Prediction of position error signal of a hard disk drive undergoing a long seek

Abstract

To expedite design cycles and to evaluate performance of designed hard disk drives, mathematical models to predict position error signal (PES) are needed. Existing mathematical model can successfully predict PES during track following. However, there is no computational efficiency approach to predict PES after a long seek presently. In this paper, we presents a feasible mathematical model to achieve this purpose. Detail mathematical derivations and numerical simulations are also included in this paper. Our mathematical models are capable to obtain reasonable qualitative predications after a long seek.

Position Error Predictions of a Hard Disk Drive Undergoing a Large Seeking Motion With Shock Excitations

“…For the simulations presented in this paper, the seeking profile starts at the outer rim, accelerates, coasts, decelerates, and settles on the target track at the inner rim. In the PES model of Wu et al [17], the seeking profile is discretized into many angular increments (Fig. 6) to calculate stiffness, damping, and mass coefficients of the HDD system at different stages of the seeking motion.…”

“…4. After its natural frequencies and mode shapes are calculated, 100 modes are retained for the PES model [17].…”

“…The four air bearings are modeled as linear springs with stiffness N/m. To incorporate the shock excitations into the existing PES model [17], we adopt the large-mass approach often used in finite element analyses as follows. First, the stationary part is attached to a large rigid block, whose mass is 1000 times of the entire HDD; see Fig.…”

“…Based on this reasoning, Wu et al [17] developed a mathematical model using component-mode synthesis to predict settling PES of an HDD in a long seeking-and-settling process. The basic configuration is similar to that of Eguchi and Nakamiya [14] except that the HSA can seek according to an arbitrarily seek profile that is assumed known a priori (e.g., specified by users).…”

“…To predict settling PES resulting from a prior shock during a large seeking motion, we modify the PES model by Wu et al [17] using a large-mass method. Although stray magnetic forces are important factors affecting settling PES [18], [19], they will not be considered in this analysis in order to manifest the effects of external shocks.…”