Abstract: A methodology of the workspace analysis and dimensional synthesis is presented for a kind of orthogonal 6R manipulator, which can be used on the biological detection robot in dangerous environment, helps to guide the task space analysis and structural optimization for the manipulator. On the basis of structural topologies and inverse displacement analysis, the influence of the dimensional parameters and allowable joint ranges on the profile of reachable workspace is investigated, leading to an optimum combination of joints ranges and a fast calculation method for the task space of the manipulator, then a set of optimized structural dimensions is also obtained for the manipulator by maximizing the reciprocal of the condition number of homogeneously dimensionless Jacobian matrix, constructed by the characteristic length and the weighted Frobenius norm. The reachable workspace and task space of the manipulator are also provided. An example is given to illustrate the effectiveness of this approach, making the advantages of clear results and easy for solvers with the manipulator having optimized flexibility performance.

Key words: 6R manipulator, characteristic length, dimensional synthesis, workspace topologies, biological detection robot