A novel mechanism for varying stiffness via changing transmission angle

Compliant actuation contributes enormously in legged locomotion robotics since it is able to alleviate control efforts in improving the robot’s adaptability and energy efficiency. In this paper, we present a novel design of a variable stiffness rotary actuator, called MESTRAN, which was especially targeted to address the limitations in terms of the amount of energy and time required to vary the stiffness of an actuated joint. We have constructed a mechanical model in simulation and a physical prototype. We conducted a series of experiments to validate the performance of the MESTRAN actuator prototype. The results from the simulation and experiments show that MESTRAN allows independent control of stiffness and position of an actuated rotary joint with a large operational range and high speed. The torque-displacement relationship is close to linear. Lastly, the MESTRAN actuator is energy-efficient since a certain stiffness level is maintained without energy input

Gait versatility through morphological changes in a new quadruped robot

In dynamic locomotion, robots’ morphology and the ability to adapt it online play an important role in energy efficiency and coping with the highly unpredictable perturbations from the environment. In this paper, we present the design and implementation of a quadruped robot whose morphology is particularly targeted towards energy-efficient dynamic locomotion. We propose a combination of mechanisms which allow for energy-efficient actuation, ground clearance, and gait versatility through adaptation of morphology (morphosis). We report on a series of experiments to validate the robot’s performance in different locomotion conditions