Fuzzy PI-LQR Steering Control Algorithm for Unmanned Agricultural Equipment
The steering system of unmanned agricultural machinery exhibits the problems of nonlinearity and time delay when operating at low flow and small angle control.This phenomenon can lead to steering control overshoot or delay,resulting in the inability to accurately track the path preview point quickly.To address this issue,an inner-outer loop control algorithm based on fuzzy proportional-integral-linear quadratic regulator(PI-LQR)data fusion was proposed.The algorithm employs fuzzy PI control as the inner loop,adapting PI parameters through fuzzy logic operations based on steering angle error and its rate of change for closed-loop control of steering angle.The algorithm utilizes LQR control as the outer loop,incorporating the steering angle error from the inner loop based on agricultural machinery XY lateral angle control to further enhance the precise control of steering for unmanned agricultural machinery.Joint simulations using Carsim and Matlab/Simulink demonstrate that for a 100 m double lane change path,the maximum lateral error is less than 0.18 m,and the maximum yaw error is less than 0.067 rad.Real vehicle tests indicate that the maximum lateral error is less than 0.26 m for a 100 m double lane change path.Compared with the PID pure tracking control algorithm,the maximum lateral error is reduced by 0.19 m.
autonomous drivingsteering systemfuzzy PILQRinner and outer loop control
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