Search

The paper presents a new conceptual design method that is capable of generating large numbers of possible design concepts of hydraulic systems automatically for specified operation requirements. A hydraulic system is regarded as a set of single-action subsystems and each subsystem is formed by a set of basic transformation units representing hydraulic components and their usage patterns. The input and output energy characteristic states of a subsystem or basic transformation unit are represented by qualitative vectors related by a diagonal characteristic matrix. Each element of the matrix defines a simple transformation and the operation rules of these transformations are defined. The subsystem characteristic matrix is the product of the characteristic matrices of the basic transformation units. The characteristic matrices of all basic transformation units are identified and classified and the decomposition rules for subsystem characteristic matrices are established. Thus, the characteristic matrix of a subsystem can be successively decomposed into various sets of characteristic matrices of basic transformation units. Each set of such basic transformation units is the topological representation of a hydraulic system. By successive decomposition of a system characteristic matrix, a thorough conceptual design process for hydraulic systems is established. The proposed method is illustrated by examples. [DOI: 10.1115/1.4001108] Keywords: conceptual design, hydraulic system, characteristic matrix, CAD

A circular surface with a fixed radius can be swept out by moving a circle with its center following a curve, which acts as the spine curve. Based on a system of Euclidean invariants, the paper identifies those circular surfaces taking lines of curvature as generating circles and further explores the properties of the principal curvatures and Gaussian curvature of the tangent circular surfaces. The paper then applies the study to mechanism analysis by proving the necessary and sufficient condition for a circular surface to be generated by a serially connected C'R, HR, or RR mechanism, where C' joint can be visualized as a special H joint with a variable pitch of one degree of freedom. Following the analysis, this paper reveals for the first time the relationship between the invariants of a circular surface and the commonly used D-H parameters of C'R, HR, and RR mechanisms. [DOI: 10.1115/1.3212679] Keywords: circular surface, lines of curvature, Euclidean invariants, mechanisms, kinematics, differential geometry, robotics, workspace

A methodology for synthesis and configuration design of metamorphic mechanisms is developed in this paper based on biological modeling and genetic evolution with biological building blocks. The goal is to conceive an appropriate source-metamorphic-mechanism configuration when the multiple phases of kinematic functions are given. The key enabler is the way of developing genetic evolution in modeling and design by capturing the metamorphic configuration characteristics. With the unique characteristic of achieving multiple working-phase functions in a mechanism, the metamorphic mechanism possesses two features: one, the ametabolic feature referring to the specified working phases that can be accomplished by a number of traditional mechanisms; two, the metamorphic feature occurring in transition between different working phases, resulting in change of topology of the mechanism. Based on this transition between phases, the concept of mechanism evolution is for the first time introduced in this paper based on biological building blocks in the form of metamorphic cells and associated intrinsic elements as the metamorphic gene. This leads to development of cell evolution and genetic aggregation with mechanism decomposition and evolutionary operation based on mapping from the source-metamorphic mechanism to multiphase working configurations. Examples are given to demonstrate the concept and principles. [DOI: 10.1115/1.2900719] Keywords: metamorphic mechanism, working-phase, kinematics, configuration, modeling, synthesis, biological building block, metamorphic cell, gene, genetic evolution, evolutionary operation

This paper presents a novel robotic hand with a metamorphic palm which changes the traditional structure of a robotic hand. Based on this new hand structure, the paper investigates motion of the robotic fingers with respect to the palm by presenting finger operation planes and by revealing the relationship between finger motion and palm motion. The study presents the normals of the finger operation planes as a function of the input angles of the palm and uses these normals to relate finger motion to palm motion. This leads to the coaxial condition of the finger-palm relationship that is then converted to the coplanar condition of normals of all finger operation planes. The condition is then used to generate a coupler trajectory, and the iterative trajectory fitting and curve approximation are used for synthesis of palm links, leading to differential geometry based synthesis of angular lengths of the metamorphic palm. [DOI: 10.1115/1.2771576] Keywords: multifingered, robotic hand, robotic palm, spherical mechanisms, metamorphic mechanism, geometry, analysis, synthesis

The paper and its companion Dong , 2011, “Kinematic Fundamentals of Planar Harmonic Drives,” ASME J. Mech. Des., 133(1), p. 011007, which treats a harmonic drive without a cup, present the geometry-relevant operation of harmonic drives under an ideal little or no-load condition. This paper shows that the cup is essentially a compliant mechanism with the unique feature of transforming a set of different tooth rotations into a single rigid body rotation and demonstrates how the cup affects tooth conjugation and the conjugate tooth profiles. It proves and demonstrates that the conjugating tooth profile should be a three-dimensional surface because of the cup deformation. The use of spur gears on both flexspline and circular spline will cause excessive interference and excessive deformation will become necessary to overcome the interference. Since no-load geometry is clearly identified, excessive deformation and errors due to incorrect geometry can be removed or filtered and the loading effects can be identified. Contact ratio of a harmonic drive is also obtained through the range of conjugate positions. Although loading is not considered, the geometric error is. Eliminating or reducing geometric error will improve the performance. [ABSTRACT FROM AUTHOR]