Brake clamping force calculation method, device and storage medium

Abstract

This application provides a method, apparatus, and storage medium for calculating the clamping force of a brake. The method includes: constructing an initial modified stiffness curve model based on the original stiffness curve model; the initial modified stiffness curve model is: where F cl The clamping force is denoted by a, b, c, and d, which are coefficients in the original stiffness curve model. ψ represents the rotation angle of the motor in the brake, ψ0 is the offset angle corresponding to the offset distance between the caliper and the brake disc contact point, and k is the stiffness correction coefficient. After the caliper approaches and squeezes the brake disc, the rotation angle parameters of the motor and the corresponding clamping force parameters are obtained. Based on the rotation angle parameters and clamping force parameters, the stiffness correction coefficient and offset angle are calculated to obtain an updated and corrected stiffness curve model. Finally, the clamping force of the brake is calculated based on the updated and corrected stiffness curve model. This method improves the accuracy of the calculation results by obtaining a mathematical model for calculating the clamping force based on the calibration of the stiffness curve.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, in particular to a method and device for calculating clamping force of a brake and a storage medium. BACKGROUND

[0002] At present, in the EMB (electronic brake) control technology, the clamping force is usually estimated by the motor displacement through the stiffness curve or by the motor torque through the force balance equation. However, the stiffness curve is easily affected by factors such as temperature and disc wear, resulting in estimation error; and the clamping force estimated by the force balance equation has large noise, which needs to rely on filtering processing.

[0003] Of course, there are also data fusion methods (for example, linearly weighting fusion of the results of the above two methods). However, there are still some factors affecting the accurate calculation results. For example: first, since the bandwidths of the above two methods are inconsistent, the weight parameter needs to be dynamically adjusted according to the working conditions, so the parameter setting is difficult; second, the noise of the force balance equation affects the control effect, resulting in reduced system stability.

[0004] That is, in the current calculation scheme of the clamping force of the brake, it is difficult to obtain a relatively accurate calculation result. SUMMARY

[0005] The purpose of the embodiments of the present application is a method and device for calculating clamping force of a brake and a storage medium, which obtains a mathematical model for calculating clamping force based on calibration of the stiffness curve, and calculates the clamping force by using the model. The accuracy of the calculation result can be improved.

[0006] In a first aspect, the embodiments of the present application provide a method for calculating clamping force of a brake, wherein the brake comprises a motor, a caliper and a brake disc; the method comprises: constructing an initial modified stiffness curve model according to an original stiffness curve model; wherein the initial modified stiffness curve model is:

[0007]

[0008] In the formula, F is the clamping force, a, b, c and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, and k is the stiffness correction coefficient; after the caliper approaches and presses the brake disc, the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter are obtained; the stiffness correction coefficient and the offset rotation angle are obtained according to the rotation angle parameter and the clamping force parameter, and an updated modified stiffness curve model is obtained; and the clamping force of the brake is calculated according to the updated modified stiffness curve model. cl is the clamping force, a, b, c and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, and k is the stiffness correction coefficient; after the caliper approaches and presses the brake disc, the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter are obtained; the stiffness correction coefficient and the offset rotation angle are obtained according to the rotation angle parameter and the clamping force parameter, and an updated modified stiffness curve model is obtained; and the clamping force of the brake is calculated according to the updated modified stiffness curve model.

[0009] The above-mentioned method for calculating the clamping force of the brake constructs an initial modified stiffness curve model by calibrating the original stiffness curve model. Then, by combining multiple sets of collected angle parameters and clamping force parameters, the coefficients to be determined in the model are extracted, resulting in a final updated modified stiffness curve model. This updated stiffness curve model can then be used to calculate the clamping force, thus improving the accuracy of the clamping force calculation.

[0010] In conjunction with the first aspect, optionally, the step of obtaining the stiffness correction coefficient and offset angle based on the rotation angle parameter and clamping force parameter to obtain the updated corrected stiffness curve model includes: defining a parameter vector and constructing a residual vector and a Jacobian matrix; wherein the parameter vector, the residual vector, and the Jacobian matrix are respectively:

[0011]

[0012]

[0013]

[0014] In the formula, , ψ i For the collected rotation angle parameters, F cl,tbe,i Let i be the clamping force parameter corresponding to the rotation angle parameter, i = 0, 1, 2…; solve the equation. We obtain Δp; where λ is the forgetting factor, I is a 2nd-order identity matrix, and ΔP = P i -P i-1 ; and by using an iterative formula to iterate and calculate the parameter vector, the updated and corrected stiffness curve model is obtained; wherein the iterative formula is:

[0015]

[0016] In the formula, P new Let P be the parameter vector obtained in the current iteration. old This is the parameter vector obtained from the previous iteration.

