Electronic mechanical brake control method and system for building pressure by dual motors in cooperation

Abstract

The application discloses a kind of electronic mechanical brake control method and system of double motor collaborative pressure building, belong to new energy automobile wire control brake control technical field.Target braking force and main, deputy motor state are obtained, target braking force is compared with single motor maximum capacity, single motor, main and deputy compensation or double motor full power mode is selected and target force is distributed according to rule;With the difference between target force and actual total force, the virtual main shaft position instruction is generated through force ring, and the target position of main and deputy motor is distributed;Position closed loop is carried out respectively to obtain basic torque;With position error, the reverse cross coupling compensation amount is generated and superposed to basic torque, to generate balance correction amount when torque deviation exceeds threshold value, which is superposed to deputy motor torque to obtain final torque instruction output driver, to drive collaborative pressure building.The application solves the problem of force distribution and synchronization coordination, realizes fast and accurate response and balanced output.

Description

Technical Field

[0001] This invention relates to the field of brake-by-wire control technology for new energy vehicles, and in particular to an electromechanical braking control method and system for dual-motor coordinated pressure building. Background Technology

[0002] As a core actuator in drive-by-wire chassis, the redundancy design of the electromechanical braking (EMB) system directly affects the vehicle's braking safety and reliability. Currently, to meet the ASIL-D functional safety level requirements, a dual-motor redundancy architecture has become the mainstream technical solution. However, under this architecture, existing braking control strategies generally adopt a single operating mode of "primary motor in operation, secondary motor as backup," meaning that during normal braking, only the primary motor participates in voltage build-up, while the secondary motor remains in standby mode, only switching on and activating when the primary motor fails.

[0003] While this mode can achieve basic redundancy, it has inherent technical defects: First, when a single motor builds up pressure independently, its response speed is limited by the peak power of the single motor and the reduction ratio of the transmission mechanism, making it difficult to further shorten the braking distance under emergency braking conditions; Second, in scenarios with high braking force requirements, a single motor operates in the nonlinear saturation region for a long time, resulting in a decrease in force control accuracy and affecting braking comfort and stability; Third, the collaborative output potential of the dual-motor architecture has not been fully explored, resulting in a waste of hardware resources.

[0004] Furthermore, existing literature on dual-motor cooperative solutions mostly focuses on functional architecture descriptions and lacks quantifiable force distribution strategies, position synchronization algorithms, and torque compensation mechanisms, making it impossible for those skilled in the art to directly implement them based on their disclosed content.

[0005] Therefore, there is an urgent need to propose a dual-motor collaborative pressure-building control method with clear algorithmic logic to overcome the above-mentioned shortcomings. Summary of the Invention

[0006] The present invention aims to at least partially solve one of the technical problems in the related art.

[0007] To address this, this invention proposes an electromechanical braking control method for coordinated pressure building using dual motors. The method acquires the target braking force and the actual states of the main and auxiliary motors. The target braking force is compared with a preset maximum capacity value for a single motor. A single-motor, master-slave compensation, or dual-motor full-power mode is selected, and the target force is allocated according to preset rules. The difference between the target force and the actual total output force is used to generate a virtual spindle position command via a force loop, which is then allocated to the target positions of the main and auxiliary motors according to preset coefficients. Independent closed-loop position adjustments are performed to obtain a basic torque command. A reverse cross-coupling compensation amount is generated based on the actual position error and superimposed on the basic torque. When the torque deviation exceeds a threshold, a balance correction amount is generated and superimposed on the auxiliary motor side to obtain the final command output driver, driving the main and auxiliary motors to collaboratively build pressure. This invention solves the problems of force distribution and synchronization coordination, achieving rapid and accurate response and balanced output.

[0008] Another objective of this invention is to propose an electromechanical braking control system with dual motors working together to build up pressure.

[0009] To achieve the above objectives, this invention proposes an electromechanical braking control method for dual-motor coordinated pressure building. The electromechanical braking system includes a main motor and an auxiliary motor connected to the same transmission mechanism via a coupling mechanism. The method is characterized by comprising: The target braking force and the actual state parameters of the main and auxiliary motors are obtained. The target braking force is compared with the preset maximum capacity value of a single motor. Based on the comparison result, the single motor mode, master-slave compensation mode or dual motor full-power mode are selected, and the target force of the main and auxiliary motors is determined according to the preset allocation rules of the selected mode. The difference between the target braking force and the actual total output force of the main and auxiliary motors is used as the total force error. A virtual spindle position command is generated through force loop control, and the virtual spindle position command is allocated to the target positions of the main and auxiliary motors according to the preset position allocation coefficient. Independent closed-loop position adjustment is performed on the error between the target position and the actual position of the main and auxiliary motors to obtain the basic torque command of the main and auxiliary motors; The actual position error of the main and auxiliary motors is used to generate a reverse cross-coupling compensation amount, which is superimposed on the basic torque command of the main and auxiliary motors. When the actual torque deviation of the main and auxiliary motors exceeds a preset threshold, a balance correction amount is generated and superimposed on the torque command of the auxiliary motor to obtain the final torque command of the main and auxiliary motors. The final torque commands for the main and auxiliary motors are output to the main and auxiliary motor drivers, which then drive the main and auxiliary motors to work together to perform braking and pressure build-up through the coupling mechanism.

