Fault-tolerant motion planning and generation of quadruped robots synthesised by posture optimization and whole body control

Abstract

Quadruped robots are likely to fall into the fault joint state in outdoor explorations. The unexpected joint lock may suddenly happen when quadruped robots are implementing normal gaits, and maintaining the primal movement patterns to finish targeted tasks could be disastrous. In this paper, a fault-tolerant motion planning and generation method for quadruped robots with joint lock is proposed. Fault-tolerant cases on three types of joints on legs are investigated, and equivalent geometric models are proposed to reconstruct kinematics. To make unnecessary deformation of gait patterns as small as possible, the body posture and standing height of quadruped robots are to be optimized based on the nonlinear equivalent geometry models with constraints. The proposed fault-tolerant method is applicable to constructing a quasi-static whole-body controller, and it does not require additional operations and constraints of the fault leg. To validate the consistency and stability of the proposed fault-tolerant method, the experiments are implemented on the three joint lock failure scenarios for quadruped robots.

Adaptive Control Strategy for Quadruped Robots in Actuator Degradation Scenarios

“…Numerous studies have delved into alternative strategies, including traditional control theories and other methodologies, to tackle the challenge of fault tolerance in quadruped robots. For instance, Cui et al [11] and Chen et al [10] introduced control-based methods to enable quadruped robots to overcome single-joint locking scenarios. Zhao et al [49] devised an adaptive fault-tolerant control law to address leg joint actuator faults in quadruped robots.…”

“…Using this mechanism, we collect a set of trajectories encompassing 12 × 𝑁 trajectories in total, each containing 𝑇 transitions: 11 ,…”

“…Additionally, immediate fault rectification often necessitates specialized expertise and tools, which may not be readily available. As a result, the design of fault-tolerant control algorithms becomes crucial, empowering robots to adapt to varying degrees of malfunction autonomously [10,11]. Implementing such algorithms not only prolongs the robot's operational lifespan but also substantially enhances its reliability.…”

“…While traditional fault-tolerant algorithms like Model Predictive Control (MPC) and whole-body control frameworks have been widely adopted, they suffer from concrete drawbacks such as heavy reliance on domain expertise, labor-intensive manual tuning, and limited adaptability to unforeseen environmental and mechanical conditions [11,12,18,24]. These conventional approaches focus on the active detection and confirmation of faults during the robot's operation.…”