[0017] The above-mentioned method for calculating the clamping force of the brake constructs a parameter vector, a residual vector, and a Jacobian matrix based on the initial modified stiffness curve, and then derives the equation based on the residual vector and the Jacobian matrix. the parameter vector variation Δp, and finally, the parameter vector variation Δp is used for iteration for a corresponding number of times, so that a more accurate stiffness correction coefficient and offset angle can be obtained, and thus an updated correction stiffness curve model used for calculating the clamping force is obtained. Compared with the method of directly using the undetermined coefficient method to obtain the coefficient in the model based on the collected multiple sets of parameters, the coefficient obtained by the multiple iteration method makes the model more approximate to the real application scenario, thereby further improving the accuracy of calculating the clamping force.

[0018] With reference to the first aspect, optionally, the iteration using the iteration formula to calculate the parameter vector comprises: judging whether the following condition is met: wherein, δ is a parameter variation threshold value; if it is determined that the condition is met, it is determined that the parameter vector obtained by the current iteration converges, and the updated correction stiffness curve model is obtained according to the parameter vector obtained by the current iteration. , and ϵ is a residual sum of squares variation threshold value; if it is determined that the condition is met, it is determined that the parameter vector obtained by the current iteration converges, and the updated correction stiffness curve model is obtained according to the parameter vector obtained by the current iteration.

[0019] The clamping force calculation method of the brake described above, by calculating the residual sum of squares variation corresponding to the parameter vector obtained by the current iteration, and judging whether the residual sum of squares variation is less than the residual sum of squares variation threshold value, in the case of determining that it is less, it is determined that the parameter vector obtained by the current iteration converges. The vector elements in the parameter vector can be used as the stiffness correction coefficient and the offset angle, so that the final updated correction stiffness curve model is obtained. Finally, the accuracy of calculating the clamping force is further improved.

[0020] With reference to the first aspect, optionally, the iteration using the iteration formula to calculate the parameter vector comprises: judging whether the following condition is met: wherein, δ is a parameter variation threshold value; if it is determined that the condition is met, it is determined that the parameter vector obtained by the current iteration converges, and the updated correction stiffness curve model is obtained according to the parameter vector obtained by the current iteration.

[0021] The clamping force calculation method of the brake described above, by judging whether the parameter variation of the parameter vector obtained by the current iteration is less than the parameter variation threshold value, and in the case of determining that it is less, it is determined that the parameter vector obtained by the current iteration converges. The vector elements in the parameter vector can be used as the stiffness correction coefficient and the offset angle, so that the final updated correction stiffness curve model is obtained. Finally, the accuracy of calculating the clamping force is also further improved.

[0022] With reference to the first aspect, optionally, the iteration using the iteration formula to calculate the parameter vector comprises: judging whether the iteration number exceeds an iteration threshold value; if it is determined that the iteration threshold value is exceeded, it is determined that the parameter vector calculated at present is invalid.

[0023] The iteration times of the brake clamping force calculation method are usually too many, which indicates that the initial value selection is not reasonable, the convergence condition setting is not reasonable, or the like in the iteration process. Therefore, by limiting the iteration times, the above problems can be investigated or excluded, thereby improving the accuracy of the coefficients in the finally obtained model. That is, the accuracy of calculating the clamping force is further improved.

[0024] With reference to the first aspect, before the parameter vector is defined and the residual vector and the Jacobian matrix are constructed, the method further includes: determining whether the data quantity of the rotation angle parameter and the corresponding clamping force parameter reaches a data quantity threshold; and if it is determined that the data quantity threshold is reached, defining the parameter vector and constructing the residual vector and the Jacobian matrix.

[0025] The brake clamping force calculation method sets a data quantity limit condition before the parameter vector is used to construct the residual vector and the Jacobian matrix for iteration to obtain the coefficients in the mathematical model, and the coefficients in the model are obtained only when the data quantity reaches a certain degree, thereby further ensuring the accuracy of the coefficients in the obtained mathematical model, and improving the accuracy of calculating the clamping force.

[0026] With reference to the first aspect, the rotation angle parameter of the motor and the corresponding clamping force parameter can be obtained by: calculating the corresponding clamping force parameter according to a pre-calibrated transmission ratio, a friction torque of the brake, and a force balance equation; and the force balance equation is:

[0027]

[0028] In the formula, F cl,tbe is the clamping force parameter, T m is the torque of the motor, T Fc is the friction torque of the brake, and γ is the transmission ratio.

[0029] The brake clamping force calculation method calculates the clamping force parameter corresponding to the rotation angle parameter by using the force balance equation, which does not need to rely on additional sensors compared with directly detecting the clamping force parameter corresponding to the rotation angle parameter by using a sensor, thereby simplifying the scheme for calculating the clamping force.