[0010] An electromechanical braking control method for dual-motor coordinated pressure building according to an embodiment of the present invention may also have the following additional technical features: In one embodiment of the present invention, a single-motor mode, a master-slave compensation mode, or a dual-motor full-power mode is selected according to the comparison result, and the target forces of the master and slave motors are determined according to the preset allocation rules of the selected mode, including: When the target braking force is determined to be less than or equal to the product of the maximum capacity of a single motor and the preset dynamic allocation threshold, the single motor mode is selected, the target braking force is used as the target force output of the main motor, and the target force of the auxiliary motor is set to zero.

[0011] In one embodiment of the present invention, the step of selecting a single-motor mode, a master-slave compensation mode, or a dual-motor full-power mode according to the comparison result, and determining the target force of the master and slave motors according to the preset allocation rules of the selected mode, further includes: When the target braking force is determined to be greater than the product of the maximum capacity of a single motor and the preset dynamic allocation threshold, and less than or equal to the maximum capacity of a single motor, the master-slave compensation mode is selected. The product of the target braking force and the first preset sharing coefficient is used as the target force output of the master motor, and the product of the target braking force and the second preset sharing coefficient is used as the target force output of the slave motor. The first preset sharing coefficient is greater than the second preset sharing coefficient.

[0012] In one embodiment of the present invention, the step of selecting a single-motor mode, a master-slave compensation mode, or a dual-motor full-power mode according to the comparison result, and determining the target force of the master and slave motors according to the preset allocation rules of the selected mode, further includes: When the target braking force is determined to be greater than the maximum capacity of a single motor, the dual-motor full-power mode is selected. The maximum capacity of a single motor is used as the target force output of the main motor, and the difference between the target braking force and the maximum capacity of a single motor is used as the target force output of the auxiliary motor.

[0013] In one embodiment of the present invention, the difference between the target braking force and the actual total output force of the main and auxiliary motors is used as the total force error. A virtual spindle position command is generated via force loop control, including: Obtain the actual output force of the main motor and the actual output force of the auxiliary motor in the current control cycle, and subtract the sum of the actual output forces of the main motor and the auxiliary motor from the target braking force to obtain the total force error; The total force error is input into the force loop controller, which consists of a preset force loop proportional gain, a preset force loop integral gain, and a preset feedforward coefficient. After proportional-integral and feedforward composite operations, a virtual spindle position command is generated, and the virtual spindle position command is subjected to upper limit processing.

[0014] In one embodiment of the present invention, the virtual spindle position command is allocated to the target positions of the main and auxiliary motors according to a preset position allocation coefficient, including: Obtain the virtual spindle position command for the current control cycle, and use the product of the preset main motor position allocation coefficient and the virtual spindle position command as the target position output of the main motor, and use the product of the preset auxiliary motor position allocation coefficient and the virtual spindle position command as the target position output of the auxiliary motor; wherein the sum of the main motor position allocation coefficient and the auxiliary motor position allocation coefficient is 1, and the main motor position allocation coefficient is greater than the auxiliary motor position allocation coefficient.

[0015] In one embodiment of the present invention, independent closed-loop position adjustment is performed based on the error between the target position and the actual position of the main and auxiliary motors to obtain the basic torque command for the main and auxiliary motors, including: The target position of the main motor is subtracted from the actual position of the main motor to obtain the position error of the main motor. The position error of the main motor is input to the main position loop PID controller, and after proportional, integral and differential discrete calculations, the basic torque command of the main motor is output. Simultaneously, the target position of the auxiliary motor is subtracted from the actual position of the auxiliary motor to obtain the position error of the auxiliary motor; the position error of the auxiliary motor is input to the auxiliary position loop PID controller, and after proportional, integral and differential discrete calculations, the basic torque command of the auxiliary motor is output.

[0016] In one embodiment of the present invention, a reverse cross-coupling compensation amount is generated based on the actual position error of the main and auxiliary motors, and superimposed on the basic torque command of the main and auxiliary motors, including: Subtracting the actual position of the auxiliary motor from the actual position of the main motor yields the synchronization error between the main and auxiliary motor positions. The PD controller, which is composed of a preset cross-coupling proportional gain and a preset cross-coupling derivative gain, takes the position synchronization error input as input. After proportional-derivative operation, it generates the main cross-coupling compensation amount and uses the opposite of the main cross-coupling compensation amount as the secondary cross-coupling compensation amount. The main cross-coupling compensation amount is superimposed on the main motor base torque command, and the secondary cross-coupling compensation amount is superimposed on the secondary motor base torque command.

