CAD environments provide very powerful tools for graphical programming and manipulation of complex geometric entities. In this thesis, we propose to exploit such potential in the design of parallel robots. These robots are considered an attractive and important alternative towards their serials counterparts in various applications, like “pick and place” and machining. However, their industrial applications are restricted due to limited workspace, complexity related to resolution of the direct geometric model, and in addition the existence of the singular configurations which bound their application field. The analysis and the characterization of the workspace therefore play an essential role in the design phase of parallel robotic manipulators. In this thesis, we suggest original geometric approaches giving rise to a set of methodologies and techniques based on the use of CAD in order to analyze and characterize the workspace of planar and spatial parallel robotic manipulators. Workspace is generated as a solid in CAD environment by using a parametric geometric model, sketches, and elementary operations such as helical scanning and performing then Boolean intersection operation. We have shown in this thesis, that the proposed methodologies represent relevant and efficient tools which assist designers of parallel mechanisms. Moreover, they allow us to solve the direct geometric problem and to plan singularity-free trajectories. Several types of robotic manipulators have been considered in this work to highlight and illustrate the proposed CAD / Geometric techniques : planar parallel manipulators having three degree of freedom such as 3-RPR, 3-RRR, 3-PPR, and 3-PRR, and spatial parallel robotic manipulators having six degree of freedom 3-CRS-type.
Computer Aided Design (CAD) technics for characterizing the workspace of parallel manipulators