Design and testing of a novel stepless lockable joint for use in reconfigurable fixtures

Reconfigurable or flexible fixtures, an important element in automotive body-welding assembly lines, can be designed as mechanisms with lockable joints. This paper proposes a new flexible fixture using stepless lockable joints allowing infinitely many configurations, and hence a broad application range and potential. Several conceptual designs of the key component, the lockable joint, are presented. Unlike existing mechanisms, which can lock the joint in a finite number of positions, the proposed solution is a stepless device. Once locked, the joint can resist high torque in both directions. These characteristics of the lockable joint guarantee the performance of the reconfigurable fixture that employs it. The load testing has been performed on the prototype of a revolute joint that can sustain 800 Nm, and the stiffness of a lockable arm which employs two lockable joints is detected.