**Singularity Analysis, Constraint Wrenches and Optimal Design of Parallel Manipulators**

Nguyen Minh Thanh1, Le Hoai Quoc2 and Victor Glazunov3 *1Department of Automation, Hochiminh City University of Transport, 2 Department of Science and Technology, People's Committee of Hochiminh City, 3Mechanical Engineering Research Institute, Russian Academy of Sciences, 1,2Vietnam* 

*3Russia* 
