Lunar monoped robot optimized for 2d jumping and landing control
A Bi-level Co-design Framework for Lunar Monoped with 2D Jump and Landing Control
Robotics
Summary
Robots that walk or jump on the Moon face special challenges because of the Moon's low gravity. This paper looks at a simple one-legged robot designed to jump vertically and sideways on the Moon. The authors use a new method that tries different leg shapes and tests two control techniques to find the best design. One control method performs better for these lunar jumps, and the authors also demonstrate stable landings with a balance controller. This work helps design robots better suited for moving and landing on the Moon.
What this means in practice
- •For lunar exploration robotics teams: Design legged robots optimized for low-gravity jumping and landing motions using co-designed leg morphology and controllers tested here.
- •For robotics control engineers: Develop control algorithms for stable impact absorption and post-landing balance in robots performing dynamic jumps.
Authors
Sanjay Ramkumar, Suraj Kumar
Abstract
Legged robots for lunar exploration must be designed for low gravity, where reduced contact forces and long flight phases make leg morphology and controller choice interdependent. We study this for a planar monoped in lunar gravity ($1.625$ m/s$^2$) using a bi-level co-design framework: a differential evolution outer loop searches over link lengths, and each candidate is evaluated on a vertical jump by either a quadratic program based task-space controller (QP-TSC) or a direct-collocation based trajectory optimization. The two controllers yield different optimal link lengths, and trajectory optimization outperforms the QP-TSC across most of the design space, with 17% lower Cost of Transport (COT) at their respective optima. We then extend to a 2D jump, where trajectory optimization with centroidal angular momentum regulation produces stable in-place and forward jumps, and an LQR controller absorbs impact and stabilizes the robot after touchdown. This is demonstrated on a baseline morphology with both links 0.3 m long.