多节连续体机械臂的预紧机构装置设计

Design of pre-tightening mechanism for multi-segment continuum manipulator

针对柔索驱动机械臂容易发生绳索松弛从而影响动作准确性和有效载荷能力的问题,设计了一种新型的连续体机械臂混合式预紧机构,并提出了对应的预紧力控制策略。首先,研究了多节柔索驱动超冗余连续机械臂的3个主要组成部分——连续体部件、预紧部件和致动部件,并给出了采用线性电位器的混合式预紧机构具体硬件设计;其次,根据电机和绳索分布,提出了相匹配的混合式预紧力控制策略,包括了2种方式——被动补偿和主动补偿,并对主动补偿的电机角度计算公式进行了推导;最后,通过有效载荷和载荷可操作性试验,对所提预紧机构和控制策略的有效性进行了验证。研究结果表明:有预紧机构机械臂的有效载荷能力增加了20 g,最大高度增加了约200 mm,避免了绳索松弛现象,从而提高了末端位置控制的精度,同时,机械臂的载荷可操作性明显提升。

Aiming at the problem that cable slack easily occurs in flexible cable-driven manipulator,which affects the action accuracy and payload capacity,a new type of hybrid pre-tightening mechanism for continuous manipulator is designed,and the corresponding pre-tightening force control strategy is proposed.Firstly,the three main components of super redundant continuous manipulator driven by multi-section flexible cables are studied:continuum component,pre-tightening component and actuating component,and the specific hardware design of hybrid pre-tightening mechanism using linear potentiometer is given.Then,according to the motor and rope distribution of the designed pre-tightening mechanism,a matching hybrid pre-tightening force control strategy is proposed,including two modes:passive compensation and active compensation,and the calculation formula of motor angle for active compensation is derived.Finally,the effectiveness of the pretightening mechanism and control strategy is verified through the payload and load operability tests.The results show that the payload capacity of the manipulator with pretensioning mechanism increases by 20 g,the maximum height increases by about 200 mm,and the rope slack phenomenon is avoided,thus improving the precision of the end position control.At the same time,the manipulator with active compensation becomes more sensitive,and the operability of load is obviously improved.