Univector field navigation method for fast mobile robots

Abstract

In this dissertation a novel navigation method is suggested. The proposed navigation method, named univector field navigation method, is an improved unified navigation method which is designed for fast mobile robots considering mechanical restrictions. It uses a normalized two-dimensional vector field as the navigation function. It provides fast moving robots with the desired posture at the target position and obstacle avoidance. Robot navigation can be categorized as separated navigation and unified navigation. In the unified navigation, such as artificial potential field navigation, path planning and path following are unified in one task. Although it can be applied to a dynamic environment for online control, it has disadvantages of oscillations or collisions. This disadvantages are caused from the assumption of omnidirectional robot ignoring mechanical properties of real robots. The requirements for the fast mobile robots are analyzed. To prevent slip of overturn, the acceleration and rotation should be restricted. Considering these restrictions, a univector field tracking controller is proposed. It enables the robot move fast satisfying mechanical constraint and providing field tacking ability. Its characteristics are compared to other unified navigation methods. Then the restrictions of univector field are considered to guarantee the univector field tracking ability of the proposed controller. In order to make the univector field appropriate to the fast mobile robot, the hyperbolic spiral is adopted to make the basic univector field (BUF). By using the basic univector field, the traveling univector field (TUF) and avoid univector field (AUF) can be obtained. These two univector fields are combined according to the position of obstacles and the destination, and subsequently the robot can navigate the environments. Moreover the proposed univector field tracking controller is improved for the dynamic environment with moving obstacls. To get optimized univect...