Hitachi, Ltd.

Hitachi Keiyo Engineering Co., Ltd.

Hitachi Keiyo Eng. Co., Ltd.

Hisakazu Ninomiya

Hiroshi Nagase

Hiroyuki Tomita

Hiroshi Sugai

Satoshi Ibori

Sumio Kobayashi

Sadayuki Igarashi

Yasuo Matsuda

Koichi Sugimoto

Toshihiko Sakai

Kyozo Tachibana

Hisaaki Hirabayashi

Kazuyuki Nakagawa

Masataka Yahara

Tadashi Ookawa

Jyun Mochizuki

Masaharu Muramatu

The present invention relates to a control system for a servomechanism device such as robot, and more particularly to a position correcting control system for a servomechanism device which is well suited to perform high-precision positioning or high-perfomance operations on the basis of a sensor feedback control system such as force detection feedback control. It is characterized in that a plurality of algorithms for correcting a position target value on the basis of a sensor signal are prepared and are switchedly used so as to readily switch functions, depending upon whether the purpose of a sensor control is a high-precision control or any other high-performance control, that the position target value is corrected through a threshold characteristic element or a dead band element so as to make effective the correction of the position target value based on the sensor signal, and that a correcting signal is applied through a response lag element so as to attain stabilization owing to a viscous effect bestowed on the position correcting operation based on the sensor signal.

Position correcting control system for servomechanism device

A fixed slit plate and a rotary slit plate which is secured to a rotating shaft are provided between two photoconductive elements and a light emitting element, and the two photoconductive elements provide two outputs which have the phase difference .pi. therebetween. These two outputs thus provided are added to extract the dc component, thereafter exerting feedback control over the light emitting element such that this dc component is maintained at a constant level.

Rotational information output device

A system consisting of a motor that drives a load, an analog signal generator that outputs an analog signal which increases as the motor is accelerated, a speed commander that determines a motor speed and commands the motor to operate at the determined speed, and an energizing circuit that receives signal representing difference between the output from the speed commander and the output from the analog signal generator and that energizes the motor so as to operate at the speed in accordance with the signal for the difference is provided with a pulse generator that outputs a pulse corresponding to the current motor speed and with a control circuit that controls the signal for the difference in such way that when the motor is operated at a low speed at which the interval of pulses output from the pulse generator becomes long the signals for the difference issued during a pulse interval sequentially increase. With the aforementioned structure of the systen, during extremely low speed motor operation during which the generated pulse interval becomes long the energizing circuit acts in the direction of increasing motor speed in the course of a pulse interval, thereby enabling the system itself to constitute a load drive apparatus having superior operating performance characteristics without any anxiety about abnnormal reduction of motor speed or motor stop in the worst case.

Load drive apparatus

An AC motor such as an induction motor or a synchronous motor is driven by a PWM inverter. Turn-on of the PWM inverter is controlled by PWM pulse signals obtained as a result of comparison between voltage command signals (a modulation signal) and a carrier wave signal. The voltage command signals are obtained as a function of errors between current command signals and detected current signals. Ripples included in the voltage command signals are so suppressed as to be decreased as the rotation speed of the AC motor becomes lower. By so suppressing the ripples, the level of noise generated from the motor can be reduced especially when the motor operates in a low-speed rotation range.

Method and apparatus for controlling PWM inverter

A control apparatus for an induction motor wherein an inverter is connected between a power source and the induction motor so as to energize the induction motor through the inverter, characterized in that when an input voltage of the inverter has lowered, a magnetizing current component command is decreased, while a torque current component command is increased.

Control apparatus for induction motor

When driving an AC motor with a PWM inverter, the width of a speed command signal is modulated by a carrier to produce width modulated pulses for controlling main switching elements. The width modulated pulses are liable to be attended with impulses which cause magnetic vibrations in the AC motor, resulting in noises. The generation of these impulses can be suppressed by changing the amplification factor of an amplifier for the speed command signal or the amplitude of the carrier on the basis of the rate of change of the speed command signal. Noises which would be attendant on low speed running of the AC motor can be reduced by changing the amplification factor of the amplifier and the amplitude of the carrier on the basis of detected frequency of the speed command signal or revolution of the AC motor during low speed running.

Control apparatus for AC motors

Disclosed is a control apparatus for an AC motor which is driven by a power converter constituted by switching elements. A current control circuit turns on/off the switching elements in accordance with a current pattern signal in the form of an AC signal to thereby control the motor current. The current pattern signal is obtained by a current pattern calculating circuit based on a current command signal and a sinusoidal signal which determines the current phase. A current correction signal proportional to the deviation of the motor current from the current command signal is obtained by a current correction control circuit and added to the current command signal to be applied to the current pattern calculating circuit.

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Funabashi, Japan

Hisakazu Ninomiya