Improved discrete proximate time optimal controller of a disk drive actuator

An important relationship between the acceleration discount factor and the closed loop control poles in a discrete Proximate Time Optimal Servo (PTOS) design has been established. This result enables the PTOS seek and tracking controllers to be designed and optimized independently without being constrained by boundary conditions. During subsequent merging, smooth transition from seek to tracking is obtained by linear, time shrinking of the boundary layer closer to the target track. The proposed controller is applied to R/W head actuation in a hard disk. Significant improvement in head settling is observed compared to conventional PTOS, specifically for longer seeks