A planar hopping robot with one actuator: Design, simulation, and experimental results

The complex musculoskeletal system of a running animal on horizontal surfaces act essentially like a simple pogo stick, and can be modeled as a hopping spring-mass model known as the Spring-loaded Inverted Pendulum (SLIP) model. The SLIP model has been extensively used as a reduced-order model in analysis and control of running legged robots. By contrast, the SLIP model itself has never been implemented in a robot and validated experimentally. This thesis addresses the development and validation of a robotic SLIP, a planar one-legged hopping robot with only one actuator. A feasibility study was performed using numerical simulation. The experimental platform was designed and built based on SLIP-model features. A hopping controller that conceptually reproduced the self-stability property of the SLIP model was implemented. Running was achieved at 6.7 leg lengths per second, which is, to date, the fastest dimension-less speed for a single-legged robot. Simulation and experimental data demonstrated periodic and robust stability. The SLIP model was qualitatively validated for a particular gait in simulation and experimentation.