[0030] With reference to the first aspect, the corresponding clamping force parameter can be calculated according to the pre-calibrated transmission ratio, the friction torque of the brake, and the force balance equation, including: when the rotation speed of the motor is in the interval of [ ], and the clamping force is in the interval of [ calibrate the transmission ratio and the friction torque of the brake in the case of a specific speed interval of the motor; wherein n min is the upper limit of the speed of the motor, n max is the lower limit of the speed of the motor, F cl,min is the upper limit of the clamping force, F cl,max is the lower limit of the clamping force.

[0031] The clamping force calculation method of the above brake, by collecting the rotation angle parameters and the clamping force parameters in a specific speed interval and a specific clamping force interval, makes the data used to obtain the coefficients in the mathematical model more effective and more reliable. Thus, the accuracy of calculating the clamping force is further improved.

[0032] In a second aspect, the embodiments of the present application also provide a clamping force calculation device of a brake, wherein the brake comprises a motor, a caliper and a brake disc; the device comprises: a construction module, configured to construct an initial modified stiffness curve model according to an original stiffness curve model; wherein the initial modified stiffness curve model is:

[0033]

[0034] In the formula, F cl is the clamping force, a, b, c and d are respectively coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, and k is a stiffness correction coefficient; a collection module, configured to obtain the rotation angle parameters of the motor and the clamping force parameters corresponding to the rotation angle parameters after the caliper approaches and presses the brake disc; a calculation module, configured to obtain the stiffness correction coefficient and the offset rotation angle according to the rotation angle parameters and the clamping force parameters, and obtain an updated modified stiffness curve model; and a calculation module, configured to calculate the clamping force of the brake according to the updated modified stiffness curve model.

[0035] The clamping force calculation device of the above brake has the same beneficial effects as the clamping force calculation method of the brake provided in the first aspect or any one of the optional embodiments of the first aspect, which will not be repeated here.

[0036] In a third aspect, the embodiments of the present application also provide a storage medium, which comprises a computer readable storage medium, and the computer readable storage medium stores a computer program, and the computer program is run by a processor to execute the above-described method.

[0037] The above storage medium has the same beneficial effects as the clamping force calculation method of the brake provided in the first aspect or any one of the optional embodiments of the first aspect, which will not be repeated here. BRIEF DESCRIPTION OF DRAWINGS

[0038] 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 as follows. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as limiting the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0039] Figure 1 The flow chart of the clamping force calculation method of the brake provided in the embodiments of the present application is shown in FIG. 1.

[0040] Figure 2 The specific flow chart of step S150 in the clamping force calculation method of the brake provided in the embodiments of the present application is shown in FIG. 2.

[0041] Figure 3 The first specific flow chart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application is shown in FIG. 3.

[0042] Figure 4 The second specific flow chart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application is shown in FIG. 4.

[0043] Figure 5 The third specific flow chart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application is shown in FIG. 5.

[0044] Figure 6 The functional module diagram of the clamping force calculation device of the brake provided in the embodiments of the present application is shown in FIG. 6. DETAILED DESCRIPTION

[0045] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0047] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly specified.

[0048] Please refer toFigure 1 , Figure 1 This is a flowchart illustrating a method for calculating the clamping force of a brake according to an embodiment of this application. In this embodiment, the brake may include a motor, a caliper, and a brake disc.

[0049] The method may include:

[0050] Step S110: Construct an initial modified stiffness curve model based on the original stiffness curve model.

[0051] In step S110 above, the initial modified stiffness curve model can be obtained from the original stiffness curve model used in commonly used EMB control technology. The original stiffness curve model is typically as follows:

[0052]

[0053] In the formula, F est,stiff Let ψ be the clamping force to be calculated, ψ be the rotation angle of the motor in the brake, and a, b, c, and d be the coefficients in the original stiffness curve model.

[0054] Due to contact point identification errors and stiffness variations caused by friction plate wear, the actual clamping force variation follows an initial corrected stiffness curve model obtained by modifying the original stiffness curve model described above. The initial corrected stiffness curve model is as follows:

[0055]

[0056] In the formula, F cl The clamping force is denoted by ψ, where a, b, c, and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset angle corresponding to the offset distance between the caliper and the brake disc contact point, and k is the stiffness correction coefficient.

[0057] The coefficients in the original stiffness curve model can be obtained using methods known to those skilled in the art. Examples include the motor drive-current characteristic detection method and the recursive least squares parameter identification method. Accordingly, in this embodiment, the coefficients in the original stiffness curve model can be known. Therefore, the subsequent objective can be to determine the stiffness correction coefficient k and the offset angle ψ0, thereby obtaining an updated and corrected stiffness curve model used to calculate the clamping force based on the motor rotation angle.

