Method for measuring driving amount of motor and apparatus therefor

An apparatus for measuring a driving amount of a motor, comprising:

• an encoder of an increment type mounted on a driving shaft of the motor and putting out driving amount pulses of the number corresponding to a driving amount of the motor;
• a counter counting the number of the driving amount pulses on the basis of an origin of the motor to detect a relative driving amount of the motor;
• an absolute driving amount detector detecting an absolute driving amount of the motor;
• a sampling command output circuit putting out a driving amount sampling command signal at each predetermined interval of the driving amount pulses;
• a coefficient and constant calculating circuit for sampling the relative driving amounts and the absolute driving amounts in response to the respective driving amount sampling command signals and obtaining coefficient and constant of at least one linear approximate equation representing the relation between the relative driving amount and the absolute driving amount from the respective sampled relative and absolute driving amounts;
• a non-volatile memory for the coefficient and constant of the linear approximate equation obtained in the coefficient and constant calculating circuit therein;
• and
• a present driving amount setting circuit for obtaining a relative driving amount of the motor at a starting time of the motor in a sampling position from the coefficient and constant read out of the non-volatile memory and an absolute driving amount sampled in response to the driving amount sampling command signal when the motor is driven from a present rotational position of the motor up to the sampling position near the present rotational position, and setting the relative driving amount of the motor at the starting time in the counter.

An apparatus for measuring a driving amount of a motor, which comprises:

• an encoder of an increment type mounted on a driving shaft of the motor and putting out driving amount pulses of the number responding to the driving amount of the motor;
• a counter counting the number of the driving amount pulses put out from the encoder on the basis of a reference pulse of the driving amount pulses corresponding to an origin of the motor to detect a relative driving amount of the motor;
• a potentiometer connected to the driving shaft of the motor through a reduction gear and putting out an absolute driving amount of the motor;
• an absolute driving amount detector detecting absolute driving amount put out from the potentiometer;
• an A/D converter converting the absolute driving amount put out from the absolute driving amount detector to a digital signal;
• a sampling command output circuit putting out a driving amount sampling command signal at a predetermined interval of the driving amount pulses on the basis of the reference pulse put out from the encoder;
• a coefficient and constant calculating circuit for sampling the relative driving amounts and the absolute driving amounts converted to the digital signal to obtain coefficient and constant of at least one linear approximate equation representing the relation between the relative driving amount and the absolute driving amount from the relative and absolute driving amounts in response to the driving amount sampling signals put out from the sampling command output circuit;
• a non-volatile memory storing the coefficient and constant of the linear approximate equation put out from the coefficient and constant calculating circuit comprising a core memory;
• a position command signal output circuit putting out a position command signal for driving the motor in response to a stop signal put out from the sampling command output circuit simultaneously with the output of the driving amount sampling signal therefrom;
• a comparator obtaining a deviation between the relative driving amount put out from the counter and the position command signal put out from the position command signal output circuit;
• a D/A converter converting the compared output from the comparator to an analog signal;
• a driver driving the driving shaft of the motor from a present rotational position of the motor to a sampling position near the present rotational position at the starting time of the motor, in response to the compared output of the comparator converted to the analog signal;
• and
• a present driving amount setting circuit obtaining a relative driving amount of the motor at a starting time of the motor in the sampling position from the coefficient and constant read out of the non-volatile memory and an absolute driving amount sampled in response to the driving amount sampling command signal when the motor is driven from a present rotational position of the motor up to the sampling position near the present rotational position, and setting the relative driving amount of the motor at the starting time in the counter.