Identifying the stiffness and damping parameters of a linear servomechanism

A direct procedure is proposed for identifying the joint parameters in a linear servomechanism with multiple joints. The linear dynamical equations of a mechanical system with gains from feedback sensors are derived. The Bode graphs are used to compare the experimental and analytical models to identify the stiffness and damping coefficients. Sensitivity techniques are applied to reduce the discrepancies in the frequency responses of the output in analytical and experimental models. The joint parameters are then identified. An industrial servomechanism with multiple joints, in which a payload is driven by a mechanism that consists of a motor, a ball screw, gears, linkages, and a feedback sensor, is used to demonstrate the utility of the proposed procedure. The values of five stiffness and six damping parameters for the joints of this servomechanism were identified successfully by this procedure. The identified joint parameters were also verified in a different operating condition of the servomechanism.