A clamping force estimation method for electromechanical brake system without force sensor

Abstract

The present invention discloses a method for estimating the clamping force of an electronic mechanical brake system without a force sensor, comprising a brake information acquisition module, an electronic mechanical brake evaluation and calculation module, a brake disc contact point detection module and an electronic mechanical brake system clamping force estimation module. The purpose of the present invention is to accurately estimate the clamping force of the electronic mechanical brake of the force sensor through the brake information acquisition module, the electronic mechanical brake evaluation and calculation module, the brake disc contact point detection module and the electronic mechanical brake system clamping force estimation module.

Description

Technical Field

[0001] The invention relates to a method for estimating the clamping force of an electronic mechanical brake system without a force sensor. Background Art

[0002] An electromechanical brake system is a braking system based on electronic control and mechanical actuation. Unlike traditional hydraulic or pneumatic brake systems, an electromechanical brake system directly controls the actuator through electronic signals, eliminating reliance on hydraulic oil or air pressure and offering higher response speed and accuracy. However, existing research on electromechanical brake systems often relies on precise clamping force control using force sensors, which suffers from high costs and reduced accuracy after prolonged operation. Clamping force control methods using forceless sensors can effectively avoid these issues. Therefore, the present invention proposes a method for estimating clamping force in an electromechanical brake system using forceless sensors. Summary of the Invention

[0003] The object of the present invention is to provide a method for estimating the clamping force of an electromechanical brake system without a force sensor, so as to solve the problems encountered in the above-mentioned background technology.

[0004] To achieve the above-mentioned object, the present invention provides the following technical solutions: a method for estimating the clamping force of an electromechanical brake system without a force sensor comprises a brake information acquisition module, an electromechanical brake evaluation and calculation module, a brake disc contact point detection module, and an electromechanical brake system clamping force estimation module;

[0005] The braking information acquisition module is used to collect the braking force request information allocated to a single wheel and the basic information of the single wheel braking system, including the expected braking force Fb of the single wheel. Target , road adhesion coefficient μ road , the vehicle's speed V, the wheel's longitudinal speed V x , Wheel brake disc temperature Temp b 、Ambient temperature Temp e , Brake motor temperature Temp m , Brake motor moment of inertia J m , brake motor speed n and brake motor output torque T m ;

[0006] The electronic mechanical brake evaluation calculation module is used to collect various data and calculate corresponding influencing factors, including:

[0007] Calculate the brake disc temperature influence factor Z1 according to the following formula:

[0008]

[0009] Among them, V represents the speed of the car, V xIndicates the longitudinal speed of the wheel, Temp b Indicates the brake disc temperature, Temp e represents the ambient temperature, Mat represents the stiffness of the brake disc material, and C1, C2, and C3 represent weight coefficients;

[0010] Calculate the brake motor evaluation factor Z2 according to the following formula:

[0011] Z2=Z 21 Z 22 Z 23 Z 24

[0012] Among them, Z 21 represents the temperature influence factor, Z 22 Indicates the output torque influence factor, Z 23 represents the running time impact factor, Z 24 Indicates the influencing factor of motor cooling efficiency;

[0013]

[0014] Among them, Temp m Indicates the brake motor temperature, Temp e Indicates the ambient temperature;

[0015]

[0016] Among them, C m Indicates the torque influence weight, T m Indicates the output torque of the brake motor;

[0017]

[0018] Among them, t m Indicates the time impact weight, T run Indicates the continuous running time of the brake motor;

[0019] Z 24 =η cool

[0020] Among them, η cool Indicates the motor cooling efficiency coefficient;

[0021] The electromechanical brake clamping force influence factor Z is based on the following formula:

[0022]

[0023] Among them, Z1 represents the brake disc temperature influence factor, Z2 represents the brake motor evaluation factor, and β1, β2, and β3 represent weight coefficients.

[0024] The brake disc contact point detection module is used to determine whether the brake caliper has reached the brake disc contact point, including:

[0025] Calculate the target braking torque Tu according to the following formula:

[0026] Tu=Fb Target Rμ road

[0027] Among them, Fb Target represents the expected braking force of a single wheel, R represents the wheel rolling radius, μ road represents the road adhesion coefficient;

[0028] The target clamping force Fn of the electromechanical brake system is calculated according to the following formula:

[0029]

[0030] Where Tu represents the target braking torque, μ represents the friction coefficient of the brake friction plate, and R b Indicates the brake disc radius;

[0031] When the target clamping force Fn is sent to the controller, the controller generates a motor drive signal to make the motor speed n=n max At this time, the chi-square test abnormal data detection method is used to detect the brake motor speed data, and the chi-square test factor X is calculated according to the following formula 2 :

[0032]

[0033] Among them, N a Indicates that N a The motor speed data at each moment, its value can be set freely, E i Indicates theoretical data, E i =n max , O i Represents the motor speed data collected at the i-th moment, i∈N a .

