Brake contact point identification method and device, electronic brake and storage medium

Abstract

The invention provides a brake contact point identification method and device, an electronic brake and a storage medium, and the method comprises the steps that in the state that calipers are separated from a brake disc, a motor is controlled to drive the calipers to get close to and extrude the brake disc; collecting a current parameter flowing through the motor and a rotation angle parameter of the motor; constructing an initial mathematical model between the current flowing through the motor and the rotation angle of the motor; solving a model coefficient by using a recursive least square parameter identification method in combination with the corner parameter to obtain an updated mathematical model; and calculating a contact disc rotation angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the phase of increasing the absolute value of the current and the updated mathematical model. According to the method, the parameters in the constructed mathematical model are solved by using the recursive least square parameter identification method, so that the identification accuracy of the contact point of the mechanical brake is improved.

Description

Technical Field

[0001] The present application relates to the field of motor control, and more particularly, to a method and apparatus for identifying a brake contact point, an electronic brake, and a storage medium. Background Art

[0002] During the operation of an electro-mechanical brake (EMB), accurate identification of the contact point is the core prerequisite for achieving high-precision gap control. Specifically, there are mainly two reasons: First, during the brake release phase, it is usually necessary to maintain a certain dynamic gap between the friction pad and the brake disc to avoid brake drag caused by residual clamping force. This requires the system to implement active retraction control after accurately calibrating the contact point. Second, for low-cost solutions without dedicated clamping force sensors, it is necessary to estimate the clamping force based on the contact point position and the pre-calibrated brake system stiffness curve (F = KΔx, where K is the stiffness coefficient and Δx is the displacement amount beyond the contact point), and its accuracy directly depends on the contact point detection error.

[0003] Currently, the main method for identifying the contact point is to use the motor drive-current characteristic detection method. That is, first, control the motor to move in the clamping direction and monitor the motor current in real time; then, when the detected current value exceeds a preset fixed threshold (I_threshold), or the current change rate (di / dt) exceeds the derivative threshold value, it is determined that the contact point has been reached.

[0004] However, since such methods do not consider the characteristics of the mechanical resistance torque changing with temperature (such as the increase in resistance torque due to the increase in the viscosity of low-temperature grease and the change in the friction coefficient due to the expansion of high-temperature materials), the set threshold value deviates from the actual contact point under wide-temperature operating conditions, resulting in detection errors. Moreover, the current derivative method (di / dt) requires a first-order differential operation that is sensitive to noise. Even with filtering processing, there is still a phase delay problem. The same will result in detection errors.

[0005] That is to say, the accuracy of the current method for identifying the contact point is not high enough. Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a method and apparatus for identifying a brake contact point, an electronic brake, and a storage medium. By using the recursive least squares parameter identification method to obtain the parameters in the constructed mathematical model and using this mathematical model to calculate the motor rotation angle corresponding to the contact point, the accuracy of identifying the contact point of the mechanical brake can be improved.

[0007] In a first aspect, the embodiments of the present application provide a method for identifying a brake contact point, where the brake includes a motor, a caliper, and a brake disc; the method includes: In a state where the caliper is separated from the brake disc, control the motor to drive the caliper to approach and press the brake disc; collect the current parameter and the rotation angle parameter of the motor flowing through the motor; construct an initial mathematical model between the current flowing through the motor and the rotation angle of the motor; where, the initial mathematical model is: ; In the formula, i k is the k-th current parameter after the caliper contacts the brake disc, , a1, …, a n are the coefficients of the initial mathematical model respectively, , x k is the k-th rotation angle parameter after the caliper contacts the brake disc; use the recursive least squares parameter identification method, combine with the rotation angle parameter to obtain the model coefficients, and obtain an updated mathematical model; and according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model, calculate the contact disk rotation angle of the motor corresponding to the contact point.

[0008] The above-mentioned brake contact point identification method, by collecting multiple groups of current parameters and rotation angle parameters after the caliper contacts the brake disc, and combining the recursive least squares parameter identification method to obtain the parameters in the constructed mathematical model, and finally using the obtained updated mathematical model to calculate the motor rotation angle corresponding to the contact point, improves the accuracy of identifying the mechanical brake contact point compared with the traditional motor drive-current characteristic detection method.

