Multi-mode control method and brake control unit

Abstract

The present invention belongs to the technical field of vehicle braking. Disclosed are a multi-mode control method and a brake control unit. In the multi-mode control method of the present invention, a plurality of sets of control solutions including position-speed-current closed-loop, pressure-current closed-loop, and independent outputs from a driving motor at a non-fault side are used, allowing for switching of a plurality of control strategies under different conditions, thereby improving the safety and reliability of the braking performance, and thus ensuring the safety of driving braking.

Description

A multi-mode control method and brake control unit

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 2, 2023, with application number 202310963125.3 and invention name “A multi-mode control method and braking control unit”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the technical field of vehicle braking, and in particular to a multi-mode control method and a braking control unit. Background Art

[0003] Electromechanical brakes (EMBs) are gaining increasing attention as the optimal braking solution for future intelligent chassis. EMBs are driven by electric motors, which achieve precise servo control of braking force through tight coupling between the motor and mechanical components, including the reducer, ball screw, and caliper. Currently, voltage, current, speed, and position sensors are commonly used in motor vector control. Current sensors and speed / position sensors are core components of motor control systems. Their operational health requires real-time monitoring during EMB operation. Mechanical components in EMBs, however, can gradually experience structural wear and gear breakage over time, requiring real-time monitoring. When an anomaly occurs, the system must be able to promptly and accurately locate each sensor and mechanical fault. Furthermore, the system should include driver and hardware redundancy to enable efficient switching between multiple control strategies under fault conditions, ensuring safe and reliable braking performance.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-mode control method and a brake control unit to achieve multi-mode control and switching of an electromechanical brake driven by dual motors, thereby improving the safety and reliability of the braking performance.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] The present invention provides a multi-mode control method, which is applied to an electromechanical brake based on dual-motor drive. The multi-mode control method includes the following steps:

[0008] A first current, a first rotation angle signal, a second current, a second rotation angle signal, and an axial pressure of an electronic mechanical brake are collected, where the first current is an input current of a first drive motor of the electronic mechanical brake, the second current is an input current of a second drive motor of the electronic mechanical brake, the first rotation angle signal is a rotation angle of the first drive motor, and the second rotation angle signal is a rotation angle of the second drive motor. The following operation is performed based on the first current, the first rotation angle signal, the second current, the second rotation angle signal, and the axial pressure:

[0009] When both the first current and the axial pressure do not satisfy a first preset condition or the first rotation angle signal does not satisfy a second preset condition, the first drive motor is controlled by adopting a pressure-current closed-loop control strategy; otherwise, the first drive motor is controlled by adopting a position-speed-current closed-loop control strategy; under the condition that the first drive motor is controlled by adopting the pressure-current closed-loop control strategy, when either the first current or the axial pressure does not satisfy the first preset condition, the first drive motor stops working;

[0010] When both the second current and the axial pressure do not meet the first preset condition or the second rotation angle signal does not meet the second preset condition, the second drive motor is controlled by a pressure-current closed-loop control strategy; otherwise, the second drive motor is controlled by a position-speed-current closed-loop control strategy; under the condition that the second drive motor is controlled by the pressure-current closed-loop control strategy, when either the second current or the axial pressure does not meet the first preset condition, the second drive motor stops working.

[0011] Optionally, the first preset condition includes an allowable current range and an allowable pressure range;

[0012] When the first current is not within the current allowable range and 1 / 2 times the axial pressure is not within the pressure allowable range, it is determined that both the first current and the axial pressure do not meet the first preset condition;

[0013] When the second current is not within the allowable current range and 1 / 2 times the axial pressure is not within the allowable pressure range, it is determined that both the second current and the axial pressure do not meet the first preset condition.

[0014] Optionally, the second preset condition includes an allowable range of motor rotation angle;

[0015] When a plurality of consecutive first rotation angle signals are not within the allowable range of the motor rotation angle, it is determined that the first rotation angle signal does not meet the second preset condition;

[0016] When a plurality of consecutive second rotation angle signals are not within the allowable range of the motor rotation angle, it is determined that the second rotation angle signal does not meet the second preset condition.

