Master-slave dual-motor steering gear

Abstract

The application discloses a master-slave type double-motor steering gear, compared with a traditional single-motor steering gear, the master-slave type double-motor steering gear is more reliable in structure, provides double power assistance, greatly increases the steering power assistance range, and improves the driving experience: with the increase of the vehicle tonnage and load, the required power assistance for steering is also increasing, the power assistance range of the single motor cannot meet the power assistance requirement, the double-motor steering gear can provide double power assistance, and the requirement of the large-tonnage vehicle for the steering power assistance is met. In addition, the double-motor steering gear provides a backup scheme for the motor and the controller, at least half of the power assistance can be provided in the case that one motor or controller fails, so that the vehicle cannot be steered, the stability and reliability of the vehicle are improved, and the double-motor steering gear is suitable for large-scale use and popularization in the industry.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of commercial vehicle steering systems, and particularly relates to a master-slave type double-motor steering gear. BACKGROUND

[0002] With the development of vehicle intelligence and steering technology, the requirements for driving comfort and safety are higher and higher, which requires the steering gear to increase steering torque and function safety and redundancy design.

[0003] The steering gear in the prior art is usually a single-motor steering gear, which can complete steering assistance, but the steering gear itself is a component with high safety requirements. If the steering gear fails during the driving of the vehicle, the disappearance of the steering assistance will cause serious safety hazards. In addition, the assistance effect of the single steering gear is relatively insufficient.

[0004] In general, the steering gear in the prior art has the problems of insufficient assistance effect and stability. SUMMARY

[0005] The purpose of the application is to provide a master-slave type double-motor steering gear to solve the problem of insufficient assistance effect and stability of the steering gear in the prior art.

[0006] In order to solve the above technical problems, the application adopts the following technical solutions:

[0007] A master-slave type double-motor steering gear, comprising a sensor, a first controller, a second controller, and corresponding first and second motors, wherein the first and second controllers are connected to the vehicle power supply and vehicle control unit of the vehicle they are in; the first and second motors are connected to the steering wheel of the vehicle they are in.

[0008] The first controller is connected to the second controller, and the first and second controllers are connected to the first and second motors, respectively.

[0009] The sensor is arranged at the steering wheel of the vehicle, and the sensor is connected to the first and second controllers, respectively; the sensor is used to detect the angle information and torque information of the steering wheel, and transmit the detected angle and torque information to the first and second controllers, respectively.

[0010] The first and second controllers are used to:

[0011] determine the real-time angle and real-time torque according to the received angle information and torque information;

[0012] determine the assistance torque required by the steering wheel;

[0013] Distribute the assist torque, and the first motor and the second motor output corresponding torque to the steering wheel respectively;

[0014] According to different fault types, corresponding processing measures are taken.

[0015] The application also has the following characteristics:

[0016] Further, the sensor uses a double-channel TAS sensor.

[0017] Further, the first controller and the second controller communicate through CAN2 private messages, the message IDs of the first controller and the second controller are different, the signal position definitions and the analysis formats are the same, and the communication period is 5 ms.

[0018] Further, the first controller and the second controller respectively use a cursor algorithm to convert the angle information transmitted by the double-channel TAS sensor into an angle signal, and use the angle signal as an initial value to determine a real-time angle.

[0019] The torque information transmitted by the double-channel TAS sensor is converted into a real-time torque using the following formula:

[0020] T q =k*(TS1-TS2) / 2

[0021] Wherein, T q represents the real-time torque;

[0022] TS1 and TS2 respectively represent the PWM torque signals of the steering wheel turning left and right, i.e. the torque information transmitted by the double-channel TAS sensor;

[0023] k represents the deformation coefficient of the steering column.

[0024] Further, the assist torque is calculated using the following formula:

[0025] The assist torque=(basic assist torque-return torque-damping torque+friction torque compensation+inertia torque compensation) / transmission ratio.

[0026] Further, the basic assist torque is calculated using the following steps:

[0027] Step a1, the first controller and the second controller respectively perform frequency separation on the real-time torque to obtain a high-frequency part and a low-frequency part;

[0028] Step a2, according to the results obtained in step a1, the high-frequency assist torque and the low-frequency assist torque are calculated, and the sum of the high-frequency assist torque and the low-frequency assist torque is taken as the intermediate assist torque.

