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.