[0034] The brake disc contact point detection module determines whether the brake caliper has reached the brake disc contact point according to the following formula:

[0035]

[0036] Among them, X 2 represents the chi-square test factor, Cp represents the contact state of the contact point. When Cp = 1, it means that the brake caliper has reached the brake disc contact point. When Cp = 0, it means that the brake caliper has not reached the brake disc contact point. Δ represents the chi-square test threshold, and the value is obtained by looking up the table.

[0037] The electronic mechanical brake system clamping force estimation module is used to estimate the actual clamping force of the electronic mechanical brake system according to the recursive least squares algorithm, including:

[0038] Calculate the friction torque T of the brake motor according to the following formula f :

[0039]

[0040] Among them, T m Indicates the output torque of the brake motor, T c represents the Coulomb friction torque, T s represents the maximum static friction torque, w represents the angular velocity of the brake motor, w s represents the Stribeck velocity, B v represents the viscous friction coefficient, w s , γ represents the empirical constant;

[0041] The brake motor torque balance model is established according to the following formula:

[0042]

[0043] Among them, J m Indicates the inertia constant of the brake motor, Indicates the angular acceleration of the brake motor, T m Indicates the output torque of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

[0044] The electronic mechanical brake system clamping force estimation module establishes the brake motor torque balance model state equation according to the following formula:

[0045]

[0046] Among them, y represents the output value, A represents the state transition, x represents the estimated value, and J m Indicates the inertia constant of the brake motor, Indicates the angular acceleration of the brake motor, T m Indicates the output torque of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

[0047] The electronic mechanical brake system clamping force estimation module establishes a cost function V according to the following formula:

[0048]

[0049] Where y(i) represents the output value at time i, A(i) represents the state transition at time i, x(k) represents the estimated value at time k, and λ represents the forgetting factor, which ranges from 0 to 1. When λ = 0, it means that the estimation result is independent of historical data. When 0 < λ < 1, it means that the influence of historical data on the estimation is weakened. When λ = 1, it means that there is no weakening effect. When λ > 1, it means that the influence of historical data on the estimation is enhanced.

[0050] The system gain matrix L(k) is obtained according to the following formula:

[0051] L(k)=P(k)A(k)=P(k-1)A(k)(λ+A(k)P(k-1)A(k)) -1

[0052] Where A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, and λ represents the forgetting factor;

[0053] The expression of the system covariance matrix P(k) is obtained according to the following formula:

[0054]

[0055] Among them, A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, L(k) represents the system gain matrix, and λ represents the forgetting factor.

[0056] The electronic mechanical brake system clamping force estimation module calculates the estimated value of x at the kth moment according to the following formula:

[0057] x(k)=x(k-1)+L(k)y(k)-A(k)x(k-1)

[0058] Where y(k) represents the output value at the kth moment, A(k) represents the state transition at the kth moment, x(k) represents the estimated value at the kth moment, x(k-1) represents the estimated value at the k-1th moment, and L(k) represents the system gain matrix.

[0059] The electronic mechanical brake system clamping force estimation module calculates the weighted clamping force estimate Fk according to the following formula cl :

[0060] Fk cl =x(k)W

[0061] Wherein, x(k) represents the estimated value at the kth moment, and W represents the influencing factor of the electronic mechanical brake clamping force.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1. A method for estimating the clamping force of an electromechanical brake system without a force sensor comprises a brake information acquisition module, an electromechanical brake evaluation and calculation module, a brake disc contact point detection module, and an electromechanical brake system clamping force estimation module;

[0064] 2. The brake disc contact point detection module of the present invention determines whether the brake caliper has reached the brake disc contact point based on the Chi-square detection algorithm to accurately determine the start time of clamping force estimation;

[0065] 3. The clamping force estimation module of the electronic mechanical brake system of the present invention estimates the actual clamping force of the electronic mechanical brake system based on a recursive least squares algorithm, thereby realizing the clamping force estimation without a force sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] The present invention will be further described below in conjunction with the accompanying drawings:

