Abstract: A position control apparatus has a variable gain-type velocity amplifier (115) provided within a servo control circuit, and a low velocity sensing circuit (114) for sensing a predetermined low velocity of a motor (100) immediately before the motor is stopped. When the rotational velocity of the motor (100) drops to the predetermined low velocity immediately before stoppage during orientation control, the velocity amplifier is changed over in response to a signal from the gain of the low velocity sensing circuit (114), thereby raising servo loop gain.

Abstract: An AC motor control apparatus having a first arithmetic device (3) which calculates an amplitude command based on a difference between the commanded velocity and the actual velocity of the AC motor (1), and delivers the amplitude command and a current command in at least one phase as outputs. Also included is a second arithmetic device (10) which calculates a pulse width command in each phase from the amplitude command and current command from the first arithmetic device (3) and the actual phase current of the AC motor (1). A timer (11) produces as an output, a pulse-width modulated signal in each phase on the basis of the pulse-width command from the second arithmetic device (10), and an inverter (8) drives the AC motor in accordance with the pulse-width modulated signals from the timer (11).

Abstract: A speed detecting apparatus having a detector (101) for generating two sine-wave signals (PA, PB) which are .pi./2 out of phase with each other and have a frequency proportional to the speed of rotation of a motor so that actual-speed voltages (V.sub.L, V.sub.H) can be produced which are proportional to the speed of rotation of the motor. The speed detecting apparatus includes a quadrupling circuit and a frequency-to-voltage converter 107. Also included is a first speed generator for generating the actual-speed voltage (V.sub.H) in a high-speed range and a second speed generator which includes a four-phase rectangular signal generating circuit (106), a differentiating circuit (109), and a synchronous rectifier circuit (110) for producing the actual-speed voltage (V.sub.L) in a low-speed range. The voltages generated by the first and second speed generators are selectively issued as an output depending on whether the motor rotates at a high speed or a low speed.

Abstract: Disclosed is an induction motor drive apparatus which produces three-phase current commands using a speed error (ER) between a speed command and an actual speed (n) for driving an induction motor (10) on the basis of the current commands. The induction motor drive apparatus receives the speed error (ER) and the actual speed (n) as input signals and generates, through digital processing, a first phase sinusoidal signal and a second phase sinusoidal signal shifted by 2.pi./3 from the first phase sinusoidal signal. The first and second sinusoidal signals are used for generating a phase current (i.sub.w) in a first and second phase currents (i.sub.u, i.sub.v) which are in turn used to generate a third phase current (i.sub.w) such that the first, second and third phase current commands will have a sum equal to zero.

Abstract: During operation of a machine tool, a motor 14 driving a spindle 17 holding a tool 18 is operated at a commanded speed by a speed control system in accordance with a speed command signal VCMD with the feedback of an actual speed signal TSA. As a stopping command ORCM is issued for stopping the spindle, the spindle is decelerated to a predetermined speed in response to a reference signal output from a constant voltage generating circuit 33. After the deceleration of the spindle to the predetermined speed, as the rotational position of the spindle comes into a region within 180.degree. from a predetermined position, a position offset signal PS', which smoothly crosses the zero level at the position at which the spindle is to be stopped, and which is generated from two signals e.sub.1 and e.sub.2 from a resolver connected to the spindle.

Abstract: A method of controlling an AC motor which exhibits a constant torque characteristic at a rotational speed N below a base speed Nb and a constant output characteristic at a rotational speed N above the base speed Nb, comprising the steps of finding a base speed N.sub.L after limiting the output power of the AC motor, N.sub.L being derived from the base speed Nb and the ratio .eta. between maximum output power Pmax.sub.1 and maximum output power Pmax.sub.2 before and after the output power of the AC is limited, respectively, rendering the slip frequency of the AC motor constant until the rotational speed N of the AC motor reaches the base speed N.sub.L, varying the slip frequency in inverse proportion to the rotational speed N for N between N.sub.L and Nb (N.sub.L <N.ltoreq.Nb), and varying the slip frequency in proportion to the rotational speed N for N above Nb (Nb<N), whereby the output power of the AC motor is rendered constant at a rotational speed N above N.sub.L.

