Realizing Linear Controllers for Quadruped Robots on Planetary Terrains

Aditya Shirwatkar, Somnath Sendhil Kumar, Shamrao Garur, Vinod Kumar, Shishir N. Y. Kolathaya

Abstract: Until now, planetary exploration has been accomplished with whee-led vehicles, making movement in highly complex, sandy, and sloping terrain incredibly tough. On the other hand, legged robots have come a long way in the last decade and have reached a stage of development where practical applications appear to be possible. To collect critical scientific data, legged robots can overcome wheeled vehicles’ difficulties when exploring harsh environments like impact craters. As a result, there is a need to develop simple, stable walking controllers given the limited power resources and reserve maximum onboard computing for scientific equipment while exploring such regions. This work proposes a walking controller for legged robots that is computationally efficient at runtime for traversing planetary terrains. We implement this walking controller on our custom-built quadruped, using learned linear feedback policies that modulate the end-foot trajectories. The proposed walking controller can traverse various planetary terrains such as flat, sloped, rugged, loose, and lower-than-Earth gravity conditions in simulation environments. Our controller outperforms the baseline open-loop controller on planetary landscapes by reducing slippage and increasing stability. We have also provided preliminary hardware testing results of our controller. In addition, video results can be found at: https://youtu.be/La3y-xhWm1U