Trajectory Optimization Strategy That Considers Body Tip-Over Stability, Limb Dynamics, and Motion Continuity in Legged Robots

We propose a limb trajectory planning method that considers both body and limb dynamics in robots, particularly suitable for those with non-trivial limb mass. To simplify the complexity and computation cost of using the full- body dynamics of the limbs, a reduced-order model that can simulate the dynamic characteristics of the original limb is proposed. The performance of the model is experimentally validated using an exemplary single leg-wheel of the leg-wheel transformable robot. The limb trajectory optimization is developed using a genetic algorithm that considers many aspects, including body and limb dynamics, limb workspace, limb motion continuity, body tip-over stability, and power consumption. The performance of the proposed limb trajectory planning strategy is experimentally validated using the same leg-wheel transformable robot, and the results confirm the effectiveness of the strategy.