully or partially integrated into a physical entity, or physically separated. And these modules can all be implemented in the form of software called by a processing element; they can also all be implemented in the form of hardware; or some modules can be implemented in the form of software called by a processing element, and some modules can be implemented in the form of hardware. For example, the acquisition module can be a separately established processing element, or can be integrated in a certain chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called and executed by a certain processing element of the above device to perform the functions of the above acquisition module. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together or independently implemented. Here, the processing element can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each of the above modules can be completed by the integrated logic circuit in the processor element or the instructions in the form of software.

[0124] Figure 6 It is a schematic hardware structure diagram of the electronic device provided in the embodiments of the present invention. The electronic device can be integrated on a vehicle, such as Figure 6 shown, the electronic device 600 may include a processor 601 and a memory 602 storing computer program instructions.

[0125] Specifically, the above-mentioned processor 601 may include a Central Processing Unit (CPU), or an Application Specific Integrated Circuit (ASIC), or may be configured as one or more integrated circuits for implementing the embodiments of the present invention.

[0126] The memory 602 may include a mass storage for data or instructions. By way of example and not limitation, the memory 602 may include a Hard Disk Drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. In one example, the memory 602 may include removable or non-removable (or fixed) media, or the memory 602 is a non-volatile solid-state memory. The memory 602 may be internal or external to the integrated gateway disaster recovery device.

[0127] In one example, the memory 602 may be a Read Only Memory (ROM). In one example, the ROM may be a mask-programmed ROM, a Programmable ROM (PROM), an Erasable PROM (EPROM), an Electrically Erasable PROM (EEPROM), an Electrically Rewritable ROM (EAROM), or a flash memory, or a combination of two or more of these.

[0128] The memory 602 may include a Read Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk storage media device, an optical storage media device, a flash memory device, an electrical, optical, or other physical / tangible memory storage device. Thus, generally, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of the present disclosure.

[0129] The processor 601 reads and executes the computer program instructions stored in the memory 602 to implement the method in the above embodiments.

[0130] In one example, the electronic device 600 may further include a communication interface 603 and a bus 604. Among them, as Figure 6As shown, a processor 601, a memory 602, and a communication interface 603 are connected via a bus 604 to complete communication with each other. The communication interface 603 is mainly used to implement communication between various modules, devices, units, and / or equipment in the embodiments of the present invention. The bus 604 includes hardware, software, or both, and couples the components of the online data flow charging device to each other. By way of example and not limitation, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an InfiniBand interconnect, a Low Pin Count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local (VLB) bus, or other suitable buses or a combination of two or more of these. Where appropriate, the bus 604 may include one or more buses. Although the embodiments of the present invention describe and illustrate specific buses, the present invention contemplates any suitable bus or interconnect.

[0131] In addition, in combination with the method in the above embodiments, an embodiment of the present invention may provide a vehicle, which includes the above electronic device.

[0132] It should be clear that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications, and additions, or change the order between steps after understanding the spirit of the present invention.

[0133] The functional blocks shown in the above structural block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, and so on. When implemented in software, the elements of the present invention are programs or code segments for performing the required tasks. The program or code segment can be stored in a machine-readable medium or transmitted via a data signal carried in a carrier wave over a transmission medium or a communication link. "Machine-readable medium" can include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, read-only memory (ROM), flash memory, erasable read-only memory (EROM), floppy disks, compact disc read-only memory (CD-ROM), optical discs, hard disks, fiber optic media, radio frequency (RF) links, and so on. The code segment can be downloaded via a computer network such as the Internet, an intranet, and so on.

[0134] It should also be noted that the exemplary embodiments mentioned in the present invention describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps can be executed in the order mentioned in the embodiments, or different from the order in the embodiments, or several steps can be executed simultaneously.

[0135] Aspects of the present disclosure have been described above with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present disclosure. It should be understood that each block in the flowcharts and / or block diagrams, and the combinations of blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the functions / actions specified in one or more blocks of the flowcharts and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It should also be understood that each block in the block diagrams and / or flowcharts, and the combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by dedicated hardware for performing the specified functions or actions, or by a combination of dedicated hardware and computer instructions.

