The Degrees Of Freedom, Constraint Singularities And Kinematics Analysis Of 3-PRRRR Translational Parallel Manipulator

Parallel manipulator is playing an unique advantage in the practical applications, especially with high stiffness,large load and high precision without accumulated error . This paper presents 3-PRRRR translational parallel manipulator which is a fully decoupled translational parallel manipulator. It is only made up of some revolute joints and prismatic joints to achieve the three translational degrees of freedom of moving platform. This paper focuses on degrees of freedom of the moving platform,constraint singularities and kinematics characteristics.With the revised Chebyshev-Grübler-Kutzbach formula proposed by Professor Huang,we analyze the degrees of freedom of parallel manipulator.Through describing the moving platform with screw, the constraints of each branch chaincan be analyzed.The redundant constraints,local degrees of freedom is used in the formula of degrees of freedom,The result indicates that the orthogonal 3-PRRRR parallel manipulator is a 3-DOF translational parallel manipulator.The paper analyzes the two kinds of constraint singularities of 3-PRRRR parallel Manipulator. We get the linear relationship between chains and the DOF of moving platform. Due to the orthogonal relationship between the three branched-chains, the constraints screws of the moving platform don't satisfy linear relation. So there exist no constraints singularities in the workspace. The orthogonal 3-PRRRR parallel manipulator is 3-DOF translational parallel manipulator without constraint singularities.With the relationship between the 3-PRRRR parallel manipulator spatial location, it is very easy to get kinematics equation. We get the Jacobian matrix based on velocity analysis. Jacobian matrix is a very important basis to further study of the Jacobian condition index,workspace and stiffness index, getting the manipulator parameters of expression with workspace and stiffness to improve these performances indices.A virtual prototype is modeled by SolidWorks software. The model is then imported to ADAMS software to do kinematics simulation. Through displacement, velocity, acceleration, motion interference analysis to confirm the istronpic of parallel manipulator. We determine the final prototype parameters and design the prototype.The control system is designed through PC +motion controller, including hardware design and software design. The single-axis and multi-axis-driven experiments prove that the orthogonal 3-PRRRR parallel manipulator is a 3-DOF translational parallel manipulator and the control system is feasible. The research results presented in this paper is of importance in the application the orthogonal 3-PRRRR parallel manipulator.