The singularity of parallel machine tools was researched, which was based on the research objects of the speed matrix determinant, Jacobian matrix determinant det([WTHX]J[WTBZ]) and operability W respectively. The researches provided a basis for the design of the structural parameters about parallel machine tools.The singularity of bodies about parallel machine tools can be divided into three categories when the speed matrix determinant was put as the research object. Parallel machine tools can be judged at the singularity when det([WTHX]J[WTBZ])=0 or the operability was zero.The singularity was researched for a new type of 3-legged 3-DOF parallel machine tool when det([WTHX]J[WTBZ]) and the operability W were [KG*4]put as the research objects. The mathematical model of the [KG*4]machine [KG*4]tool [KG*4]was [KG*4]established. The [KG*4]Jacobian [KG*4]matrix [KG*4]of [KG*4]the [KG*4]machine [KG*4]tool [KG*4]were [KG*4]derived. [KG*4]The [KG*4]expressions [KG*4]of [KG*4]|det([WTHX]J[WTBZ])| and the operability W about the machine tool by Matlab had been worked out. |det([WTHX]J[WTBZ])|=W>0 and |det([WTHX]J[WTBZ])|=W≠∞ were obtained by the analysis. That is, there is no singularity about the machine tool. Besides, the machine tool has good operability. The stationarity of the machine tool was researched in the environment of Matlab. The simulation results show that the machine tool has good stationarity.

Parallel machine tools,   ,  Jacobian matrix,   ,  Singularity,   ,  Stationarityc