It is difficult to find out a suitable type for desired purpose among a large number of mechanisms that can be made by the spatial combination of links and joints. Here, quick calculation of correct mobility is the basic requirement for structural synthesis of parallel robot mechanisms.
Various methods reported in the literature for mobility calculation of closed loop mechanisms fall into two basic categories: an approach for mobility calculation based on setting up kinematic constraint equations and calculating their rank and an approach for finding formulae for quick calculation of mobility without constraint equations. Among them, the former is very useful.
Kim Yong Ho, a researcher at the Faculty of Mechanical Science and Technology, proposed a new method of calculating the mobility of parallel mechanisms by automatically generating velocity constraint equations and calculating the rank.
For automatic generation of kinematic constraint equations, he used formulae which enable automatic generation of the homogeneous transformation matrix and the Jacobian matrix of serial robot mechanisms.
He applied this method to CPM mechanism, Bennett mechanism and Bricard mechanism to validate its correctness, availability and prospectiveness.
For more information, please refer to his paper “Calculation of Correct Mobility of Special Mechanisms Based on Automatic Generation of Jacobian Matrix and Velocity Constraint Equation” in “Proceedings of KUTIC-2025”.