Browsing by Author "LIN, CF"

Now showing 1 - 2 of 2

MOTION PLANNING FOR MULTIPLE ROBOTS WITH MULTIMODE OPERATIONS VIA DISJUNCTIVE GRAPHS
(1991-10-01)
LIN, CF
;
TSAI, WH
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
A new approach to motion planning for multiple robots with multi-mode operations is proposed in this paper. Although sharing a common workspace, the robots are assumed to perform periodical tasks independently. The goal is to schedule the motion trajectories of the robots so as to avoid collisions among them. Rather than assigning the robots with different priorities and planning safe motion for only one robot at a time, as is done in most previous studies, an efficient method is developed that can simultaneously generate collision-free motions for the robots with or without priority assignment. Being regarded as a type of job-shop scheduling, the problem is reduced to that of finding a minimaximal path in a disjunctive graph and solved by an extension of the Balas algorithm. The superiority of this approach is demonstrated with various robot operation requirements, including "non-priority", "with-priority", and "multicycle" operation modes. Some techniques for speeding up the scheduling process are also presented. The planning results can be described by Gantt charts and executed by a simple "stop-and-go" control scheme. Simulation results on different robot operation modes are also presented to show the feasibility of the proposed approach.
OPTIMAL ASSIGNMENT OF ROBOT TASKS WITH PRECEDENCE FOR MULTIROBOT COORDINATION BY DISJUNCTIVE GRAPHS AND STATE-SPACE SEARCH
(1995-04-01)
LIN, CF
;
TSAI, WH
;
資訊工程學系
;
Department of Computer Science
An approach to optimal assignment of tasks with precedence relationships to multiple robots is proposed. The robots are assumed to share a common workspace and work cooperatively to accomplish a given process plan consisting of a set of tasks. The optimal task assignment is defined to be the one that results in spending the least amount of time to complete the plan under the criterion that no robot collision will occur when the assigned tasks are performed. The ordering of the tasks in the process plan is described by a topological tree, which is then expanded to form a larger state-space tree without redundant tree paths. Each path in the expanded tree represents a partially developed assignment of the tasks to the robots, and a graph formulation scheme is presented for estimating the cost of the assignment. A collision-free motion schedule for each robot based on each task assignment can be obtained by finding the minimaximal path in a disjunctive graph formulated by the scheme. By using the A* algorithm, a search method for finding the optimal assignment with the minimum cost is presented. Some heuristic rules are also proposed to speed up the search process. Simulation results are illustrated to show the effectiveness of the proposed approach. (C) 1995 John Wiley & Sons, Inc.