1. Pennock, G.R., Hasan, A.: A polynomial equation for a coupler curve of the double butterfly linkage. J. Mech. Des. 124(1), 39–46 (2002)
2. Kong, X., Gosselin, C.M.: Generation and forward displacement analysis of RPR-PR-RPR analytic planar parallel manipulators. J. Mech. Des. 8(18), 2195–2304 (2001)
3. Liu, A., Yang, T.: Kinematics Design of Mechanical System. China Petrochemical Press, Beijing (1999)
4. Liu, A., Yang, T.: Finding all positive solutions of a general 6-SPS parallel robot mechanism. Mech. Sci. Technol. 15(4), 543–546 (1996)
5. Liao, Q., Seneviratne, L.D., Earles, S.W.E.: Forward positional analysis for the general 4-6 In parallel platform. Proc. Inst. Mech. Eng. Part C J. Mech. Eng. Sci., 209, 55–67 (1995)