In robotics, static stiffness maps are used as tools for the performance analysis of robots employed in production tasks, such as pick-and-place or manufacturing. This paper evaluates the relevance of a numerical tool built from a commercial finite element package to generate stiffness maps for any type of robot (serial, parallel, hybrid or compliant). The key points are the spatial resolution, the precision, and the calculation time of a stiffness map. The method for obtaining the 36 static stiffness maps of a 3-D robotic structure in its operational space is presented. The mechanical model is based on a finite element calculation using beam elements for the links and spring elements for the joints. The approach is first applied to a rigid-body mechanism. Numerical results show that a good compromise can be obtained between spatial resolution, precision, and calculation time. Then, the method is applied to a compliant structure requiring processing in a large displacement framework for the relevant estimation of a stiffness map. The numerical tool opens new prospects for the design of robotic structures, in terms of both optimization and use of various material behaviors.

This paper presents the modeling of a new mini-invasive neurosurgical resection robot. This robot aims to help to remove brain tumors and is incorporated into a multi-robot neurosurgical system. We focus especially on the resection task. The robot is composed of three serial bending modules actuated by wires (cables) and uses an additional translation. The redundancy of the robot (seven degrees of freedom) allows more dexterity for the resection task. A kinematic (geometric) model is built distinguishing the structure and the actuation models, and integrating the influence of the wires into the kinematic behaviour of the robot. A method for kinematic redundancy handling is defined and assigns different parts of the robot to different tasks. An interactive path planning based on arbitrary sequence of elementary procedures assembled by the neurosurgeon is proposed and the yielding procedures are computed from the kinematic model.