Design and Experimental Validation of Closed-Form CBF-Based Safe Control for Stewart Platform Under Multiple Constraints

TL;DR

This paper introduces a closed-form control barrier function approach for safe control of Stewart platforms, enabling real-time safety enforcement under multiple constraints without solving optimization problems.

Contribution

It provides a novel explicit control law for multi-constraint safety, eliminating the need for quadratic programming, and validates its effectiveness through simulations and hardware experiments.

Findings

Achieves safety guarantees comparable to QP-based methods

Reduces computation time by over an order of magnitude

Demonstrates real-time applicability on hardware

Abstract

This letter presents a closed-form solution of Control Barrier Function (CBF) framework for enforcing safety constraints on a Stewart robotic platform. The proposed method simultaneously handles multiple position and velocity constraints through an explicit closed-form control law, eliminating the need to solve a Quadratic Program (QP) at every control step and enabling efficient real-time implementation. This letter derives necessary and sufficient conditions under which the closed-form expression remains non-singular, thereby ensuring well-posedness of the CBF solution to multi-constraint problem. The controller is validated in both simulation and hardware experiments on a custom-built Stewart platform prototype, demonstrating safetyguaranteed performance that is comparable to the QP-based formulation, while reducing computation time by more than an order of magnitude. The results confirm that the proposed approach provides a reliable and computationally lightweight framework for real-time safe control of parallel robotic systems. The experimental videos are available on the project website. (https://nail-uh.github.io/StewartPlatformSafeControl.github.io/)