[0009] Combined with the first aspect, optionally, the using the recursive least squares parameter identification method, combining with the rotation angle parameter to obtain the model coefficients, and obtaining an updated mathematical model includes: defining the initial covariance matrix as: ; In the formula, P0 is the initial covariance matrix, α is a constant, and I is an n-order identity matrix; based on the initial covariance matrix, use the gain matrix calculation formula, the updated model parameter calculation formula and the updated covariance matrix calculation formula for iteration to obtain the model coefficients; where, the gain matrix calculation formula is: ; In the formula, K k is the gain matrix calculated in the k-th iteration, P k-1 is the updated covariance matrix calculated in the (k - 1)-th iteration, and λ is the forgetting factor; the updated model parameter calculation formula is: ; In the formula, θ k is the model coefficient calculated in the k-th iteration, θ k-1The model coefficients calculated in the (k - 1)-th iteration; the formula for updating the covariance matrix is: ; where P k-2 is the updated covariance matrix calculated in the (k - 2)-th iteration, K k-1 is the gain matrix calculated in the (k - 1)-th iteration, , x k is the (k - 1)-th corner parameter after the caliper contacts the brake disc.

[0010] In the above method for identifying the brake contact point, by defining the initial covariance matrix and performing multiple iterations through calculating the gain matrix, covariance matrix, and estimation of model parameters, the coefficients in the initial mathematical model are finally calculated, thereby obtaining an updated mathematical model, improving the accuracy of the constructed mathematical model between the current of the motor and the rotation angle of the motor, and ultimately further improving the accuracy of identifying the mechanical brake contact point.

[0011] Combined with the first aspect, optionally, the step of collecting the current parameters and rotation angle parameters of the motor flowing through the acquisition group includes: collecting the current parameters and rotation angle parameters in real time; grouping the current parameters at fixed time intervals according to the moments corresponding to the current parameters; and calculating the average current parameter of all the current parameters in each group; where i k is the average current parameter of the k-th group.

[0012] In the above method for identifying the brake contact point, by grouping the collected current parameters at specific time intervals and calculating the average current parameter within each group, and finally using it to obtain the coefficients in the initial mathematical model, the accuracy of the constructed mathematical model between the current of the motor and the rotation angle of the motor is also improved, and ultimately the accuracy of identifying the mechanical brake contact point is further improved.

[0013] Combined with the first aspect, optionally, the step of calculating the rotation angle of the contact disc of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model includes: determining whether the current parameter satisfies the first condition and the second condition simultaneously; where the first condition is: ; The second condition is: ; where i is the current parameter, RLS_Threshold1 is the dynamic trigger threshold, i fittedThe fitted current parameter is calculated based on the current parameter and the updated mathematical model, and RLS_Threshold2 is the residual tolerance threshold. If it is determined that both the first condition and the second condition are satisfied, then RLS_Threshold3 is used as the current parameter in the updated mathematical model to calculate the contact disk rotation angle of the motor corresponding to the contact point, where RLS_Threshold3 is the third current threshold.

[0014] The above-mentioned brake contact point identification method determines whether both the dynamic trigger threshold condition and the residual tolerance threshold condition are satisfied, and when it is determined that both conditions are satisfied, the third current threshold is used as the effective contact disk current value, so as to calculate the contact disk rotation angle of the motor in combination with the updated mathematical model, eliminating the interference of abnormal data on the calculation result and improving the robustness of the calculation of the contact disk rotation angle. Finally, the accuracy of identifying the mechanical brake contact point is further improved.

[0015] Combined with the first aspect, optionally, the step of using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disk rotation angle of the motor corresponding to the contact point includes: determining whether the average value of the currently calculated minimum absolute value current is less than the average value of the minimum absolute value current calculated in the previous adjacent calculation; if it is determined that it is not less than, it is regarded as a current increase, and the continuous increase count is recorded; determining whether the continuous increase count exceeds the count threshold; if it is determined that it exceeds, the average value of the motor rotation angle calculated by RLS_Threshold3 is used as the contact disk rotation angle.

[0016] The above-mentioned brake contact point identification method determines, by comparing the calculated average current values successively, that the calculated average current value is in a continuous upward trend, and when the number of increases exceeds the count threshold, the third current threshold is used as the current value for calculating the contact disk rotation angle, further improving the accuracy of calculating the contact disk rotation angle, and thus further improving the accuracy of identifying the mechanical brake contact point.

[0017] Combined with the first aspect, optionally, the step of using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disk rotation angle of the motor corresponding to the contact point further includes: if it is determined that it is less than, then the updated third current threshold is used to calculate the contact disk rotation angle of the motor corresponding to the contact point, where the updated third current threshold is calculated according to the following formula: ; In the formula, RLS_Threshold3 is the third current threshold, I avg_current is the average value of the currently calculated minimum absolute value current, and I0 is a constant.

