This paper focuses on the elastodynamic analysis of cable-driven parallel manipulators. Dynamic stiffness matrix of a single sagging cable is introduced. This matrix considers the effect of both cable mass and elasticity. Dynamic response functions are evaluated for cable-driven parallel manipulators. As an example, the dynamic analysis of a 6-DOF cable-suspended parallel manipulator is achieved considering the dynamic behavior of sagging cables. Numerical simulations and tests are demonstrated to validate the model by identifying the natural frequencies. Effects of cable sag on the static pose error are also experimentally investigated. Results show the importance of taking into consideration the cable dynamics for cable-driven parallel manipulators when it comes to perform applications such as high speed pick-and-place or large working volume.

This paper presents the design optimization of a Delta-like robot manipulator with respect to multiple global stiffness objectives. For this purpose, a systematic elasto-geometrical modeling method is used to derive the analytical manipulator stiffness models by taking into account their link and joint compliances. The models are then involved within a statistically sensitivity analysis of the influence of the geometric parameters on four global indices that describe the structure stiffness over the workspace. Multi-Objective Genetic Algorithm, i.e. Pareto-optimization, is taken as the appropriate framework for the definition and the solution of the addressed multi-objective optimization problem. Our approach is original in the sense that it is systematic and it can be applied to any serial and parallel manipulators for which stiffness is a critical issue.

The purpose of this work is to propose a new approach for the calculation of PKM stiffness matrix by using an analytical method based on matrix structural analysis. This method has as the main advantage to be systematic and it also can be applied to hyper-static PKM stiffness analysis. The implementation of the proposed method is fast and convenient and it can easily be involved during PKM design optimization. Moreover, as the stiffness matrix is obtained in a close form, it can be implemented directly on the robot controller. In other words, the proposed method could be used to reduce the gap existing between actual PKM and those that have to meet the high accuracy specifications required for machining applications. At first this paper presents the proposed analytical method that is applied to calculate the stiffness matrix of a delta parallel structure. Then the experimental results that have been done to evaluate and validate its efficiency are presented

The increasing applications of parallel robots in domains such as medical or machine-tools require a high accuracy. As a result, the geometrical calibration of these mechanisms becomes a major step to reach the expected accuracy. An effective and simple calibration method based on 1D and 3D measurements of a new low cost artifact is presented and then validated on the Surgiscope/spl reg/, a structure based on a delta parallel robot used in neurosurgery.