Development, Analysis, and Control of Series Elastic Actuator-Driven Robot Leg

The mass-spring system-like behavior is a powerful analysis tool to simplify human running/locomotion also known as Spring Loaded Inverted Pendulum (SLIP) model. Beyond an analysis tool, the SLIP model is utilized as a template for implementing human-like locomotion by using the articulated robot. Since the dynamics of the articulated robot exhibits complicated behaviour when projected into the operational space of the SLIP template, various considerations are required from the robot’s mechanical design to its control and analysis. Hence, the required technologies are the realisation of pure mass-spring behaviour during the interaction with the ground and the robust position control capability in the operational space of the robot. This paper develops a robot leg driven by the Series Elastic Actuator (SEA) that is a suitable actuator system to interact with the environment such as the ground. A robust hybrid control method is developed for the SEA-driven robot leg to achieve the required technologies. Furthermore, the developed robot leg has biarticular coordination which is a human-inspired design that can effectively transmit the actuator torque to the operational space. This paper also employs Rotating Workspace (RW) that specializes in the control of the biarticulated robots. Various experiments are conducted to verify the performance of the developed robot leg with the control methodology.