[0018] In the above brake contact point identification method, when the currently calculated current value is less than the previously calculated current value, indicating a decrease in the current value, the third current threshold is updated with the currently calculated value plus a constant current value to be used as the current value for calculating the contact disk rotation angle, making the brake contact point identification method provided by the embodiments of the present application more flexible and applicable. This also improves the accuracy of identifying the mechanical brake contact point.

[0019] In combination with the first aspect, optionally, calculating the rotation angle of the contact disk of the motor corresponding to the contact point using the updated third current threshold includes: calculating the rotation angle of the contact disk using the third current threshold; and clearing the average value of the continuously increasing times and the corresponding calculated motor rotation angles.

[0020] In the above brake contact point identification method, when the current shows a decreasing phenomenon, based on calculating the rotation angle of the contact disk using the third current threshold, the number of current increases recorded in the buffer is cleared, facilitating subsequent re-recording starting from 0. This further improves the accuracy of determining the contact disk current, and correspondingly improves the accuracy of identifying the mechanical brake contact point.

[0021] In a second aspect, an embodiment of the present application further provides a brake contact point identification device. The brake includes a motor, a caliper, and a brake disk. The device includes: a control module for controlling the motor to drive the caliper to approach and press the brake disk in a state where the caliper is separated from the brake disk; a collection module for collecting the current parameter flowing through the motor and the rotation angle parameter of the motor; a construction module for constructing an initial mathematical model between the current flowing through the motor and the rotation angle of the motor. The initial mathematical model is: ; where i k is the k-th current parameter after the caliper contacts the brake disk, , a1…a n are the coefficients of the initial mathematical model respectively, , x k is the k-th rotation angle parameter after the caliper contacts the brake disk; an obtaining module for obtaining the model coefficients using the recursive least squares parameter identification method in combination with the rotation angle parameters to obtain an updated mathematical model; a calculation module for calculating the rotation angle of the contact disk of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model.

[0022] The above-mentioned brake contact point identification device has the same beneficial effects as the brake contact point identification method provided in the above first aspect or any optional implementation manner of the first aspect, which will not be elaborated here.

[0023] In a third aspect, an embodiment of the present application further provides an electronic brake, including: a brake and a controller; the controller is electrically connected to the brake; the controller is configured to control the brake according to the method described in the first aspect.

[0024] The above-mentioned electronic brake has the same beneficial effects as the brake contact point identification method provided in the above first aspect or any optional implementation manner of the first aspect, which will not be elaborated here.

[0025] In a fourth aspect, an embodiment of the present application further provides a storage medium, the storage medium includes a computer-readable storage medium, and a computer program is stored on the computer-readable storage medium, and the computer program, when run by a processor, executes the method described above.

[0026] The above-mentioned storage medium has the same beneficial effects as the brake contact point identification method provided in the above first aspect or any optional implementation manner of the first aspect, which will not be elaborated here. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a flowchart of the brake contact point identification method provided by the embodiment of the present application; Figure 2 It is a specific flowchart of step S170 in the brake contact point identification method provided by the embodiment of the present application; Figure 3 It is a specific flowchart of step S130 in the brake contact point identification method provided by the embodiment of the present application; Figure 4 It is a specific flowchart of step S190 in the brake contact point identification method provided by the embodiment of the present application; Figure 5 It is a specific flowchart of step S192 in the brake contact point identification method provided by the embodiment of the present application; Figure 6It is a specific flowchart of step S1925 in the brake contact point identification method provided by the embodiments of this application; Figure 7 It is a functional module diagram of the brake contact point identification device provided by the embodiments of this application. Detailed implementation manners

[0029] Next, embodiments of the technical solutions of this application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solutions of this application more clearly, and thus are only examples and cannot be used to limit the protection scope of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0031] In the description of the embodiments of this application, technical terms such as "first" and "second" are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order or primary-secondary relationship of the indicated technical features. In the description of the embodiments of this application, "a plurality" means more than two unless otherwise specifically defined.

[0032] Please refer to Figure 1 , Figure 1 It is a flowchart of the brake contact point identification method provided by the embodiments of this application. In the brake contact point identification method provided by the embodiments of this application, the brake may include a motor, a caliper, and a brake disc.

[0033] This method may include: Step S110: In a state where the caliper is separated from the brake disc, control the motor to drive the caliper to approach and press the brake disc.

[0034] In the above step S110, the motor can be first controlled to drive the caliper to retract so that the caliper is separated from the brake disc. For example, control the motor to rotate 2500° in the direction of driving the caliper to retract. Subsequently, control the motor to drive the caliper to approach and press the brake disc. During the process of the caliper contacting and pressing the brake disc, the motor can operate at a uniform speed to drive the caliper.