[0017] Optionally, the multi-mode control method further includes the following steps:

[0018] When the first current meets the first preset condition and the axial pressure does not meet the first preset condition, outputting a warning message indicating that the first current sampling is abnormal;

[0019] When the second current meets the first preset condition and the axial pressure does not meet the first preset condition, outputting a warning message indicating that the second current sampling is abnormal;

[0020] When the first current or the second current satisfies a first preset condition and the axial pressure does not satisfy the first preset condition, a warning message indicating that the pressure sensor is abnormal is output.

[0021] Optionally, under the condition that the first drive motor is controlled by a pressure-current closed-loop control strategy, when the first current and the axial pressure both meet a first preset condition, a warning message of an abnormality of the electronic mechanical brake is output; when either the first current or the axial pressure does not meet the first preset condition, a warning message of an abnormality of the first drive system is output; the first drive system includes a first drive motor, a first rotary transformer provided on the first drive motor, and a current sensor for detecting the current of the first drive motor;

[0022] Under the condition that the second drive motor is controlled by a pressure-current closed-loop control strategy, when the second current and the axial pressure both meet the first preset condition, a warning message of an abnormality of the electronic mechanical brake is output; when either the second current or the axial pressure does not meet the first preset condition, a warning message of an abnormality of the second drive system is output; the second drive system includes a second drive motor, a second rotating transformer arranged on the second drive motor, and a current sensor for detecting the current of the second drive motor.

[0023] Optionally, the electromechanical brake comprises: a first drive motor, a second drive motor, a transmission gear set, a ball screw, a nut-type piston and a caliper;

[0024] The first drive motor and the second drive motor are both fixedly connected to one end of the ball screw through the transmission gear set, and the other end of the ball screw extends into the nut-type piston and engages with the internal thread of the nut-type piston;

[0025] The nut-type piston is correspondingly arranged to the caliper. When the wheel is braked, the caliper and the nut-type piston clamp the wheel.

[0026] Optionally, the transmission gear set includes a first primary reducer gear, a second primary reducer gear, a first secondary reducer gear, a second secondary reducer gear, a third secondary reducer gear, a third primary reducer gear and a fourth primary reducer gear;

[0027] The output shaft of the first drive motor is connected to the first primary reducer gear shaft, the first primary reducer gear is meshed with the second primary reducer gear, the second primary reducer gear is connected to the first secondary reducer gear shaft, and the first secondary reducer gear is meshed with the second secondary reducer gear;

[0028] The output shaft of the second drive motor is connected to the fourth primary reducer gear shaft, the fourth primary reducer gear is meshed with the third primary reducer gear, the third primary reducer gear is connected to the third secondary reducer gear shaft, and the third secondary reducer gear is meshed with the second secondary reducer gear;

[0029] The second secondary reducer gear is connected to one end shaft of the ball screw.

[0030] Optionally, a through-axis pressure sensor is provided on the second-stage reducer gear.

[0031] Optionally, a first rotary transformer is installed on the first drive motor; and a second rotary transformer is installed on the second drive motor.

[0032] A brake control unit, the brake control unit is used to execute the above-mentioned multi-mode control method;

[0033] The brake control unit is connected to the electronic mechanical brake and the electronic control unit of the vehicle respectively;

[0034] The electronic control unit is used to send a target brake pressure, a target rotation angle, and a target current for closed-loop control to the brake control unit.

[0035] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0036] An embodiment of the present invention provides a multi-mode control method and a braking control unit. The multi-mode control method includes: when neither the first current nor the axial pressure satisfies a first preset condition or the first rotation angle signal satisfies a second preset condition, a pressure-current closed-loop control strategy is adopted to control the first drive motor; otherwise, a position-speed-current closed-loop control strategy is adopted to control the first drive motor; under the condition that the pressure-current closed-loop control strategy is adopted to control the first drive motor, when either the first current or the axial pressure does not satisfy the first preset condition, the first drive motor stops working; when neither the second current nor the axial pressure satisfies the first preset condition or the second rotation angle signal does not satisfy the second preset condition, the pressure-current closed-loop control strategy is adopted to control the second drive motor; otherwise, a position-speed-current closed-loop control strategy is adopted to control the second drive motor; under the condition that the pressure-current closed-loop control strategy is adopted to control the second drive motor, when either the second current or the axial pressure does not satisfy the first preset condition, the second drive motor stops working. The multi-mode control method of the present invention adopts multiple control schemes including position-speed-current closed loop, pressure-current closed loop, and independent output of the non-fault side drive motor, thereby realizing the switching of multiple control strategies under different conditions, improving the safety and reliability of braking performance, and thus ensuring the safety of vehicle braking.

