Online Trajectory Optimization for Dynamic Aerial Motions of a Quadruped Robot

TL;DR

This paper introduces a real-time capable framework for planning and executing dynamic aerial motions on quadruped robots, combining nonlinear optimization for motion planning with a high-frequency optimal controller for robust execution.

Contribution

It presents a novel two-part framework that enables online planning and robust execution of complex aerial motions on quadruped robots, adaptable to various dynamic maneuvers.

Findings

Successfully performed jumps, spins, flips, and obstacle jumps on MIT Mini Cheetah.

Motion planning takes 0.05-0.15 seconds, enabling near real-time operation.

The control system maintains stability despite modeling errors and disturbances.

Abstract

This work presents a two part framework for online planning and execution of dynamic aerial motions on a quadruped robot. Motions are planned via a centroidal momentum-based nonlinear optimization that is general enough to produce rich sets of novel dynamic motions based solely on the user-specified contact schedule and desired launch velocity of the robot. Since this nonlinear optimization is not tractable for real-time receding horizon control, motions are planned once via nonlinear optimization in preparation of an aerial motion and then tracked continuously using a variational-based optimal controller that offers robustness to the uncertainties that exist in the real hardware such as modeling error or disturbances. Motion planning typically takes between 0.05-0.15 seconds, while the optimal controller finds stabilizing feedback inputs at 500 Hz. Experimental results on the MIT Mini Cheetah demonstrate that the framework can reliably produce successful aerial motions such as jumps onto and off of platforms, spins, flips, barrel rolls, and running jumps over obstacles.