[0035] Step S130: Collect the current parameter flowing through the motor and the rotation angle parameter of the motor.

[0036] In the above step S130, there is usually a certain functional relationship between the current of the motor and the displacement of the caliper, and the displacement of the caliper is mainly determined by the rotation angle of the motor and the linkage relationship (that is, the transmission ratio) between the caliper and the motor. Therefore, the specific functional relationship can usually be determined by using the current parameter and the rotation angle parameter of the motor.

[0037] Step S150: Construct an initial mathematical model between the current flowing through the motor and the rotation angle of the motor.

[0038] In the above step S150, the initial mathematical model is: ; where i k is the k-th current parameter after the caliper contacts the brake disc, , a1, …, a n are the coefficients of the initial mathematical model respectively, , x k is the k-th rotation angle parameter after the caliper contacts the brake disc.

[0039] Exemplarily, when n = 4, the above mathematical model becomes , that is, the mathematical model is a cubic function. When n = 3, the above mathematical model becomes , that is, the mathematical model is a cubic function. Regarding the specific value of n, those skilled in the art can determine it according to the specific situation in actual applications.

[0040] Step S170: Use the recursive least squares parameter identification method and combine with the rotation angle parameter to obtain the model coefficients and get an updated mathematical model.

[0041] In the above step S170, according to the multiple groups of current parameters and rotation angle parameters collected, combined with the recursive least squares parameter identification method, the coefficients 1, …, a in the above initial mathematical model can be obtained n , and the final updated mathematical model can be obtained.

[0042] Step S190: Calculate the rotation angle of the contact disk of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model.

[0043] In the above step S190, after the caliper contacts the brake disc, as the motor continues to drive the caliper to squeeze the brake disc, the absolute value of the current flowing through the motor usually increases. Therefore, in the trend of the increase of the absolute value of the current, the current at the initial moment can be used as the current when the caliper just contacts the brake disc, that is, the current corresponding to the contact point. And by using this current and combining with the updated mathematical model obtained above, the rotation angle of the motor corresponding to the contact point, that is, the rotation angle of the contact disk, can be calculated.

[0044] In the above implementation process, by collecting multiple groups of current parameters and rotation angle parameters after the caliper contacts the brake disc, and combining the recursive least squares parameter identification method to obtain the parameters in the constructed mathematical model, and finally using the obtained updated mathematical model to calculate the motor rotation angle corresponding to the contact point, compared with the traditional motor drive-current characteristic detection method, the accuracy of identifying the mechanical brake contact point is improved.

[0045] Please refer to Figure 2 , Figure 2 is the specific flowchart of step S170 in the brake contact point identification method provided by the embodiments of the present application. In some alternative embodiments, step S170 may include: Step S171: Define the initial covariance matrix as: . In the formula, P0 is the initial covariance matrix, α is a constant, and I is an n-order identity matrix.

[0046] In the above step S171, exemplarily, the value of α can be 10 4 , combined with the example described above, when n = 3, the mathematical model becomes , then I can also be a 3-order identity matrix, that is .

[0047] Step S172: Based on the initial covariance matrix, use the gain matrix calculation formula, the updated model parameter calculation formula, and the updated covariance matrix calculation formula for iteration to obtain the model coefficients.

[0048] In the above step S172, the gain matrix calculation formula is: ; In the formula, K k is the gain matrix calculated in the kth iteration, P k-1 is the updated covariance matrix calculated in the (k - 1)th iteration, and λ is the forgetting factor.

[0049] The updated model parameter calculation formula is: ; In the formula, θ k is the model coefficient calculated in the kth iteration, θ k-1 is the model coefficient calculated in the (k - 1)th iteration.

[0050] The updated covariance matrix calculation formula is: ; In the formula, P k-2 is the updated covariance matrix calculated in the (k - 2)th iteration, K k-1is the gain matrix calculated in the (k - 1)-th iteration, , x k is the (k - 1)-th rotation angle parameter after the caliper contacts the brake disc.

[0051] That is to say, to obtain the coefficients in the initial mathematical model, the gain matrix needs to be obtained. The gain matrix in the current iteration process requires the covariance matrix obtained in the previous adjacent iteration, and the calculation of the covariance matrix in the previous iteration process requires the covariance matrix obtained in the iteration before the previous iteration and the gain matrix in the previous iteration process. Therefore, such a cyclic relationship requires a corresponding number of iterations to obtain the coefficients in the initial mathematical model. The specific number of iterations can be determined by those skilled in the art according to the actual requirements for the model accuracy. In the embodiments of the present application, no specific limitation is made thereto.

