As is well known, a wire-driven parallel manipulator is a manipulator whose end-effector is driven by a number of cables instead of rigid links. It shows several promising advantages over its rigid-link counterpart, such as simple light-weight mechanical structure, low moment inertia, large reachable workspace and high-speed motion. In the 1980s, the National Institute of Standards and Technolo...

In engineering applications, the singularity, and the forward and inverse displacement of spatial parallel manipulators have received a great deal of attention. This paper presents a new simple but effective methodology to investigate these problems based on the analysis of the degree of freedom (DoF) of the spatial parallel manipulator. Through numerical method, the singularity and the forward...

In order to achieve accurate dynamic identification of parallel manipulators, the exciting trajectories have to be specially designed according to some optimal criteria. Two different criteria are developed based on the Weighted Least Squares (WLS) dynamic equations of parallel manipulators. Then the exciting trajectories are parameterized with the finite Fourier series, and optimized by the no...

Cable-based robots build upon mechanisms that not only use rigid links in their structures but also utilize unilateral force elements such as cables to deliver the desired motion. Cables may be either connected to active winches to provide a variable length and hence to actuate the mechanism or may be only to provide a kinematic constraint to eliminate an undesired motion of the endeffector. Ma...

Drawing mainly on linear algebra and screw theory, this paper presents a general and systematic approach for force/motion/stiffness transmissibility analyses of redundantly actuated and overconstrained parallel manipulators. A set of normalized transmission indices is proposed for representing the closeness to singularities as well as for dimensional optimization of the redundantly actuated and...

The goal of this paper is to define the n-connected regions in the Cartesian workspace of fully-parallel manipulators, i.e. the maximal regions where it is possible to execute pointto-point motions. The manipulators considered in this study may have multiple direct and inverse kinematic solutions. The N-connected regions are characterized by projection, onto the Cartesian workspace, of the conn...

Parallel manipulators (PMs) have been the subject of study, of much robotic research during the past three decades. A parallel manipulator (PM) is a closed loop kinematic chain mechanism, that is connected to the base via multiple independent chains. The scope of this research work is to perform the position analyses of the three degrees of freedom PMs (TRIPOD and TRI-GLIDE). The present work h...

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-DO...

The large amount of computation necessary for obtaining time optimal solution for moving a manipulator on specified path has made it impossible to introduce an on line time optimal control algorithm. Most of this computational burden is due to calculation of switching points. In this paper a learning algorithm is proposed for finding the switching points. The method, which can be used for both ...