[0136] As described above, the foregoing is only a specific implementation manner of the present invention. Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, modules, and units described above may refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein. It should be understood that the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A braking gap compensation method for an electro-mechanical braking system, characterized in that, The electro-mechanical braking system includes a motor, a transmission mechanism, a piston, and a brake actuator. The motor is used to drive the transmission mechanism to drive the piston to move. The piston is used to drive the brake actuator to clamp or release the brake disc of the wheel. The method includes: Obtaining the driving state data of the wheel after the vehicle brakes; Determining whether the driving state data has returned to a target value, where the target value is associated with the driving state data of the wheel before braking; Determining whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle; When the driving state data has not returned to the target value and there is no pressure building requirement for the brake disc, obtaining the estimated braking parameter of the wheel; When the estimated braking parameter is less than a second threshold, controlling the motor to drive the transmission mechanism to drive the piston, so that the piston drives the brake actuator to release the brake disc.

2. The method according to claim 1, wherein The determining whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle includes: Obtaining a target braking force and / or a target torque of the motor according to the control instruction of the vehicle; When the target braking force is less than a first threshold, determining that there is no pressure building requirement for the brake disc, and / or when the target torque is less than a torque threshold, determining that there is no pressure building requirement for the brake disc.

3. The method according to claim 1, wherein The estimated braking parameter is the braking force collected by the sensor of the wheel. The controlling the motor to drive the transmission mechanism to drive the piston, so that the piston drives the brake actuator to release the brake disc includes: When the estimated braking parameter is less than the second threshold, determining whether the position of the piston is greater than a third threshold; When the position of the piston is greater than the third position, controlling the motor to drive the transmission mechanism to drive the piston to retract to a target position point at a target speed, so that the piston drives the brake actuator to release the brake disc.

4. The method according to claim 3, wherein It further includes: Obtaining the contact point between the brake actuator and the brake disc; Determining whether the position of the piston is greater than the third threshold according to the position of the contact point and the position of the piston.

5. The method according to claim 3, wherein It further includes: When any preset condition is satisfied, continuing to maintain the brake actuator to clamp the brake disc. The preset conditions include that the driving state data has returned to the target value, there is a pressure building requirement, the estimated braking parameter is greater than or equal to the third threshold, and the position of the piston is less than or equal to the third position.

6. The method according to claim 3, characterized in that, The transmission mechanism includes a speed reduction and torque increase mechanism, a ball screw, and a screw nut. The motor drives the speed reduction and torque increase mechanism, the speed reduction and torque increase mechanism drives the ball screw, and the ball screw drives the piston. The method further includes: Obtaining the mechanical angle of the motor rotation, the transmission ratio of the speed reduction and torque increase mechanism, the thread pitch and the pitch circle radius of the screw nut; Determining the position of the piston according to the mechanical angle, the transmission ratio, the thread pitch, and the pitch circle radius.

7. The method according to claim 1, wherein The driving state data includes wheel speed and / or slip ratio. Obtaining the driving state data of the wheel after the vehicle brakes includes: After the vehicle brakes, obtaining the angular velocity of the wheel, the wheel radius, and the vehicle speed; Determining the slip ratio according to the angular velocity, the wheel radius, and the vehicle speed.

8. The method according to claim 1, characterized in that, After the method further includes, after controlling the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to release the brake disc: When the driving state data returns to the target value, determining whether there is a pressure building requirement for the brake disc of the vehicle; When there is the pressure building requirement, continuing to control the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to clamp the brake disc.

9. A braking clearance compensation device for an electro-mechanical braking system, characterized in that, Includes: An acquisition module, configured to acquire the driving state data of the wheel after the vehicle brakes; A data determination module, configured to determine whether the driving state data returns to a target value, where the target value is associated with the driving state data of the wheel before braking; A requirement determination module, configured to determine whether there is a pressure building requirement for the brake disc of the vehicle according to the control instruction of the vehicle; A parameter acquisition module, configured to acquire the estimated braking parameter of the wheel when the driving state data does not return to the target value and the brake disc does not have the pressure building requirement; A control module, configured to control the motor to drive the transmission mechanism to drive the piston so that the piston drives the brake actuator to release the brake disc when the estimated braking parameter is less than a second threshold.

10. An electronic device, characterized in that, Includes: a processor and a memory storing computer program instructions; the processor reads and executes the computer program instructions to implement the method according to any one of claims 1-8.

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