A new type of PKM based on the special universal joint

This paper presents a new type of parallel kinematic machines (PKM), which can be used for drill point grinding, based on a special universal joint. The special universal joint is composed of a parallel mechanism with three legs as the inputs. One can rotate as a spindle; other ones can drive a moving platform and make a cutting tool get an accurate position in workspace. Due to the simple mechanical structure comparing the parallel kinematic machines with the existing conventional CNC machine tools, it should be easy for the parallel kinematic machines to manufacture at a low cost. In addition, inverse kinematic equations of the special type of universal joint are derived.