UCLA

This thesis proposes a novel mechanism and its control strategy for generating a controllable resistance force for exercise and rehabilitation. Instead of measuring force with a load cell, the idea of a series elastic actuator is applied to perform a feedback force control by calculating force from spring deflection. By introducing series elasticity to an exercise machine, the proposed mechanism is able to achieve the active resistance force control under safe operations and in a cost effective way compared with existing systems. A prototype hardware was manufactured and an impedance control algorithm was developed in order to simulate the effects of a virtual damper, spring and constant force. The hardware design and control algorithm were examined through dynamic simulation and a prototype hardware was used to further verify the ideas.