四足机器人前小腿系弹性牵拉驱动机构设计

Design of the Spring-Stretching Shank Mechanism of Quadruped Robots

为实现四足机器人腿机构轻量、柔性以及高刚度的设计,从生物学出发,研究了狗在高速运动中肌肉牵拉对其前腿骨骼刚度的影响.应用ADAMS动力学仿真软件模拟了狗单条腿在对角步态下的运动与受力环境,研究并比较了骨骼受肌肉牵拉和无肌肉牵拉两种状态.仿真结果证明,肌肉牵拉对骨骼刚度有大幅度的增强作用,能够使骨骼支撑动物实现稳定的运动而不被破坏.进一步提出并验证了采用弹簧弹性力牵拉能够达到与肌肉牵拉力相同的效果,并将此结论应用于四足机器人前小腿弹性牵拉驱动机构设计中,将关节弹性力耦合作用与机构两端形成牵拉作用,并研究了弹性力作用点变化与弹簧刚度以及机构最大应力值之间的约束关系.结果表明,这种设计在保证关节弹性力输出控制特性不受影响的情况下能够有效提高腿机构的刚度.

In order to design quadruped robot legs with characteristics of light weight,flexibility and high stiffness,the effect of muscle-stretching on the stiffness of the bone of a dog’s foreleg in high speed movement is studied from the view of biology.Then two states,i.e.muscle-stretching and non-muscle-stretching,are investigated and compared by kinematics and dynamics simulation in ADAMS,which imitates the movement of a dog’s foreleg in trotting gait.The results show that the bone with muscle stretching has higher stiffness,which is able to support the body’s weight and realize stable movement without being damaged.Furthermore,it is proposed and verified that the spring elastic stretching force has the same effect as the muscle-stretching force,and a shank mechanism equipped with an elastic stretching actuator is designed based on this conclusion.The joint elastic force is converted into the stretching force acting on both ends of the shank through the mechanical design,and the correlation among the change of acting point,spring stiffness,and the maximal stress of this mechanism is investigated.The results suggest that this design not only effectively enhances the stiffness of the leg,but also remains the controlling characteristics of the joint elastic force.