Geometrical Errors of Parallel Robots

Abstract

The goal of this paper is to determine and make a graphical representation of the geometrical errors occurred when commanding a parallel manipulator. It is also proposed to establish a relation between errors and position of the robot in the workspace and to create an error map. There is a complex knowledge available about the drive system and precision in the joints. An imposed position of the tool centre point (TCP) is compared with the real value which is a result of solving the inverse geometrical problem, rounding the length of the legs, and then the direct problem for the new values. Certainly, there are a lot of other errors (for example: imprecision of the joints, elastic deformation of the structure, etc.). These errors will form subject of other papers.