FT-WBC: Learning Fault-Tolerant Whole-Body Control for Legged Loco-Manipulation

2026-06-23

AI Summary

Legged manipulation robots are prone to instability under actuator failures due to disturbances from the manipulator arm, and existing fault-tolerant control approaches struggle to simultaneously maintain base stability and preserve the arm’s workspace. This work proposes the FT-WBC framework, which introduces, for the first time, a fault-aware posture adaptation mechanism. By estimating faulty joints through proprioceptive history and leveraging a decoupled upper–lower body policy architecture, the method translates destabilizing base posture requests into safe commands and generates compensatory gaits. Evaluated in both simulation and real-world environments, the approach significantly improves survival rates and arm reachability under faults, and demonstrates zero-shot transfer to physical robots without fine-tuning.

Abstract

Legged manipulators combine the mobility of legged platforms with the manipulation capability of robotic arms. However, arm-induced Center-of-Mass shifts and dynamic disturbances make the system more prone to instability under actuator failures, potentially leading to falls, task failures, or safety risks. Existing fault-tolerant control methods mainly focus on locomotion alone, leaving the coupled problem of whole-body stability and arm reachability in fault-tolerant loco-manipulation largely unaddressed. To bridge this gap, we propose FT-WBC, a fault-tolerant loco-manipulation framework for robust whole-body control of legged manipulators under actuator failures. FT-WBC adopts a decoupled upper- and lower-body policy architecture and introduces two key modules: a Fault Estimator (FE) and a Posture Adaptation Module (PAM). The FE predicts faulty joints from lower-body proprioceptive histories, while the PAM uses this fault information to adapt the base posture plan generated by the arm policy, converting potentially unstable posture requests into safe and executable base posture commands. Through this fault-aware posture adaptation mechanism, FT-WBC synthesizes compensatory gaits under actuator failures and preserves as much arm workspace as possible while maintaining whole-body stability. Simulation and real-world experiments show that FT-WBC significantly improves survival rate and workspace under weakening or locked failures, and transfers zero-shot to a real legged manipulator in the real world.

Problem

• fault-tolerant control
• legged loco-manipulation
• whole-body stability
• actuator failures
• arm reachability

Innovation

• fault-tolerant control
• whole-body control
• legged loco-manipulation
• posture adaptation
• zero-shot transfer