Hole detection algorithm for square peg-in-hole using force-based shape recognition

It is very difficult to assemble precision parts using only position control. To deal with these problems, force control approaches, which provide a proper motion response against the contact force, were investigated. Moreover, hole detection is a crucial step to eliminate the uncertainty in robotic assembly. Without a proper hole detection algorithm, assembly time increases along with the position difference between the peg and the hole. In this study, we propose a shape recognition algorithm based on a 6 axis F/T sensor and the hole detection algorithm. The proposed hole detection algorithm can find the direction of the hole regardless of the size of the position error between a peg and a hole. The same algorithm can be implemented not only to a circular peg, but also to a polygonal convex peg. A series of experimental results show that the proposed algorithms can estimate the shape and location of a peg reasonably well.