Analysis and Optimisation of 4UPS - 1UPU Parallel robots

This thesis is motivated, on the one hand, by the outstanding success of several parallel robots and, on the other hand, by the lack of unified and straightforward approaches for the analysis, synthesis and implementation of parallel robots, in general, and those featuring five degrees of freedom, in particular. Accordingly, this thesis aspires to provide an insight into these issues and proposes novel approaches in order to deal with the modelling, performance analysis, dimensional synthesis and control of parallel robots. A special attention is given to finding a balance between problem complexity and accurate results within the scope of both the analysis and synthesis of parallel robots. First, an approach is proposed to cope with type synthesis. It consists in breaking down the main task to the synthesis of open-loop kinematic chains, which is more straightforward. Second, the kinematic, first-order error, dynamic and elastodynamic models are derived. These are based on symbolic equations and are computationally more efficient than a simulation, especially when dimensional synthesis is concerned. Third, this thesis points out the importance of the preliminary evaluation of the kinetostatic performances of parallel manipulators and proposes adequate indices that allow characterizing accuracy, velocity and force transmission along and about each direction of the Cartesian space. Within the scope of dimensional synthesis, it will also be shown that these indices enable the designer to identify appropriate manipulator geometries already at an early stage of the design process. The implementation of an appropriate control system for parallel manipulators is also tackled and experimental results are given.