[0058] Step S130: After the caliper approaches and squeezes the brake disc, obtain the motor's rotation angle parameters and the clamping force parameters corresponding to the rotation angle parameters.

[0059] The rotation angle parameter of the motor can be recorded every interval of time or every interval of distance during the movement of the caliper in step S130. Or the movement distance of the caliper is converted into the rotation angle parameter. The clamping force parameter can be obtained by calculating while recording the rotation angle parameter, for example, by a torque and force balance equation.

[0060] Step S150: obtaining the stiffness correction coefficient and the offset rotation angle according to the rotation angle parameter and the clamping force parameter, and obtaining the updated correction stiffness curve model.

[0061] In step S150, after collecting multiple sets of rotation angle parameters and clamping force parameters, the stiffness correction coefficient k and the offset rotation angle ψ0 can be obtained by combining these parameters, so as to obtain the final updated correction stiffness curve model.

[0062] Step S170: calculating the clamping force of the brake according to the updated correction stiffness curve model.

[0063] In step S170, after obtaining the final updated correction stiffness curve model, the corresponding clamping force can be obtained by obtaining the rotation angle of the motor.

[0064] In the above implementation process, by calibrating the original stiffness curve model to construct the initial correction stiffness curve model, and combining the collected multiple sets of rotation angle parameters and clamping force parameters to obtain the to-be-solved coefficients in the model, the final updated correction stiffness curve model is obtained, and the updated stiffness curve model can be used to calculate the clamping force. The accuracy of calculating the clamping force is improved.

[0065] Please refer to Figure 2 , Figure 2 is the specific flowchart of step S150 in the brake clamping force calculation method provided by the embodiment of the application. In some optional embodiments, step S150 can include:

[0066] Step S153: defining a parameter vector, and constructing a residual vector and a Jacobian matrix.

[0067] In step S153, the parameter vector, the residual vector, and the Jacobian matrix are respectively:

[0068]

[0069]

[0070]

[0071] In the formula, , ψ i is the collected rotation angle parameter, F cl,tbe,iis the clamping force parameter corresponding to the corner parameter, i = 0, 1, 2, ….

[0072] The partial derivative of is obtained as follows:

[0073]

[0074] The partial derivative of is obtained as follows:

[0075]

[0076] Step S154: solving the equation to obtain Δp.

[0077] In the above step S154, λ is a forgetting factor, I is a 2-order unit matrix, and ΔP = P i -P i-1 . That is, based on the parameter vector, the residual vector, and the Jacobian matrix constructed based on the initial modified stiffness curve model, Δp in the above equation can be solved. Since P is the parameter vector, Δp represents the change amount of the parameter vector.

[0078] Step S155: using an iterative formula to perform iteration to calculate the parameter vector to obtain an updated modified stiffness curve model.

[0079] In the above step S155, the iterative formula is:

[0080]

[0081] In the formula, P new is the parameter vector obtained by the current iteration, and P old is the parameter vector obtained by the last iteration. That is, the change amount of the parameter vector obtained by solving the equation can be used for iteration. After multiple iterations, the final required parameter vector can be obtained, and the vector elements in the parameter vector are the stiffness modification coefficients and the offset corner angles that need to be solved.

[0082] In the above implementation process, the parameter vector, the residual vector, and the Jacobian matrix are constructed based on the initial modified stiffness curve, and the equation the parameter vector variation Δp, and finally, the parameter vector variation Δp is used to perform iteration for a corresponding number of times, so that a more accurate stiffness correction coefficient and offset angle can be obtained, and thus an updated correction stiffness curve model used to calculate the clamping force is obtained. Compared with the method of directly using the undetermined coefficient method to obtain the coefficients in the model based on the collected multiple sets of parameters, the coefficients obtained by the multiple iteration method make the model more approximate to the real application scenario, thereby further improving the accuracy of calculating the clamping force.

[0083] Please refer to Figure 3 , Figure 3 is the first specific flowchart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application. In some optional embodiments, step S155 can include:

[0084] Step S1551: determining whether the following condition is met: .

[0085] In the above step S1551, , , and ε is a residual sum of squares variation threshold value. As to the determination of the residual sum of squares variation threshold value, a person skilled in the art can determine it according to the convergence degree of the final structure corresponding to the demand for the accuracy of the model in actual application.

[0086] If the determination is met, step S1552 is performed: determining whether the parameter vector obtained by the current iteration converges, and obtaining an updated correction stiffness curve model according to the parameter vector obtained by the current iteration.

