DEVELOPMENT OF AN ADAPTIVE FORCE POSITION CONTROLLER FOR ROBOT-AUTOMATED COMPOSITE TAPE-LAYERING

The quality of parts produced by a composite tape-laying process is se nsitive to the contact force exerted and the abutment of adjacent tape courses kept when the tapes are laid. Thus, a prerequisite for a high performance laying process automated by means of industrial manipulat ors is the ability to regulate laying force and position precisely in the presence of robot motion inaccuracies and laying contour variation s. An on-line adaptive force/position controller for robot-automated l aying processes was presented. The contact force error normal to a lay ing surface is measured by a wrist sensor in real time, while the posi tion error tangent to the surface is measured by sensors found in mani pulator joints. Both are modeled as autoregressive (AR) processes, on the basis of which future errors in Cartesian coordinates are forecast ed. Via a compliance selection matrix, both predicted errors are fed t o joint actuators in a similar manner for taking compensatory actions. In view of the similarity, the force control portion of the scheme wa s implemented in an experiment using a three degree-of-freedom manipul ator and the results indicated a 40 percent average reduction in conta ct force variations.