[0029] Step a3, using one-dimensional table interpolation to calculate filter pole ATFLfPole, determine compensation filter factor CFlt1 and factor CFlt2;

[0030] Step a4, using the following formula, respectively calculate the low frequency, medium frequency and high frequency corresponding to the intermediate assist torque compensation coefficient A0, A1 and A2:

[0031] A x =(A x _Slope×ATFLfPole)+A x _Bias

[0032] Wherein, A x represents any one compensation coefficient;

[0033] A x _Slope represents the proportion of the selected compensation coefficient;

[0034] A x _Bias represents the bias of the selected compensation coefficient;

[0035] Step a5, according to the three compensation coefficients obtained in step a4, using the following formula to calculate the basic assist torque:

[0036] CFResult=(AssitTorq×A0+CFIt1×A1+CFIt2×A2)

[0037] Wherein, CFResult represents the basic assist torque.

[0038] Further, the first controller and the second controller both include a torque coordination module;

[0039] The first controller and the second controller distribute the assist torque according to the actual torque demand of the first motor and the second motor through the torque coordination module.

[0040] Further, the control identifiers of the first controller and the second controller are different;

[0041] The first controller and the second controller can convert the master-slave control relationship.

[0042] Further, the different fault types include first controller failure, second controller failure and double controller common failure;

[0043] The first controller is the master controller, and the second controller is the slave controller;

[0044] The first controller failure includes: vehicle message loss, steering wheel information loss, first motor failure and second controller loss;

[0045] The one-to-one corresponding processing measures of the first controller when the above failures occur are as follows:

[0046] The second controller switches to the main controller;

[0047] The second controller switches to the main controller;

[0048] The first controller is disconnected, and the second motor is controlled by the second controller to provide assist torque;

[0049] The first controller controls the first motor to output half of the assist torque, and the second motor requires 0 torque;

[0050] The second controller failure includes: whole vehicle message loss, steering wheel information loss, second motor failure and first controller loss;

[0051] The one-to-one corresponding processing measures of the second controller when the above failures occur include:

[0052] Do not process;

[0053] Do not process;

[0054] The second controller is disconnected, and the first motor is controlled by the first motor to provide assist torque;

[0055] The second controller switches to the main controller, controls the second motor to output half of the assist torque, and the first motor requires 0 torque;

[0056] The double controller common failure includes: whole vehicle message loss, steering wheel information loss and double motor steering gear common failure;

[0057] The one-to-one corresponding processing measures of the double controller common failure include:

[0058] The first controller and the second controller jointly provide fixed assist force capable of guaranteeing the minimum steering function of the vehicle;

[0059] The first controller and the second controller jointly provide fixed assist force capable of guaranteeing the minimum steering function of the vehicle;

[0060] Disconnect the first motor and the second motor, and do not output torque.

[0061] Compared with the prior art, the present application has the following technical effects:

[0062] Compared with the traditional single motor steering gear, the master-slave double motor steering gear of the application has more reliable structure, provides double power assistance, greatly increases the steering power assistance range, and improves the driving experience: as the vehicle tonnage and load increase, the required steering power assistance also increases, and the power assistance range of the single motor cannot meet the power assistance requirement, and the double motor steering gear can provide double power assistance, solving the steering power assistance requirement of large tonnage vehicles.

[0063] In addition, the double motor steering gear of the application provides backup solutions for the motor and the controller, and at least half of the power assistance can be provided in the case of failure of one motor or controller, so that the vehicle cannot be steered, the stability and reliability of the vehicle are improved, and the application is suitable for large-scale use and promotion in industry. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is a control block diagram of the master-slave double motor steering gear of the application;

[0065] Figure 2 is a master-slave controller conversion logic diagram of the master-slave double motor steering gear of the application. DETAILED DESCRIPTION

[0066] It should be noted that all components in the application, such as those without special instructions, are all known components in the prior art. For example, the vehicle power supply, vehicle control unit, controller and motor steering gear are all known units or devices in the prior art.