[0087] In the above step S1552, that is, the residual sum of squares variation is calculated based on the parameter vector obtained by the current iteration, and in the case that the residual sum of squares variation is less than the residual sum of squares variation threshold value, it can be determined that the parameter vector obtained by the current iteration converges, and the process of calculating the stiffness correction coefficient and the offset angle by iteration is completed, thereby obtaining the final updated correction stiffness curve model.

[0088] In the above implementation process, the residual sum of squares variation corresponding to the parameter vector obtained by the current iteration is calculated, and it is determined whether the residual sum of squares variation is less than the residual sum of squares variation threshold value. In the case that it is less, it is determined that the parameter vector obtained by the current iteration converges. The vector elements in the parameter vector can be used as the stiffness correction coefficient and the offset angle, thereby obtaining the final updated correction stiffness curve model. Finally, the accuracy of calculating the clamping force is further improved.

[0089] Please refer to Figure 4 , Figure 4is a second specific flowchart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application. In some optional implementation, step S155 can include:

[0090] Step S1553: judging whether the parameter variation threshold is met.

[0091] In step S1553, the parameter variation threshold is determined. The skilled in the art can also determine the parameter variation threshold according to the convergence degree of the final structure corresponding to the requirement of the model accuracy in the actual application.

[0092] If the judgment is met, step S1554 is performed: judging whether the parameter vector obtained by the current iteration converges, and obtaining the updated correction stiffness curve model according to the parameter vector obtained by the current iteration.

[0093] In step S1554, that is, in the case that the variation of the parameter vector obtained by the current iteration is less than the parameter variation threshold, it can also be determined that the parameter vector obtained by the current iteration converges, and the process of calculating the stiffness correction coefficient and the offset angle by iteration is completed, so that the final updated correction stiffness curve model is obtained.

[0094] As an optional implementation, in combination with the previous embodiment of judging the variation of the residual sum of squares, in the case that any one of the two conditions (one is that the variation of the residual sum of squares is less than the variation threshold of the residual sum of squares; the other is that the parameter variation is less than the parameter variation threshold) is met, it can be determined that the parameter vector obtained by the current iteration converges. Otherwise (that is, both conditions are not met), it is determined that the parameter vector obtained by the current iteration does not converge, and the final parameter vector converges and the final updated correction stiffness curve model is obtained by continuing iteration.

[0095] In the above implementation process, whether the parameter variation of the parameter vector obtained by the current iteration is less than the parameter variation threshold is judged, and in the case that it is less, it is determined that the parameter vector obtained by the current iteration converges. The vector elements in the parameter vector can be used as the stiffness correction coefficient and the offset angle, so that the final updated correction stiffness curve model is obtained. Finally, the accuracy of calculating the clamping force is further improved.

[0096] Please refer to Figure 5 , Figure 5 is a third specific flowchart of step S155 in the clamping force calculation method of the brake provided in the embodiments of the present application. In some optional implementation, step S155 can include:

[0097] ​Step S1555: judging whether the iteration number exceeds an iteration threshold.

[0098] If it is determined that the iteration threshold is exceeded, step S1556 is performed: determining that the current calculated parameter vector is invalid.

[0099] In the above steps S1555 and S1556, that is, in the process of calculating the stiffness correction coefficient and the offset angle in the model, if the iteration number is too large, it can be determined that the current result is invalid. That is, the current calculation of the stiffness correction coefficient and the offset angle fails, and the iteration calculation can be restarted.

[0100] In the above implementation process, if the iteration number is too large, it usually indicates that the initial value selection in the iteration process is not reasonable, the convergence condition setting is not reasonable, etc. Therefore, by limiting the iteration number, the above problems can be investigated or excluded, thereby improving the accuracy of the coefficients in the finally calculated model. That is, the accuracy of calculating the clamping force is further improved.

[0101] Please continue to refer to Figure 2 In some optional embodiments, before step S153, the method can further include:

[0102] Step S152: judging whether the data quantity of the angle parameters and the corresponding clamping force parameters reaches a data quantity threshold.

[0103] If it is determined that the data quantity threshold is reached, step S153 is performed.

[0104] In the above step S152, that is, when the data quantity of the collected angle parameters and clamping force parameters reaches a certain degree, the subsequent steps of defining the parameter vector, constructing the residual vector and the Jacobian matrix, calculating the coefficients to be solved in the initial correction stiffness curve model, and obtaining the final updated correction stiffness curve model are started.

[0105] In the above implementation process, before the iteration is performed by using the parameter vector, constructing the residual vector and the Jacobian matrix to calculate the coefficients in the mathematical model, a limitation condition for the data quantity is set, and the calculation of the coefficients in the model is started only when the data quantity reaches a certain degree, thereby further ensuring the accuracy of the coefficients in the calculated mathematical model. The accuracy of calculating the clamping force is improved.