[0017] In one embodiment of the present invention, when the actual torque deviation between the main and auxiliary motors exceeds a preset threshold, a balance correction amount is generated and superimposed on the torque command on the auxiliary motor side, including: Subtract the actual torque of the auxiliary motor from the actual torque of the main motor to obtain the real-time torque deviation; When the absolute value of the real-time torque deviation is less than or equal to the preset torque difference threshold, the output of the balance correction amount is canceled; when the absolute value of the real-time torque deviation is greater than the preset torque difference threshold, the result of subtracting the product of the preset torque difference threshold and the sign function from the real-time torque deviation and then multiplying it by the preset balance coefficient is used as the balance correction amount output, and the balance correction amount is superimposed on the current torque command on the auxiliary motor side.

[0018] To achieve the above objectives, another aspect of the present invention proposes an electromechanical braking control system with dual motors coordinating pressure build-up, comprising: The main motor and the auxiliary motor are connected to the same braking transmission mechanism through a coupling mechanism. They are used to output driving force in response to the main motor drive signal and the auxiliary motor drive signal, respectively. After being coupled by the coupling mechanism, they jointly drive the braking transmission mechanism to perform braking pressure build-up. Force sensors are installed on the force output paths of the main motor and the auxiliary motor to collect the actual output force of the main motor and the auxiliary motor, and output the corresponding actual force signals. Position sensors are installed on the main motor and the auxiliary motor respectively to collect the actual position of the main motor and the auxiliary motor, and output the corresponding actual position signals; The current sensors are connected to the power supply circuits of the main motor and the auxiliary motor respectively, and are used to collect the actual current of the main motor and the actual current of the auxiliary motor, and output the corresponding current signals. The torque estimation module receives the actual current signals of the main motor and the auxiliary motor, converts them into the actual torque of the main motor and the actual torque of the auxiliary motor respectively, and outputs them. The electronic control unit is connected to the force sensor, position sensor, current sensor and torque estimation module respectively, and is electrically connected to the driver control terminals of the main motor and the auxiliary motor. The electronic control unit is configured to execute the electromechanical braking control method of dual motor cooperative pressure building.

[0019] This invention discloses an electromechanical braking control method and system for dual-motor coordinated pressure building. By acquiring the target braking force and the state parameters of the main and auxiliary motors, and selecting a single-motor mode, master-slave compensation mode, or dual-motor full-power mode based on the single-motor capability classification, the total force error is used to generate a virtual master shaft position command via a force loop, which is then allocated to the target positions of the main and auxiliary motors. A position closed-loop adjustment is then performed to obtain the base torque. A reverse cross-coupling compensation amount is superimposed on the base torque, and a balance correction amount is generated and superimposed on the auxiliary motor side when the torque deviation exceeds a threshold. This achieves full-process coordinated control from mode identification, force loop coordination, position closed-loop to dynamic compensation. This invention effectively solves the problems of limited response speed, decreased accuracy under high braking force conditions, and underutilized dual-motor collaborative potential in existing "main operation, auxiliary backup" modes. It significantly improves the braking pressure building response speed and control accuracy, and enhances the adaptability and engineering practical value of the method under complex conditions such as emergency braking and high loads.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of an electromechanical braking control method for dual-motor cooperative pressure building according to an embodiment of the present invention; Figure 2 This is a schematic diagram of an electromechanical braking control system for dual-motor cooperative pressure building according to an embodiment of the present invention. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] The following description, with reference to the accompanying drawings, describes an electromechanical braking control method and system for dual-motor cooperative pressure building according to an embodiment of the present invention.

[0025] The core idea of ​​this invention is to address the limitations of existing dual-motor redundant braking systems in terms of response speed under "master operation, slave backup" mode, decreased accuracy under high braking force conditions, and insufficient exploitation of collaborative potential. This is achieved by constructing a collaborative pressure-building control method covering the entire process of "mode discrimination—force loop coordination—position closed loop—dynamic compensation," thus resolving the difficulty in simultaneously achieving both speed and accuracy in single-motor pressure building. First, the target braking force and motor status are acquired. The target force is compared with the maximum capacity of a single motor, and the single-motor, master-slave compensation, or dual-motor full-power mode is selected and the target force is allocated. Based on this, a virtual master shaft position command is generated using the total force error via the force loop, and the target positions of the master and slave motors are allocated according to coefficients. Position closed-loop adjustment is performed separately to obtain the base torque. Finally, a reverse cross-coupling compensation amount is generated based on the position error and superimposed on the base torque. A balance correction amount is generated based on the torque deviation exceeding a threshold and superimposed on the slave motor side. The final command is output to drive collaborative pressure building. By integrating mode switching, force-position conversion, cross-coupling, and balance correction, the present invention transforms traditional backup control into an intelligent control system that adapts to different needs, dynamically coordinates the output of dual machines, and suppresses synchronization errors in real time, significantly improving braking response speed, control accuracy, and adaptability to operating conditions.

[0026] The following describes, with reference to the accompanying drawings, an electromechanical braking control method and system for dual-motor coordinated pressure building according to an embodiment of the present invention.

