Jyh-Jone Lee

Modeling of the dynamics of tendon-driven robotic mechanisms with flexible tendons

Abstract In this paper, a systematic methodology for the dynamic analysis of tendon-driven robotic mechanisms with compliant tendons is presented. The compliance of tendons and inertias of the intermediate links in the mechanism are taken into account. Representing the tendon force by use of a rectifying operator, the unidirectional force transmission characteristic of tendons can be preserved. The dynamic equations can then be systematically established in a recursive manner using the Newton–Euler equations. The joint reaction forces and the tension in each segment of tendon can be also obtained. The methodology can be applied to both endless and open-ended tendon-driven robotic mechanisms.

Kinematic synthesis of tendon-driven robotic manipulators using singular value decomposition

This work describes a systematic methodology for the synthesis of tendon-driven manipulators. A method for enumerating the topology of tendon routings is first established. To conform with the enumerated structures, the kinematic synthesis of the manipulator using singular value decomposition is then developed. Design equations for synthesizing a general tendon-driven manipulator with isotropic transmission characteristics are subsequently derived. It is shown that the design methodology may give designers wider selection in determining the tendon routing topology than prior methods by other literature.

On the kinematics of a new parallel mechanism with Schoenflies motion

This paper investigates the kinematics of one new isoconstrained parallel manipulator with Schoenflies motion. This new manipulator has four degrees of freedom and two identical limbs, each having the topology of Cylindrical–Revolute–Prismatic–Helical (C–R–P–H). The kinematic equations are derived in closed-form using matrix algebra. The Jacobian matrix is then established and the singularities of the robot are investigated. The reachable workspaces and condition number of the manipulator are further studied. From the kinematic analysis, it can be shown that the manipulator is simple not only for its construction but also for its control. It is hoped that the results of the evaluation of the two-limb parallel mechanism can be useful for possible applications in industry where a pick-and-place motion is required.

Kinematic synthesis of a four-link mechanism with rolling contacts for motion and function generation

In this paper, the kinematic synthesis of a four-link mechanism with rolling contacts is investigated. This mechanism comprises a two-fingered gripper and a grasped object. The synthesis equations used for motion generation and function generation are established. The number of free choices in design variables for the kinematic synthesis is also discussed. Furthermore, the optimization-based numerical technique is applied to solve the design equations. The optimized solutions are illustrated to discuss the kinematic states of the mechanism. It is also shown that the optimization-based method is effective in finding the admissible synthesis solution of the mechanism.

Synthesis of tendon-driven manipulators with high fault tolerance

The purpose of this work is the realization of a methodology for synthesizing tendon-driven manipulators with high fault tolerance. Characteristics of tendon-driven manipulators are briefly discussed. Criteria for the tendon-driven manipulators to have positive tension are then established. Constraints for such manipulator are subsequently derived from the null space of the structure matrix. With these constraints, manipulators can remain controllable when one of the tendons is failed to function. Finally, a procedure for determining the structure matrix that satisfies the constraints is developed via geometric method.

On the Design of the Latch Mechanism for Wafer Containers in a SMIF Environment

This paper presents the design of a latch mechanism for wafer containers in a standard mechanical interface environment. For an integrated circuits fabrication factory, the standard mechanical interfaced wafer container is an effective tool to prevent wafers from particle contamination during wafer storage, transporting or transferring. The latch mechanism inside the container door is used to latch and further seal the wafer container for safety and air quality. Kinematic characteristics of the mechanism are established by analyzing the required functions of the mechanisms. Based on these characteristics, a methodology for enumerating feasible latch mechanisms is developed. New mechanisms with one degree-of-freedom and up to five links are generated. An optimum design is also identified with respect to the criteria pertinent to the application. The computer-aided simulation is also built to verify the design.

A decomposition methodology for design of mechanisms from functional and structural perspectives

Abstract This paper presents an innovative methodology for the design of mechanisms. The course of design is decomposed functionally and structurally into two portions as the design of two mechanism modules: the functioning module and the constraining module. Conceptual functions of mechanisms are embodied as the functional requirements to construct admissible functioning modules. Following that, the functioning module is then assigned into feasible kinematic structures existing in the graph atlas to yield admissible structures for the mechanism. Finally, remaining characteristics featured by the constraining module are determined according to the structural requirements of the mechanism. By this methodology, both functional and structural requirements are concurrently taken into account during the design process, to obtain feasible mechanisms without an exhaustive enumeration process. The design of mechanisms can thus be performed in an effective and systematic manner.

Design of a Reciprocal Hip Mechanism with Adjustable Flexion-Extension Coupling Ratios for Prosthetic Applications

From the past research, the researchers found that higher hip flexion/extension coupling ratio was associated with lower energy cost and higher walking speed. In this work, a reciprocal hip mechanism with adjustable hip FECR for prosthetic applications was developed. An experiment was also performed to identify whether the hip motion of the simulator was in accordance with the desired hip flexion/extension coupling ratio in the mechanism by means of the motion measurement system. The results of the experiment supported the satisfaction of the hip mechanism designed.

Optimization design of tendon-driven manipulators with high fault tolerance

A tendon-driven manipulator having redundant tendons may possess additional flexibility in operation such as being capable of optimizing the performance of tendons, reducing the burden on each tendon, and allowing fault tolerance for actuation. The purpose of this paper is to develop a methodology for synthesizing tendon-driven manipulators with high actuation redundancy for fault tolerance, and also to optimize the distribution of tendon force in the system. Characteristics of tendon-driven manipulators are briefly discussed. Criteria for the tendon-driven manipulator associated with high actuation redundancy are then established. Subsequently, constraints for such systems are derived from the null space of the structure matrix. With these constraints, manipulators can remain controllable when one of the tendons fails to function. Finally, a procedure for determining the structure of the tendon-driven manipulator is developed via an optimization-based numerical method.

On the Design of An Innovative Latch Mechanism in SMIFed Wafer Containers

This paper presents the design process for an innovative latch mechanism in a standard mechanical interfaced (SMIFed) wafer container, in which the manufactured integrated circuits are stored. An innovative latch mechanism is proposed and applied to the wafer container, such that the container door can be latched and air-tightly sealed during storage or transportation. The design process is divided into two stages. In the first stage, an output slot-cam is designed in order to generate decoupled fine motions of the output link. The issue is formulated as an optimization problem where the output link dimensions are optimized to minimize the resultant pin forces subject to an adequate transmission angle. In the second stage, the input slot-cam is designed to achieve that kinetic energy of the elastic gasket on the container lid is absorbed at a uniform rate. Finally, a numerical example and computer simulations are given to demonstrate the results of design process. It is believed that this work could aid in enhancing the performance and reliability of the latch mechanism in the SMIF environment.