Car like robot finds fastest paths without wheel slipping
Minimum Time Trajectories for a Car-Like Mobile Robot Moving with Rigid Wheels Under Non-Sliding Constraints
Robotics
Summary
This paper looks at how a robot shaped like a car can move from one place to another as fast as possible without its wheels slipping. The robot can drive forwards or backwards, but its wheel turns and speeds are limited. The authors extend earlier simplified models by including realistic rules that prevent the wheels from sliding. They find new types of motions the robot must use because of these no-slipping rules and show examples of how these affect the fastest routes.
What this means in practice
- •For autonomous vehicle engineers: Design control algorithms that plan quickest routes without wheel slipping for four-wheeled robots with realistic steering limits.
- •For robot motion planners: Incorporate new motion types to improve path planning accuracy when wheel slip must be avoided in wheeled robots.
Authors
Joseph Ben-Asher, Elon Rimon, Leeor Ravina
Abstract
This paper studies the minimum time trajectoriesvof a car-like mobile robot navigating in an obstacle free environment. The robot, with forward and backward speeds, is controlled by bounded front-wheels acceleration and limited front-wheels steering rate. The paper extends previous results which solved this problem for the kinematic car-like robot. However, the kinematic model assumes pure rolling at the wheels ground contacts. This assumption requires non-sliding constraints for the front and rear wheels that can only be handled by the robot dynamics. This paper formulates the non-sliding constraints based on the robot dynamics then augments the kinematic model time-optimal path primitives with three new path primitives associated with the non-sliding constraints. The three non-sliding path primitives together with the kinematic model twelve path primitives form the car-like robot time optimal trajectories. Approximate analytic solutions for the non-sliding path primitives are also provided. Examples study the time-optimal path primitives along representative maneuvers, illustrating how the non-sliding constraints influence the time optimal trajectories of the car-like robot.