This article presents a special 6-degree-of freedom parallel manipulator, and the mechanical structure of this robot has been introduced; with this structure, the kinematic constrain equations are decoupled. Based on this character, the polynomial solutions of the forward kinematics problem are also presented. In this method, the closed-loop kinematic chain of the manipulator is divided into two parts, the solution forward position kinematics is obtained by a first-degree polynomial equation first, and then an eighth-degree polynomial equation in a single variable for the forward orientation kinematics is obtained. Based on those solutions, the configurations of the robot, including position and orientation of the end-effector, are graphically displayed. A numerical simulation is given to verify the algorithm, and the result implies that for a given set of input values, the manipulator can be assembled in eight different configurations at most. And a set of experiments illustrate the motion ability for forward kinematics of the prototype of this manipulator.
This paper presents a novel three-degree-of-freedom (3-DOF) parallel manipulator and introduces its mechanical structure. Analytical solutions of the forward kinematics have been worked out, and all configurations of this robot are graphically displayed. On the basis of several special positions in the kinematics, a task workspace is prescribed to find the smallest feasible dimensional parameters of the robot. An algorithm describing this method is also introduced. This method can easily find appropriate parameters that can size a robot having the smallest workspace enclosing a predefined task workspace. This improves the design efficiency and ensures that the robot has a small mechanical size possessing a large workspace volume and, in terms of dimension design, meets the lightweight-design requirements. With examples illustrating the design results, we further introduce a design stability in dextoensure that the robot remains a safe distance from the boundary of its actual workspace. One prototype of the robot has already been developed.
Abstract. This paper investigates the kinematic performances of kinematics, Jacobian, singularity and interferences of a novel six-degree-of freedom (DOF) parallel manipulator. Analytical solutions of the forward position kinematics have been worked out. Three-dimensional Cartesian space generated by a stroke interval from lmin to lmax fulfils the point workspace are illustrated, and the reachable workspaces are obtained. The notion of pure translational Jacobian of constraint matrix is introduced, and two types of conventional singularities are analyzed. Finally, auxiliary vectors are introduced to determine the link interferences, shown that there are two kinds of interferences in the system, one is angle-interference in one limb, and the other is distance-interference in adjacent limbs.
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