Two-degree-of-freedom (2DOF) pointing mechanisms have been widely used in areas such as stabilized platforms, tracking devices, etc. Besides the commonly used serial gimbal structures, another two types of parallel pointing mechanisms, i.e., spherical parallel manipulators (SPMs) and equal-diameter spherical pure rolling (ESPR) parallel manipulators, are increasingly concerned. Although all these pointing mechanisms have two rotational DOFs, they exhibit very different motion characteristics. A typical difference existing in these three pointing mechanisms can be found from their characteristics of self-motion, also called spinning motion by the authors. In this paper, the spinning motions of three pointing mechanisms are modeled and compared via the graphical approach combined with the vector composition theorem. According to our study, the spinning motion is essentially one component of the moving platform's real rotation. Furthermore, image distortions caused by three spinning motions are identified and distinguished when the pointing mechanisms are used as tracking devices. Conclusions would facilitate the design and control of the pointing devices and potentially improve the measuring accuracy for targets pointing and tracking.
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April 2016
Research-Article
A Comparative Study on Motion Characteristics of Three Two-Degree-of-Freedom Pointing Mechanisms
Kang Wu,
Kang Wu
R&D Center,
Sunward Intelligent Equipment Co., Ltd.,
Changsha 410100, China;
Sunward Intelligent Equipment Co., Ltd.,
Changsha 410100, China;
Robotics Institute,
Beihang University,
Beijing 100191, China
Beihang University,
Beijing 100191, China
Search for other works by this author on:
Guanghua Zong,
Guanghua Zong
Robotics Institute,
Beihang University,
Beijing 100191, China
Beihang University,
Beijing 100191, China
Search for other works by this author on:
Xianwen Kong
Xianwen Kong
School of Engineering and Physical Sciences,
Heriot-Watt University,
Edinburgh EH14 4AS, UK
Heriot-Watt University,
Edinburgh EH14 4AS, UK
Search for other works by this author on:
Jingjun Yu
Kang Wu
R&D Center,
Sunward Intelligent Equipment Co., Ltd.,
Changsha 410100, China;
Sunward Intelligent Equipment Co., Ltd.,
Changsha 410100, China;
Robotics Institute,
Beihang University,
Beijing 100191, China
Beihang University,
Beijing 100191, China
Guanghua Zong
Robotics Institute,
Beihang University,
Beijing 100191, China
Beihang University,
Beijing 100191, China
Xianwen Kong
School of Engineering and Physical Sciences,
Heriot-Watt University,
Edinburgh EH14 4AS, UK
Heriot-Watt University,
Edinburgh EH14 4AS, UK
1Corresponding author.
Manuscript received October 11, 2014; final manuscript received November 6, 2015; published online February 24, 2016. Assoc. Editor: Federico Thomas.
J. Mechanisms Robotics. Apr 2016, 8(2): 021027 (10 pages)
Published Online: February 24, 2016
Article history
Received:
October 11, 2014
Revised:
November 6, 2015
Citation
Yu, J., Wu, K., Zong, G., and Kong, X. (February 24, 2016). "A Comparative Study on Motion Characteristics of Three Two-Degree-of-Freedom Pointing Mechanisms." ASME. J. Mechanisms Robotics. April 2016; 8(2): 021027. https://doi.org/10.1115/1.4032403
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