Research On Trajectory Planning Of Wheeled Mobile Robot

Aiming to improve the autonomous operation capability of wheeled mobile robots,this paper studies the multi-constrained trajectory planning problem of wheeled mobile robots,and proposes a improved RRT path planning algorithm and a MPC-based trajectory generation scheme that satisfies terminal constraints and process constraints.The main work of this paper can be summarized as follows:Firstly,the motion process of the wheeled mobile robot is analyzed and its kinematic model is built.At the same time,in order to facilitate the design of following trajectory planning scheme,the Taylor series expansion at the reference point is used for linearization to obtain the linear time-varying model of the wheeled mobile robot.Then the various constraints in the trajectory planning of the wheeled mobile robot are analyzed and mathematically described.Then,the common path searching algorithms for wheeled mobile robots are analyzed and compared.Combined with the multi-constraint problem of the path searching of the wheeled mobile robot and the searching speed requirements,this paper determines the path searching scheme.To overcome the poor repeatability and non-smooth characteristic of the classic RRT algorithm,a multi-step RRT algorithm based on probabilistic P is proposed for path searching to ensure that the probability of growth from a random point to a target point is reduced under the premise of obstacle avoidance for wheeled mobile robots.Then the smooth algorithm is employed to smooth the path.Finally,the contrast experiments of the original RRT algorithm and the improved RRT algorithm in two work environments are conduced to verify the performance of the improved RRT algorithm.Finally,in virtue of the receding horizon optimization thought and combining with various constraints and tracking performance requirement,a reasonable objective function is constructed and a MPC controller is designed for the linearized pose error model of the wheeled mobile robot controller.Consequently the trajectory planning problem is transformed into a QP problem which is easy to resolved.Then,a trajectory planning scheme based on MPC controller and fourth-order Runge-Kutta algorithm is proposed to generated feasible trajectory satisfying terminal constraints and process constraints.The effectiveness of the proposed trajectory planning strategy is verified via simulation.Although this paper takes the wheeled mobile robot as the object of study,the proposed method is also applicable to similar systems such as unmanned vehicles and underwater robots.It provides a certain reference value for solving the trajectory planning problems under multi-constrained conditions.