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		机械臂臂杆刚度主动控制下的末端振动特性研究$^{\bf 1)}$
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			RESEARCH ON VIBRATION CHARACTERISTICS OF THE MANIPULATOR END UNDER ACTIVE CONTROL OF ARM STIFFNESS$^{\bf 1)}$
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| 图6. 预紧力为 20N 时机械臂末端 $X$ 方向加速度及频谱图 | 
| Fig.6. The $X$-direction acceleration and spectrum of manipulator end with 20N preloading force | 
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