Load to Motor Inertia Mismatch: Unveiling The Truth

This paper addresses the issue of inertia mismatch from a theoretical and practical standpoint. Fundamentally, power transmission is optimized in a mechanical system if the load inertia matches the motor inertia. This may, or may not be practically implemented with gearing between motor and load. Gearing inertia, inefficiency, mechanical limits, and cost all factor into the decision as to whether power transfer should be optimized. From a practical viewpoint, large inertia mismatches between load and motor can play havoc on the stable operation of a servo system. This is most pronounced when there is lost motion or compliance between motor and load. Consideration must be made for the type of mechanism being driven, and the practical allowable limit for inertia mismatch. For example, the tolerable limit of inertia mismatch is much higher for a direct driven stiffly coupled load compared to that of a load coupled by a belt or chain drive.