[0037] Figures in the specification

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] FIG1 is a schematic diagram of a multi-mode control method according to an embodiment of the present invention;

[0040] FIG2 is a schematic diagram of a position-speed-current closed-loop control strategy provided by an embodiment of the present invention;

[0041] FIG3 is a schematic diagram of a pressure-current closed-loop control strategy according to an embodiment of the present invention;

[0042] FIG4 is a schematic diagram of the overall structure of an electromechanical brake based on dual-motor drive according to an embodiment of the present invention;

[0043] FIG5 is a cross-sectional view of an electromechanical brake based on dual motor drive according to an embodiment of the present invention;

[0044] FIG6 is a schematic structural diagram of a transmission gear set provided in an embodiment of the present invention;

[0045] FIG7 is a connection diagram of a brake control unit provided by an embodiment of the present invention.

[0046] Explanation of the accompanying drawings: 1. Caliper, 2. First drive motor, 3. Second drive motor, 4. First rotary transformer, 5. Second rotary transformer, 6. Transmission mechanism connecting shell, 7. Transmission mechanism fixed shell, 8. Through-axis pressure sensor, 9. Nut-type piston, 10. Ball screw, 11. Deep groove ball bearing, 12. First drive motor output shaft, 13. First transmission shaft, 14. Output shaft, 15. Second transmission shaft, 16. Second drive motor output shaft, 17. First primary reducer gear, 18. First secondary reducer gear, 19. Second primary reducer gear, 20. Second secondary reducer gear, 21. Third secondary reducer gear, 22. Third primary reducer gear, 23. Fourth primary reducer gear. DETAILED DESCRIPTION

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0048] The purpose of the present invention is to provide a multi-mode control method and a brake control unit to achieve multi-mode control and switching of an electromechanical brake driven by dual motors, thereby improving the safety and reliability of the braking performance.

[0049] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] Example 1

[0051] As shown in FIG1 , embodiment 1 of the present invention provides a multi-mode control method, which is applied to the electronic mechanical brake based on dual motor drive in embodiment 1. The multi-mode control method includes:

[0052] A first current, a first rotation angle signal, a second current, a second rotation angle signal, and an axial pressure of an electronic mechanical brake are collected, where the first current is an input current of a first drive motor of the electronic mechanical brake, the second current is an input current of a second drive motor of the electronic mechanical brake, the first rotation angle signal is a rotation angle of the first drive motor, and the second rotation angle signal is a rotation angle of the second drive motor. The following operation is performed based on the first current, the first rotation angle signal, the second current, the second rotation angle signal, and the axial pressure:

[0053] When both the first current and the axial pressure do not meet the first preset condition or the first angle signal does not meet the second preset condition, the first drive motor is controlled by a pressure-current closed-loop control strategy; otherwise, the first drive motor is controlled by a position-speed-current closed-loop control strategy; under the condition that the first drive motor is controlled by a pressure-current closed-loop control strategy, when either the first current or the axial pressure does not meet the first preset condition, the first drive motor stops working.

[0054] When the second current and the axial pressure do not meet the first preset condition or the second angle signal does not meet the second preset condition, the second drive motor is controlled by a pressure-current closed-loop control strategy; otherwise, the second drive motor is controlled by a position-speed-current closed-loop control strategy; under the condition that the second drive motor is controlled by a pressure-current closed-loop control strategy, when either the second current or the axial pressure does not meet the first preset condition, the second drive motor stops working.

[0055] Among them, the first preset condition includes an allowable current range and an allowable pressure range; when the first current is not within the allowable current range and 1 / 2 times the axial pressure is not within the allowable pressure range, it is determined that both the first current and the axial pressure do not meet the first preset condition; when the second current is not within the allowable current range and 1 / 2 times the axial pressure is not within the allowable pressure range, it is determined that both the second current and the axial pressure do not meet the first preset condition.

