A novel absolutely symmetrical 3-RRRU parallel mechanism was proposed that can perform three-dimensional translations.Based on the screw theory,the mechanism principles that the mechanism performed the three-dimensional translations were analyzed,the drive input joints were chosen and discussed,the singularity of the parallel mechanism were emphatically analyzed,and the problem that how could the singularities be avoided was discussed.The kinematics model was set up,the analytic solution of the inverse position kinematics was obtained,and using some methods such as coordinate transformation,and variable expansion,the forward position kinematics solution was discussed and proved by use of numerical simulation.Since the 3-RRRU parallel mechanism is absolutely symmetrical, the mechanism manufacturing is simple and inexpensive,and the singularities can be avoided,the parallel mechanism can be applied in the fields of industrial assembly robots,coordinate measuring machines,material handling devices.
