Robo-Centric ESDF: A Fast and Accurate Whole-Body Collision Evaluation Tool for Any-Shape Robotic Planning

For letting mobile robots travel flexibly through complicated environments, increasing attention has been paid to the whole-body collision evaluation. Most existing works either opt for the conservative corridor-based methods that impose strict requirements on the corridor generation, or ESDF-based methods that suffer from high computational overhead. It is still a great challenge to achieve fast and accurate whole-body collision evaluation. In this paper, we propose a Robo-centric ESDF (RC-ESDF) that is pre-built in the robot body frame and is capable of seamlessly applied to any-shape mobile robots, even for those with non-convex shapes. RC-ESDF enjoys lazy collision evaluation, which retains only the minimum information sufficient for whole-body safety constraint and significantly speeds up trajectory optimization. Based on the analytical gradients provided by RC-ESDF, we optimize the position and rotation of robot jointly, with whole-body safety, smoothness, and dynamical feasibility taken into account. Extensive simulation and real-world experiments verified the reliability and generalizability of our method.

I. Introduction

Collision evaluation is a core module of mobile robot trajectory optimization, ensuring that robot can move safely in narrow environments. Commonly, a simplified model for robot collision evaluation, for instance, modeling a robot as a mass point with linear dynamics [1]-[3], is sufficient for simple tasks. However, for precisely moving among dense obstacles, the shape of a robot, especially for non-convex shape, needs to be explicitly considered in collision evalu-ation. Generating a trajectory with a robot's shape, namely whole-body planning, not only requires careful consideration of robot's position, but also its rotation. This demands much more complicated computation, making whole-body collision evaluation hard to meet limited onboard resources in practice. How to efficiently generate collision-free trajectories for an any-shape robot in real-time is still a great challenge.