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 a systematic procedure for the elastodynamic modeling of industrial robots that is applicable to either serial or parallel manipulators. This procedure is based on a 3-D space generalization of the equivalent rigid link system (ERLS) description, the finite-element method (FEM), and the Lagrange principle. It considers flexible links and joints, and leads to generic equations of motion expressed according to the angles of the actuated joints and the independent elastic degrees of freedom. An efficient identification process through modal analysis is detailed, and the description of damping and joint behavior according to the model application is discussed. The method is applied to a 3-D delta-like parallel structure and successfully validated through an experimental impact testing-based modal analysis.

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.