[0027] like Figure 1 As shown, the electromechanical braking control method for dual-motor cooperative pressure building according to the present invention includes the following steps: S1. Obtain the target braking force and the actual state parameters of the main and auxiliary motors. Compare the target braking force with the preset maximum capacity value of a single motor. Select the single motor mode, master-slave compensation mode or dual motor full-power mode according to the comparison result. Determine the target force of the main and auxiliary motors according to the preset allocation rules of the selected mode. S2, using the difference between the target braking force and the actual total output force of the main and auxiliary motors as the total force error, generates a virtual spindle position command through force loop control, and distributes the virtual spindle position command to the target positions of the main and auxiliary motors according to the preset position allocation coefficient; S3, independently adjusts the position closed loop based on the error between the target position and the actual position of the main and auxiliary motors to obtain the basic torque command of the main and auxiliary motors; S4 generates a reverse cross-coupling compensation amount based on the actual position error of the main and auxiliary motors, which is then superimposed on the basic torque command of the main and auxiliary motors. When the actual torque deviation of the main and auxiliary motors exceeds a preset threshold, a balance correction amount is generated and superimposed on the torque command of the auxiliary motor side to obtain the final torque command of the main and auxiliary motors. S5 outputs the final torque commands of the main and auxiliary motors to the main and auxiliary motor drivers, driving the main and auxiliary motors to work together to perform braking and pressure build-up through the coupling mechanism.

[0028] In summary, the method provided by the embodiments of the present invention achieves dual optimization of pressure build-up speed and force control accuracy through dynamic allocation of master and slave roles, synchronous control of virtual spindle, cross-coupling position compensation, and torque balancing strategy, and provides a complete quantifiable algorithm to ensure that those skilled in the art can implement it directly.

[0029] Furthermore, the method in this embodiment of the invention specifically includes: Step 1: Initialization and parameter setting.

[0030] Set the maximum capacity of a single motor, F_max (in N), where the master motor is the primary motor and the slave motor is the secondary motor. Set the dynamic allocation threshold. The start threshold for dual-motor full-power mode is F_max. The control cycle T_s is set to 10ms, and the sampling time is synchronized with the motor control cycle. The position allocation coefficient is set. , ,and Set the cross-coupling proportional gain K_c, differential gain K_cd, torque difference threshold T_th, and equalization coefficient K_t.

[0031] Step 2: Real-time data acquisition.

[0032] Within each control cycle, the following data are collected: the current target braking force F_target (given by the driver's pedal travel or the automatic driving system), the actual output force F_m of the main motor, the actual output force F_s of the auxiliary motor, and the actual position of the main motor. (or lead screw position), actual position of auxiliary motor The main motor output torque T_m and the auxiliary motor output torque T_s.

[0033] Step 3: Dynamically assign master and slave roles.

[0034] Based on the relationship between F_target and F_max, the master and slave motor roles and output targets are assigned according to the following state machine: State A (Single Motor Mode): If If the output force is 0, then only the main motor will work, and the auxiliary motor will be in standby mode (output force is 0). The target force of the main motor is F_m_target = F_target, and the target force of the auxiliary motor is F_s_target = 0.

[0035] State B (Master-Slave Compensation Mode): If If the main motor bears 70% of the target force and the auxiliary motor bears 30%, then F_m_target = 0.7·F_target and F_s_target = 0.3·F_target.

[0036] State C (Dual-motor full-capacity mode): If F_target > F_max, the main motor outputs its maximum capacity, and the auxiliary motor outputs the remaining capacity. That is, F_m_target = F_max, F_s_target = F_target - F_max.

[0037] Step 4: Force ring control generates virtual spindle position commands.

[0038] The force ring controller uses PI+feedforward control. The input is the total force error e_f(k) = F_target(k) - (F_m(k) + F_s(k)), and the output is the position command of the virtual spindle. (Unit: mm or rad). Its discretization equation is: θ_ref(k) = θ_ref(k-1) + Kp_f·(e_f(k) - e_f(k-1)) + Ki_f·e_f(k)·T_s+ FF·F_target(k) Where Kp_f is the force loop proportional gain, Ki_f is the force loop integral gain, FF is the feedforward coefficient (usually set to 1 / F_max), and T_s is the control period. To prevent integral saturation, ... Limit the amplitude, upper limit (The lead screw stroke corresponding to the maximum braking force).

[0039] Step 5: Virtual spindle synchronization control.

[0040] The position commands of the virtual spindle are assigned to the main motor and the auxiliary motor, using the following formula: θ_m_ref(k) = λ_m·θ_ref(k) θ_s_ref(k) = λ_s·θ_ref(k) in, The target position of the main motor. This represents the target position for the auxiliary motor. Typical value. , This means that the main motor is responsible for 80% of the positional movement, and the auxiliary motor is responsible for 20%.

[0041] Step 6: Independent control of the position loop.

