Abstract
We propose a mixed design of machine elements and control systems which aims at avoiding metal fatigue in two-inertia systems. On the basis of an elementary knowledge of material mechanics and machine design, we derive an allowable torsional angle of rotary shafts. Using the ciritical control design framework and the method of inequalities, we design both the diameter of shafts and a feedback controller so as to bound the torsional angle within the allowable value and achieve satisfactory closed-loop performance. An iterative design procedure using bisection algorithm and numerical nonlinear optimization is developed. We finally give a numerical example to evaluate the proposed mixed design method.
