Continuous Reachability Task Transition Using Control Barrier Functions

TL;DR

This paper introduces a method for smooth, continuous transitions between sequential reachability tasks in robotic systems using control barrier functions, avoiding control discontinuities and ensuring real-time safety guarantees.

Contribution

It proposes a novel approach that incorporates a time-varying component into control barrier functions for continuous task transitions, improving upon discrete switching methods.

Findings

Successfully implemented on robotic systems demonstrating smooth task transitions.

Ensured safety and finite-time reachability with real-time control performance.

Reduced control input discontinuities compared to existing methods.

Abstract

In this paper, a method to achieve smooth transitions between sequential reachability tasks for a continuous time mobile robotic system is presented. Control barrier functions provide formal guarantees of forward invariance of safe sets and finite-time reachability and are able to enforce task execution. Barrier functions used in quadratic programs result in implementation of controllers with real-time performance guarantees. Existing approaches for multi-objective task execution using control barrier functions leverage discretely switched, sequential quadratic programs to achieve successive tasks. However, discrete switching can lead to control input discontinuities which can affect a robot's performance. Hence, we propose a method which ensures continuous transitions between sequential quadratic programs. In particular, a time varying component to the barrier function constraint is introduced which allows for a smooth transition between objectives. Robotic implementation results are also provided.