[0042] Both the main motor and the auxiliary motor employ PID position closed-loop controllers, and their discretization equations are as follows (taking the main motor as an example): u_m(k) = Kp_p·e_θ_m(k) + Ki_p·Σ(e_θ_m(i)·T_s) + Kd_p·(e_θ_m(k) -e_θ_m(k-1)) / T_s in, The position error is the main motor position error; Kp_p, Ki_p, and Kd_p are the position loop PID parameters. u_m(k) is the motor torque command (or current command). The auxiliary motor u_s(k) is obtained similarly.

[0043] Step 7: Cross-coupling position error compensation.

[0044] To overcome the position asynchrony between the master and slave motors, a cross-coupling controller is introduced. The master and slave motor position errors are defined. A cross-coupled controller of proportional-derivative (PD) form is used to generate the compensation quantity. and : Δu_m(k) = -K_c·e_cross(k) - K_cd·(e_cross(k) - e_cross(k-1)) / T_s Δu_s(k) = +K_c·e_cross(k) + K_cd·(e_cross(k) - e_cross(k-1)) / T_s Where K_c is the cross-coupling proportional gain and K_cd is the cross-coupling differential gain. When the main motor position leads the auxiliary motor (e_cross>0), Negative, If it is positive, then the position difference will be reduced.

[0045] The final torque command is: u_m_final(k) = u_m(k) + Δu_m(k) u_s_final(k) = u_s(k) + Δu_s(k).

[0046] Step 8: Torque balancing and anti-collision logic.

[0047] When the main and auxiliary motors are coupled via gears or planetary gear sets, it is also necessary to monitor the output torque difference. The torque difference is defined as follows: Where T_m and T_s are the motor output torque (which can be estimated from the current). If Then the torque equalization regulator will be activated: δ(k) = K_t·(ΔT(k) - T_th·sign(ΔT(k))) Will As an additional correction, it is proportionally added to the auxiliary motor torque command (or the main motor command): u_s_final(k) = u_s_final(k) + δ(k) like If so, no balancing adjustment will be performed. Meanwhile, when If the duration exceeds 1.5·T_th and 100ms, it is considered a mechanical fault, and the system is degraded to single-motor mode.

[0048] Step 9: Security monitoring and troubleshooting.

[0049] During each control cycle, the main and auxiliary motors are checked for overcurrent, overheating, and out-of-range positioning. If either motor fails, the system immediately switches to single-motor mode (using the healthy motor) and operates at reduced power, while simultaneously sending a fault code via the vehicle network.

[0050] The method of this invention effectively solves the problems of limited response speed, decreased accuracy under high braking force conditions, and insufficient exploitation of collaborative potential in the existing "main working, secondary backup" mode. It also provides a complete and quantifiable algorithm system to ensure that those skilled in the art can implement it directly, significantly improving the braking pressure build-up response speed, force control accuracy, and engineering practical value under complex working conditions.

[0051] In addition, the embodiments of the present invention also provide application scenarios for the method: Example 1: Single motor mode (conventional braking).

[0052] Operating conditions: Urban following, target braking force F_target = 500N, maximum single motor capacity F_max = 2000N. Due to... The system enters state A (single motor mode).

[0053] Parameter design: The force loop proportional gain Kp_f = 0.5, integral gain Ki_f = 10, and feedforward coefficient FF = 1 / 2000 = 0.0005. These parameters are obtained through theoretical calculations: the desired force loop cutoff frequency is 20Hz, the phase margin is 60°, and the corresponding PI parameters are solved.

[0054] Position loop PID parameters: Kp_p = 80, Ki_p = 5, Kd_p = 0.2. Tuned using the frequency method, the position loop cutoff frequency is approximately 50Hz, with a phase margin greater than 60°.

[0055] Cross-coupling gain: Cross-coupling compensation is disabled because the auxiliary motor is in standby mode, but it is still retained in the algorithm and is only enabled when the auxiliary motor is activated.

[0056] The torque equalization threshold T_th = 10 Nm, and the equalization coefficient K_t = 0.1.

[0057] Theoretical description of the control process: Only the main motor operates, while the auxiliary motor remains stationary and does not output torque. Virtual spindle position command. According to the force loop calculation, since F_s_target=0, the total force feedback in the force loop is only F_m. It accurately reflects the required position of the main motor. The position loop independently controls the main motor; cross-coupling compensation is ineffective, and torque equalization is not triggered.

[0058] Expected performance: Based on theoretical calculations, the pressure build-up time (from 0 to 500N) in this mode is expected to be 105ms, and the steady-state force error can be controlled within ±8N (i.e., ±0.4%). Energy consumption is approximately 55% of that in the dual-motor full-operation mode. There is no gear impact, and the system operates quietly.

[0059] Example 2: Master-slave compensation mode (medium intensity braking).

[0060] Operating conditions: Vehicle fully loaded downhill, target braking force F_target = 1800N, F_max = 2000N. Due to... The system enters state B (master-slave compensation mode).

[0061] Parameter design: The force ring parameters are the same as in Example 1.

[0062] The position loop parameters are the same as in Example 1.

