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摘要:
为满足航天飞行器壳体套装过程中位姿调整机构刚度大、精度高的要求,对传统的支链结构进行有针对性的改进,设计了一种支链为闭环结构的新型5-U(RRP)S/(8U)PU并联机构,并进行了分析研究。应用螺旋理论计算机构的自由度;建立封闭矢量方程,进行运动学正反解;应用螺旋理论求解机构的全雅可比矩阵;利用杆长约束条件绘制机构的定姿态工作空间;通过求解静刚度矩阵分析机构的刚度随位姿的变化情况;利用软件进行仿真,并与一般机构进行对比。通过分析,验证了该机构的可行性和实际应用价值,为实现航天飞行器壳体套装的自动化奠定基础。
Abstract:In order to meet the requirements of high stiffness and accuracy of the position and posture adjusting mechanism in the assembly process of spacecraft shell, a novel 5-U(RRP)S/(8U)PU parallel mechanism with closed-loop limbs, which are improved from conventional limb structure, is proposed and analyzed. The degree of freedom of the mechanism is calculated by screw theory. The positional positive and negative solutions are figured out through establishing the seal vector constraints equation. The complete Jacobian matrix is calculated by screw theory. The fixed posture workspace is drawn by the restrained link length. The changes of mechanism stiffness with the position and posture are analyzed by solving the static stiffness matrix. The software is used to simulate and compare with the general mechanism. Through the above analysis, the feasibility and practical application value are verified, which lays the foundation for the automatic assembly process of spacecraft shell.
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Key words:
- parallel mechanism /
- closed-loop structure /
- high stiffness /
- high accuracy /
- kinematics analysis
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表 1 并联机构尺寸参数
Table 1. Dimension parameters of parallel mechanism
参数 数值 a/mm 200 b/mm 160 c/mm 160 d/mm 100 r/mm 215 l1/mm 220 l2/mm 340 θ6m/(°) 60 l6min/mm 100 l6max/mm 800 l3, imin/mm 150 l3, imax/mm 550 θimin/(°) 15 θimax/(°) 45 表 2 各支链驱动副位移量
Table 2. Displacement of driving joint on each limb
动平台沿z方向的坐标值/mm P1位移量/mm P2/P5位移量/mm P3/P4位移量/mm 本文 对比 本文 对比 本文 对比 300 0 0 0 0 0 0 310 18.03 10.04 18.03 10.01 16.85 9.74 320 36.07 20.03 36.06 19.96 33.63 19.32 330 54.15 30.18 54.12 30.11 50.55 29.07 340 72.26 40.14 72.19 40.08 67.32 38.66 350 90.48 50.18 90.37 50.06 84.26 48.31 360 108.65 60.16 108.56 60.11 101.05 58.15 370 126.88 70.11 126.74 70.09 117.76 67.63 380 144.81 80.18 144.73 80.12 134.54 77.24 390 162.93 90.01 162.75 89.95 151.38 96.99 400 180.11 100.04 179.94 100.00 168.01 96.51 表 3 各支链驱动副电机运行速度
Table 3. Motor operation speed of driving joint on each limb
支链驱动副编号 速度/(mm·s-1) P1 -2 P2 2 P3 4 P4 4 P5 2 表 4 各支链驱动副受力
Table 4. Force of driving joint on each limb
电机工作时间/s P1受力/N P2/P5受力/N P3/P4受力/N 本文 对比 本文 对比 本文 对比 0 -323.29 -610.14 38.46 72.19 158.15 -291.08 0.5 -338.51 -673.73 49.51 113.77 159.93 -298.71 1.0 -354.46 -737.49 61.43 155.43 161.85 -306.40 1.5 -365.83 -801.16 72.59 197.16 163.71 -314.15 2.0 -385.18 -864.83 84.16 238.86 165.65 -321.84 2.5 -400.57 -1928.53 95.54 280.52 167.58 -329.53 3.0 -416.16 -992.24 107.37 322.24 169.41 -337.27 3.5 -431.19 -1055.96 118.51 363.93 171.35 -344.91 4.0 -447.74 -1119.67 130.74 405.66 173.25 -352.62 4.5 -462.57 -1183.34 141.53 447.31 175.17 -360.30 5.0 -478.15 -1247.18 153.44 489.25 177.06 -368.43 -
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