[0067] All methods in the application, such as those without special instructions, are known methods in the prior art or content that can be directly obtained by those skilled in the art based on existing knowledge, such as CAN communication, which is known in the prior art, and the torque coordination module, which can be implemented by those skilled in the art,

[0068] The following gives a specific embodiment of the application, and it should be noted that the application is not limited to the following specific embodiments, and any equivalent transformation based on the technical solutions of the application falls within the protection scope of the application.

[0069] A master-slave double motor steering gear, comprising a vehicle, the vehicle comprising a vehicle power supply and a vehicle control unit, characterized in that the vehicle is internally provided with a first controller and a second controller and corresponding first and second motors;

[0070] The first controller is a master controller, and the second controller is a slave controller;

[0071] The first controller and the second controller are respectively connected with the vehicle power supply and the vehicle control unit of the vehicle where they are located;

[0072] The first controller is connected with the second controller, and the first controller and the second controller are connected with the first motor and the second motor respectively;

[0073] A sensor is arranged at a steering wheel of the vehicle, and the sensor is connected with the first controller and the second controller respectively;

[0074] The sensor is used for detecting angle information and torque information of the steering wheel, and transmitting the detected angle and torque information to the first controller and the second controller respectively;

[0075] The first controller and the second controller are used for:

[0076] According to the received angle information and torque information, real-time angle and real-time torque are determined;

[0077] According to the real-time torque data, the assist torque required by the steering wheel is determined;

[0078] The assist torque is distributed, and the first motor and the second motor output corresponding torques to the steering wheel respectively;

[0079] According to different fault types, corresponding processing measures are taken.

[0080] As a preferred scheme, the sensor adopts a double-channel TAS sensor.

[0081] In actual work, the angle and hand torque of the steering wheel are input to the first controller and the second controller through the double-channel TAS sensor. Each channel of the double-channel TAS sensor is powered separately, and each channel provides a separate torque signal and a rotation angle signal. One channel can still work independently when the other channel has a problem, and they do not affect each other.

[0082] As a preferred scheme, the first controller and the second controller communicate with each other through CAN2 private message, and exchange torque control and fault information. The message IDs of the first controller and the second controller are different, the signal position definitions and analysis formats are the same, the communication period is 5ms, and the signal is not delayed.

[0083] The main information is given below:

[0084] 1. Master-slave controller identification: the master controller is 1, and the slave controller is 0.

[0085] 2. Torque and motor control interface: request torque, system ready.

[0086] 3. Fault information: motor fault, sensor fault, motor angle fault, controller loss.

[0087] To realize the redundancy design of master-slave controller, the master-slave switching function, and ensure the safety of the system, the slave controller is part of the backup of the master controller and can replace the master controller under certain conditions. Therefore, most of the software functions of the master-slave controller are the same.

[0088] However, the master-slave controller shares a calibration brush CAN line and needs to communicate and exchange information with each other. There are also differences between the active motor control and the passive motor controller. The software of the master-slave controller cannot be completely the same. Specifically, the software of the master-slave controller has the following differences:

[0089] 1. Different master-slave identification: The master-slave identification is the unique identification of the master-slave controller. It not only needs to be sent from the interactive message to identify its own master-slave positioning, but also is the identification of the motor demand torque source in the controller software. The motor demand torque of the master controller comes from the calculation of the torque module and the distribution torque of the torque coordination module. The motor demand torque of the slave controller comes from the torque request received from the master controller interactive message. The master-slave controller switching only switches the master-slave identification.

[0090] 2. Different master-slave interactive message ID: The master-slave controller interacts with the message on a CAN line. The message ID on the CAN line must be different. The software bottom layer configures the receiving and sending ID of the master-slave controller to be opposite, that is, the A controller sends id1 and receives id2, and the B controller sends id2 and receives id1. The interactive ID is only related to the default master-slave controller and does not change with the master-slave controller switching.

[0091] 3. Different diagnostic protocol physical addressing message target address and response source address: The software of the master-slave controller is separately programmed, and the diagnostic request and response message ID is different to ensure correct programming and avoid incorrect programming of the master-slave software. The diagnostic tool can also read the diagnostic information and software version of the master-slave controller. The diagnostic ID does not change with the master-slave controller switching.

