1988 Volume 6 Issue 6 Pages 489-498
This paper describes a general method using configuration space for planning the collision-free path of a manipulator with 6 d. o. f. The basic approach taken in this method is to restrict the free space concerning path planning and to avoid executing unnecessary collision detections, based on the idea that the collision-free path can be planned using only partial information of the configuration space. The configuration space is equally quantized into cells, and cells concerning path planning are efficiently enumerated based on a heuristic graph search algorithm. A heuristic function which characterizes the search strategy can be defined to give priority to the gross motion using the first few joints. A bi-directional search strategy is also introduced to improve efficiency. Consequently, the total amount of necessary data representing the free space defined in the 6 dimensional configuration space is greatly restricted, and necessary collision detections are reduced. The memory is allocated only to the portion of the configuration space concerning path planning, and the data of the free space defined in the 6 dimensional configuration space can be efficiently stored. This algorithm of free space enumeration is independent of the kinematic characteristics of the manipulator. Therefore, this method is generally applicable to any type of manipulator. This method has been actually implemented and has been applied to a 6 d. o. f. articulated manipulator.