Abstract: A speed control circuit and position control circuit are connected to a spindle drive motor in a machine tool or the like in order to drive the spindle at a predetermined speed and stop the spindle at a predetermined angular position. When an orientation command is issued while the spindle is being rotated at the predetermined speed by a speed control loop, a speed command signal from a speed command circuit is interrupted, the speed reduced to zero, and an initially set voltage is then employed as a speed command to rotate the spindle by a predetermined amount. Next, a integral value of the actual spindle speed is employed as the speed command to further rotate the spindle by a predetermined amount. When this has been accomplished, a constant bias voltage of a low level replaces the speed command, thereby to rotate the spindle still further by a predetermined amount until a specified portion of the spindle approaches extremely close to the predetermined angular position.

Abstract: In a memory protection system for a computer, memory protection information provided for each of the memory areas of a memory and memory protection information provided for each of the programs executed by a processor are collated to determine allowance/inhibition of access to the memory. By detecting that an instruction to be executed is an instruction having a particular operation and that an address of the memory to be accessed by the instruction is a particular address, the memory protection information for the program executed by the processor is alterd to allow the memory access. The alteration of memory protection information is carried out with no intervention of a control program.

Abstract: A control circuit for stopping a spindle at a predetermined rotational position, of the type having a position sensor for producing a zero volt signal when a specified point on the spindle arrives at the predetermined rotational position, and for producing a voltage which is positive or negative when the specified point on the spindle is in the vicinity of the predetermined rotational position on either the left or right side thereof. The control circuit includes an orientation control circuit for stopping the spindle drive motor when the output signal from the position sensor attains the value of zero volts, thereby stopping the specified point on the spindle at the predetermined rotational position. The control circuit further includes a position adjustment circuit for adjusting the rotational position, of the specified point on the spindle, at which the output signal from the position sensor crosses the zero volt line.

Abstract: A system for stopping a spindle, which is provided in a machine tool, in such a manner that a specified point on the spindle is stopped at a predetermined rotational position. The system includes device for detecting the direction of spindle rotation. When the spindle arrives at a region where it is to be controlled in order to stop at the predetermined rotational position, a position deviation signal is applied as the input signal of a speed control loop for controlling the rotation of the spindle. This signal turns the specified point on the spindle to the predetermined rotational position, in the same direction in which the spindle is rotating, on the basis of the direction signal from the detecting means. That is, the specified point on the spindle is rotated to the predetermined rotational position in a direction which is the same as the direction of rotation during tool operation.

Abstract: A spindle orientation control system having a speed control circuit and a position control circuit for rotating the spindle of a machine tool at a commanded speed and for stopping the spindle at a designated position with a high accuracy, the speed control circuit decelerating the spindle drive motor on the basis of a spindle stopping command. When a predetermined speed has been attained, a counter contained in the position control circuit is triggered by a one-revolution pulse generated whenever the spindle makes one full revolution, whereby the counter begins to count up position pulses which are generated whenever the spindle rotates by a predetermined angle. After a preset predetermined number of pulses have been counted, operation shifts from the speed control mode to a position control mode, and said counter is preset to a number of pulses corresponding to the angle from the present position of the spindle to the desired stopping position.

Abstract: A motor drive control system for use in a machine tool having spindle and feed shaft motors. If the spindle motor, which is rotating at a constant speed during a machining operation, is subjected to an overload, and consequently experiences a drop in speed, this fact is detected by a detector for detecting the armature current of the spindle motor. The feed shaft motor is slowed down to a predetermined speed if the overloaded condition continues for a prescribed period of time. The feed shaft motor is stopped if an even greater armature current is detected to be flowing due to a continuing overload despite the fact that the feed shaft motor has been slowed to the predetermined speed.

Abstract: A system for controlling the rotation of a spindle includes a motor, a speed detecting circuit for detecting the speed of the motor and for producing a signal indicative of the actual speed thereof, a speed control circuit for controlling the motor so as to narrow to zero a deviation between the actual speed thereof and a commanded speed, a spindle driven by the motor, and a position control circuit for producing a position deviation signal on the basis of a commanded stopping position and the rotational position of the spindle. The spindle is rotated at a commanded speed by the speed control circuit and is rotationally controlled by an orientation command signal so as to make the position deviation signal zero.