[0092] 4. Different calibration protocol ID: The master-slave controller can be calibrated separately to avoid ID conflict on a CAN line and does not switch with the master-slave switching.

[0093] Specifically, the dual-channel TAS sensor design itself defines the fixed relationship between the two angle signals output by the sensor in the normal working state. The combination relationship of the large angle signal and the small angle signal is used to calculate the angle. The vernier algorithm is a known algorithm in the prior art. Through the vernier algorithm, the two signals can be converted into an angle signal.

[0094] When the steering wheel speed is fast, the angle calculated by the vernier algorithm is the initial value, and the periodical change of the small angle signal is collected to calculate the real-time angle.

[0095] As a further description of the dual-channel TAS sensor, the dual-channel TAS sensor transmits two-channel PWM angle signals, the duty cycle increases from 12.5% to 87.5% with the steering wheel rotation, wherein the small angle signal circulates every 40 degrees, and the large angle signal circulates every 296 degrees, and the least common multiple of the two cycles is 1480, which is the maximum angle that can be measured by the dual-channel TAS sensor, and each side is 740 degrees.

[0096] Further, since the dual-channel TAS sensor angle magnetic ring can be randomly rotated during installation, the zero angle of the steering wheel can be any angle of the original angle signal. After the steering system is installed, the angle of the vehicle straight driving needs to be self-learned as the zero angle. This part is only used as a further description of the use scene of the dual-channel TAS sensor, and does not belong to the discussion scope of the present embodiment. Those skilled in the art are capable of realizing the above content, and will not be described here.

[0097] The first controller and the second controller use the vernier algorithm to convert the angle information transmitted by the dual-channel TAS sensor into an angle signal; and the angle signal is used as an initial value to determine a real-time angle.

[0098] The torque information transmitted by the dual-channel TAS sensor is converted into a real-time torque using the following formula:

[0099] T q =k*(TS1-TS2) / 2

[0100] Wherein, T q represents the real-time torque;

[0101] TS1 and TS2 represent the PWM torque signals of the left and right steering wheel rotation, i.e. the angle information transmitted by the dual-channel TAS sensor;

[0102] k represents the deformation coefficient of the steering wheel torsion bar, which can be directly obtained.

[0103] Wherein, the steering wheel torque is represented as two-channel differential PWM torque signals, and the signals are 50% when the torsion bar is in a relaxed state without force, i.e. zero torque, and TS1 increases and TS2 decreases when the steering wheel is turned to the left.

[0104] Further, the assist torque includes a basic assist torque, a return torque, a damping torque, a friction torque compensation, and an inertia torque compensation;

[0105] The assist torque is calculated using the following method:

[0106] The assist torque=(basic assist torque-return torque-damping torque+friction torque compensation+inertia torque compensation) / transmission ratio.

[0107] Wherein, the return torque, damping torque, friction torque compensation and inertia torque compensation are all contents that can be directly obtained by those skilled in the art, or obtained by known methods in the art in combination with the actual situation of the vehicle and the road conditions. The following is a brief principle description of the return torque, damping torque, friction torque compensation and inertia torque compensation.

[0108] Return torque: the greater the absolute value of the steering wheel angular displacement, the greater the initial value of the return torque; the higher the vehicle speed, the smaller the initial value of the return torque. The absolute value of the steering wheel hand torque and the absolute value of the steering wheel angular velocity are taken as inputs to interpolate the return torque coefficient. The final return torque = return torque initial value x return torque coefficient x steering wheel angular displacement sign. The return torque initial value, the return torque coefficient and the steering wheel angular displacement sign are contents that can be directly obtained by those skilled in the art, or obtained by known methods in the art in combination with the actual situation of the vehicle and the road conditions.

[0109] Damping torque: prevent the steering wheel from shaking at high vehicle speed. The greater the absolute value of the steering wheel angular velocity, the greater the absolute value of the damping torque; the higher the vehicle speed, the greater the absolute value of the damping torque.

[0110] Friction torque compensation: the friction compensation torque is equal to the initial friction compensation torque multiplied by the friction compensation torque coefficient. The input motor speed is first-order low-pass filtered, and the greater the absolute value of the low-frequency part of the motor speed, the greater the initial value of the friction compensation torque. The friction compensation torque coefficient is calculated by difference according to the vehicle speed.

