POSITION TRACKING SERVO CONTROL SYSTEMS AND METHODS

The invention is a transducer carriage servo control system and subsystem for a data disk storage system providing markedly improved carriage response time and positioning accuracy. The servo control system uses for feedback control a position error signal having an amplitude dependent at all times upon the amplitudes of both of a pair of normal and quadrature signals indicating actual carriage position. Moving and stationary control is provided through a reference position generator held at a stationary value for stationary (track following) control and incrementally changed for movement control during an access mode of operation. A velocity profile function generator is used to control the incrementation of the reference position in the generator at a nominal modeled velocity rate. Feedback control of incrementation is also provided by the position error signal converted to a velocity error signal through a voltage controlled oscillator. The incrementing system includes a motor adaptive circuit measuring distance moved during an acceleration portion of an access operation and comparing the distance displaced with a predetermined value to further vary the frequency of the velocity error signal, thereby adjusting the modeled servo control system to actual system performance. The motor adaptive circuit is employable with other servo systems utilizing a signal having a variable characteristic for feedback control.