蛇形机器人蜿蜒运动的摩擦机理及推进条件

Tribological Mechanism and Propulsion Conditions for Creeping Locomotion of the Snake-like Robot

针对带有从动轮的蛇形机器人,考虑实际结构中从动轮在蛇形机器人关节连杆上的安装位置,建立蛇形机器人蜿蜒运动的动力学模型。提出一种库伦-粘滞混合摩擦力模型,整体的库伦摩擦力特性和临界点处的粘滞摩擦力特性,避免了库伦摩擦力模型本身的非光滑性,以提高动力学模型的求解效率与计算稳定性。基于改进的动力学与摩擦力模型,利用摩擦系数比来表征法向与切向摩擦力的各向异性程度,通过对蜿蜒运动的仿真分析,讨论了摩擦系数比对前向运动速度与推进效率的影响规律,并对运动过程中蛇形机器人各个关节模块的速度和摩擦力变化进行了分析,明确了蛇形机器人蜿蜒运动的摩擦学机理,解释了蛇的蜿蜒抬起运动能够有效减少摩擦阻力而适用于高速运动的原因。最后通过带从动轮的蛇形机器人样机实验,对实现蜿蜒运动的摩擦学推进条件进行了验证。研究对于实现蛇形机器人的结构优化,步态规划与运动控制具有重要的理论意义与实际指导价值。

Considering the installation position of the passive wheel on the joint link of the snake-like robot in the actual structure,the dynamic model of the snake-like robot’s creeping locomotion is established.A Coulomb-Viscous mixed friction model is proposed.The overall Coulomb friction characteristics and the Viscous friction characteristics at the critical point can avoid the non smoothness of the Coulomb friction model itself,so as to improve the solution efficiency and computational stability of the dynamic model.Based on the improved dynamics model and friction model,the anisotropic degree of normal friction and tangential friction is represented by the friction coefficient ratio.Through the simulation and analysis of creeping locomotion,the influence of friction coefficient ratio on forward motion speed and propulsion efficiency is discussed,and the velocity and friction variation of each joint module in the moving process of snake-like robot are analyzed.The tribological mechanism of snake-like robot’s creeping locomotion explains the reason why the snake’s sinus-lifting motion can effectively reduce the friction resistance and is suitable for high-speed motion.Finally,the condition of tribological propulsion to realize the creeping locomotion of the snake-like robot with passive wheels are verified by the prototype experiment.The research in this paper has important theoretical significance and practical guidance value for the realization of snake-like robot structure optimization,gait planning and motion control.