Path Following Control Of Tracked Mobile Robot Based On Adaptive Dynamic Programming

With the wide application of mobile robots in agriculture,the complex terrain and changeable environment put forward higher requirements for motion control of the mobile robot.How to improve the autonomous optimization ability of mobile robots for unfamiliar environments has beeome a research hotspot.Aiming at the problem that the traditional path following control method of mobile robot requires manual tuning parameters and lacks of self-optimization ability,a path following control method based on adaptive dynamic programming(ADP)is proposed in this paper.This paper focuses on the path following control method based on adaptive dynamic programming for robots with different linear reference paths.The main research contents of this paper are summarized as follows:(1)Firstly,the structure of path following control system for tracked robot is designed.Based on the tracked robot system,the kinematics model with the speed of motor on both sides as control variables is derived,and the error state equation of path following system is established.Secondly,coordinate transformation of discrete GPS point longitude and latitude path information and robot position information is carried out,which is converted into the same coordinate system.Finally,the method of curve fitting based on cubic polynomial is designed for the converted discrete points.(2)For the traditional "preview-follow" model ignoring the system model,it is difficult to achieve high control accuracy.In this paper,a path following controller based on linear quadratic regulator(LQR)is designed according to the error state equation of the path following system of tracked robot.The reference path of combination line and helix is simulated,and the straight line,obtuse angle steering curve and acute angle steering curve are tested on campus road.The simulation and test results show that the controller can achieve better control effect than pure tracking by adjusting parameters.(3)A path following control method based on adaptive dynamic programming algorithm is proposed.The path following controllers based on heuristic dynamic programming(HDP)and dual heuristic programming synthesizing the error performance index and the following stability index.A multi-layer feedforward(DHP)are designed respectively.Firstly,the return fiunction is designed by neural network is used to establish the actuator and evaluation modules,and the online optimization rules of network parameters are derived.Thirdly,the path following performance of ADP method is verified by numerical simulation and system test.The tracking accuracy is more accurate than pure tracking and LQR algorithm,and this method can achieve high-precision control efifect without repeatedly debugging the control parameters.It has better environmental adaptability and self-optimization ability.