Research On Attitude Decoupling Method For Wheel Force Transducer Based On Mimu

By using the vehicle kinematics model and the wheel force,we can get the vehicle’s motion state.The wheel force transducer(WFT)can measure the force of the wheel.The WFT provides a certain reference for the security performance assessment and the state of motion of the intelligent vehicle.Because the WFT is fixedly connected to the wheel,the coordinate of the wheel force measurement system and the solution are inconsistent.There is a problem that the result is coupled with the angle of rotation,steering,and heeling.At present,the WFT mainly uses an encoder,which only measures the rotation angle of the wheel.At the same time,the deflection of the wheel will lead to inaccurate calculation of the wheel force while the vibration of the wheel will cause the encoder to sway,deflect,and damage.Hence,the measurement of the wheel attitude is very important for the WFT.This paper studies the attitude decoupling method for WFT based on MIMU and designs a WFT with attitude decoupling function.The main research content is as follows:Firstly,the principle and design of wheel force sensing are studied.The hardware circuit is mainly composed of a microcontroller unit,power,a signal conditioning circuit,an A/D sampling circuit,and Bluetooth.In this system,the signal conditioning circuit is used to amplify the wheel force output from the elastomer.The A/D converter circuit uses the AD7606 chip for accurate high-speed sampling.The Bluetooth wirelessly transmits the signals of the wheel force and dynamic parameters of MIMU.The communication protocol is designed according to the commands and responses of the system.Secondly,the coupling principle of the WFT and the dynamic parameter measurement such as high and low angular velocity and attitude angles are studied.The transducer coordinate system,automobile coordinate system,and navigation coordinate system are established,and the relationship between wheel force and wheel attitude is given.Since the rotational angular velocity of the wheel exceeds the range of the gyroscope in MIMU,a large-range angular velocity measurement sensor is designed by using the accelerometer.And the calibration method is given to decrease the installation errors of the accelerometers.Thirdly,a method for resolving the wheel attitude using the quaternion recursion is proposed.The gradient descent method is used to solve the wheel attitude by fusing the accelerometer and the magnetometer data.The error analysis of the accelerometer,gyroscope,and magnetometer in MIMU is carried out.The adaptive filter algorithm is used to denoise the accelerometer output.The complementary filter is used to compensate for the gyroscope error.The ellipsoid fitting method is used for the error of the magnetometer correction,and the quadrature Kalman filter is used for solving the wheel force model.Finally,the large-range angular velocity sensor,attitude in static,high,and low angular velocity rotation and wheel force simulation has been tested.The test results meet the requirements of the desired accuracy.