[0052] In the above implementation process, by defining the initial covariance matrix and performing multiple iterations by calculating the gain matrix, covariance matrix, and estimation of model parameters, the coefficients in the initial mathematical model are finally calculated, thereby obtaining an updated mathematical model, improving the accuracy of the constructed mathematical model between the current of the motor and the rotation angle of the motor, and ultimately further improving the accuracy of identifying the contact point of the mechanical brake.

[0053] Please refer to Figure 3 , Figure 3 which is a specific flowchart of step S130 in the brake contact point identification method provided in the embodiments of the present application. In some optional implementation manners, step S130 may include: Step S131: Real-time collect current parameters and rotation angle parameters.

[0054] Step S132: Group the current parameters at fixed time intervals according to the moments corresponding to the current parameters.

[0055] Step S133: Calculate the average current parameter of all current parameters in each group.

[0056] In the above steps S131 to S133, exemplarily, among the collected current parameters and rotation angle parameters, taking the corresponding time as a reference, the current parameters and rotation angle parameters corresponding within every 10 ms are taken as a group of parameters, and the average current parameter in each group of parameters is calculated. Among them, i k is the average current parameter of the k-th group.

[0057] In the above implementation process, the collected current parameters are grouped at specific time intervals, and the average current parameter of each group of current parameters is calculated. Finally, it is used to obtain the coefficients in the initial mathematical model, which also improves the accuracy of the constructed mathematical model between the current of the motor and the rotation angle of the motor, and ultimately further improves the accuracy of identifying the contact point of the mechanical brake.

[0058] Please refer to Figure 4 , Figure 4 is the specific flowchart of step S190 in the brake contact point identification method provided by the embodiment of the present application. In some optional implementation manners, step S190 may include: Step S191: Determine whether the current parameter satisfies the first condition and the second condition at the same time.

[0059] In the above step S191, the first condition is: ; The second condition is: ; In the formula, i is the current parameter, RLS_Threshold1 is the dynamic trigger threshold, i fitted is the fitted current parameter calculated based on the current parameter and the updated mathematical model, RLS_Threshold2 is the residual tolerance threshold, which can be set to 2-3 times the noise peak value in the collected current data. For example, if the noise peak value is 0.2A, then the residual tolerance threshold can be specifically determined as 0.5A.

[0060] If it is determined that both the first condition and the second condition are satisfied, then execute step S192: Use RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the disk rotation angle of the motor corresponding to the contact point.

[0061] In the above step S192, RLS_Threshold3 is the third current threshold. That is to say, in the embodiment of the present application, only when both the dynamic trigger threshold condition and the residual tolerance threshold condition are satisfied, the third current threshold used to calculate the disk rotation angle is valid, so that this current value can be substituted into the obtained updated mathematical model to calculate the disk rotation angle of the motor corresponding to the contact point.

[0062] In the above implementation process, by determining whether the dynamic trigger threshold condition and the residual tolerance threshold condition are simultaneously satisfied, and when it is determined that both conditions are satisfied, the third current threshold is used as the effective disc current value, so as to calculate the disc rotation angle of the motor by combining and updating the mathematical model, excluding the interference of abnormal data on the calculation result, and improving the robustness of calculating the disc rotation angle. Finally, the accuracy of identifying the contact point of the mechanical brake is further improved.

[0063] Please refer to Figure 5 , Figure 5 which is the specific flowchart of step S192 in the brake contact point identification method provided by the embodiment of the present application. In some optional implementation manners, step S192 may include: Step S1921: Determine whether the average value of the currently calculated minimum absolute value current is less than the average value of the minimum absolute value current calculated in the previous adjacent calculation.

[0064] If it is determined that it is not less than, then execute step S1922: Consider the current to be rising, and record the number of consecutive rises.

[0065] Step S1923: Determine whether the number of consecutive rises exceeds the number threshold.

[0066] If it is determined that it exceeds, then execute step S1924: Use the average value of the motor rotation angles calculated by RLS_Threshold3 as the disc rotation angle.

[0067] In the above steps S1921 to S1924, that is to say, when the number of times of rising of the absolute value of the current exceeds the threshold, the average current is calculated based on the current in this rising stage, and this average current is used as the current value for calculating the disc rotation angle.

[0068] In the above implementation process, by comparing the calculated average current values successively, it is determined that the calculated average current value is in a continuous rising trend, and when the number of rises exceeds the number threshold, the third current threshold is used as the current value for calculating the disc rotation angle, further improving the accuracy of calculating the disc rotation angle, and thus further improving the accuracy of identifying the contact point of the mechanical brake.