[0106] In some optional embodiments, step S130 can include:

[0107] Step S131: calculating the corresponding clamping force parameters according to the pre-calibrated transmission ratio, the friction torque of the brake, and combining the force balance equation.

[0108] In step S131 above, the force balance equation is:

[0109]

[0110] In the formula, F cl,tbe T is the clamping force parameter. m It is the torque of the motor, T Fc γ is the friction torque of the brake, and γ is the transmission ratio. The friction torque and transmission ratio can be pre-calibrated offline.

[0111] In other words, among the data used to obtain the coefficients in the model, the rotation angle parameter can be directly collected by the encoder on the motor or other sensors. The corresponding clamping force parameter can be calculated based on the force balance equation.

[0112] In the above implementation process, the clamping force parameter corresponding to the rotation angle parameter is calculated by using the force balance equation, which eliminates the need for additional sensors and simplifies the calculation of the clamping force.

[0113] Referring to the figure, in some optional embodiments, step S131 may include:

[0114] Step S1311: When the motor speed is at [ The clamping force is located within the range of [ ], and the clamping force is located within [ ]. In the case of the range of ], the transmission ratio and the friction torque of the brake are calibrated.

[0115] In step S132 above, n min n is the upper limit of the motor's speed. max The lower limit of motor speed, F cl,min F is the upper limit of the clamping force. cl,max This is the lower limit of the clamping force. The upper limit of the rotational speed, the lower limit of the rotational speed, the upper limit of the clamping force, and the lower limit of the clamping force can be determined by those skilled in the art based on the configuration parameters of the braking system in actual applications.

[0116] In the above implementation process, by collecting angular and clamping force parameters within specific speed and clamping force ranges, the collected data used to derive coefficients from the mathematical model becomes more valid and reliable. This further improves the accuracy of clamping force calculation.

[0117] Please see Figure 6 , Figure 6 This is a functional block diagram of the clamping force calculation device 600 for a brake provided in an embodiment of this application. Based on the same concept, this application provides a clamping force calculation device 600 for a brake. The brake may include a motor, a caliper, and a brake disc.

[0118] The device can include a construction module 610, an acquisition module 620, a solving module 630, and a calculation module 640.

[0119] The construction module 610 can be configured to construct an initial modified stiffness curve model according to an original stiffness curve model. The initial modified stiffness curve model is:

[0120]

[0121] In the formula, F cl is the clamping force, a, b, c, and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, and k is the stiffness correction coefficient.

[0122] The acquisition module 620 can be configured to acquire the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter after the caliper approaches and presses the brake disc.

[0123] The solving module 630 can be configured to solve the stiffness correction coefficient and the offset rotation angle according to the rotation angle parameter and the clamping force parameter, and obtain an updated modified stiffness curve model.

[0124] The calculation module 640 can be configured to calculate the clamping force of the brake according to the updated modified stiffness curve model.

[0125] As some optional embodiments, in the process of solving the stiffness correction coefficient and the offset rotation angle according to the rotation angle parameter and the clamping force parameter, and obtaining the updated modified stiffness curve model, the solving module 630 can be specifically configured to define a parameter vector, and construct a residual vector and a Jacobian matrix. The parameter vector, the residual vector, and the Jacobian matrix are respectively:

[0126]

[0127]

[0128]

[0129] In the formula, , ψ i is the acquired rotation angle parameter, F cl,tbe,i is the clamping force parameter corresponding to the rotation angle parameter, and i=0, 1, 2, ….

[0130] Solve the equation to obtain Δp. In the formula, λ is a forgetting factor, I is a 2-order unit matrix, and ΔP=P i -P i-1 Use the iterative formula to perform iteration, calculate the parameter vector, and obtain the updated modified stiffness curve model. In the formula, the iterative formula is:

[0131]

[0132] wherein P new is the parameter vector obtained in the current iteration, P old is the parameter vector obtained in the last iteration.

[0133] As some optional embodiments, in the process of calculating the parameter vector by iteration using the iteration formula, the obtaining module 630 can be more specifically configured to determine whether the following condition is met: wherein , and ϵ is the residual sum of squares variation threshold. If the condition is met, it is determined that the parameter vector obtained in the current iteration converges, and the updated correction stiffness curve model is obtained according to the parameter vector obtained in the current iteration.

[0134] As some optional embodiments, in the process of calculating the parameter vector by iteration using the iteration formula, the obtaining module 630 can be more specifically configured to determine whether the following condition is met: wherein δ is the parameter variation threshold. If the condition is met, it is determined that the parameter vector obtained in the current iteration converges, and the updated correction stiffness curve model is obtained according to the parameter vector obtained in the current iteration.

