Characteristic Research On The 4-DOF Parallel Manipulator With SPS+SPR-Type Legs

With the development of parallel manipulator research, lower-mobility parallel manipulators have attracted much attention due to their simple in structure, easy control, and low cost. The lower-mobility parallel manipulators are the new and the focus in this field and have very vast application vistas in industry. Based on the analyses of the current situation of the lower-mobility parallel manipulators home and abroad, this dissertation focuses on the characteristic of 4-DOF parallel manipulators with SPS-type leg and SPR- type leg by using analytic approach and computer aided geometry approach.(1)Three representative 4-DOF parallel mechanisms of 2SPS+2SPR: 2SPR+2SPS I,2SPR+2SPS II,2SPR+2SPS III are proposed. Based on the constraint equations, the reverse position equations are deduced. The formulae for inverse/forward velocity and inverse/forward acceleration are derived using one new kind of analytic approach. After the constraint equations are differentiated, the equations of the components of the velocity and the components of the acceleration are deduced. Based on the principle of virtual work, the active/constrained forces are solved.(2)By using the geometric constraint, the dimension constraint, the dimension equation and the dimension driving techniques of CAD, the position simulation mechanisms of the three parallel manipulators are created, and based on the principle of the uniformly accelerated motion, the simulation mechanisms for solving velocity and acceleration are created. The kinetic characteristic is analyzed using the simulation mechanisms.(3)Three 4-DOF parallel manipulators having the similar kinetic characteristic with 2SPS+2SPR II are obtained through changing the position of joints.(4)The workspaces of 2SPS+2SPR I and 2SPS+2SPR II are constructed by using the position simulation mechanisms.