[0111] Inertia torque compensation: the inertia compensation torque is equal to the inertia compensation torque initial value multiplied by the inertia compensation torque coefficient. First, the rate of change of the motor speed is calculated, and the inertia compensation torque initial value is calculated by one-dimensional table interpolation according to the rate of change of the motor speed. The inertia compensation torque coefficient is calculated according to the vehicle speed.

[0112] Further, the real-time torque is frequency-separated, the low-frequency part reflects the actual hand torque of the driver, which is used to calculate the basic assist torque, and the high-frequency part reflects the road excitation while leading the phase, which is used to maintain the road feeling and improve the sensitivity of the assist. The higher the vehicle speed, the smaller the high-low frequency assist torque; the greater the absolute value of the steering wheel high-low frequency hand torque, the greater the high-low frequency assist torque. The calculated high-frequency assist torque and low-frequency assist torque are added to obtain the intermediate assist torque.

[0113] Wherein, those skilled in the art know the specific range defined by "high frequency" and "low frequency", in addition to which those skilled in the art can also limit the frequency range of high frequency and low frequency by known methods in combination with the actual situation of the vehicle and the road conditions. The same applies to "low frequency, medium frequency and high frequency" hereinafter.

[0114] The basic assist torque is calculated using the following steps:

[0115] Step a1, the first controller and the second controller respectively perform frequency separation on the real-time torque to obtain a high-frequency part and a low-frequency part;

[0116] Step a2, the high-frequency assist torque and the low-frequency assist torque are calculated, and the sum of the high-frequency assist torque and the low-frequency assist torque is taken as the intermediate assist torque;

[0117] Step a3, the filter pole ATFLfPole is calculated by using one-dimensional table interpolation, and the compensation filter factors CFlt1 and CFlt2 are determined;

[0118] Step a4, the compensation coefficients A0, A1 and A2 corresponding to the low frequency, the medium frequency and the high frequency of the intermediate assist torque are respectively calculated using the following formula:

[0119] A x =(A x _Slope×ATFLfPole)+A x _Bias

[0120] Wherein, A x represents any one compensation coefficient;

[0121] A x _Slope represents the proportion of the selected compensation coefficient, which can be directly obtained;

[0122] A x _Bias represents the bias of the selected compensation coefficient, which can be directly obtained;

[0123] Step a5, according to the three compensation coefficients, the base assist torque is calculated using the following formula:

[0124] CFResult=(AssitTorq×A0+CFIt1×A1+CFIt2×A2)

[0125] Wherein, CFResult represents the base assist torque.

[0126] Further, the first controller and the second controller each include a torque coordination module; the control block diagram of the master-slave dual-motor steering device is as shown in Figure 1 .

[0127] The first controller and the second controller distribute the assist torque according to the actual torque demand of the first motor and the second motor through the torque coordination module.

[0128] Further, the control software built in the first controller and the second controller is the same, and the control identifiers are different; for fault information, the master-slave controllers can be converted, i.e. the slave controller is converted into the master controller, and the master controller is converted into the slave controller.

[0129] The torque distribution is performed from the controller acting as a master controller computing system demand torque.

[0130] Specifically, different fault types include a first controller fault, a second controller fault, and a double controller common fault;

[0131] The first controller fault includes: whole vehicle message loss, steering wheel information loss, first motor fault, and second controller loss;

[0132] The one-to-one corresponding processing measures when the first controller has the above faults include:

[0133] The second controller is switched to the master controller;

[0134] The second controller is switched to the master controller;

[0135] The first controller is disconnected, and the second motor provides assist torque;

[0136] The first controller controls the first motor to output half of the assist torque, and the second motor demand torque is 0;

[0137] The second controller fault includes: whole vehicle message loss, steering wheel information loss, second motor fault, and first controller loss;

[0138] The one-to-one corresponding processing measures when the second controller has the above faults include:

[0139] Do not process;

[0140] Do not process;

[0141] The second controller is disconnected, and the first motor controls the first motor to provide assist torque;

[0142] The second controller is switched to the master controller, controls the second motor to output half of the assist torque, and the first motor demand torque is 0;

[0143] The double controller common fault includes: whole vehicle message loss, steering wheel information loss, and double motor steering gear common fault;

[0144] The one-to-one corresponding processing measures when the double controller common fault occurs include:

[0145] The first controller and the second controller jointly provide fixed assist force capable of guaranteeing the minimum steering function of the vehicle;

[0146] The first controller and the second controller jointly provide fixed assist force capable of guaranteeing the minimum steering function of the vehicle;

[0147] Disconnect the first motor and the first motor, and do not output torque.