[0135] As some optional embodiments, in the process of calculating the parameter vector by iteration using the iteration formula, the obtaining module 630 can be more specifically configured to determine whether the number of iterations exceeds the iteration threshold. If it is determined that the iteration threshold is exceeded, it is determined that the parameter vector calculated in the current iteration is invalid.

[0136] As some optional embodiments, before the process of defining the parameter vector and constructing the residual vector and the Jacobian matrix, the obtaining module 630 can be specifically configured to determine whether the data quantity of the turning angle parameters and the corresponding clamping force parameters reaches the data quantity threshold. If it is determined that the data quantity threshold is reached, the parameter vector is defined, and the residual vector and the Jacobian matrix are constructed.

[0137] As some optional embodiments, in the process of obtaining the turning angle parameters of the motor and the clamping force parameters corresponding to the turning angle parameters, the collecting module 620 can be specifically configured to calculate the corresponding clamping force parameters according to the pre-calibrated transmission ratio, the friction torque of the brake, and in combination with the force balance equation. Wherein, the force balance equation is:

[0138]

[0139] wherein F cl,tbe is the clamping force parameter, T m is the torque of the motor, T Fc is the friction torque of the brake, and γ is the transmission ratio.

[0140] As some optional embodiments, in the process of calculating the corresponding clamping force parameter according to the pre-calibrated transmission ratio, the friction torque of the brake, and in combination with the force balance equation, the collection module 620 can be specifically used for: in the case that the rotating speed of the motor is located in the interval of [n ], and the clamping force is located in the interval of [F ], the transmission ratio and the friction torque of the brake are calibrated. Wherein, n min is the upper limit of the rotating speed of the motor, n max is the lower limit of the rotating speed of the motor, F cl,min is the upper limit of the clamping force, and F cl,max is the lower limit of the clamping force.

[0141] It should be understood that the device corresponds to the above-mentioned brake clamping force calculation method embodiments, and can perform each step involved in the above-mentioned method embodiments. The specific functions of the device can be referred to the description in the above, and the detailed description is appropriately omitted here to avoid repetition. The device includes at least one software function module that can be stored in the memory in the form of software or firmware or solidified in the operating system (OS) of the device.

[0142] The embodiments of the present application also provide a storage medium, which includes a computer readable storage medium. The computer readable storage medium stores a computer program, and the computer program is run by a processor to execute the method as above.

[0143] Wherein, the computer readable storage medium can be realized by any type of volatile or non-volatile storage device or their combination, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0144] It should be understood that the disclosed apparatus and method can also be implemented in other manners. The embodiments described above are merely exemplary embodiments of the present application. In the embodiments of the present application, the described apparatus embodiments are merely schematic, and the functions of the flowcharts and the block diagrams can be implemented in other manners. For example, the flowcharts and the block diagrams can be implemented by using a computer program, a digital signal processor, an application-specific integrated circuit, a field programmable gate array, a processor, a controller, another hardware device, or a combination thereof. In this case, the disclosed apparatus and method can be implemented in a form of a computer program product. The computer program product is directly downloadable from a network, or stored in a computer-readable storage medium, and includes a plurality of instructions. When the instructions are executed by a processor, the processor performs the method according to the embodiments of the present application.

[0145] In addition, each functional module in each of the embodiments of the present application can be integrated together to form a separate part, or each module can exist independently, or two or more modules can be integrated to form a separate part.

[0146] The above description is merely optional implementation of the embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the embodiments of the present application, which should be covered within the protection scope of the embodiments of the present application.

Claims

1. A method of calculating a clamping force of a brake, characterized by, wherein, The brake comprises a motor, a caliper, and a brake disc; The method comprises: According to the original stiffness curve model, an initial modified stiffness curve model is constructed; wherein, the initial modified stiffness curve model is: where F cl is the clamping force, a, b, c, and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, and k is a stiffness correction coefficient. After the caliper is close to and presses the brake disc, the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter are obtained; According to the rotation angle parameter and the clamping force parameter, the stiffness correction coefficient and the offset rotation angle are obtained, and an updated modified stiffness curve model is obtained; and According to the updated modified stiffness curve model, the clamping force of the brake is calculated; According to the rotation angle parameter and the clamping force parameter, the stiffness correction coefficient and the offset rotation angle are obtained, and an updated modified stiffness curve model is obtained, comprising: A parameter vector is defined, and a residual vector and a Jacobian matrix are constructed; wherein, the parameter vector, the residual vector, and the Jacobian matrix are respectively: , , In the formula, , ψ i is the collected corner parameter, F cl,tbe,i is the clamping force parameter corresponding to the corner parameter, i = 0, 1, 2…N; solving the equation , to obtain Δp; in the formula, λ is a forgetting factor, Δp is an iteration step increment, I is a 2-order unit matrix, and ΔP=P i -P i-1 ; and performing iteration by using an iteration formula to calculate the parameter vector to obtain the updated correction stiffness curve model; wherein the iteration formula is: where P new is the parameter vector resulting from the current iteration, P old is the parameter vector resulting from the previous iteration; The rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter are obtained, comprising: According to the pre-calibrated transmission ratio, the friction torque of the brake, and combining the force balance equation, the corresponding clamping force parameter is calculated; wherein, the force balance equation is: where F cl,tbe is the clamping force parameter, T m is the torque of the electric motor, T Fc is the friction torque of the brake, and γ is the transmission ratio.

