Design of an Shape Memory Alloy-Actuated Biomimetic Mobile Robot with the Jumping Gait

This paper reports the design, simulation, analysis, and experiments of mesoscale four-legged robots that can locomote by a jumping gait using only shape memory alloy (SMA) wires as actuators. Through studies of the structure and function of leg muscle groups in vertebrates' lower musculoskeletal system, three types of muscles are selected for robot leg design, and each muscle is then replaced by an SMA wire in the robot model. Two types of robot models are proposed and analyzed using three sets of computer simulation. It can be concluded from the simulation that the sequence of SMA muscle activation, activation arrangement of the rear and the front legs, and the foot length are primary factors determining the jumping performance. It is observed that when the robot has three degrees of freedom for each leg and a foot length of 40 mm, the maximum jumping height is approximately 120% of the robot's height and the maximum distance per jump is about 35% of its length. In addition, two robot prototypes are presented based on the design models and experimental results. The simulation and experimental results are found to show good agreement. The overall results show that the proposed robot design and SMA actuation method are feasible for all SMA-driven jumping robots.