Precise Velocity Control of a Hard Disk Drive

The ramp technology was integrated in the Hard Disk Drive a couple of years ago, this technology allows a safer parking position for the heads, but also allow the heads to fly closer from the media, increasing the data density. The Load and Unload operations need a precise velocity control of the Voice Coil Motor (VCM) to avoid permanent damage of the heads and the media. This velocity control has, of course, to be achieved without sensors