[0069] Please continue to refer to Figure 5 , in some optional implementation manners, step S192 may further include: If it is determined that it is less than, then execute step S1925: Calculate the disc rotation angle of the motor corresponding to the contact point using the updated third current threshold.

[0070] In the above step S1925, the updated third current threshold is calculated according to the following formula: ; Wherein, RLS_Threshold3 is the third current threshold, and I avg_current is the average value of the currently calculated minimum absolute value of the current, and I0 is a constant, for example: 1.5 A.

[0071] In the above implementation process, when the currently calculated current value is less than the previously calculated current value of the adjacent previous time and the current value shows a downward trend, the third current threshold is updated with the currently calculated current value plus a constant current value to be used as the current value for calculating the contact disk rotation angle, making the brake contact point identification method provided by the embodiments of the present application more flexible and applicable. This also equivalently improves the accuracy of identifying the mechanical brake contact point.

[0072] Please refer to Figure 6 , Figure 6 which is the specific flowchart of step S1925 in the brake contact point identification method provided by the embodiments of the present application. In some alternative embodiments, step S1925 may include: Step S19251: Calculate the contact disk rotation angle with the third current threshold.

[0073] Step S19252: Clear the recorded consecutive rise times and the average value of the corresponding calculated motor rotation angles.

[0074] In the above steps, that is to say, when calculating the average current value each time, if the current is in the rising stage, it can be recorded once in the buffer area to indicate that the current has risen once. If the current shows a downward trend, the previously recorded current rise times are cleared for subsequent re-recording starting from 0.

[0075] In the above implementation process, when the current shows a downward trend, based on calculating the contact disk rotation angle with the third current threshold, the recorded current rise times in the buffer area are cleared, which facilitates subsequent re-recording starting from 0. This further improves the accuracy of determining the contact disk current and correspondingly improves the accuracy of identifying the mechanical brake contact point.

[0076] Please refer to Figure 7 , Figure 7 which is the functional module diagram of the brake contact point identification device 700 provided by the embodiments of the present application. Based on the same concept, the present application provides a brake contact point identification device 700. Among them, the brake may include a motor, a caliper, and a brake disc.

[0077] The brake contact point identification device 700 may include a control module 710, a collection module 720, a construction module 730, an obtaining module 740, and a calculation module 750.

[0078] The control module 710 can be used to control the motor to drive the caliper to approach and press the brake disc in a state where the caliper is separated from the brake disc.

[0079] The acquisition module 720 can be used to acquire the current parameters and the rotation angle parameters of the motor flowing through the motor.

[0080] The construction module 730 can be used to construct an initial mathematical model between the current flowing through the motor and the rotation angle of the motor. Among them, the initial mathematical model is: ; In the formula, i k is the kth current parameter after the caliper contacts the brake disc, , a1…a n are the coefficients of the initial mathematical model respectively, , x k is the kth rotation angle parameter after the caliper contacts the brake disc.

[0081] The obtaining module 740 can be used to obtain the model coefficients by using the recursive least squares parameter identification method and combining the rotation angle parameters to obtain an updated mathematical model.

[0082] The calculation module 750 can be used to calculate the contact disk rotation angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model.

[0083] As some optional implementation manners, in the process of obtaining the model coefficients by using the recursive least squares parameter identification method and combining the rotation angle parameters to obtain an updated mathematical model, the obtaining module 740 can specifically be used to: define the initial covariance matrix as: . In the formula, P0 is the initial covariance matrix, α is a constant, and I is an n-order identity matrix.

[0084] Based on the initial covariance matrix, perform iteration by using the gain matrix calculation formula, the updated model parameter calculation formula, and the updated covariance matrix calculation formula to obtain the model coefficients. Among them, the gain matrix calculation formula is: ; In the formula, K k is the gain matrix calculated in the kth iteration, P k-1 is the updated covariance matrix calculated in the (k - 1)th iteration, and λ is the forgetting factor.

[0085] The updated model parameter calculation formula is: ; In the formula, θ k is the model coefficient calculated in the kth iteration, θ k-1The model coefficients calculated in the (k - 1)-th iteration.

[0086] The formula for updating the covariance matrix is: ; where P k-2 is the updated covariance matrix calculated in the (k - 2)-th iteration, K k-1 is the gain matrix calculated in the (k - 1)-th iteration, , x k is the (k - 1)-th angular parameter after the caliper contacts the brake disc.

[0087] As some alternative embodiments, during the process of collecting the current parameters and angular parameters of the motor when the acquisition group flows through the motor, the acquisition module 720 can specifically be used to: collect the current parameters and angular parameters in real time. Group the current parameters at fixed time intervals according to the moments corresponding to the current parameters. And calculate the average current parameter of all the current parameters in each group. Wherein, i k is the average current parameter of the k-th group.

