Bennett单元阵列可展机构的动力学分析

为分析Bennett单元阵列可展机构的几何特性、运动学特性和动力学特性,建立通用的Bennett单元阵列可展机构的运动学和动力学分析模型. 采用拆解法将Bennett单元阵列可展机构中的单元机构分成4个空间串联开链机构；根据开链机构的特性,引入坐标变换法结合螺旋理论建立Bennett单元阵列可展机构的运动学分析模型,用虚功原理法将各空间串联开链机构组装在一起,构建动力学分析模型和动力学分析方法；以4×4 Bennett单元阵列可展机构为例分析其运动学和动力学,并用仿真和实验来验证所建立的动力学分析模型和动力学分析方法. 结果表明:算例中的Bennett单元阵列可展机构在其运动范围内运动平稳,对角线上的单元机构距离驱动单元愈远,其驱动角的角速度和角加速度变化范围越大. 广义力矩的变化比较平缓,在其运动范围内不会引起较大冲击. 仿真结果、实验结果与运动学和动力分析模型计算结果吻合较好,说明该运动学和动力学分析模型和方法是准确的,可以用来指导Bennett单元阵列可展机构的构型设计、轨迹规划和动力系统参数的选定等.
To study the geometrical, kinematic characteristic and dynamic characteristic of Bennett unit array deployable mechanism, the decomposition method is used to disassemble a unit mechanism of the deployable mechanism into 4 spatial serial open-chain mechanisms, and according to its characteristic, the kinematic analysis model of Bennett unit array deployable mechanism is set up by the transformation of coordinates method combining with screw theory. And then, all spatial serial open-chain mechanisms are assembled by the virtual principle to build the dynamics analysis model by which the kinematic and dynamic of a 4×4 Bennett unit array deployable mechanism are studied, and simulations and experiments are carried out to testify the validity of this model. Results show that the deployable mechanism in the example can move smoothly and steady in their motion range. The farther the units on diagonal is away from the driving unit, the greater the variation range of angular velocity and acceleration of its driving angular will be. Since the generalized driving force moment changes gradually, it won’t cause a greater impact in the motion range. The simulation results, the experimental results and the model calculation results tend to be identical, and this proves that these kinematic and dynamic analysis models are accurate.