[0063] Cross-coupling gain: K_c = 2, K_cd = 0.05. Theoretical analysis determined that 0.25 times the proportional gain of the main motor position loop was used as the initial value, and then adjusted according to simulation to ensure that the position difference convergence time was less than 0.1 seconds and there was no oscillation.

[0064] Torque equalization threshold T_th = 10Nm, K_t = 0.1.

[0065] Theoretical description of the control process: Main motor target force .

[0066] auxiliary motor target force .

[0067] Force cycle calculation Then allocate , .

[0068] The torque calculation commands u_m and u_s are given for the position loops of the main and auxiliary motors, respectively.

[0069] The cross-coupled controller monitors the position difference e_cross. If the main motor is ahead, it generates a reverse compensation torque to bring the position difference closer.

[0070] When the torque balancing module detects that ΔT is too large, it increases the torque command of the auxiliary motor to gradually reduce the torque difference to within the threshold.

[0071] Expected performance: Theoretical analysis and simulations show that the pressure build-up time in this mode is approximately 98ms, and the steady-state force error can be controlled within ±15N (i.e., ±0.83%). The position difference between the main and auxiliary motors is expected to be less than 0.08mm, and the torque difference can be stabilized within 10Nm. Compared to the single-motor mode (pressure build-up time 125ms, error ±35N), the response speed is improved by approximately 22%, the accuracy is improved by approximately 57%, and there is no gear knocking noise.

[0072] Example 3: Dual-motor full-power mode (emergency braking).

[0073] Operating condition: Emergency braking, target braking force F_target = 2400N (more than 20% of F_max), F_max = 2000N, the system enters state C (dual motor full power mode).

[0074] Parameter design: To improve the response, the force ring parameters were adjusted to Kp_f = 0.6 and Ki_f = 15.

[0075] The position loop parameters are adjusted to Kp_p = 100, Ki_p = 8, and Kd_p = 0.3.

[0076] The cross-coupling gain is adjusted to K_c = 3 and K_cd = 0.1.

[0077] The torque equalization threshold is T_th = 12 Nm, and K_t = 0.12.

[0078] Derivation of the control process theory: At the initial moment, F_m=0, F_s=0, and the force error e_f = 2400N.

[0079] Force ring output The initial value is determined by the feedforward term: The integrator then gradually accumulates until it reaches the limit value (set to 10mm).

[0080] Location allocation: , .

[0081] The position loop calculates the torque commands u_m and u_s based on the position error, which correspond to force outputs of approximately 2000N and 400N, respectively.

[0082] Cross-coupling compensation: Assuming the main motor position is ahead by 0.1mm, then , Correcting positional differences.

[0083] Torque balance: Assuming the main motor torque is 200 N·m and the auxiliary motor torque is 40 N·m, the difference of 160 N·m is greater than 12 N·m. The torque difference is superimposed on the auxiliary motor and converges after several cycles of iteration.

[0084] Expected performance: Based on the simulation results, the pressure build-up time (0→2400N) is expected to be 85ms.

[0085] In steady state, the main motor outputs approximately 2000N, the auxiliary motor outputs approximately 400N, and the total force is 2400N, with a steady-state error close to 0.

[0086] The maximum overshoot during the dynamic process is expected to be less than 8% (approximately 192N), with a settling time of approximately 0.3 seconds.

[0087] The peak position difference is expected to be less than 0.12 mm, which is below the gear safety clearance.

[0088] The comparison with expectations is shown in Table 1: Table 1

[0089] Theoretical guidance for parameter calibration.

[0090] All control parameters can be calculated offline or calibrated through simulation, without the need for actual measurement. Force loop parameters: The force loop is simplified to a PI controller, and the open-loop transfer function is: Where K_m is the motor force constant and J is the reduced moment of inertia. Set the desired cutoff frequency. (e.g., 20Hz) and phase margin PM (e.g., 60°), Kp_f and Ki_f can be solved analytically.

[0091] Position loop parameters: Also using the frequency response method, the desired cutoff frequency is... (e.g., 50Hz), phase margin > 60°, solve for the PID parameters. Alternatively, the Ziegler-Nichols empirical formula can be used.

[0092] Cross-coupling gain: Theoretically, K_c = 0.5·Kp_p (proportional gain of the main motor position loop) and K_cd = 0.1·Kp_p·T_d can be taken, where T_d is the differential time constant. The result was fine-tuned through simulation until there was no overshoot and the convergence time was <0.1s.

[0093] Torque equalization threshold: set according to 20% of the maximum allowable torque of the gear. For example, if the rated torque of the gear is 60 Nm, then 12 Nm is used. The equalization coefficient K_t is set to 0.1~0.2.

[0094] The above parameter calibration methods are all well-known technologies in the field of control. Those skilled in the art can obtain appropriate parameter values ​​based on specific motors and loads without any creative effort.