[0056] The second preset condition includes the allowable range of the motor angle; when multiple consecutive first angle signals are not within the allowable range of the motor angle, it is determined that the first angle signal does not meet the second preset condition; when multiple consecutive second angle signals are not within the allowable range of the motor angle, it is determined that the second angle signal does not meet the second preset condition.

[0057] As shown in Figure 2, the braking process of the position-speed-current closed-loop control strategy is as follows: the target braking pressure that each drive motor needs to provide at that moment sent by the vehicle's electronic control unit is Ptarget, and the target rotation angle of the motor shaft is θ target , and the q-axis target current is I q,target (Under normal braking, the target braking requirements of the motors on both sides (the first drive motor 2 and the second drive motor 3) are the same. It should be noted that the allowable amplitude of the pressure response at this moment (i.e., the allowable pressure range) is (P tmin ,P tmax ), the allowable amplitude of the motor angle response (i.e. the allowable range of the motor angle) is (θ tmin ,θ tmax ), the allowable amplitude of the motor q-axis current response (i.e., the allowable current range) is (Itmin ,I tmax ).

[0058] Taking the response output of the first drive motor 2 as an example, when the target rotation angle θ of the first drive motor is obtained target After that, the first rotary transformer 4 measures the rotation angle signal θ of the first drive motor shaft at that moment. t , and calculate the target speed V of the speed loop input target The first rotary transformer 4 further measures the speed signal V of the first drive motor shaft at that moment. t , and calculate the current loop input target current I q Driven by the input current, the first drive motor output shaft 12 rotates, thereby driving the second primary reducer gear 19, the first secondary reducer gear 18, the second secondary reducer gear 20, as well as the output shaft 14 and the ball screw 10. The rotation of the ball screw 10 and the circumferential limit grooves combine to create axial translation of the nut piston 9, eliminating the brake clearance and applying the braking force.

[0059] As shown in Figure 3, the braking process of the pressure-current closed-loop control strategy: Taking the response output of the first drive motor as an example, when the target braking pressure P of the first drive motor is obtained, target Then, the through-axis pressure sensor 8 measures the system axial braking pressure at that moment, and calculates the current loop input target current I q Driven by the input current, the output shaft 12 of the first drive motor rotates, thereby driving the rotation of the corresponding gear and the axial translation of the nut-type piston 9, completing the elimination of the brake clearance and the loading of the brake force.

[0060] The multi-mode control method in the embodiment of the present invention not only has the function of multi-mode switching, but also has the function of fault diagnosis. As shown in Figure 1, the response output of the first drive motor is taken as an example, and it is assumed that there is no abnormality in the opposite drive system. When conventional braking is applied, the drive motor is controlled by the position-speed-current closed loop, and the first rotary transformer 4 collects the rotation angle signal θ of the first drive motor shaft at that moment. t and the allowable amplitude corresponding to the motor angle (θ tmin ,θ tmax ) to make comparative judgments.

[0061] 1. When the rotation angle signals collected multiple times all meet the motor rotation angle amplitude requirements, the q-axis current of the first drive motor and the brake axial pressure are sampled, and the corresponding allowable amplitudes (I tmin ,I tmax ) and the corresponding allowable amplitude of pressure (P tmin ,P tmax ) to make comparative judgments.

[0062] 1.1. When the collected current I t and axial pressure P t / 2 both meet the amplitude requirements, the system operates normally, and all sensors and mechanisms are free of faults.

[0063] 1.2. When the collected current I t Does not meet the amplitude requirements, axial pressure P t / 2 meets the amplitude requirement, the current sampling is determined to be abnormal, and prompts timely maintenance of the BCU hardware.

[0064] 1.3. When the collected current I t Meet the amplitude requirements, axial pressure P t / 2 does not meet the amplitude requirement, the pressure sensor is judged to be abnormal, and it is prompted to repair the pressure sensor in time.

[0065] 1.4. When the collected current I t and axial pressure P t / 2 do not meet the amplitude requirements, the system immediately switches to the pressure-current closed-loop control mode and continues to sample the q-axis current of the first drive motor and the axial pressure of the brake.

