Path Following with a Time-Convergence Penalty Term for a Mobile Robot

Abstract

In this paper, we focus on a combination of path following and trajectory tracking for a mobile robot. Both are basic motion control schemes for a robot. The advantages of path following over trajectory tracking are that path following can avoid the use of large control signals for large path errors; therefore, it can eliminate aggressiveness by converging to the path smoothly, and control inputs are less likely to be forced to saturation. However, there is no temporal specification for path following. Therefore, in this work, we propose to add a time-convergence penalty term into the optimization problem of model predictive control (MPC) that we use to control robot motion. MPC can handle the saturation of control signals explicitly. As a result, the robot can move safely. However, the major concern in the use of MPC is whether such an open-loop control scheme can guarantee system stability. To solve this problem, we apply the idea of a contractive constraint to guarantee the stability of our MPC framework. To illustrate its effectiveness, numerous simulation scenarios have been conducted. Furthermore, we depict remarkable advantages of path following over trajectory tracking. doi:10.14456/WJST.2015.11

Keywords

• Path following
• contractive model predictive control
• mobile robots
• trajectory tracking
• time-convergence