Vision-aided Dynamic Quadrupedal Locomotion on Discrete Terrain using Motion Libraries

TL;DR

This paper introduces a control and planning framework that enables quadrupedal robots to navigate challenging discrete terrains using visual feedback and motion libraries, allowing for dynamic, aperiodic gait transitions.

Contribution

It presents a novel approach combining offline motion libraries with visual terrain mapping to enable adaptive, aperiodic quadrupedal locomotion on complex terrains.

Findings

Successful real-world navigation of unknown terrains by the robot.

Effective switching between gait primitives for diverse step lengths.

Integration of visual terrain mapping with motion control.

Abstract

In this paper, we present a framework rooted in control and planning that enables quadrupedal robots to traverse challenging terrains with discrete footholds using visual feedback. Navigating discrete terrain is challenging for quadrupeds because the motion of the robot can be aperiodic, highly dynamic, and blind for the hind legs of the robot. Additionally, the robot needs to reason over both the feasible footholds as well as robot velocity by speeding up and slowing down at different parts of the terrain. We build an offline library of periodic gaits which span two trotting steps on the robot, and switch between different motion primitives to achieve aperiodic motions of different step lengths on an A1 robot. The motion library is used to provide targets to a geometric model predictive controller which controls stance. To incorporate visual feedback, we use terrain mapping tools to build a local height map of the terrain around the robot using RGB and depth cameras, and extract feasible foothold locations around both the front and hind legs of the robot. Our experiments show a Unitree A1 robot navigating multiple unknown, challenging and discrete terrains in the real world.