Real-time Perceptive Motion Control using Control Barrier Functions with Analytical Smoothing for Six-Wheeled-Telescopic-Legged Robot Tachyon 3

TL;DR

This paper presents a real-time motion control system for the Tachyon 3 robot that uses control barrier functions and a novel smooth collision detection method to ensure safe, efficient locomotion in complex environments.

Contribution

It introduces a lightweight, high-speed control framework integrating Smooth SAT with CBF for real-time, safe motion planning of a complex six-wheeled telescopic-legged robot.

Findings

Collision detection time is 1 microsecond or less.

Control cycle is as short as 1 millisecond.

Successful stair-climbing motion demonstrated in simulation and real robot.

Abstract

To achieve safe legged locomotion, it is important to generate motion in real-time considering various constraints in robots and environments. In this study, we propose a lightweight real-time perspective motion control system for the newly developed six-wheeled-telescopic-legged robot, Tachyon 3. In the proposed method, analytically smoothed constraints including Smooth Separating Axis Theorem (Smooth SAT) as a novel higher order differentiable collision detection for 3D shapes is applied to the Control Barrier Function (CBF). The proposed system integrating the CBF achieves online motion generation in a short control cycle of 1 ms that satisfies joint limitations, environmental collision avoidance and safe convex foothold constraints. The efficiency of Smooth SAT is shown from the collision detection time of 1 us or less and the CBF constraint computation time for Tachyon3 of several us. Furthermore, the effectiveness of the proposed system is verified through the stair-climbing motion, integrating online recognition in a simulation and a real machine.