Jyh-Jone Lee

Bio: Jyh-Jone Lee is an academic researcher from National Taiwan University. The author has contributed to research in topics: Kinematics & Finite element method. The author has an hindex of 14, co-authored 42 publications receiving 465 citations. Previous affiliations of Jyh-Jone Lee include University of Maryland, College Park & Industrial Technology Research Institute.

Kinematic Analysis of Tendon-Driven Robotic Mechanisms Using Graph Theory.

Abstract: Analyse cinematique par la theorie des graphes d'un mecanisme de robot utilisant des commandes par câbles

Force Transmissibility Performance of Parallel Manipulators

Abstract: In this paper, a new force transmission index called the mean force transmission index (MFTI) is proposed, and the force transmissibility analysis procedure is established for parallel manipulators. The MFTI is an extended definition of the force transmission index (FTI) introduced by the authors previously. It is shown that the FTI is a function of the input velocity ratio (IVR) for a multi-DOF mechanism of the same configuration. To represent the force transmissibility by a definite value, the MFTI is defined as the mean value of the normalized FTIs function over the whole range of the IVR. The force transmissibility analysis of two planar parallel manipulators is illustrated using the MFTI method. The result is compared with that of the Jacobian matrix method and the joint force index (JFI) method. It shows that, especially for symmetric parallel manipulators, an approximate inverse-proportionality relationship exists between the JFI and MFTI, and between the maximum input torque/force and MFTI. It is concluded that the MFTI can be used as a quantitative measure of the force transmissibility performance for parallel manipulators. In the end, a design optimization problem is studied by taking the

Jacobian, Manipulability, Condition Number, and Accuracy of Parallel Robots

Abstract: Although the concepts of Jacobian matrix, manipulability, and condition number have existed since the very early beginning of robotics their real significance is not always well understood. In this paper we revisit these concepts for parallel robots as accuracy indices in view of optimal design. We first show that the usual Jacobian matrix derived from the input-output velocities equations may not be sufficient to analyze the positioning errors of the platform. We then examine the concept of manipulability and show that its classical interpretation is erroneous. We then consider various common local dexterity indices, most of which are based on the condition number of the Jacobian matrix. It is emphasized that even for a given robot in a particular pose there are a variety of condition numbers and that their values are not coherent between themselves but also with what we may expect from an accuracy index. Global conditioning indices are then examined. Apart from the problem of being based on the local accuracy indices that are questionable, there is a computational problem in their calculation that is neglected most of the time. Finally, we examine what other indices may be used for optimal design and show that their calculation is most challenging.

Jacobian, manipulability, condition number and accuracy of parallel robots

Abstract: Parallel robots are nowadays leaving academic laboratories and are finding their way in an increasingly larger number of application fields such as telescopes, fine positioning devices, fast packaging, machine-tool, medical application. A key issue for such use is optimal design as performances of parallel robots are very sensitive to their dimensioning. Optimal design methodologies have to rely on kinetostatic performance indices and accuracy is clearly a key-issue for many applications. It has also be a key-issue for serial robots and consequently this problem has been extensively studied and various accuracy indices have been defined. The results have been in general directly transposed to parallel robots. We will now review how well these indices are appropriate for parallel robots.

Analysis of the Workspace of Tendon-based Stewart Platforms

Abstract: Tendon-based Stewart platforms are a concept for innovative manipulators where the load to move almost coincides with the payload. After an overview over the state of research and some concepts of kinematics (singularity and redundancy), the thesis discusses aspects of the technically usable workspace (positive tendon forces, limits of tension, singularity, stiffness, collisions between tendens). A representation of the controllablwe workspace by means of polynomial inequalities is developed. Optimal solutions are provided to the problem of finding appropriate force distributions in the tendons. These solutions can be discontinuous in time, but they can be approximated with continuous ones. An algorithm is given for this. From these results, a quality measure for workspace is derived and used to state design rules which help achieving good workspaces. For some systems, sample trajectories are simulated.

Substrate storage container

Abstract: A substrate storage container includes a container body for accommodating and aligning semiconductor wafers, a door which opens and closes the front of the container body and a pair of valve units disposed at the bottom of the container body for controlling gas flow. Each valve unit includes a fixed sleeve for gas flow, fitted in a rib of a through-hole of the container body, a holding sleeve fitted in the through-hole of the container body with an o-ring interposed therebetween and mated and threaded with the fixed sleeve, a check valve built between the fixed sleeve and the holding sleeve, leaving a clearance, an elastically deformable element for opening and closing the check valve, an interior lid sleeve for gas flow, opposing the check valve and supporting the elastically deformable element, and a filter interposed between the holding sleeve and the interior lid sleeve.