Fault-Tolerant, Rigidity-Preserving Control of Inflatable Truss Robots

2026-05-19

AI Summary

This work addresses the vulnerability of inflatable truss robots to loss of functionality and structural rigidity under motor failures. To enhance resilience, the authors propose a fault-tolerant control framework that integrates kinematic optimization capable of accommodating arbitrary combinations of motor failures, discrete-time control barrier functions (DTCBFs) to ensure structural rigidity, and closed-loop position control leveraging forward kinematics and onboard encoder feedback. Evaluated on a 6-motor 2D configuration, the approach preserves over 69% of the nominal workspace following a single motor failure and improves trajectory tracking accuracy by more than 25%, thereby significantly enhancing system safety and mission continuity.

Abstract

Isoperimetric robotic trusses can adapt to different tasks and environments because they have a high strength-to-weight ratio, can change their own shape dramatically, and can be reconfigured into a variety of different shapes. However, motor failures in operational environments can severely limit operational capabilities if not properly addressed. This paper presents a fault-tolerant control framework for an inflatable robotic truss that maintains functionality despite motor failures, shown through three key contributions. First, we extend the kinematic optimization to handle arbitrary combinations of motor failures by imposing equality constraints to ensure failed actuators are not used. Second, we introduce discrete-time control barrier function (DTCBF) constraints that mathematically guarantee structural rigidity while maximizing workspace utilization, a critical requirement for reliable operation of truss robots under discrete-time control. Third, we implement closed-loop position control using onboard encoder feedback and a forward kinematics-based state estimator, improving positional accuracy in the presence of disturbances. We validate our approach through simulation and hardware experiments on a 2D isoperimetric truss testbed. For a 2D configuration with 6 actuators, we demonstrate >69% workspace preservation under single-motor failures and a >25% improvement in tracking accuracy with closed-loop control. These results establish a foundation for more robust and resilient isoperimetric truss robots operating under degraded actuation.

Problem

• fault-tolerant control
• inflatable truss robots
• motor failures
• structural rigidity
• isoperimetric trusses

Innovation

• fault-tolerant control
• inflatable truss robots
• discrete-time control barrier functions
• kinematic optimization
• closed-loop position control