Research On The Path Planning And Trajectory Tracking Of Transfer Vehicle

The path planning and trajectory tracking of mobile robots are the key technologies in the field of robots and the basis for mobile robots to complete self-service operations.Traditional path planning methods and trajectory smoothing methods do not consider the dynamics of mobile robots.The path does not conform to the actual motion,which leads to unsatisfactory trajectory tracking effects.There is a problem of lateral instability for mobile robots with a high center of gravity.With the application needs,people put forward higher requirements for path planning and trajectory tracking technology.This paper takes transfer vehicle as a research object to study the stable path planning and trajectory tracking of the high-gravity center transport vehicle,and designs a trajectory tracking controller for the transport vehicle based on the linear time-varying model predictive control to make the transport vehicle It can drive stably and reach the target point with the required trajectory and posture.Based on the requirements,the kinematics model and dynamics model of transfer vehicle are established,the multilateral positioning algorithm of the laser navigator is analyzed,and the requirements for the layout of the reflector are proposed according to the reflector matching principle.The grid method is used to model the environment,and a potential field ant colony path planning algorithm is proposed.Introduce the two-way obstacle detection method to solve the defects of traditional artificial potential field method deadlock and target unreachable,improve the initial allocation of pheromone,pheromone update mechanism,coordinate algorithm convergence speed and global search ability.In order to meet the actual operation of the transfer vehicle and the position and posture of the target point,it is necessary to smooth the polyline path to achieve a trajectory plan that is consistent with the actual driving.After analyzing the shortcomings of the traditional Bezier curve that may pass through obstacles,obstacle points are introduced to optimize the inflection point of the path,and the path is divided according to the obstacle points,and each path is smoothed.Parameterized fourth-order Bezier curve,considering the constraints of the transfer vehicle dynamics including rollover,side slip,front wheel rotation angle,and continuous curve and curvature between each trajectory problem.Finally,the reference trajectory is obtained by combining speed planning and trajectory curve.Aiming at the problem of trajectory tracking control,a linear time-varying model based on kinematics model is used to predict the trajectory tracking controller to ensure the real-time performance of the algorithm.In this paper,the dynamic weighting strategy is adopted to adjust the weighting coefficient according to the vertical and horizontal errors when there is a large error,to speed up the trajectory error convergence.At the same time,according to the prediction time domain and control time domain parameters of different path optimization algorithms,the algorithm can adapt to different road conditions and improve the efficiency of the transfer vehicle.Build a simulation platform on Matlab to verify the tracking effect of the trajectory tracker on straight and circular reference trajectories.