[0088] As some alternative embodiments, during the process of calculating the contact disc angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model, the calculation module 750 can specifically be used to: determine whether the current parameter satisfies both the first condition and the second condition. Wherein, the first condition is: ; The second condition is: ; where i is the current parameter, RLS_Threshold1 is the dynamic trigger threshold, i fitted is the fitted current parameter calculated based on the current parameter and the updated mathematical model, and RLS_Threshold2 is the residual tolerance threshold.

[0089] If it is determined that both the first condition and the second condition are satisfied, then use RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disc angle of the motor corresponding to the contact point; wherein, RLS_Threshold3 is the third current threshold.

[0090] As some optional implementations, in the process of using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact plate angle of the motor corresponding to the contact point, the calculation module 750 can be specifically used to: determine whether the average value of the currently calculated minimum absolute current value is less than the average value of the last calculated minimum absolute current value; if it is determined to be not less than, it is regarded as a current rise, and the number of consecutive rises is recorded; determine whether the number of consecutive rises exceeds the number threshold; if it is determined to exceed, the average value of the motor angle calculated by RLS_Threshold3 is used as the contact plate angle.

[0091] As some optional implementations, in the process of using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact plate angle of the motor corresponding to the contact point, the calculation module 750 can also be specifically used to: if it is determined to be less than, then use the updated third current threshold to calculate the contact plate angle of the motor corresponding to the contact point. The updated third current threshold is calculated according to the following formula: ; Where RLS_Threshold3 is the third current threshold, I avg_current is the average value currently calculated, and I0 is a constant.

[0092] As some optional implementations, in the process of calculating the contact disk angle of the motor corresponding to the contact point with the third current threshold, the calculation module 750 can be more specifically used to: calculate the contact disk angle with the third current threshold, and clear the recorded continuous rise times and the corresponding calculated average value of the motor angle.

[0093] It should be understood that the device corresponds to the above-mentioned brake contact point identification method embodiment and can execute the various steps involved in the above-mentioned method embodiment. The specific functions of the device can be found in the above description. To avoid repetition, the detailed description is appropriately omitted here. The device includes at least one software function module that can be stored in a memory in the form of software or firmware or fixed in the operating system (OS) of the device.

[0094] Based on the same concept, an embodiment of the present application provides an electronic brake, comprising: a brake and a controller, wherein the controller is electrically connected to the brake; The controller is used to control the brake according to the brake contact point identification method described above.

[0095] The embodiments of the present application also provide a storage medium, which includes a computer-readable storage medium. A computer program is stored on the computer-readable storage medium, and when the computer program is run by a processor, it executes the method as described above.

[0096] Among them, the computer-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM for short), electrically erasable programmable read-only memory (EEPROM for short), erasable programmable read-only memory (EPROM for short), programmable read-only memory (PROM for short), read-only memory (ROM for short), magnetic memory, flash memory, magnetic disk or optical disk.

[0097] In several embodiments provided by the embodiments of the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are only illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions, and operations of devices, methods, and computer program products according to multiple embodiments of the present application. In this regard, each block in the flowchart or block diagram may represent a module, a program segment, or a part of code, and the module, program segment, or part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order from that marked in the accompanying drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, as well as the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system that executes the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0098] In addition, in each embodiment of the embodiments of the present application, the various functional modules can be integrated together to form an independent part, or each module can exist alone, or two or more modules can be integrated to form an independent part.

[0099] The above description is only an optional implementation manner of the embodiments of the present application, but the protection scope of the embodiments of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the embodiments of the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the embodiments of the present application.

Claims

1. A method for identifying a brake contact point, characterized in that, Among them, the brake includes a motor, a caliper, and a brake disc; the method includes: in a state where the caliper is separated from the brake disc, controlling the motor to drive the caliper to approach and press the brake disc; collecting the current parameter flowing through the motor and the rotation angle parameter of the motor; constructing an initial mathematical model between the current flowing through the motor and the rotation angle of the motor; where the initial mathematical model is: where i k is the k-th current parameter after the caliper contacts the brake disc, , a1, …, a n are the coefficients of the initial mathematical model respectively, , x k is the k-th rotation angle parameter after the caliper contacts the brake disc; using the recursive least squares parameter identification method and combining the rotation angle parameter to obtain the model coefficients, and obtaining an updated mathematical model; and calculating the contact disc rotation angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model.

