Variational approach for robust design and sensitivity analysis of mechatronic systems

The behavior of mechatronics systems has a very complex inter-relation between several components, depending on the magnitudes of their parameters and variables. To ensure a certain level of quality and to improve design robustness, the deviations between actual and target definition should be restricted by specified tolerances. The upper and lower limits of these values must be wisely determined. Moreover, the deviation margin of variables should be controlled to evaluate system performance in regard to the specifications, requirements and user needs. In this paper, a variational approach is used to evaluate the impact of parameters' deviation on the system behavior. It consists of defining the relationship between parameters' tolerances and variables' fluctuations. This method helps designers to identify the sensitivity of system performances to parameter variations and can, thus, help the designer to attain a compromise between system performance and manufacturing cost in mechatronic systems. The proposed methodology is explained with an example in the aeronautic field, namely an electromechanical actuator driving an aileron which is an aircraft primary flight control surface. This method is general and it can be adapted for other mechatronic systems. The results show that the proposed method affords a new way for determining mechatronic tolerances.