Whole-body Dynamic Collision Avoidance with Time-varying Control Barrier Functions

Recently, there has been increasing attention in robot research towards the whole-body collision avoidance. In this paper, we propose a safety-critical controller that utilizes time-varying control barrier functions (time varying CBFs) constructed by Robo-centric Euclidean Signed Distance Field (RC-ESDF) to achieve dynamic collision avoidance. The RCESDF is constructed in the robot body frame and solely relies on the robot’s shape, eliminating the need for real-time updates to save computational resources. Additionally, we design two control Lyapunov functions (CLFs) to ensure that the robot can reach its destination. To enable real-time application, our safety-critical controller which incorporates CLFs and CBFs as constraints is formulated as a quadratic program (QP) optimization problem. We conducted numerical simulations on two different dynamics of an L-shaped robot to verify the effectiveness of our proposed approach.

I. Introduction

Collision avoidance is a crucial technology in robotics [1]. Recently, as robots are being increasingly utilized in various fields such as autonomous driving, military operations, delivery services, and medical procedures, whole-body collision avoidance has been gaining increasing attention. Whole-body collision avoidance considers the shape of the robot instead of treating it as a point mass. However, achieving real-time whole-body collision avoidance with any-shaped robot and obstacles remains a significant challenge. In addition, control barrier function (CBF) has recently been widely employed for safety-critical control which prioritize safety aspects such as collision avoidance and physical limits over navigation and tracking [2].