基于AB/DTS算法的闭链六足机器虫动力学

Dynamics of Hexapod with Closed-loop Based on AB/DTS Algorithm

闭环机构在工程实际中有着广泛的应用,但在对其进行动力学分析时,由于约束耦合的存在大大增加了计算的复杂度。把针对固定基座操作手高效的动力学关节体(Articulated-body,AB)算法、地面和足部接触的解耦结构树(Decoupled tree-structure,DTS)建模方法和处理运动约束的硬约束方法结合起来对闭环机构进行动力学分析。同时采用一种能动态选择的Baumgarte修正参数方法来处理运算过程出现的违约问题。作为计算实例,根据使步行机器人运动时机身产生较小的起伏变化对足部运动轨迹的要求,设计一种采用闭环的六连杆作为腿部机构的六足机器虫。基于推导所得到的算法,通过C++语言编写程序对该机器虫进行仿真,结果和由ADAMS得到结果近似,表明了该算法的正确性;同时由运动位移曲线验证了所设计的机器虫满足预定的运动要求。

Closed-loop mechanism is widely used in engineering practice, but when processing its dynamics analysis, the computation complexity is greatly enhanced due to the coupled constraints. The articulated-body （AB） algorithm which is efficient for the dynamics of a manipulator with a fixed base, the decoupled tree-structure （DTS） method which models the contact between the foot of robot and the ground and the hard-constraint method for treating the motion constraint problem are combined to process the dynamic analysis of the closed-loop mechanism. Meanwhile, a method which can select the Baumgert parameters dynamically is used to treat the violated constraint problem during the computational period. As a computational example, a hexapod using a closed-loop six-bar mechanism as its leg is developed based on the requirements of producing a small up-down change of the body when walking robot moves. The correctness of algorithm is validated by comparing the results of simulation of the hexapod in a program written by C＋＋ based on the developed algorithm and ADAMS, meanwhile the motion displacement diagram shows that the hexapod satisfies the prescribed motion requirement.