Review on rotation angle measurement method for spherical joint

Spherical joint is provided with three dimensional rotation motion, which has been widely applied in robots, parallel mechanisms, automobiles and medical devices on account of its smooth motion, compact structure, high load capacity. If the position of the spherical joint can be detected accurately in real time, it will be helpful to improve the accuracy of subsequent mechanical control. How to obtain the rotation angle of the spherical joint in real time has attracted lots of eyes at home and abroad. Currently, there are many kinds of measuring methods and instruments in this field. Focusing on the different measurement principles, as well as the measurement strategies, we systematically summaries the technology involved, which includes the recent work of our team. Their principles, advantage and disadvantages are analyzed, and the trend of development is also discussed in the paper.