2. The method according to claim 1, wherein The using the recursive least squares parameter identification method and combining the rotation angle parameter to obtain the model coefficients and obtaining an updated mathematical model includes: Define the initial covariance matrix as: ; where P0 is the initial covariance matrix, α is a constant, and I is an n-order identity matrix; Based on the initial covariance matrix, performing iterations using the gain matrix calculation formula, the updated model parameter calculation formula, and the updated covariance matrix calculation formula to obtain the model coefficients; where the gain matrix calculation formula is: where K k is the gain matrix calculated in the k-th iteration, and P k-1 is the updated covariance matrix calculated in the (k - 1)-th iteration, and λ is the forgetting factor; The updated model parameter calculation formula is: where θ k is the model coefficient calculated in the k-th iteration, and θ k-1 is the model coefficient calculated in the (k - 1)-th iteration; The updated covariance matrix calculation formula is: where P k-2 is the updated covariance matrix calculated in the (k - 2)-th iteration, K k-1 is the gain matrix calculated in the (k - 1)-th iteration, , x k is the (k - 1)-th corner parameter after the caliper contacts the brake disc.

3. The method according to claim 1, characterized in that, The collecting the current parameter flowing through the motor and the rotation angle parameter of the motor includes: real-time collecting the current parameter and the rotation angle parameter; grouping the current parameters at a fixed time length according to the time corresponding to the current parameters; and calculating the average current parameter of all the current parameters in each group. wherein, i k is the average current parameter of the k-th group.

4. The method according to claim 2, wherein The calculating the contact disc rotation angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model includes: judging whether the current parameter satisfies the first condition and the second condition at the same time; where the first condition is: The second condition is: Wherein, i is the current parameter, RLS_Threshold1 is the dynamic trigger threshold, and i fitted is the fitted current parameter calculated based on the current parameter and the updated mathematical model, and RLS_Threshold2 is the residual tolerance threshold; If it is determined that both the first condition and the second condition are satisfied, then use RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disc rotation angle of the motor corresponding to the contact point; where RLS_Threshold3 is the third current threshold.

5. The method according to claim 4, wherein The using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disc rotation angle of the motor corresponding to the contact point includes: judging whether the average value of the currently calculated minimum absolute value current value is less than the average value of the minimum absolute value current value calculated in the previous adjacent time; If it is determined that it is not less than, it is regarded as the current rising, and the continuous rising times are recorded; judging whether the continuous rising times exceed the times threshold; If it is determined that it exceeds, then use the average value of the motor rotation angle calculated by RLS_Threshold3 as the contact disc rotation angle.

6. The method according to claim 4, wherein The using RLS_Threshold3 as the current parameter in the updated mathematical model to calculate the contact disc rotation angle of the motor corresponding to the contact point further includes: If it is determined that it is less than, then calculate the contact disc rotation angle of the motor corresponding to the contact point using the updated third current threshold; where the updated third current threshold is calculated according to the following formula: wherein, RLS_Threshold3 is the third current threshold, I avg_current is the average value of the currently calculated minimum absolute value current, and I0 is a constant.

7. The method according to claim 6, characterized in that, Calculating the contact disk rotation angle of the motor corresponding to the contact point based on the updated third current threshold includes: Calculating the contact disk rotation angle based on the third current threshold; and Clearing the recorded number of consecutive increases and the average value of the calculated motor rotation angles.

8. A brake contact point identification device, characterized in that, Wherein, The brake includes a motor, a caliper, and a brake disk; The device includes: A control module for controlling the motor to drive the caliper to approach and press the brake disk in a state where the caliper is separated from the brake disk; An acquisition module for acquiring the current parameters and the rotation angle parameters of the motor flowing through the motor; A construction module for constructing an initial mathematical model between the current flowing through the motor and the rotation angle of the motor; wherein, the initial mathematical model is: where i k is the k-th current parameter after the caliper contacts the brake disc, , a1…a n are the coefficients of the initial mathematical model respectively, , x k is the k-th rotation angle parameter after the caliper contacts the brake disc; An obtaining module for obtaining the model coefficients by using the recursive least squares parameter identification method and combining the rotation angle parameters to obtain an updated mathematical model; A calculation module for calculating the contact disk rotation angle of the motor corresponding to the contact point according to the minimum absolute value current value corresponding to the stage where the absolute value of the current increases and the updated mathematical model.

9. An electronic brake, characterized in that, Includes: A brake and a controller, The controller is electrically connected to the brake; The controller is used to control the brake according to the method described in any one of claims 1 to 7.

10. A storage medium, characterized in that, The storage medium includes a computer-readable storage medium; a computer program is stored on the computer-readable storage medium, and when the computer program is run by a processor, it executes the method described in any one of claims 1 to 7.

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