Parallel Robot Mechanism Research Articles

Forward displacement analysis of generalized 5SPS-1CCS parallel robot mechanism based on quaternion

The generalized 5SPS-1CCS parallel robot mecha-nism and its forward displacement analysis are presented. The mathematic model of the parallel mechanism is created based on quaternion. It is proved theoretically that the forward displacement problem of the generalized 5SPS-1CCS parallel platform has at most 80 nonsingular solutions using Mourrain variety. All 80 nonsingular solutions of the forward displace- ment problem are obtained using homotopy continuation method. The procedure of quaternion manipulation is transformed into that of matrix manipulation and 4 quadric equations are reduced into bi-linear equations in the procedure of the calculation. The efficiency and feasibility are improved through the method proposed above. The result is verified by a numerical example. The analysis results prove that the proposed algorithm is simple and can be used to forward displacement analysis of other generalized parallel mechanisms. The research builds the theory basis for dimensional design, trajectory planning and control of this type of manipulator.

A New Method of Structural Synthesis about the Partly-DOF Parallel Robot Mechanisms Based on the Screw Theory

In this paper, based on some disciplinarians about the configuration design of Parallel Robot Mechanisms (PRM), the theory bases was established for parallel structural configuration design by developing different types of the partly degrees of freedom (DOF) parallel configuration designs. The new method to synthesize the partly DOF parallel mechanisms, called constraint accession, is provided to the classification of kinematical chains by use of screw theory. The active kinematical chains control the necessary DOF and the passive kinematical chains control the needless ones. In this paper, the relevant active and passive kinematical chains are put forward and the constraint chains are classified in detail. It is demonstrated by an example that new configurations can be obtained by assembling different kinematical limbs.

Synthesis and structure analysis of kinematic structures of 6-dof parallel robotic mechanisms

Based on basic structure theory of parallel robotic mechanisms, this paper presents a novel type synthesis methodology for synthesizing kinematic structures of 6-dof parallel mechanisms, which considers hybrid single-opened chain as the “limbs” connecting the moving platform with the base. The 27 promising 6-dof parallel kinematic structures with lower coupling degree between independent loops, actuated by six rotation joints mounted on the base, are presented originally in this paper. The moving platform of these parallel structures can possess general spatial motions, i.e. three translation motions and three rotation motions. Many more alternatives to these kinematic structures can also be obtained by altering the location and the type of driving joints within loops or by changing some partial sub-structures relevant to the branch loops. The classification of these parallel kinematic structures is identified according to the four structure evaluation criteria suggested here by the authors, i.e. (a) structure topological symmetry; (b) coupling degree between independent loops, (c) structure simplicity (with fewer links and fewer joints); (d) manufacturability, from which optimal 6-dof parallel kinematic structures are recommended in terms of different design requirements. Lastly, structural characteristics analysis for a promising parallel mechanism is illustrated.

Structure and displacement analysis of a novel three-translation parallel mechanism

A novel 3-DOF parallel robot mechanism with three-translation is synthesized and analyzed according to the structural theory of parallel robotic mechanisms based on single-opened-chain limbs. First, motion output type and mobility analysis of the parallel mechanism are addressed. Second, the closed-form analytic solutions are developed for both forward and inverse kinematics. Then input–output de-coupling analysis is discussed. Finally, numerical solutions and computer simulations for forward kinematics of the parallel mechanism with given specific dimensions are demonstrated.

Sprained Ankle Physiotherapy Based Mechanism Synthesis and Stiffness Analysis of a Robotic Rehabilitation Device

Rehabilitation robotics is a growing field where the study of human movement is one of the key topics. Mechanisms development in terms of analysis and synthesis in the field is relatively new, particularly in the case of parallel robotic mechanisms. This paper presents the background and details of current research into the use of parallel robotic mechanisms for rehabilitation of sprained ankles, and proposes a new device based on a parallel mechanism with a central strut. The paper investigates a new technique in motion analysis of ankle movement which is presented in an orientation image space and in that of a rehabilitation therapy, presents an approach of mechanism synthesis based on this analysis, and develops several parallel mechanisms with a central strut for ankle rehabilitation. This is then related to the analysis of the stiffness effect of the central strut in the platform-type mechanism and the stiffness matrix is decomposed with the part resulting from the central strut which supports ankle rehabilitation. In presenting this new research, the paper relates the study of mechanisms to that of rehabilitation robotics and presents a strong case in the new application of parallel robotic mechanisms.

Structure synthesis of 4-DOF parallel robot mechanisms based on screw theory

Structure synthesis of 4-DOF parallel robot mechanisms based on screw theory

New kinematic structures for 2-, 3-, 4-, and 5-DOF parallel manipulator designs

In this paper, several types of composite pairs and new kinds of sub-chains (limbs or legs) with specific degrees of freedom are proposed. Based on the special Plücker coordinates for describing the displacement of the output link of a limb, the principle for design of structures of parallel robotic mechanisms is presented. And several new types of 2-, 3-, 4- and 5-DOF parallel robotic mechanisms are obtained.

STRUCTURAL SYNTHESIS AND CLASSIFICATION OF THE 3DOF TRANSLATIONAL PARALLEL ROBOT MECHANISMS BASED ON THE UNITS OF SINGLE-OPENED-CHAIN

Based on the units of single-opened-chain limb, some structural laws of degenerate-rank parallel robot mechanisms are revealed, and a systematic and effective new method for structural synthesis of 3DOF translational parallel robot mechanisms is put forward. 33 mechanisms are synthesized and classified, 29 of which are presented for the first time. The method is of universal significance and is used for the structural synthesis of degenerate-rank parallel robot mechanisms with other kinematics output types.

Performance atlases of the workspace for planar 3-DOF parallel manipulators

The design of the robotic mechanisms is most important because they determine the performance characteristics of the robots. This paper concerns the issue of computer-aided design (CAD) for planar 3-DOF parallel robotic mechanisms by means of the physical model of the solution space, which can be used systematically to express the relationships between the performance criteria and all link lengths of one type of the robtic mechanism. The performance atlases of the workspace volume for the manipulators are plotted in the physical model of the solution space. The characteristics of the distribution of the workspace shapes in the physical model of the solution space are presented. The results are useful for the optimum design of the robotic mechanisms. This paper proposes a new way for robotic CAD.

203 ACサーボモータを用いた6自由度パラレルメカニズムロボットの運動特性(GS.1 運動機構・メカトロニクス)

203 ACサーボモータを用いた6自由度パラレルメカニズムロボットの運動特性(GS.1 運動機構・メカトロニクス)

Kinematics of a three-degree-of-freedom in-parallel actuated manipulator mechanism

This paper presents the first and second order kinematic analysis of a three-degrees-of-freedom 3-RPS parallel robot mechanism. The position and orientation parameters of the moving platform of this mechanism are six, however only three of them are independent. The Jacobian of the mechanism is a 3 by 6 rectangular matrix. This imposes difficulties on the kinematic analysis of this mechanism. This paper presents a method to formulate three motion constrain equations which are consistent with the kinematic structure of the mechanism, and establishes the velocity and acceleration relationship between the independent output motions and three input parameters in close form.