Human-inspired underactuated bipedal robotic walking with AMBER on flat-ground, up-slope and uneven terrain

This work presents human-inspired control strategies required for achieving three motion primitives in walking—flat-ground, uneven terrain and up-slope—in an underactuated physical bipedal robot: AMBER. Formal models and controllers which provably guarantee the stability of walking are developed and verified in the simulation. Computationally tractable conditions are given that allow for the experimental implementation of these formal methods through the closed form approximation of constraints that restrict maximum torque, maximum velocity and ensure proper foot clearance. Considering the special property of the motors used in the robot, i.e., low leakage inductance and high angular speed, we approximate the motor model and translate the formal controllers satisfying these constraints into an efficient voltage-based controller that can be directly implemented on AMBER. The end result is robotic walking on AMBER for the three motion primitives that shows good agreement with the formal results from which it was derived.