A Simplified 4-DOF Suspension Model for Dynamic Load/Unload Simulation and Its Application

Abstract

The mathematical models are critical for accurate simulation of the dynamic load/unload (L/UL) process in disk drives. The air bearing slider and the suspension are the most important parts in the L/UL mechanism. The air bearing modeling has been well researched, but an adequate and efficient suspension model is not available. A simplified 4-DOF suspension model is proposed in this paper. In this model the slider’s pitch angle change due to the motion of the L/UL tab on the ramp is included in the simulation, and the forces applied by the ramp can be directly obtained. The effects of the suspension inertia are included in the effective inertia moments of the slider to improve the loading simulation. The model is implemented and applied to simulate the L/UL process of a pico slider that has been used in recent IBM mobile drives. The effects of the pitch static attitude (PSA), the roll static attitude (RSA), and some initial disturbances to the loading process are investigated. It is found that a positive PSA can significantly smoothen the loading process. The effects of the PSA, the disk rpm, and the unload velocity on the unloading process are also simulated, and it is found that a positive PSA can also greatly improve the unloading performance of the slider. The results show that the unloading process can be accurately simulated by using the proposed model, and the loading process can be more accurately simulated by using this 4-DOF model than the 3-DOF model. [S0742-4787(00)03601-8]