Abstract: A system employed in a machine tool of the type in which a gear mechanism disposed between the spindle and spindle motor transmits the rotational motion of the motor to the spindle. The system allows the spindle to be brought to a stop at a predetermined rotational position in a shorter period of time when the gear mechanism is set in low gear, that is, while the rotational speed of the motor is being reduced by the gear mechanism as it is being transferred to the spindle. This permits the spindle to be stopped at the predetermined position in the same amount of time which is required when no reduction in speed takes place between the motor and spindle. When the spindle arrives at a region where it is to be controlled in order to stop at the predetermined rotational position, a position deviation signal for guiding the spindle to the position is applied as an input signal to a speed control loop for controlling spindle rotation.

Abstract: A tachometer generator comprising a generator section for producing rectangular polyphase alternating voltages having a peak value which is proportional to the speed of the rotor, and a commutator section including contactless change-over switches for successively transferring the alternating voltages from the generator section, and sensors for producing switching signals which actuate the change-over switches in accordance with the rotational position of the rotor of the generator section. In the commutator section the sensors are equivalent in number to the change-over switches and comprise Hall devices arrayed about a rotary shaft which is coupled to the generator section. The alternating voltages which are obtained successively from the coils of the generator section as the rotary shaft rotates, are transferred in order by the change-over switches to produce a speed signal, in analog form; which is proportional to the rotating speed of the rotor.

Abstract: Disclosed is a DC motor drive circuit adapted to prevent thyristor commutation failure when a thyristor-controlled three-phase full-wave reversible bridge undergoes a transition in operating mode from a power inversion mode to a power rectification mode.

Abstract: A control system for stopping a spindle at a predetermined rotational position, for driving a spindle in such a manner that a positional deviation between the present rotational position of a specified point on the spindle and a predetermined rotational position at which the specified point is to be stopped, is reduced to zero, thereby to stop the specified point on the spindle at the predetermined rotational position. First and second rotational position sensors are attached to the spindle at first and second specified points thereof, the position at which at least the first rotational position sensor is attached being adjustable. Further provided are changeover means and an orientation control circuit. The first position sensor produces a rotational position deviation signal when a tool is inserted into and withdrawn from a workpiece at the time of a boring operation, and the second position sensor produces a rotational position deviation signal when tools are changed.

Abstract: An improved control system for facilitating tapping work in a machining center of the type which performs a variety of machining operations automatically. Control is effected by establishing and maintaining a certain relationship between the operation of a spindle motor which rotates a tap, and the operation of a Z-axis feed motor which transports a table longitudinally of the tap, the table mounting a workpiece. Specifically, the spindle motor and Z-axis feed motor are driven in relation to one another at all times in such a manner that the equation N.sub.s =f.sub.m /P will be satisfied, where N.sub.s (rpm) is the rotational speed of the spindle motor, f.sub.m is the feed speed of the table along the Z-axis, and P is the thread pitch of the tap. Apparatus for controlling the spindle motor includes a control circuit which is adapted to stop the spindle at a prescribed angle of rotation.

Abstract: A spindle orientation control apparatus having a motor for driving a spindle, speed control means for rotating the spindle at a speed in accordance with a command speed, and position control means for stopping the spindle at a commanded stopping position. The apparatus is further provided with stopping position command means for digitally instructing the spindle stopping position, a position sensor, error monitoring means for monitoring an error between the commanded stopping position and the actual rotational position of the spindle and for generating a signal when the error attains a predetermined value, and means for generating a signal indicative of an orientation speed. When the apparatus is in a spindle orientation control mode, the spindle is speed-controlled so as to rotate at the orientation speed until the error monitoring means generates said signal, and is position-controlled after the generation of the signal so as to reduce the error to zero.

Abstract: A control system for rigidly stopping the spindle of a machine tool at a prescribed angular position when a tool is to be changed, without the use of a mechanical brake. Provided for this purpose is an orientation control circuit adapted to produce an output signal of zero potential when the spindle is at a prescribed stopping position, and an output signal of a potential proportional to the amount of angular deviation when the spindle is displaced from the prescribed stopping position. To stop the spindle at a prescribed stopping position, the output signal from the orientation control circuit is delivered in place of a speed command signal to a speed control loop of the type which limits to zero the difference between the speed command signal and a speed feedback signal. When the spindle is at rest, the feedback function of the speed control loop holds the rotary shaft of the spindle motor rigidly at the stopping position as if a mechanical brake were applied thereto.