Method and apparatus for reducing track misregistration due to digital-to-analog converter quantization noise

A actuator system, comprising:

• a voice coil motor being driven by a digital-to-analog converter;
• a processor providing a control signal for controlling the voice coil motor, the control signals each having a precision of a first predetermined number of bits further comprising a first group of most significant bits and at least one least significant bit;
• and
• a quantization error feedback circuit for reducing a control error of a servo loop due to quantization noise of the digital-to-analog converter driving the voice coil motor, the quantization noise resulting from the digital-to-analog converter having a lower precision than the processor driving the digital-to-analog converter, the quantization error feedback circuit providing control signals for controlling a plant, the control signals each having a precision of a first predetermined number of bits further comprising a first group of most significant bits and at least one least significant bit, accumulating the at least one least significant bit until a new most significant bit is generated, adding the new most significant bit to a first group of most significant bits to generate a modified plant control signal and providing the modified plant control signal to the plant to control operation of the plant.

A data storage system, comprising:

• a data storage disk;
• a motor for rotating the data storage disk;
• and
• an actuator system for moving a transducer relative to the rotating data storage disk, the actuator system further comprising:
• a voice coil motor being driven by a digital-to-analog converter;
• a processor providing a control signal for controlling the voice coil motor, the control signals each having a precision of a first predetermined number of bits further comprising a first group of most significant bits and at least one least significant bit;
• and
• a quantization error feedback circuit for reducing a control error for a servo loop due to quantization noise of the digital-to-analog converter driving the voice coil motor, the quantization noise resulting from the digital-to-analog converter having a lower precision than the processor driving the digital-to-analog converter, the quantization error feedback circuit providing each of the first group of most significant bits to the voice coil motor to control operation of the voice coil motor, accumulating the at least one least significant bit until a new most significant bit is generated, and adding the new most significant bit to a first group of most significant bits before being provided to the voice coil motor.

An article manufacture for reducing track misregistration due to quantization noise of a digital-to-analog converter driving a plant in a servo loop, the quantization noise resulting from the digital-to-analog converter having a lower precision than a processor driving the digital-to-analog converter, the article of manufacture comprising a computer readable medium having instructions for causing a computer to perform a method comprising:

• providing control signals for controlling a plant, the control signals each having a precision of a first predetermined number of bits further comprising a first group of most significant bits and at least one least significant bit;
• accumulating the at least one least significant bit until a new most significant bit is generated;
• adding the new most significant bit to a first group of most significant bits to generate a modified plant control signal;
• and
• providing the modified plant control signal to the plant to control operation of the plant.

A data storage system, comprising:

• a data storage disk;
• a motor for rotating the data storage disk;
• and
• an actuator system for moving a transducer relative to the rotating data storage disk, the actuator system further comprising:
• a voice coil motor being driven by a digital-to-analog converter;
• a digital signal processor providing a control signal for controlling the voice coil motor, the control signals each having a precision of a first predetermined number of bits further comprising a first group of most significant bits and at least one least significant bit, wherein the processor reduces a control error for a servo loop due to quantization noise of the digital-to-analog converter driving the voice coil motor, the processor accumulating the at least one least significant bit until a new most significant bit is generated, and adding the new most significant bit to a first group of most significant bits before being provided to the voice coil motor.