Workspace Analysis of a Hybrid Kinematic Machine Tool with High Rotational Applications

Abstract

This paper presents a novel parallel manipulator with one translational and two rotational (1T2R) degrees of freedom that can be employed to form a five-degree-of-freedom hybrid kinematic machine tool for large heterogeneous complex structural component machining in aerospace field. Compared with serial or parallel machine, hybrid machine has the merits of high stiffness, high speed, large workspace, and complicated surface processing ability. To increase stiffness, three-degree-of-freedom redundantly actuated and overconstrained 2PRU-PRPS parallel manipulator (P denotes the active prismatic joint) is proposed, which is utilized as the main body of hybrid machine. By resorting to the screw theory, the degree of freedom of the proposed mechanism is briefly addressed including the initial configuration and general configuration and validated by Grübler-Kutzbach (G-K) equation. Next, kinematic inverse solution and parasitic motion of the parallel manipulator are deduced and the transformational relations between the Euler angle and Tilt-Torsion (T-T) angle are identified. Thirdly, the performance evaluation index of orientation workspace is introduced, and the reachable workspace and joint workspace are formulated. Through specific examples, the reachable workspace, task workspace, and joint workspace of the redundant actuation parallel manipulator are depicted. Compared with overstrained 2PRU-PRS parallel manipulator, corresponding analyses illustrate that the proposed parallel manipulator owns much better orientation capability and is very meaningful to the development of the five-axis hybrid machine tool.

Trajectory Tracking Control Study of a New Parallel Mechanism with Redundant Actuation

“…The serial-parallel hybrid kinematic machine (HKM) structure was selected as a candidate architecture for complicated surface milling in aerospace domain [29] (as shown in Figure 1), whose parallel module is a 2RPU-2SPR parallel mechanism with redundant actuation (R, P, U, and S standing for rotational, prismatic, universal, and spherical kinematic joint, respectively). The underline format (P) represents the actuated joint.…”

Forward Kinematics and Workspace Determination of a Novel Redundantly Actuated Parallel Manipulator

“…The determination of joint and workspace is one of the most important issues of the redundant actuation parallel manipulator, which directly reflects the comprehensive performance of the parallel manipulator; its analysis results provide a theoretical basis for the design and application of the 2RPU-2SPR parallel manipulator [32][33][34]. A real experiential prototype (as depicted in Figure 8) is fabricated, whose workspace is generated by adopting the main loop algorithm based on the forward kinematics combining the structural parameters and the limitation conditions.…”

Design Optimization of 3-DOF Redundant Planar Parallel Kinematic Mechanism Based Finishing Cut Stage for Improving Surface Roughness of FDM 3D Printed Sculptures

“…However, owing to this structure, the PKM has a high dependence on kinematic parameters, and thus many constraint conditions limiting the range of motion at the tool tip exist in the PKM, and it does not have a wide workspace [7][8][9][10][11][12][13]. Therefore, a hybrid mechanism that combines the SKM and the PKM has been researched and developed in a field where a wide workspace compared to the size of the mechanism and high stiffness is required [14][15][16][17][18][19][20]. However, because of the characteristics of the hybrid structure in which the PKM and SKM are connected in series, issues regarding the area, shape, and singularity of the workspace of the PKM are still inherent.…”