[0148] For further convenience of understanding, the embodiment gives a fault information table 1:

[0149]

[0150] Table 1 Fault information table

[0151] Among them, "the fixed assistance of the minimum steering function of the vehicle" is the content that can be directly obtained by those skilled in the art according to different vehicle conditions, and does not belong to the discussion category of the embodiment, and will not be described here.

[0152] The following will be described in combination with Figure 2 The master controller conversion logic is described. When a fault occurs and the master and slave controllers need to be converted to each other, the conversion logic is as follows:

[0153] The default A controller is the master controller, and the B controller is the slave controller.

[0154] When the communication between the A and B controllers is normal, if the vehicle information and the steering wheel information received by the A controller have problems, the A controller is converted to a slave controller, and the B controller is converted to a master controller.

[0155] If A and B cannot normally communicate, A and B are both master controllers, and control their respective motors to work.

[0156] The master-slave dual motor cooperative control of the embodiment has the following advantages:

[0157] Compared with the traditional single motor steering gear, the master-slave dual motor steering gear has a more complex structure, an additional motor and controller, and a higher cost. The cooperative control is more complex than the one-to-one control method of the original controller and motor.

[0158] After adopting the method proposed in the embodiment to solve the problem of cooperative control, the master-slave dual motor steering gear solves the technical problems that cannot be solved by the single motor steering gear, and exhibits its unique advantages, mainly including the following two points:

[0159] Provide double power assistance, greatly increase the steering assistance range, and improve the driving experience: with the increase of vehicle tonnage and load, the required steering assistance is also increasing, and the assistance range of the single motor cannot meet the assistance requirements. The use of a dual motor steering gear can provide double power assistance, solve the steering assistance requirements of large-tonnage vehicles, and improve the driving experience.

[0160] The need for functional safety: single motor steering gear once the motor or controller failure can not provide steering assist, and the steering gear is a safety component of the vehicle, which will cause the vehicle to be unable to drive. And double motor steering gear provides backup for motor and controller, at least half of the assist can be provided in the case of a motor or controller failure, so as not to cause the vehicle to be unable to steer, improve the safety and reliability of the vehicle.

[0161] In addition, on the basis of traditional single motor steering gear control, a cooperative control module is added. The cooperative control module includes master-slave identification conversion, torque distribution, message control, fault classification and safety response processing functions, and the underlying software changes the communication, diagnosis and calibration message id of the slave controller to distinguish it from the master controller. The management and control of the double motor steering gear are realized, so that the two motors can work together to realize the steering assist function, and the steering ability and safety reliability of the steering component are improved. It has been applied in the software development process of master-slave double motor steering gear, and has passed the test on the sample vehicle.

