| dc.description.abstract | Several studies have shown that mechanisms with Remote Center of Motion (RCM) are very useful for some medical applications, such as Minimally Invasive Surgery or tele-echography. In these applications, medical devices or instruments are being rotated around a point that is called the Center of Rotation (CoR). In both cases however, it is necessary to control the position of the CoR of the manipulated object, either during the process, or as a preliminary adjustment. But most RCM mechanism are unable to reposition the CoR of their end effector. A simple solution to this issue is to mount them on a platform that provides linear motions. However, this conceptual design suffers from a significant increase in volume and weight.
By the mean of reconfigurable mechanisms, the present study suggests a more compact, lighter and possibly cheaper alternative. In this regard, a new concept of Spherical Reconfigurable Linkage (SRL). Classical spherical architecture mechanisms rely on spherical linkages which are known for constraining the CoR by the intersection of their revolute joint axes. In the present concept, the SRL has been specifically imagined to change its radius while maintaining its joint axes, in order to reposition the mechanism CoR by themselves, thus suppressing the need for an additional linear platform.
Following the conceptual definition of the SRL, its kinematic analysis is provided to find the relationship between its reconfiguration and the resulting CoR motion. A prototype is then designed and fabricated to test the feasibility of such concept. Using the SRL, a Spherical Parallel Mechanism (SPM) with two angular Degree of Freedom (DoF), which is classically mounted as 5-bar Spherical Linkage is improved into a new mechanism capable of displacing its CoR with two additional linear DoF. After defining the architectural modification required for the integration of the SRL, its kinematic and velocity models are studied. | en_US |