[0066] 1.4.1. When the collected current I t and axial pressure P t If both / 2 meet the amplitude requirements, it is determined that the system mechanical components are severely worn or the structure is broken, resulting in the system being unable to provide sufficient braking force after the motor shaft reaches the target angle, and prompting timely maintenance of the mechanical components;

[0067] 1.4.2. When the collected current I t and axial pressure P t / 2 When one of the items does not meet the amplitude requirement, the drive system on that side is judged to be abnormal, and the opposite side motor is quickly switched to output the target braking force. At the same time, the drive system and sensors on that side are prompted to be repaired in time.

[0068] 2. When multiple sets of angle signals collected continuously do not meet the motor angle amplitude requirements, the system immediately switches to the pressure-current closed-loop control mode and continues to sample the q-axis current of the first drive motor and the axial pressure of the brake.

[0069] 2.1. When the collected current I t and axial pressure P t / 2 both meet the amplitude requirements, indicating that the sampling of the resolver is accurate and that the mechanical body is stuck or has other faults, prompting timely maintenance of the mechanical parts.

[0070] 2.2. When the collected current I t and axial pressure P t / 2 When one of the items does not meet the amplitude requirement, the drive system on that side is judged to be abnormal, and the opposite side motor is quickly switched to output the target braking force. At the same time, the drive system and sensors on that side are prompted to be repaired in time.

[0071] As shown in Figures 4 and 5 , the electromechanical brake in this embodiment of the present invention includes a caliper 1, a first drive motor 2, a second drive motor 3, a ball screw 10, a nut-type piston 9, a transmission mechanism fixed housing 7, and a transmission gear set. The transmission gear set, ball screw 10, and nut-type piston 9 are all disposed within the transmission mechanism fixed housing 7. The nut-type piston 9 can extend out of the transmission mechanism fixed housing 7. The caliper 1 is connected to the transmission mechanism fixed housing 7, and the nut-type piston 9 is positioned corresponding to the caliper 1. When braking a wheel, the caliper 1 and the nut-type piston 9 clamp the wheel.

[0072] As a specific embodiment, a first rotary transformer 4 is provided on the first drive motor 2, a second rotary transformer 5 is provided on the second drive motor 3, the caliper 1 is connected to the transmission mechanism fixed shell 7 through the transmission mechanism connecting shell 6, and a through-axis pressure sensor 8 is provided on the transmission gear set for detecting axial pressure.

[0073] As shown in Figure 6, the transmission gear set includes: a first primary reducer gear 17, a first secondary reducer gear 18, a second primary reducer gear 19, a second secondary reducer gear 20, a third secondary reducer gear 21, a third primary reducer gear 22 and a fourth primary reducer gear 23. The first drive motor output shaft 12 is connected to the first primary reducer gear 17, the first primary reducer gear 17 is meshed with the second primary reducer gear 19, the second primary reducer gear 19 is connected to the first secondary reducer gear 18, and the first secondary reducer gear 18 is meshed with the second secondary reducer gear 20; the second drive motor output shaft 16 is connected to the fourth primary reducer gear 23, the fourth primary reducer gear 23 is meshed with the third primary reducer gear 22, the third primary reducer gear 22 is connected to the third secondary reducer gear 21, and the third secondary reducer gear 21 is meshed with the second secondary reducer gear 20; the second secondary reducer gear 20 is connected to one end shaft of the ball screw 10 through the output shaft 14. The first secondary reducer gear 18 is axially connected to the first transmission shaft 13, and the third secondary reducer gear 21 is axially connected to the second transmission shaft 15. Among them, the first primary reducer gear 17 and the fourth primary reducer gear 23 are primary reducer pinions, the second primary reducer gear 19 and the third primary reducer gear 22 are primary reducer gears, the first secondary reducer gear 18 and the third secondary reducer gear 21 are secondary reducer pinions, and the second secondary reducer gear 20 is a secondary reducer gear.

[0074] As shown in FIG. 5 , the output shaft 14 in the embodiment of the present invention is disposed in a deep groove ball bearing 11 , and is connected to the transmission mechanism fixed housing 7 via the deep groove ball bearing 11 , and rolls relatively thereto.

[0075] The second primary reducer gear 19 and the first secondary reducer gear 18 are connected via a flat key on the first transmission shaft 13. The third primary reducer gear 22 and the third secondary reducer gear 21 are connected via a flat key on the second transmission shaft 15. The second secondary reducer gear 20 is connected to the output shaft 14 via a flat key, and the output shaft 14 is splined to the ball screw 10. The nut-type piston 9 achieves axial translation under the combined action of the rotation of the ball screw 10 and the circumferential limit groove, completing the elimination of the brake clearance and the application of the braking force.

