Determination of a force control law for an industrial robot in contact with a rigid environment

Deformations occurring in a robot working in contact with the environment is a real problem in the industrial world. This problem can be solved by taking into account forces exerted at the end-effector level. The goal of this paper is to determine a force control scheme which can be implemented on a non-modified industrial robot controller. Various existing force control schemes are investigated and the reasons for discarding them are given. Then, the emphasis is put on a so-called external force control scheme, which seems to be a solution to our problem. The control law appearing in such a scheme is determined by means of a realistic robot simulator developed on a SUN workstation. A simple integral term on the force error gives acceptable results in various robot configurations. This is illustrated in the form of graphs