Claims

1. A master slave dual motor steering gear, characterized by, The sensor, the first controller, the second controller, and the corresponding first motor and second motor are included, the first controller and the second controller are connected with the power supply and the vehicle control unit of the vehicle respectively, and the first motor and the second motor are connected with the steering wheel of the vehicle. The first controller is connected with the second controller, and the first controller and the second controller are connected with the first motor and the second motor respectively. The sensor is arranged at the steering wheel of the vehicle, and the sensor is connected with the first controller and the second controller respectively; the sensor is used for detecting the angle information and the torque information of the steering wheel, and transmitting the detected angle and torque information to the first controller and the second controller respectively. The first controller and the second controller are used for: determining the real-time angle and the real-time torque according to the received angle information and torque information; determining the assist torque required by the steering wheel; allocating the assist torque to make the first motor and the second motor output corresponding torques to the steering wheel respectively; taking corresponding processing measures according to different fault types; The assist torque is calculated using the following formula: assist torque = (base assist torque - return torque - damping torque + friction torque compensation + inertia torque compensation) / transmission ratio; The base assist torque is calculated using the following steps: Step a1, the first controller and the second controller respectively separate the real-time torque into high-frequency part and low-frequency part; Step a2, according to the results obtained in step a1, the high-frequency assist torque and the low-frequency assist torque are calculated, and the sum of the high-frequency assist torque and the low-frequency assist torque is taken as the intermediate assist torque; Step a3, filter pole is calculated using one-dimensional table interpolation ATFLfPole , determine compensation filter factor CFlt1 and factor CFlt2 ; Step a4, the compensation coefficients corresponding to the low, medium and high frequencies of the intermediate assist torque are calculated respectively using the following formula 、 and : =（ _ Slope × ATFLfPole ）+ _ Bias wherein represents any one of the compensation coefficients; Slope a proportion representing the selected compensation factor;​ Bias bias representing the selected compensation factor;​ Step a5, according to the three compensation coefficients obtained in step a4, the base assist torque is calculated using the following formula: CFResult =（ AssitTorq × + CFIt1 × + CFIt2 × ） wherein, CFResult represents the base assist torque.

2. The master slave dual electric motor steering gear of claim 1 wherein, The sensor uses a double-channel TAS sensor.

3. The master slave dual electric motor steering gear of claim 2, wherein, The first controller and the second controller communicate through CAN2 private messages, the message IDs of the first controller and the second controller are different, the signal position definitions and analysis formats are the same, and the communication period is 5ms.

4. The master slave dual electric motor steering gear of claim 2, wherein, The first controller and the second controller respectively use a vernier algorithm to convert the angle information transmitted by the double-channel TAS sensor into an angle signal; and the angle signal is taken as an initial value to determine the real-time angle. The torque information transmitted by the double-channel TAS sensor is converted into real-time torque using the following formula: = k* （ - ） / 2 wherein, represents real-time torque; and L and R represent the PWM torque signals for steering wheel left and right turns, respectively, i.e. the torque information transmitted by the two-channel TAS sensor; k represents a coefficient of deformation of the steering wheel torsion bar.

5. The master slave dual electric motor steering gear of claim 4 wherein, The first controller and the second controller both include a torque coordination module; The first controller and the second controller allocate the assist torque according to the actual torque demand of the first motor and the second motor through the torque coordination module.

6. The master slave dual electric motor gear of claim 5, wherein, The control identifiers of the first controller and the second controller are different; The first controller and the second controller can convert the master-slave control relationship.

7. The master slave double electric gear steering apparatus according to claim 6, wherein, The different fault types include first controller failure, second controller failure, and double-controller common failure. The first controller is a master controller, and the second controller is a slave controller; The first controller failure includes: whole vehicle message loss, steering wheel information loss, first motor failure and second controller loss; The one-to-one corresponding processing measures of the first controller when the above failures occur are as follows: When the whole vehicle message is lost, the second controller is switched to the master controller; When the steering wheel information is lost, the second controller is switched to the master controller; When the first motor fails, the first controller is disconnected, and the second motor provides assist torque controlled by the second controller; When the second controller is lost, the first controller controls the first motor to output half of the assist torque, and the second motor demand torque is 0; The second controller failure includes: whole vehicle message loss, steering wheel information loss, second motor failure and first controller loss; The one-to-one corresponding processing measures of the second controller when the above failures occur include: When the whole vehicle message is lost, do not process; When the steering wheel information is lost, do not process; When the first motor fails, the second controller is disconnected, and the first motor provides assist torque controlled by the first motor; When the second controller is lost, the second controller is switched to the master controller, controls the second motor to output half of the assist torque, and the first motor demand torque is 0; The double controller common failure includes: whole vehicle message loss, steering wheel information loss and double motor steering gear common failure; The one-to-one corresponding processing measures of the double controller common failure include: When the whole vehicle message is lost, the first controller and the second controller jointly provide fixed assist force that can guarantee the minimum steering function of the vehicle; When the steering wheel information is lost, the first controller and the second controller jointly provide fixed assist force that can guarantee the minimum steering function of the vehicle; When the double motor steering gear common failure occurs, the first motor and the second motor are disconnected, and no torque is output.

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