Time optimal function generator for disk file magnetic recording head servo position control loop

In a control circuit for controlling a transducer in movement from one position to another, the improvement comprising a function generator for controling said movement wherein said function generator is adapted to receive an input signal representative of the instantaneous position of the transducer and the desired new position and has an output signal which is adapted to control movement of said transducer, wherein said function generator is comprised of:

• input signal means having first and second inputs for producing an output signal representative of electronic analog combination of signals received at said first and second inputs, wherein said first input signal is a signal representative of the difference between the instantaneous position of the transducer and the desired new position and wherein said second input signal is an internal reference voltage signal,
• summation amplifier means for receiving the output signal of said input signal means, said amplifier means producing an output signal which is the function generator output signal,
• an electronic analog multiplier having first and second input pairs, the positive terminal of said first pair being connected to the output of said function generator,
• a first and second resistor in series, said first resistor being connected to the output of said multiplier and said second resistor being connected to the negative terminal of said first input pair of said multiplier,
• operational amplifier means for receiving an input from the connection between said first and second resistor and providing an output to the positive terminal of said second input pair of said multiplier and to said second input of said input signal means as the internal reference voltage, and
• an external reference voltage source connected to said second resistor, the adjustment of said external voltage source causing an adjustment in the output signal amplitude of said function generator and wherein the output of said function generator contains a square root function of the input.