It is known that two primary disadvantages of parallel manipulators are the complicated forward kinematics and limited workspace. This paper mainly addressed the kinematics and workspace analyses of a 3/3-RRRS 6-DOF parallel manipulator. After a brief introduction of the 3/3 -RRRS 6-DOF parallel manipulator, a three-dimensional model and its relevant structure diagram are constituted, the forward and inverse displacement analyses of the 3/3-RRRS parallel manipulator are discussed in detail, especially, a novel geometrical method referred as equivalent mechanism is proposed for the forward displacement analysis of the manipulator under consideration. Based on the displacement analyses of the manipulator, a discretization method is proposed for the computation of the reachable position/orientation workspace of the 3/3-RRRS parallel manipulator, respectively. Examples of a 3/3-RRRS parallel manipulator are given to demonstrate these theoretical results.

This paper mainly addresses the principle of the singularity elimination of the Stewart parallel platform. By adding appropriate redundant actuation, the rank of the Jacobian matrix of the parallel platform is always full, accordingly the singular value of the Jacobian matrix of the parallel platform is nonzero. Then the singular configuration of the parallel platform can be eliminated by adding one redundant actuation. Numerical examples are taken to illuminate the principle’s effectiveness. It is shown that not only singular configurations of the Stewart parallel platform can be eliminated, but also performances of kinematics and dynamics of the parallel platform can be greatly perfected by adding appropriate redundant actuation.

The dynamic model of a 6-DOF wire-driven parallel manipulator is established, based on influence coefficient method for wire-driven parallel manipulator trajectory planning algorithm is proposed, the orientation parameters by Euler angles of moving platform of time first-order and second-order derivative which is not a moving platform angular velocity and angular acceleration is verified. For the moving platform position and orientation workspace trajectory planning, the kinematic characteristics of wires are discussed. The simulation results show that the tension of the wires are always greater than 0, the expressions of velocity, acceleration and tension of wires are exceptionally clear and simple. Also, the method of trajectory planning proposed is suitable for general 6-DOF wire-driven parallel manipulator.