[0076] Taking the first drive motor as an example, the working process of the electronic mechanical brake provided in Example 1 of the present invention is: under the drive of the input current, the output shaft 12 of the first drive motor rotates, thereby driving the second-stage first-stage reducer gear 19, the second-stage first-stage reducer gear 18, and the second-stage second-stage reducer gear 20 to rotate, as well as the output shaft 14 and the ball screw 10 to rotate, thereby driving the axial translation of the nut-type piston 9, completing the elimination of the braking clearance and the loading of the braking force.

[0077] Example 2

[0078] Embodiment 2 of the present invention provides a braking control unit, which is used to execute the multi-mode control method of embodiment 1; the braking control unit is connected to the electronic mechanical brake and the electronic control unit of the vehicle respectively; the electronic control unit is used to send the target braking pressure, target steering angle and target current for closed-loop control to the braking control unit.

[0079] As shown in Figure 7, the brake control unit BCU is connected to the vehicle's electronic control unit ECU. When the pedal position changes, the pedal's displacement, velocity, and acceleration signals are collected through the service brake and transmitted to the vehicle's electronic control unit ECU. The electronic control unit ECU analyzes and calculates the above signals to obtain the target brake pressure that each drive motor (the first drive motor 2 and the second drive motor 3) needs to provide at that moment, which is P target , the target rotation angle of the motor shaft is θ target , and the q-axis target current is I q,target (Under normal braking conditions, the target braking requirements of the motors on both sides are the same), and the signal is transmitted to the brake control unit BCU, which controls the EMB actuator (i.e., the electronic mechanical brake in Example 1).

[0080] The beneficial effects of the technical solution of the present invention based on the above embodiments are:

[0081] The electromechanical brake provided by the embodiment of the present invention adopts a dual-motor drive mode, thereby achieving structural redundancy of the drive system and improving the safety and reliability of the braking performance.

[0082] The multi-mode control method provided by the present invention utilizes multiple control schemes, including position-speed-current closed-loop control, pressure-current closed-loop control, and independent output from the drive motor on the non-faulty side. By cross-checking the signals collected by multiple sensors, it enables timely and accurate diagnosis of faults in the electronic mechanical brake's sensor hardware or mechanical components. Furthermore, when a fault occurs, it provides multiple control strategy mode switching to ensure service braking safety.

[0083] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0084] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A multi-mode control method, characterized in that: The multi-mode control method is applied to an electromechanical brake based on dual-motor drive, and the multi-mode control method comprises the following steps: A first current, a first rotation angle signal, a second current, a second rotation angle signal, and an axial pressure of an electronic mechanical brake are collected, wherein the first current is an input current of a first drive motor of the electronic mechanical brake, the second current is an input current of a second drive motor of the electronic mechanical brake, the first rotation angle signal is a rotation angle of the first drive motor, and the second rotation angle signal is a rotation angle of the second drive motor, and the following operations are performed based on the first current, the first rotation angle signal, the second current, the second rotation angle signal, and the axial pressure: When both the first current and the axial pressure do not satisfy the first preset condition or the first rotation angle signal does not satisfy the second preset condition, the first drive motor is controlled by a pressure-current closed-loop control strategy; otherwise, the first drive motor is controlled by a position-speed-current closed-loop control strategy; under the condition that the first drive motor is controlled by the pressure-current closed-loop control strategy, when either the first current or the axial pressure does not satisfy the first preset condition, the first drive motor stops working; When both the second current and the axial pressure do not meet the first preset condition or the second rotation angle signal does not meet the second preset condition, the second drive motor is controlled by a pressure-current closed-loop control strategy; otherwise, the second drive motor is controlled by a position-speed-current closed-loop control strategy; under the condition that the second drive motor is controlled by a pressure-current closed-loop control strategy, when either the second current or the axial pressure does not meet the first preset condition, the second drive motor stops working.

