Design of kinematically-redundant two-module robots

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When precise positioning is needed (as in a machine tool, or in an alignment table), parallel robots are a choice of predilection due to their high rigidity. However, one of the major disadvantages of parallel robots is their relatively small workspace, which is further limited by the presence of so-called Type 2 singularities. When a parallel robot is close to a Type 2 singular configuration, its ability to withstand loads with its end-effector is significantly compromised. Because of these singularities, very few companies have managed to come up with innovative designs and most stick to the popular hexapod, which is often overdesigned (e.g., too big) for the application at hand.*** The divide-and-concur strategy is promising for achieving affordable high-accuracy robot systems. Instead of designing a single n-degree-of-freedom (n-DOF) parallel robot, the applicant would opt for the use of two separate robots, one with i DOFs aimed at manipulating the tool (possibly being a serial robot) and another with j DOFs for holding the workpiece. Furthermore, this two-module robot system will be kinematically redundant, which means that the sum of i and j will be greater than n.**** The main idea behind the proposed research program is to use a combination of two robots (at least one of which is parallel) with one or two degrees of kinematic redundancy, i.e., i + j = n + 1 or i + j = n + 2, in order to completely eliminate problems with singularities. The first objective of the proposed program is therefore to develop a systematic approach for analysing the geometric conditions leading to kinematically redundant designs with large workspace and singularity manifolds of reduced dimension. Particular attention will be paid to lower-mobility spatial parallel mechanisms with mixed DOFs, which have proven to be an excellent choice for machine tools. The second objective will be designing secondary modules for existing serial and parallel robots. Finally, the third objective will be the development of novel low-cost automated calibration techniques for these two-module robots.*** **