2. The method of claim 1, wherein, The parameter vector is calculated by using the iterative formula, comprising: determining whether the following equation is true; wherein, , r represents a residual vector, and e is a residual sum of squares variation threshold value; if the equation is true, it is determined that the parameter vector obtained by the current iteration converges, and the updated modified stiffness curve model is obtained according to the parameter vector obtained by the current iteration.

3. The method of claim 1, wherein, The parameter vector is calculated by using the iterative formula, comprising: determining whether the following holds: delta parameter change threshold; if the determination is positive, then determining that the parameter vector resulting from the current iteration is converged, and obtaining the updated modified stiffness curve model based on the parameter vector resulting from the current iteration.

4. The method of claim 1, wherein, The parameter vector is calculated by using the iterative formula, comprising: It is judged whether the number of iterations exceeds an iteration threshold value; If it is judged that the iteration threshold value is exceeded, it is judged that the currently calculated parameter vector is invalid.

5. The method of claim 1, wherein, Before the parameter vector is defined, and the residual vector and the Jacobian matrix are constructed, the method further comprises: It is judged whether the data quantity of the rotation angle parameter and the corresponding clamping force parameter reaches a data quantity threshold value; If it is judged that the data quantity threshold value is reached, the parameter vector is defined, and the residual vector and the Jacobian matrix are constructed.

6. The method of claim 1, wherein, According to the pre-calibrated transmission ratio, the friction torque of the brake, and combining the force balance equation, the corresponding clamping force parameter is calculated, comprising: In the case where the rotation speed of the motor is located in the interval of , and the clamping force is located in the interval of , the transmission ratio and the friction torque of the brake are calibrated; wherein n min is the upper limit of the rotation speed of the motor, n max is the lower limit of the rotation speed of the motor, F cl,min is the upper limit of the clamping force, and F cl,max is the lower limit of the clamping force.

7. A clamp force calculation device of a brake, characterized by, wherein, The brake comprises a motor, a caliper, and a brake disc; The device comprises: A construction module is configured to construct an initial modified stiffness curve model according to an original stiffness curve model; wherein, the initial modified stiffness curve model is: wherein F cl is the clamping force, a, b, c and d are coefficients in the original stiffness curve model, ψ is the rotation angle of the motor in the brake, ψ0 is the offset rotation angle corresponding to the offset distance of the contact point of the caliper and the brake disc, k is the stiffness correction coefficient; a collection module for obtaining the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter after the caliper approaches and presses the brake disc. A calculation module is configured to calculate the clamping force of the brake according to the updated modified stiffness curve model; In the process of obtaining the stiffness correction coefficient and the offset rotation angle according to the rotation angle parameter and the clamping force parameter, the calculation module is specifically configured to define a parameter vector, and construct a residual vector and a Jacobian matrix; wherein, the parameter vector, the residual vector, and the Jacobian matrix are respectively: The storage medium comprises a computer readable storage medium; the computer readable storage medium stores a computer program, and the computer program is run by the processor to execute the method according to any one of claims 1 to 6. 、 、 In the formula, , ψ i is the collected corner parameter, F cl,tbe,i is the clamping force parameter corresponding to the corner parameter, i=0, 1, 2…N; the equation is solved , to obtain Δp; in the formula, λ is a forgetting factor, Δp is an iteration step increment, I is a 2-order unit matrix, and ΔP=P i -P i-1 ; and the parameter vector is calculated by iteration using an iteration formula to obtain the updated and corrected stiffness curve model; wherein the iteration formula is: P = P + (P - P ) / k new P = P + (P - P ) / k old P = P + (P - P ) / k In the process of obtaining the rotation angle parameter of the motor and the clamping force parameter corresponding to the rotation angle parameter, the collection module is specifically configured to calculate the corresponding clamping force parameter according to the pre-calibrated transmission ratio, the friction torque of the brake, and the force balance equation; wherein the force balance equation is: where F cl,tbe is the clamping force parameter, T m is the torque of the motor, T Fc is the friction torque of the brake, and γ is the transmission ratio.

8. A storage medium, characterized by ​

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