Guaranteed-Safe MPPI Through Composite Control Barrier Functions for Efficient Sampling in Multi-Constrained Robotic Systems

TL;DR

This paper introduces a guaranteed-safe MPPI control algorithm that combines composite control barrier functions with model predictive path integral control to improve safety and efficiency in multi-constrained robotic systems.

Contribution

It proposes a novel integration of composite CBFs with MPPI for provably safe and computationally efficient control in nonlinear systems with multiple safety constraints.

Findings

Enhanced sample efficiency in safety-constrained control

Provably safe trajectories in simulations of ground robots

Addresses myopic behavior with long-term performance considerations

Abstract

We present a new guaranteed-safe model predictive path integral (GS-MPPI) control algorithm that enhances sample efficiency in nonlinear systems with multiple safety constraints. The approach use a composite control barrier function (CBF) along with MPPI to ensure all sampled trajectories are provably safe. We first construct a single CBF constraint from multiple safety constraints with potentially differing relative degrees, using it to create a safe closed-form control law. This safe control is then integrated into the system dynamics, allowing MPPI to optimize over exclusively safe trajectories. The method not only improves computational efficiency but also addresses the myopic behavior often associated with CBFs by incorporating long-term performance considerations. We demonstrate the algorithm's effectiveness through simulations of a nonholonomic ground robot subject to position and speed constraints, showcasing safety and performance.