Design and Performance Evaluation of a Bio-Inspired and Single-Motor-Driven Hexapod Robot With Dynamical Gaits

Over its lifetime, the hexapedal robot RHex has shown impressive performance. Combining preflexes with a range of control schemes, various behaviors such as leaping, running, bounding, as well as running on rough terrain have been exhibited. In order to better determine the extent to which the passive and mechanical aspects of the design contribute to performance, a new version of the hexapedal spring-loaded inverted pendulum (SLIP)-based runner with a novel minimal control scheme is developed and tested. A unique drive mechanism is utilized to allow for operation (including steering) of the robot with only two motors. The simplified robot operates robustly and it exhibits walking, SLIP-like running, or high-speed motion profiles depending only on the actuation frequency. In order to better capture the critical nonlinear properties of the robot’s legs, a more detailed dynamic model termed R2-SLIP is presented. The performance of the robot is compared to the basic SLIP, the R-SLIP, and this new R2-SLIP model. Furthermore, these results suggest that, in the future, the R2-SLIP model can be used to tune/improve the design of the leg compliance and noncircular gears to optimize performance.