A novel approach for positional sensing of a spherical geometry

Due to the proliferation of new technologies and demands for dexterous robotics manipulators, multi-degree-of-freedom (MDOF) spherical actuators are widely sought after. These actuators are utilized primarily in the assembly sectors, precision machining and active tracking devices. Prior to realizing a feasible MDOF actuator for any practical use, positional closed loop feedback is of paramount importance. To date, commercially available encoders are mainly limited to single-DOF sensing. Furthermore, integration of these sensors inherently introduces mechanical linkages that compromise the overall performance of the system. This paper introduces an alternative approach in orientation sensing leverages on contactless sensing of conventional optical mouse sensors. The theory and design methodology of this sensing method is being discussed and presented. Experimentation was also conducted for conceptual verification. The uniqueness of this technique lies in the exploitation of the imaging capability of the mouse sensor generating incremental counts of the displacement of the spherical rotor surface. The test platform being established is expected to lay the foundation for optimizing key parameters. With the successful implementation and validation of this new sensing system, future development will be improving its performance for real-time feedback control.