A method and a circuit arrangement is described by means of which a stepper motor can be operated by an adaptive control over a large rotational speed range, including a standstill, in which the motor is electrically fixed in a specific rotational position, and with high precision and running smoothness corresponding to a specified motor current course. This is achieved essentially by the fact that the motor is operated in a low rotational speed range including a standstill with a voltage-controlled or voltage-regulated first operating mode and in a higher or high rotational speed range with a current-controlled second operating mode.

A method and a circuit arrangement is described by means of which a stepper motor can be operated by an adaptive control over a large rotational speed range, including a standstill, in which the motor is electrically fixed in a specific rotational position, and with high precision and running smoothness corresponding to a specified motor current course. This is achieved essentially by the fact that the motor is operated in a low rotational speed range including a standstill with a voltage-controlled or voltage-regulated first operating mode and in a higher or high rotational speed range with a current-controlled second operating mode.

A first differential amplifier output drives a first winding of a stepper motor and a second differential amplifier output drives a second winding of the stepper motor. Inputs of the first and second differential amplifiers receive input drive signals generated by either a digital to analog converter or a pulse width modulator, where the input drive signals are phase offset sinusoids. Current flowing through a stepper motor winding is sensed to generate a current sense signal. A stall sensing circuit processes the current sense signal to determine whether the stepper motor has stalled by: taking a first derivative of the current sense signal to generate a first derivative signal; taking a second derivative of the current sense signal to generate a second derivative signal; and processing one or more of the current sense signal, the first derivative signal and the second derivative signal to detect a stepper motor stall condition.

In an indicating-needle type meter device, when starting excitation of a stepping motor, a controller sets the phase of an excitation signal to a predetermined excitation start position and returns the phase of the excitation signal by a predetermined reversal angle such that an indicating-needle rotates in the backward direction, thereby positioning the indicating-needle at a stopper position. Subsequently, the controller advances the phase of the excitation signal by an origin return angle to rotate the indicating-needle in the forward direction to an origin position apart from the stopper position by a predetermined angle, thereby positioning the indicating-needle at the origin position. Here, the origin return angle is an angle obtained by adding a backlash angle, a predetermined positive pre-offset angle, and a positive placing error correction angle set based on a placing error of the indicating-needle with respect to the stopper.

In an indicating-needle type meter device, when starting excitation of a stepping motor, a controller sets the phase of an excitation signal to a predetermined excitation start position and returns the phase of the excitation signal by a predetermined reversal angle such that an indicating-needle rotates in the backward direction, thereby positioning the indicating-needle at a stopper position. Subsequently, the controller advances the phase of the excitation signal by an origin return angle to rotate the indicating-needle in the forward direction to an origin position apart from the stopper position by a predetermined angle, thereby positioning the indicating-needle at the origin position. Here, the origin return angle is an angle obtained by adding a backlash angle, a predetermined positive pre-offset angle, and a positive placing error correction angle set based on a placing error of the indicating-needle with respect to the stopper.

An object of the present invention is to prevent unnecessary driving stop of a stepping motor. A robot arm section includes a robot arm, a stepping motor 31a, a motor driver 31b, an encoder 31c and a step-out detection section 31e. The robot arm has a joint J1. The stepping motor generates power for operating the joint. The motor driver drives the stepping motor according to a target angle. The encoder outputs an encoder pulse every time a drive shaft of the stepping motor rotates by a predetermined angle. The step-out detection section detects a step-out of the stepping motor based on the target angle and a current angle of the stepping motor that is identified based on the encoder pulse. When the stepping motor does not recover from the step-out before a predetermined grace time elapses from a time at which the step-out is detected, the motor driver stops driving the stepping motor at the time point at which the grace time elapses.

An object of the present invention is to prevent unnecessary driving stop of a stepping motor. A robot arm section includes a robot arm, a stepping motor 31a, a motor driver 31b, an encoder 31c and a step-out detection section 31e. The robot arm has a joint J1. The stepping motor generates power for operating the joint. The motor driver drives the stepping motor according to a target angle. The encoder outputs an encoder pulse every time a drive shaft of the stepping motor rotates by a predetermined angle. The step-out detection section detects a step-out of the stepping motor based on the target angle and a current angle of the stepping motor that is identified based on the encoder pulse. When the stepping motor does not recover from the step-out before a predetermined grace time elapses from a time at which the step-out is detected, the motor driver stops driving the stepping motor at the time point at which the grace time elapses.

A pulse generation unit is configured to output pulse signals for driving the stepping motor. A control unit is configured to perform acceleration control or deceleration control of the stepping motor via the pulse generation unit. The control unit is configured to calculate a number of the pulse signals to be output from the pulse generation unit to the stepping motor when accelerating or decelerating the stepping motor at constant acceleration in the acceleration control or the deceleration control based on an initial speed of the stepping motor when the acceleration control or the deceleration control starts, a target rotation speed, and time from start control of the stepping motor to time when the stepping motor reaches the target rotation speed, and change a rotation speed of the stepping motor in the acceleration control or the deceleration control along a sinusoidal waveform.

A method and a circuit arrangement is described by means of which a stepper motor can be operated by an adaptive control over a large rotational speed range, including a standstill, in which the motor is electrically fixed in a specific rotational position, and with high precision and running smoothness corresponding to a specified motor current course. This is achieved essentially by the fact that the motor is operated in a low rotational speed range including a standstill with a voltage-controlled or voltage-regulated first operating mode and in a higher or high rotational speed range with a current-controlled second operating mode.

A method and a circuit arrangement is described by means of which a stepper motor can be operated by an adaptive control over a large rotational speed range, including a standstill, in which the motor is electrically fixed in a specific rotational position, and with high precision and running smoothness corresponding to a specified motor current course. This is achieved essentially by the fact that the motor is operated in a low rotational speed range including a standstill with a voltage-controlled or voltage-regulated first operating mode and in a higher or high rotational speed range with a current-controlled second operating mode.