A method for improving the resolution of active and passive balancing schemes for disc drives

Abstract

Some of the current imbalance compensation methods used in hard disk drives are based on using fixed compensating masses that are placed at uniformly spaced angular positions. Several masses of predefined fixed weights are placed at predefined angular positions and algorithms are used to choose the best combination of masses and their locations in order to compensate the imbalance. The main disadvantage of using uniformly distributed locations for the placement of compensating masses is that some of the possible combinations may be overlapping and the distribution of all resulting compensations is not uniform. This reduces the resolution of the balancing algorithms. This article proposes a novel method for finding the optimal angular distribution of locations that are used for the placement of compensating masses. The method finds such a distribution of the locations that there are minimum overlapping combinations and hence almost all possible compensations are utilized. Furthermore, it optimizes the distribution of all possible compensations and thus results in significant improvement in the resolution of balancing algorithms.