Chung-Ching Lee

Bio: Chung-Ching Lee is an academic researcher from National Kaohsiung University of Applied Sciences. The author has contributed to research in topics: Revolute joint & Motion (geometry). The author has an hindex of 11, co-authored 44 publications receiving 493 citations.

Cartesian Parallel Manipulators With Pseudoplanar Limbs

Abstract: Based on the Lie-group-algebraic properties of the displacement set, the three-degree-of-freedom (3DOF) pseudoplanar motion often termed Y motion for brevity is first introduced. Then, all possible general architectures of the mechanical generators of a given Y subgroup are obtained by implementing serial arrays of 1DOF Reuleaux pairs or hinged parallelograms. In total, five distinct mechanical generators of Y motion are revealed and seven ones having at least one parallelogram are also derived from them. In order to avoid the singularity that may occur in the limbs, all singular postures of Y-motion generators are also located by detecting the possible linear dependency of the joint twists and the group dependency of displacement sets. The parallel layout of three 4DOF limbs including Y-motion generators with orthogonal planes make up a Cartesian translational parallel manipulator, which produces a motion set of spatial translations. The 3DOF translation of the moving platform is directly controlled by the three 1DOF translations in three orthogonal prismatic fixed joints.

Isoconstrained Parallel Generators of Schoenflies Motion

Abstract: Based on the Lie-group-algebraic properties of the displacement set, the 4-dof primitive generators of Schoenflies motion termed X-motion for short are briefly recalled. An X motion includes 3-dof spatial translation and any 1-dof rotation provided that the axes are parallel to a given direction. The serial concatenation of two generators of 4-dof Xmotion produces a 5-dof motion called double-Schoenflies motion or X-X motion for brevity, which includes 3 dofs of translations and any 2 dofs of rotations if the axes are parallel to two independent vectors. This is established using the composition product of two Lie subgroups of X-motion. All possible 5-dof serial chains with distinct general architectures for the generation of X-X motion are comprehensively introduced in the beginning. The parallel setting between a fixed base and a moving platform of two 5-dof X-X limbs, under particular geometric conditions, makes up a 4-dof isoconstrained parallel generator (abbreviated as IPG-X) of a Schoenflies motion set. “Isoconstrained” is synonymous with “non-overconstrianed” and the corresponding chains are trivial chains of the 6D group of general 6-dof motions and can move in presence of manufacturing errors. Moreover, related families of IPG-Xs are also deducted by using the reordering or the commutation of factor method, which yields more 5D subsets of displacements containing also the X motion of the end effector. In that way, several novel general-type architectures of 4-dof parallel manipulators with potential applications are synthesized systematically in consideration of the actuated pairs near the fixed base.

Matrix Representation of Topological Changes in Metamorphic Mechanisms

Abstract: Metamorphic mechanisms form a class of mechanisms that has the facilities to change configuration from one kind to another with a resultant change in the number of effective links and mobility of movement. This paper develops formal matrix operations to describe the distinct topology of configurations found in a metamorphic mechanism and to complete transformation between them. A new way is hence introduced for modeling topological changes of metamorphic mechanisms in general. It introduces a new elimination E-elementary matrix together with a U-elementary matrix to form an EU-elementary matrix operation to produce the configuration transformation. The use of these matrix operations is demonstrated in both spherical and spatial metamorphic mechanisms, the mechanistic models taken from the industrial packaging operations of carton folding manipulation that stimulated this study.

A Geometric Theory for Analysis and Synthesis of Sub-6 DoF Parallel Manipulators

Abstract: Mechanism synthesis is mostly dependent on the designer's experience and intuition and is difficult to automate. This paper aims to develop a rigorous and precise geometric theory for analysis and synthesis of sub-6 DoF (or lower mobility) parallel manipulators. Using Lie subgroups and submanifolds of the special Euclidean group SE(3), we first develop a unified framework for modelling commonly used primitive joints and task spaces. We provide a mathematically rigorous definition of the notion of motion type using conjugacy classes. Then, we introduce a new structure for subchains of parallel manipulators using the product of two subgroups of SE(3) and discuss its realization in terms of the primitive joints. We propose the notion of quotient manipulators that substantially enriches the topologies of serial manipulators. Finally, we present a general procedure for specifying the subchain structures given the desired motion type of a parallel manipulator. The parallel mechanism synthesis problem is thus solved using the realization techniques developed for serial manipulators. Generality of the theory is demonstrated by systematically generating a large class of feasible topologies for (parallel or serial) mechanisms with a desired motion type of either a Lie subgroup or a submanifold.

1T2R Parallel Mechanisms Without Parasitic Motion

Abstract: Parasitic motion is a major drawback of the general 1T2R parallel mechanism (PM), where T denotes a translation degree of freedom (DOF) and R a rotational DOF. This paper investigates the type synthesis of the 1T2R PM without parasitic motion. First, a brief review on the planar-spherical bond and its mechanical generators is presented. Then, the difference between the general and special aT bR motion is discussed. Relations between the parasitic motion and the general and special aTbR motion are revealed. An infinitesimal 1T2R PM with rotation bifurcation is presented as a special case. Further, the definition of the 1T2R PM without parasitic motion is presented, and the limb bond {G(u)}{S(N )} is identified. Geometrical conditions to construct an 1T2R PM without parasitic motion are presented, and nonoverconstrained 1T2R PMs without parasitic motion are synthesized. Idle pairs in the nonoverconstrained 1T2R PMs without parasitic motion are detected. Finally, overconstrained 1T2R PMs without parasitic motion are obtained by removing the idle pairs in the nonoverconstrained 1T2R PMs.

Parallel Mechanisms With Bifurcation of Schoenflies Motion

Abstract: Type synthesis of lower mobility parallel mechanisms (PMs) has attracted extensive attention in research community of robotics over the last seven years. One important trend in this area is to synthesize PMs with prespecified motion properties. This paper focuses on the type synthesis of a special family of PMs whose moving platform can undergo a bifurcation of Schoenflies motion. First, bifurcation of Schoenflies motion in PMs is interpreted in terms of displacement group theory and the basic limb bond {X(y)}{R(N, x)} is identified. Further, the geometric condition for constructing a PM with bifurcation of Schoenflies motion is presented. The kinematic equivalence between {X (y)}{R(N, x)} and {X(y)}{X( x)} is proven. Four subcategories of irreducible representation of the product { X(y )}{X(x)} are proposed and the limb chains that produce the desired limb bond are synthesized. Finally, the partitioned mobility of PMs with bifurcation of Schoenflies motion and its effect on actuation selection are discussed.