Autonomous calibration of single-loop closed kinematic chains formed by manipulators with passive endpoint constraints

The authors present a kinematic calibration method that does not require endpoint measurements or precision points. By forming manipulators into mobile closed kinematic chains, it is shown that consistency conditions in the kinematic loop closure equations are adequate to calibrate the manipulator from joint angle readings alone. This closed-loop kinematic calibration method is an adaptation of an iterative least-squares algorithm used in calibrating open-chain manipulators. Example tasks include a fixed endpoint (zero-degree-of-freedom (DOF) task), the opening of a door (one-DOF task), and point contact (three-DOF task)