Digital servo system for obtaining by calculation a control signal corresponding to a desired value on the basis of the change of a control signal and a controlled signal

A digital servo system for obtaining by calculation a control signal corresponding to a target value of control on the basis of a change of the control signal and a change of a controlled signal, the system comprising:

• control means for outputting the control signal;
• digital-to-analog converting means for effectuating digital-to-analog conversion of the control signal from the control means and outputting a converted control signal;
• controlled means, to be controlled by inputting the converted control signal from the digital-to-analog converting means, for outputting the controlled signal representing a state of the controlled means controlled by the inputted converted control signal;
• and
• analog-to-digital converting means for effectuating analog-to-digital conversion of the controlled signal and outputting a converted controlled signal;
• the control means receiving the converted controlled signal from the analog-to-digital converting means and outputting the control signal;
• the control means comprising:
• signal detecting means for detecting at least two instances of the converted controlled signal obtained from the analog-to-digital converting means by sequentially outputting at least two different instances of the control signal to the digital-to-analog converting means;
• learning means for obtaining a first difference, Delta.sub.-- DA, between the at least two instances of the control signal and a second difference, Delta.sub.-- AD, between the at least two instances of the converted controlled signal detected by the signal detecting means, and obtaining a relation between the control signal and the controlled signal by calculating Delta.sub.-- DA/Delta.sub.-- AD, the relation between the control signal and the controlled signal being a linear relation;
• and
• target control signal calculating means for calculating a value of the control signal corresponding to a predetermined value of the controlled signal which is the target value of control of the servo system as a function of the predetermined value of the controlled signal, the relation between the control signal and the controlled signal obtained by the learning means, and the value of one of the at least two instances of the converted controlled signal.