3-DOF索杆桁架式欠驱动机械手运动控制

索杆桁架式机械手是将绳轮传动系统和平行四边形机构结合而提出的一种新型欠驱动机械手。绳索驱动力同时驱动手指关节耦合运动,而手指关节运动又会直接改变绳拉力在各指节单元的驱动力分布,导致索杆桁架式欠驱动系统具有强非线性和运动耦合特点。针对该问题,利用虚功原理,将绳轮传动系统等效为耦合的关节驱动力矩,并建立3-DOF手指准静态运动学模型。根据手指最大运动空间约束条件,确定关节弹簧配置分布并开展手指准静态运动空间分析。采用拉格朗日方程法建立手指一般动力学方程,并转换为"A-P"型等效动力学模型。在此基础上,开展预变形阶段运动控制研究。通过仿真分析和样机试验验证所提分析方法和运动控制策略的有效性。

Motion Control of 3-DOF Under-actuated Cable-truss Robotic Hand

The cable-truss robotic hand is a novel type of under-actuated hand that is proposed by tendon-pulley transmission and parallel four-linkage mechanism. The joint movements are driven by cable driving force simultaneously and coupled with each other, and which directly changes the distribution of cable driving force in each phalange. Therefore, the cable-truss underactuated system has the characteristics of strong nonlinearity and motion coupling. Then, the finger driven by the TP transmission is translated to the equivalent joint driven mechanism, and a quasi-static kinematic model of a 3-DOF finger is established. On the basis of the constraints of maximum movement space of the finger, the distributions of joint springs are determined and the finger quasi-static movement space is analyzed. The general dynamic equation of the finger is established by using Lagrange's method, and the equivalent dynamic model in "A-P" form is obtained. On the basis of "A-P" dynamic model, research on motion control in the pre-bending stage is carried out. The effectiveness of the proposed analysis method and motion control strategy is verified by simulation analysis and prototype experiment.