[0067] Figure 1 This is a framework diagram of a clamping force estimation method for an electromechanical brake system without a force sensor proposed in the present invention. DETAILED DESCRIPTION

[0068] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0069] like Figure 1 As shown, the present invention is a method for estimating the clamping force of an electro-mechanical brake system without a force sensor, comprising a brake information acquisition module, an electro-mechanical brake evaluation calculation module, a brake disc contact point detection module, and an electro-mechanical brake system clamping force estimation module;

[0070] The braking information acquisition module is used to collect the braking force request information allocated to a single wheel and the basic information of the single wheel braking system, including the expected braking force Fb of the single wheel. Target , road adhesion coefficient μ road , the vehicle's speed V, the wheel's longitudinal speed V x , Wheel brake disc temperature Temp b 、Ambient temperature Temp e , Brake motor temperature Temp m , Brake motor moment of inertia J m , brake motor speed n and brake motor output torque T m ;

[0071] The electronic mechanical brake evaluation calculation module is used to collect various data and calculate corresponding influencing factors, including:

[0072] Calculate the brake disc temperature influence factor Z1 according to the following formula:

[0073]

[0074] Among them, V represents the speed of the car, V x Indicates the longitudinal speed of the wheel, Temp b Indicates the brake disc temperature, Temp e represents the ambient temperature, Mat represents the stiffness of the brake disc material, and C1, C2, and C3 represent weight coefficients;

[0075] Calculate the brake motor evaluation factor Z2 according to the following formula:

[0076] Z2=Z 21 Z 22 Z 23 Z 24

[0077] Among them, Z 21 represents the temperature influence factor, Z 22 Indicates the output torque influence factor, Z 23 represents the running time impact factor, Z 24 Indicates the influencing factor of motor cooling efficiency;

[0078]

[0079] Among them, Temp m Indicates the brake motor temperature, Temp e Indicates the ambient temperature;

[0080]

[0081] Among them, C m Indicates the torque influence weight, T m Indicates the output torque of the brake motor;

[0082]

[0083] Among them, t m Indicates the time impact weight, T run Indicates the continuous running time of the brake motor;

[0084] Z 24 =η cool

[0085] Among them, η cool Indicates the motor cooling efficiency coefficient;

[0086] The electromechanical brake clamping force influence factor Z is based on the following formula:

[0087]

[0088] Among them, Z1 represents the brake disc temperature influence factor, Z2 represents the brake motor evaluation factor, and β1, β2, and β3 represent weight coefficients.

[0089] The brake disc contact point detection module is used to determine whether the brake caliper has reached the brake disc contact point, including:

[0090] Calculate the target braking torque Tu according to the following formula:

[0091] Tu=Fb Target Rμ road

[0092] Among them, Fb Target represents the expected braking force of a single wheel, R represents the wheel rolling radius, μ road represents the road adhesion coefficient;

[0093] The target clamping force Fn of the electromechanical brake system is calculated according to the following formula:

[0094]

[0095] Where Tu represents the target braking torque, μ represents the friction coefficient of the brake friction plate, and R b Indicates the brake disc radius;

[0096] When the target clamping force Fn is sent to the controller, the controller generates a motor drive signal to make the motor speed n=n max At this time, the chi-square test abnormal data detection method is used to detect the brake motor speed data, and the chi-square test factor X is calculated according to the following formula 2 :

[0097]

[0098] Among them, N a Indicates that N a The motor speed data at each moment, its value can be set freely, E i Indicates theoretical data, E i =n max , O i Represents the motor speed data collected at the i-th moment, i∈N a .

[0099] The brake disc contact point detection module determines whether the brake caliper has reached the brake disc contact point according to the following formula:

[0100]

[0101] Among them, X 2 represents the chi-square test factor, Cp represents the contact state of the contact point. When Cp = 1, it means that the brake caliper has reached the brake disc contact point. When Cp = 0, it means that the brake caliper has not reached the brake disc contact point. Δ represents the chi-square test threshold, and the value is obtained by looking up the table.

