基于能耗优化的六足步行机器人力矩分配

Optimization of energy-efficient torque distribution for hexapod walking robot

针对步行机器人的节能需求,提出以降低系统能耗为目标的六足步行机器人力矩分配算法.通过建立六足步行机器人的运动学模型和改进的波浪步态模型,提出六足机器人足端脚力分配问题.在分析机器人的平衡条件并结合摩擦约束的基础上,建立机器人足端脚力的约束方程.利用机器人的动力学模型,得到机器人足端脚力约束方程与关节力矩约束之间的变换关系.在考虑直流电机的有效功率和热损耗的基础上,通过求解线性等式与不等式约束下的二次规划问题,对各关节力矩进行优化分配.通过与传统的以内力平方和最小化为优化目标的脚力分配方法相比较证明,在合适的步进速度和步态占地系数下,机器人采用新的力矩分配方法时能够节省系统能耗22%～39%.

The torque distribution algorithm for minimizing the energy cost of hexapod robots was estab- lished to meet the energy-efficient demand of multi-legged robot. The tip-point force distribution problem was proposed based on the kinematic model and phase modified wave gait. The constraint equation of the tip-point forces for six legs was established by combining the body equilibrium and constraints analysis of friction. The relation between the tip-point forces and joint torques was determined by dynamic model. Considering the mechanical energy cost and the energy loss by heat emission of the electric engine, the torque distribution problem was formulated to minimize the quadratic objective function with respect to lin- ear equality and inequality constraints. In contrast to the force distribution method whose objective func- tion corresponds to the sum of the squares of the tip-point force components, the torque distribution scheme could save the system energy cost about 22% to 39% with appropriate walking velocities and duty factors of robot.