A target approachable force-guided control for complex assembly

Abstract

This paper presents a rarget approachable forceguided control for the complex assembly. In this stua), U complex assembly (CA) is defined as a task which deals with complex shaped parts including concavity or whose environment is so complex that unexpected contacts occur frequently during insertion. CA tasks are encountered ,frequently in the,field of the manufacturing uutomution and various robot applications. To make CA successful, both the bounded wrench condition and the target approachability condition should lie satisfied simultaneously during insertion. The bounded wrench condition can he satisfied by properly designing the dumping control parameters not to exceed the prescribed conlact wrench. On the other hand, the target upproacliahility condition can be satisfied 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 he 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 ob, ject involving concavity, its feasib ility and applicability have heen verified. The task of inserting a T-shaped part into a slot with a tight tolerance was successfully executed by the proposed target approachable forceguided controller. ？ 1998 IEEE.