A target approachable force-guided control for complex assembly

Abstract

Presents a target approachable force-guided control for complex assembly. A complex assembly (CA) is a task which deals with complex shaped parts including concavity or whose environment is so complex that unexpected contacts occur during insertion. CA tasks are encountered frequently in manufacturing automation and robot applications. To make CA successful, both the bounded wrench condition and the target approachability condition should be satisfied simultaneously during insertion. The former can be satisfied by properly designing the damping control parameters, and the latter by determining an admissible twist minimizing the difference between the current and the target direction. By applying the convex optimization technique, the target approachable twist can be determined at each instantaneous contact state as a global minimum solution. Incorporated with an admissible perturbation method, a new CA algorithm using only the sensed resultant wrench and the target direction vector is developed without motion planning nor contact kinematic analysis procedure, which requires the geometry of the part and the environment. As a result of the simulation for the task of inserting a T-shaped object involving concavity, its feasibility and applicability have been verified The task of inserting a T-shaped part into a slot with a tight tolerance was successfully executed by the proposed target approachable force-guided controller.