[0095] The application scenarios of the method in this invention's embodiments show that, in single-motor mode, the pressure build-up time is approximately 105ms and the steady-state error is ±8N; in master-slave compensation mode, the response speed is improved by approximately 22% and the accuracy by approximately 57%; in dual-motor full-power mode, the pressure build-up time is approximately 85ms and the steady-state error is approximately ±2%, with the position difference between the master and slave motors being less than 0.12mm. This invention effectively solves the problems of limited response, decreased accuracy, and unrealized collaborative potential in existing modes. It provides complete quantifiable algorithm parameters and theoretical calibration basis, ensuring that those skilled in the art can directly implement it, significantly improving braking response speed, control accuracy, and adaptability to operating conditions.

[0096] To achieve the above invention, such as Figure 2 As shown, this embodiment also provides an electromechanical braking control system with dual motors coordinating pressure build-up. The system includes: The main motor and the auxiliary motor are connected to the same braking transmission mechanism through a coupling mechanism. They are used to output driving force in response to the main motor drive signal and the auxiliary motor drive signal, respectively. After being coupled by the coupling mechanism, they jointly drive the braking transmission mechanism to perform braking pressure build-up. Force sensors are installed on the force output paths of the main motor and the auxiliary motor to collect the actual output force of the main motor and the auxiliary motor, and output the corresponding actual force signals. Position sensors are installed on the main motor and the auxiliary motor respectively to collect the actual position of the main motor and the auxiliary motor, and output the corresponding actual position signals; The current sensors are connected to the power supply circuits of the main motor and the auxiliary motor respectively, and are used to collect the actual current of the main motor and the actual current of the auxiliary motor, and output the corresponding current signals. The torque estimation module receives the actual current signals of the main motor and the auxiliary motor, converts them into the actual torque of the main motor and the actual torque of the auxiliary motor respectively, and outputs them. The electronic control unit is connected to the force sensor, position sensor, current sensor and torque estimation module respectively, and is electrically connected to the driver control terminals of the main motor and the auxiliary motor. The electronic control unit is configured to execute an electromechanical braking control method of dual motor cooperative pressure building.

[0097] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0098] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

Claims

1. A dual-motor coordinated pressure-building electromechanical braking control method, wherein the electromechanical braking system includes a main motor and an auxiliary motor connected to the same transmission mechanism via a coupling mechanism, characterized in that, include: The target braking force and the actual state parameters of the main and auxiliary motors are obtained. The target braking force is compared with the preset maximum capacity value of a single motor. Based on the comparison result, the single motor mode, master-slave compensation mode or dual motor full-power mode are selected, and the target force of the main and auxiliary motors is determined according to the preset allocation rules of the selected mode. The difference between the target braking force and the actual total output force of the main and auxiliary motors is used as the total force error. A virtual spindle position command is generated through force loop control, and the virtual spindle position command is allocated to the target positions of the main and auxiliary motors according to the preset position allocation coefficient. Independent closed-loop position adjustment is performed on the errors between the target position and the actual position of the main and auxiliary motors to obtain the basic torque command for the main and auxiliary motors; The actual position error of the main and auxiliary motors is used to generate a reverse cross-coupling compensation amount, which is superimposed on the basic torque command of the main and auxiliary motors. When the actual torque deviation of the main and auxiliary motors exceeds a preset threshold, a balance correction amount is generated and superimposed on the torque command of the auxiliary motor to obtain the final torque command of the main and auxiliary motors. The final torque commands for the main and auxiliary motors are output to the main and auxiliary motor drivers, which then drive the main and auxiliary motors to work together to perform braking and pressure build-up through the coupling mechanism.

2. The method as described in claim 1, characterized in that, Based on the comparison results, select the corresponding single-motor mode, master-slave compensation mode, or dual-motor full-power mode, and determine the target force of the master and slave motors according to the preset allocation rules of the selected mode, including: When the target braking force is determined to be less than or equal to the product of the maximum capacity of a single motor and the preset dynamic allocation threshold, the single motor mode is selected, the target braking force is used as the target force output of the main motor, and the target force of the auxiliary motor is set to zero.

3. The method as described in claim 1, characterized in that, The steps of selecting the single-motor mode, master-slave compensation mode, or dual-motor full-power mode based on the comparison results, and determining the target force of the master and slave motors according to the preset allocation rules of the selected mode, also include: When the target braking force is determined to be greater than the product of the maximum capacity of a single motor and the preset dynamic allocation threshold, and less than or equal to the maximum capacity of a single motor, the master-slave compensation mode is selected. The product of the target braking force and the first preset sharing coefficient is used as the target force output of the master motor, and the product of the target braking force and the second preset sharing coefficient is used as the target force output of the slave motor. The first preset sharing coefficient is greater than the second preset sharing coefficient.

4. The method as described in claim 1, characterized in that, The steps of selecting the single-motor mode, master-slave compensation mode, or dual-motor full-power mode based on the comparison results, and determining the target force of the master and slave motors according to the preset allocation rules of the selected mode, also include: When the target braking force is determined to be greater than the maximum capacity of a single motor, the dual-motor full-power mode is selected. The maximum capacity of a single motor is used as the target force output of the main motor, and the difference between the target braking force and the maximum capacity of a single motor is used as the target force output of the auxiliary motor.