[0102] The electronic mechanical brake system clamping force estimation module is used to estimate the actual clamping force of the electronic mechanical brake system according to the recursive least squares algorithm, including:

[0103] Calculate the friction torque T of the brake motor according to the following formula f :

[0104]

[0105] Among them, T m Indicates the output torque of the brake motor, T c represents the Coulomb friction torque, T s represents the maximum static friction torque, w represents the angular velocity of the brake motor, w s represents the Stribeck velocity, B v represents the viscous friction coefficient, w s , γ represents the empirical constant;

[0106] The brake motor torque balance model is established according to the following formula:

[0107]

[0108] Among them, J m Indicates the inertia constant of the brake motor, Indicates the angular acceleration of the brake motor, T m Indicates the output torque of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

[0109] The electronic mechanical brake system clamping force estimation module establishes the brake motor torque balance model state equation according to the following formula:

[0110]

[0111] Among them, y represents the output value, A represents the state transition, x represents the estimated value, and J m Indicates the inertia constant of the brake motor, T m Indicates the output torque of the brake motor, Indicates the angular acceleration of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

[0112] The electronic mechanical brake system clamping force estimation module establishes a cost function V according to the following formula:

[0113]

[0114] Where y(i) represents the output value at time i, A(i) represents the state transition at time i, x(k) represents the estimated value at time k, and λ represents the forgetting factor, which ranges from 0 to 1. When λ = 0, it means that the estimation result is independent of historical data. When 0 < λ < 1, it means that the influence of historical data on the estimation is weakened. When λ = 1, it means that there is no weakening effect. When λ > 1, it means that the influence of historical data on the estimation is enhanced.

[0115] The system gain matrix L(k) is obtained according to the following formula:

[0116] L(k)=P(k)A(k)=P(k-1)A(k)(λ+A(k)P(k-1)A(k)) -1

[0117] Where A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, and λ represents the forgetting factor;

[0118] The expression of the system covariance matrix P(k) is obtained according to the following formula:

[0119]

[0120] Among them, A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, L(k) represents the system gain matrix, and λ represents the forgetting factor.

[0121] The electronic mechanical brake system clamping force estimation module calculates the estimated value of x at the kth moment according to the following formula:

[0122] x(k)=x(k-1)+L(k)y(k)-A(k)x(k-1)

[0123] Where y(k) represents the output value at the kth moment, A(k) represents the state transition at the kth moment, x(k) represents the estimated value at the kth moment, x(k-1) represents the estimated value at the k-1th moment, and L(k) represents the system gain matrix.

[0124] The electronic mechanical brake system clamping force estimation module calculates the weighted clamping force estimate Fk according to the following formula cl :

[0125] Fk cl =x(k)W

[0126] Wherein, x(k) represents the estimated value at the kth moment, and W represents the influencing factor of the electronic mechanical brake clamping force.

Claims

1. A method for estimating the clamping force of an electromechanical brake system without a force sensor, characterized in that: The method includes the following: Braking information acquisition module, electro-mechanical brake evaluation calculation module, brake disc contact point detection module and electro-mechanical brake system clamping force estimation module; The braking information acquisition module is used to collect the braking force request information allocated to a single wheel and the basic information of the single wheel braking system, including the expected braking force Fb of the single wheel. Target , road adhesion coefficient μ road , the vehicle's speed V, the wheel's longitudinal speed V x , Wheel brake disc temperature Temp b 、Ambient temperature Temp e , Brake motor temperature Temp m , Brake motor moment of inertia J m , brake motor speed n and brake motor output torque T m ; The electronic mechanical brake evaluation calculation module is used to collect various data and calculate corresponding influencing factors, including: Calculate the brake disc temperature influence factor Z1 according to the following formula: Among them, V represents the speed of the car, V x Indicates the longitudinal speed of the wheel, Temp b Indicates the brake disc temperature, Temp e represents the ambient temperature, Mat represents the stiffness of the brake disc material, and C1, C2, and C3 represent weight coefficients; Calculate the brake motor evaluation factor Z2 according to the following formula: Z2=Z 21 WITH 22 WITH 23 WITH 24 Among them, Z 21 represents the temperature influence factor, Z 22 Indicates the output torque influence factor, Z 23 represents the running time impact factor, Z 24 Indicates the influencing factor of motor cooling efficiency; Among them, Temp m Indicates the brake motor temperature, Temp e Indicates the ambient temperature; Among them, C m Indicates the torque influence weight, T m Indicates the output torque of the brake motor; Among them, t m Indicates the time impact weight, T run Indicates the continuous running time of the brake motor; WITH 24 =η cool Among them, η cool Indicates the motor cooling efficiency coefficient; The electromechanical brake clamping force influence factor Z is based on the following formula: Among them, Z1 represents the brake disc temperature influence factor, Z2 represents the brake motor evaluation factor, and β1, β2, and β3 represent weight coefficients.

2. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, characterized in that: The brake disc contact point detection module is used to determine whether the brake caliper has reached the brake disc contact point, including: Calculate the target braking torque Tu according to the following formula: Your Facebook Target Rμ road Among them, Fb Target represents the expected braking force of a single wheel, R represents the wheel rolling radius, μ road represents the road adhesion coefficient; The target clamping force Fn of the electromechanical brake system is calculated according to the following formula: Where Tu represents the target braking torque, μ represents the friction coefficient of the brake friction plate, and R b Indicates the brake disc radius; When the target clamping force Fn is sent to the controller, the controller generates a motor drive signal to make the motor speed n=n max At this time, the chi-square test abnormal data detection method is used to detect the brake motor speed data, and the chi-square test factor X is calculated according to the following formula 2 : Among them, N a Indicates that N a The motor speed data at each moment, its value can be set freely, E i Indicates theoretical data, E i =n max , O i Represents the motor speed data collected at the i-th moment, i∈N a .

3. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The brake disc contact point detection module determines whether the brake caliper has reached the brake disc contact point according to the following formula: Among them, X 2 represents the chi-square test factor, Cp represents the contact state of the contact point. When Cp = 1, it means that the brake caliper has reached the brake disc contact point. When Cp = 0, it means that the brake caliper has not reached the brake disc contact point. Δ represents the chi-square test threshold, and the value is obtained by looking up the table.

4. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The electronic mechanical brake system clamping force estimation module is used to estimate the actual clamping force of the electronic mechanical brake system according to the recursive least squares algorithm, including: Calculate the friction torque T of the brake motor according to the following formula f : Among them, T m Indicates the output torque of the brake motor, T c represents the Coulomb friction torque, T s represents the maximum static friction torque, w represents the angular velocity of the brake motor, w s represents the Stribeck velocity, B v represents the viscous friction coefficient, w s , γ represents the empirical constant; The brake motor torque balance model is established according to the following formula: Among them, J m Indicates the inertia constant of the brake motor, Indicates the angular acceleration of the brake motor, T m Indicates the output torque of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

5. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The electronic mechanical brake system clamping force estimation module establishes the brake motor torque balance model state equation according to the following formula: Among them, y represents the output value, A represents the state transition, x represents the estimated value, and J m Indicates the inertia constant of the brake motor, T m Indicates the output torque of the brake motor, Indicates the angular acceleration of the brake motor, T f Represents the friction torque of the brake motor, T L represents the load torque caused by the estimated clamping force, k cl Indicates the clamping force gain, F cl Indicates the estimated clamping force.

6. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The electronic mechanical brake system clamping force estimation module establishes a cost function V according to the following formula: Where y(i) represents the output value at time i, A(i) represents the state transition at time i, x(k) represents the estimated value at time k, and λ represents the forgetting factor, which ranges from 0 to 1. When λ = 0, it means that the estimation result is independent of historical data. When 0 < λ < 1, it means that the influence of historical data on the estimation is weakened. When λ = 1, it means that there is no weakening effect. When λ > 1, it means that the influence of historical data on the estimation is enhanced. The system gain matrix L(k) is obtained according to the following formula: L(k)=P(k)A(k)=P(k-1)A(k)(λ+A(k)P(k-1)A(k)) -1 Where A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, and λ represents the forgetting factor; The expression of the system covariance matrix P(k) is obtained according to the following formula: Among them, A(k) represents the state transition at the kth moment, P(k) represents the system covariance matrix at the kth moment, P(k-1) represents the system covariance matrix at the k-1th moment, L(k) represents the system gain matrix, and λ represents the forgetting factor.

7. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The electronic mechanical brake system clamping force estimation module calculates the estimated value of x at the kth moment according to the following formula: x(k)=x(k-1)+L(k)y(k)-A(k)x(k-1) Where y(k) represents the output value at the kth moment, A(k) represents the state transition at the kth moment, x(k) represents the estimated value at the kth moment, x(k-1) represents the estimated value at the k-1th moment, and L(k) represents the system gain matrix.

8. The method for estimating the clamping force of an electromechanical brake system without a force sensor according to claim 1, wherein: The electronic mechanical brake system clamping force estimation module calculates the weighted clamping force estimate Fk according to the following formula cl : Fk cl =x(k)W Wherein, x(k) represents the estimated value at the kth moment, and W represents the influencing factor of the electronic mechanical brake clamping force.

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