2. The multi-mode control method according to claim 1, characterized in that: The first preset condition includes an allowable current range and an allowable pressure range; When the first current is not within the allowable current range and 1 / 2 times of the axial pressure is not within the allowable pressure range, it is determined that both the first current and the axial pressure do not meet the first preset condition; When the second current is not within the allowable current range and 1 / 2 times the axial pressure is not within the allowable pressure range, it is determined that both the second current and the axial pressure do not satisfy the first preset condition.

3. The multi-mode control method according to claim 1, characterized in that: The second preset condition includes an allowable range of the motor rotation angle; When a plurality of consecutive first rotation angle signals are not within the motor rotation angle allowable range, it is determined that the first rotation angle signal does not meet the second preset condition; When a plurality of consecutive second rotation angle signals are not within the allowable range of the motor rotation angle, it is determined that the second rotation angle signal does not satisfy the second preset condition.

4. The multi-mode control method according to claim 1, characterized in that: The multi-mode control method further comprises the following steps: When the first current meets the first preset condition and the axial pressure does not meet the first preset condition, outputting a warning message indicating that the first current sampling is abnormal; When the second current meets the first preset condition and the axial pressure does not meet the first preset condition, outputting a warning message indicating that the second current sampling is abnormal; When the first current or the second current satisfies a first preset condition and the axial pressure does not satisfy the first preset condition, a warning message indicating that the pressure sensor is abnormal is output.

5. The multi-mode control method according to claim 1, characterized in that: Under the condition that the first drive motor is controlled by a pressure-current closed-loop control strategy, when both the first current and the axial pressure meet a first preset condition, a warning message of an abnormality of the electronic mechanical brake is output; when either the first current or the axial pressure does not meet the first preset condition, a warning message of an abnormality of the first drive system is output; The first drive system includes a first drive motor, a first rotary transformer arranged on the first drive motor, and a current sensor for detecting the current of the first drive motor; Under the condition of controlling the second drive motor by adopting a pressure-current closed-loop control strategy, when the second current and the axial pressure both meet the first preset condition, a warning message of abnormal electronic mechanical brake is output; when either the second current or the axial pressure does not meet the first preset condition, a warning message of abnormal second drive system is output; the second drive system includes a second drive motor, a second rotating transformer arranged on the second drive motor, and a current sensor for detecting the current of the second drive motor.

6. The multi-mode control method according to claim 1, characterized in that: The electronic mechanical brake comprises: a first drive motor, a second drive motor, a transmission gear set, a ball screw, a nut-type piston and a caliper; The first drive motor and the second drive motor are both fixedly connected to one end of the ball screw through the transmission gear set, and the other end of the ball screw extends into the nut-type piston and meshes with the internal thread of the nut-type piston; The nut-type piston is arranged corresponding to the caliper. When the wheel is braked, the caliper and the nut-type piston clamp the wheel.

7. The multi-mode control method according to claim 6, characterized in that: The transmission gear set includes a first primary reducer gear, a second primary reducer gear, a first secondary reducer gear, a second secondary reducer gear, a third secondary reducer gear, a third primary reducer gear and a fourth primary reducer gear; The output shaft of the first drive motor is connected to the first primary reducer gear shaft, the first primary reducer gear is meshed with the second primary reducer gear, the second primary reducer gear is connected to the first secondary reducer gear shaft, and the first secondary reducer gear is meshed with the second secondary reducer gear; The output shaft of the second drive motor is connected to the fourth primary reducer gear shaft, the fourth primary reducer gear is meshed with the third primary reducer gear, the third primary reducer gear is connected to the third secondary reducer gear shaft, and the third secondary reducer gear is meshed with the second secondary reducer gear; The second secondary reducer gear is connected to one end shaft of the ball screw.

8. The multi-mode control method according to claim 7, characterized in that: The second secondary reducer gear is provided with a through-axis pressure sensor.

9. The multi-mode control method according to claim 6, characterized in that: A first rotary transformer is installed on the first drive motor; and a second rotary transformer is installed on the second drive motor.

10. A brake control unit, characterized in that: The brake control unit is used to execute the multi-mode control method according to any one of claims 1 to 9; The brake control unit is connected to the electronic mechanical brake and the electronic control unit of the vehicle respectively; The electronic control unit is used to send a target signal for closed-loop control to the brake control unit. Target brake pressure, target steering angle and target current.

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