5. The method as described in claim 1, characterized in that, The difference between the target braking force and the actual total output force of the main and auxiliary motors is used as the total force error. A virtual spindle position command is generated via force loop control, including: Obtain the actual output force of the main motor and the actual output force of the auxiliary motor in the current control cycle, and subtract the sum of the actual output forces of the main motor and the auxiliary motor from the target braking force to obtain the total force error; The total force error is input into the force loop controller, which consists of a preset force loop proportional gain, a preset force loop integral gain, and a preset feedforward coefficient. After proportional-integral and feedforward composite operations, a virtual spindle position command is generated, and the virtual spindle position command is subjected to upper limit processing.

6. The method as described in claim 1, characterized in that, The virtual spindle position command is assigned to the target positions of the main and auxiliary motors according to the preset position allocation coefficient, including: Obtain the virtual spindle position command for the current control cycle, and use the product of the preset main motor position allocation coefficient and the virtual spindle position command as the target position output of the main motor, and use the product of the preset auxiliary motor position allocation coefficient and the virtual spindle position command as the target position output of the auxiliary motor; wherein the sum of the main motor position allocation coefficient and the auxiliary motor position allocation coefficient is 1, and the main motor position allocation coefficient is greater than the auxiliary motor position allocation coefficient.

7. The method according to claim 1, characterized in that, Independent closed-loop position adjustments are performed on the target and actual positions of the main and auxiliary motors respectively to obtain the basic torque commands for the main and auxiliary motors, including: The target position of the main motor is subtracted from the actual position of the main motor to obtain the position error of the main motor. The position error of the main motor is input to the main position loop PID controller, and after proportional, integral and differential discrete calculations, the basic torque command of the main motor is output. Simultaneously, the target position of the auxiliary motor is subtracted from the actual position of the auxiliary motor to obtain the position error of the auxiliary motor; the position error of the auxiliary motor is input to the auxiliary position loop PID controller, and after proportional, integral and differential discrete calculations, the basic torque command of the auxiliary motor is output.

8. The method according to claim 1, characterized in that, The actual position errors of the main and auxiliary motors are used to generate a reverse cross-coupling compensation amount, which is then superimposed on the basic torque commands of the main and auxiliary motors, including: Subtracting the actual position of the auxiliary motor from the actual position of the main motor yields the synchronization error between the main and auxiliary motor positions. The PD controller, which is composed of a preset cross-coupling proportional gain and a preset cross-coupling derivative gain, takes the position synchronization error input as input. After proportional-derivative operation, it generates the main cross-coupling compensation amount and uses the opposite of the main cross-coupling compensation amount as the secondary cross-coupling compensation amount. The main cross-coupling compensation amount is superimposed on the main motor base torque command, and the secondary cross-coupling compensation amount is superimposed on the secondary motor base torque command.

9. The method according to claim 1, characterized in that, When the actual torque deviation between the main and auxiliary motors exceeds a preset threshold, a balance correction amount is generated and added to the torque command on the auxiliary motor side, including: Subtract the actual torque of the auxiliary motor from the actual torque of the main motor to obtain the real-time torque deviation; When the absolute value of the real-time torque deviation is less than or equal to the preset torque difference threshold, the output of the balance correction amount is canceled; when the absolute value of the real-time torque deviation is greater than the preset torque difference threshold, the result of subtracting the product of the preset torque difference threshold and the sign function from the real-time torque deviation and then multiplying it by the preset balance coefficient is used as the balance correction amount output, and the balance correction amount is superimposed on the current torque command on the auxiliary motor side.

10. An electromechanical braking system with dual motors coordinating pressure build-up, characterized in that, include: The main motor and the auxiliary motor are connected to the same braking transmission mechanism through a coupling mechanism. They are used to output driving force in response to the main motor drive signal and the auxiliary motor drive signal, respectively. After being coupled by the coupling mechanism, they jointly drive the braking transmission mechanism to perform braking pressure build-up. Force sensors are installed on the force output paths of the main motor and the auxiliary motor to collect the actual output force of the main motor and the auxiliary motor, and output the corresponding actual force signals. Position sensors are installed on the main motor and the auxiliary motor respectively to collect the actual position of the main motor and the auxiliary motor, and output the corresponding actual position signals; The current sensors are connected to the power supply circuits of the main motor and the auxiliary motor respectively, and are used to collect the actual current of the main motor and the actual current of the auxiliary motor, and output the corresponding current signals. The torque estimation module receives the actual current signals of the main motor and the auxiliary motor, converts them into the actual torque of the main motor and the actual torque of the auxiliary motor respectively, and outputs them. The electronic control unit is connected to the force sensor, position sensor, current sensor and torque estimation module respectively, and is electrically connected to the driver control terminals of the main motor and the auxiliary motor. The electronic control unit is configured to execute the electromechanical braking control method of dual motor cooperative pressure building as described in any one of claims 1 to 9.

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