Research On Motion Planning Of Unmanned Logistics Transport Vehicle In Structured Environment

Motion planning is one of the key common technologies to realize autonomous navigation of robots,and it is an important support for mobile robots to complete complex tasks safely and efficiently.In the decoupled planning framework,motion planning is mainly divided into two parts: Path planning and Trajectory planning.Path planning technology is responsible for generating feasible paths for mobile robots that satisfy certain constraints.Trajectory planning is responsible for generating the optimal trajectory for a mobile robot while satisfying various physical constraints such as motor speed and acceleration.For the robot path planning problem,the existing solution strategies cannot well meet the actual needs.In practical applications,high-order curves as collision avoidance paths will improve the motion efficiency of the robot,but with the increase of free parameters of the curves,the optimization time will increase,while low-order curves may lead to unreachable local positions of the robot.For the trajectory planning problem along a given path,the model-free trajectory planning may lead to the phenomenon of robot kinematics or dynamics saturation.Although the piecewise parameter polynomial can be used to solve this problem,it generates the maximum value in the parameter space.Excellent trajectory.The numerical integration strategy can output the optimal trajectory in the global space,but its control quantity has discontinuity.For the tracking control problem along a given path,the hysteresis of the system and the inaccuracy of the system parameters of the control object can easily lead to unsatisfactory control of errors.Although methods such as model prediction and intelligent control can be used to increase the control accuracy of the system,this is at the expense of control efficiency.In view of the above problems and the shortcomings of existing strategies,this paper studies from the following aspects.First,taking the logistics transportation in a structured environment as the experimental scene,taking the transport vehicle driven by a single steering gear as the research object,the kinematics and dynamic equations of the transport vehicle about a given path are deduced,and the dynamic characteristics of the steering gear of the transport vehicle are deduced.As constraints,a trajectory curve on a given path is generated using the numerical integration strategy of the Pontryagin maximum principle.Then,based on the trajectory curve and the path acceleration as the research object,the research on the acceleration discontinuity points on the trajectory is carried out,and a trajectory segmentation scheme of the charge mutual exclusion model and a path acceleration continuity scheme are proposed,and then a trajectory with continuous acceleration is obtained.curve.Finally,in order to solve the hysteresis problem in the path tracking control,the numerical optimization toolkit is used to realize the fast solution of the pose error of the mapping point,and the Lyapunov direct method is used to design the tracking control law of the path mapping point error,and the positioning of the transport vehicle is carried out.Posture control.The experimental results show that the proposed path acceleration continuation scheme and control strategy have a good error convergence effect on the tracking control along a given path.