A procedure to analyse and compare the sensitivity to geometrical parameter variations of one-dof mechanisms

Sensitivity analysis to geometrical parameter variations aims at assessing how small changes in a mechanism parameters, for instance due to tolerances and clearance, can alter its nominal motion. This issue is very important for the characterization of a mechanism and has been widely addressed in the literature, but it needs further investigations. The high number of parameters characterizing the problem and their mutual influence indeed make it difficult to assess the sensitivity from a global point of view. In this paper, a procedure is presented to characterize and evaluate the sensitivity of one-degree-of-freedom mechanisms. As an example, such a procedure is applied on two mechanisms which are the basis to design knee prosthetic devices. In this context, sensitivity analysis is important to understand how the motion generated by a prosthetic device can be influenced by small variations of its geometry or by small misalignments during the installation phase on the patient.