Precision Assembly Among Multiple Thin Objects with Various Fit Types

Abstract

This paper investigates precision assembly combining several subprocesses on a platform with multiple robot arms. The task manipulates irregular objects and incorporates interference and clearance assemblies. We use a mechanism with six robot arms and three microscopes to fulfill this assignment, and propose a general control strategy to attain high precision and protect objects. System calibration includes the image Jacobian matrix to connect Cartesian motion with the image movement and force transformation matrix to relate between coordinates of force sensor and manipulators. In the control structure, a general strategy is proposed for assembly with multiple manipulators, in which we present an assembly plan module to generate desired states of each object by using an optimization approach, design a method to determine the collision when blocking, and propose a hybrid control scheme for both contact and clearance assembly controllers. Experiments are carried out to demonstrate the validation of the proposed methods.