Motor control device and image forming apparatus

A motor control device comprising:

• a motor control unit that controls a motor;
• and
• a signal output unit that outputs a signal according to rotation of the motor,
• wherein the motor control unit controls the motor based on an output signal of the signal output unit so that a driven object driven by the motor is displaced to a target stop position,
• wherein the motor control unit is configured to function as:
• a first control unit that performs a first motor control, in which an upper current limit, which is an upper limit of current applicable to the motor and is adjusted by current degradation caused by a counter-electromotive force, is estimated based on the output signal of the signal output unit, and in which a first control input corresponding to the estimated upper current limit is determined as a control input of the motor and then the motor is controlled based on the first control input;
• a second control unit that performs a second motor control, in which a second control input of the motor is determined based on both of at least one of a displacement amount and a speed, as an operated amount of one of the motor or the driven object, specified by the output signal of the signal output unit and an target trajectory of the operated amount and then the motor is controlled based on the second control input;
• a switching unit that enables the first control unit to perform the first motor control before a time point when a condition for start of the second motor control by the second control unit is satisfied and enables the second control unit to perform the second motor control, instead of the first control unit, after the time point when the condition for the start of the motor control by the second control unit is satisfied;
• a first calculating unit that calculates a displacement amount of the driven object from the time point of start of the motor control by the second control unit to the time point of stop of the driven object, as an amount necessary for stop, in case that the second control unit starts the controlling of the motor based on a standard target trajectory, which is determined based on both of the speed specified by the output signal of the signal output unit and elapsed time from a driving start time point of the driven object, wherein a time period from the driving start time point of the driven object to the driving stop time point of the driven object in the standard target trajectory is constant, and
• a second calculating unit that calculates a remaining displacement amount of the driven object to the target stop position, based on the displacement amount specified by the output signal of the signal output unit,
• wherein, when the remaining displacement amount calculated by the second calculating unit reaches the amount necessary for stop calculated by the first calculating unit, the switching unit determines that the condition for start of the second motor control by the second control unit is satisfied and then starts the second motor control of the second control unit, and
• wherein, when the second control unit starts the motor control, the second control unit determines the control input of the motor, based on both of the operated amount specified by the output signal of the signal output unit and the target trajectory corresponding to the standard target trajectory and then starts the second motor control based on the control input to stop the driven object at the target stop position.