Smooth Stride Length Change of Rat Robot with a Compliant Actuated Spine Based on CPG Controller.

The aim of this research is to investigate the relationship between spinal flexion and quadruped locomotion in a rat robot equipped with a compliant spine, controlled by a central pattern generator (CPG). The study reveals that spinal flexion can enhance limb stride length, but it may also cause significant and unexpected motion disturbances during stride length variations. To address this issue, this paper proposes a CPG model driven by spinal flexion and a novel oscillator that incorporates a circular limit cycle and accounts for the anticipated stride length transition process. This approach effectively matches the torque change with the dynamics of stride length changes, leading to lower energy consumption. Extensive simulations are conducted to evaluate the efficacy of the proposed oscillator and compare it with the original kinetic model and other CPG models. The results demonstrate that the designed CPG model with the proposed oscillator yields smoother gait transitions during stride length variations and reduces energy consumption.