JP2819411B2 - Fixed position stop control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for stopping a spindle of a machine tool for rotating a working tool or a workpiece at a predetermined position, for example. 2. Description of the Related Art A spindle motor that drives a spindle of a normal machine tool is controlled by a stop control device that can switch between a speed control mode and a position control mode. Thus, during machining by the machine tool, the spindle motor rotates the tool or the like at a predetermined speed in accordance with the speed control command, and can stop at the stop position instructed by the command at the time of tool change. [Problems to be Solved by the Invention] In such a conventional spindle motor control method,
It is necessary to perform a home position return operation for position control. For this purpose, the motor speed is once reduced to zero and then switched to the position control mode to perform stop control. That is, in the conventional method that requires mode switching, monitoring from the reference stop position to the stop position is not performed until after shifting to position control, and it is difficult to smoothly shift from normal speed control to position control. For this reason, there is a problem that the motor once stopped must be rotationally driven at an orientation speed different from the command speed. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and when performing position control of a spindle motor, it is possible to smoothly switch the control and reduce a fixed position stop operation time. It is an object to obtain a fixed position stop control device. [Means for Solving the Problems] A fixed position stop control device according to a first aspect of the present invention outputs a motor that drives a rotating shaft, and a pulse train signal and a one-rotation one-pulse signal as the rotating shaft rotates. Means for determining a rotation speed and a rotation position of the rotation shaft based on an output signal of the rotation detector in a control for controlling the motor by inputting a fixed position stop command and stopping the rotation shaft at the fixed position. Means for comparing the rotation speed of the rotating shaft with a predetermined reference speed serving as a reference for switching the control system; and in the comparison, it is determined that the rotation speed of the rotating shaft is higher than the predetermined reference speed. Means for controlling the rotation speed of the rotating shaft to decelerate, and in the comparison, when it is determined that the rotating speed of the rotating shaft is equal to or less than the predetermined reference speed, the rotating speed of the rotating shaft and the Based on rotational position Then, the position deviation for position control and the position amount to the target point are calculated and calculated on the assumption that linear inclination smoothing is performed, and linear smoothing processing with constant inclination is performed on these, and the rotation axis is set as a reference value. Means for controlling the position of the rotating shaft and stopping the rotating shaft at a fixed position. The fixed position stop control device according to the second invention comprises a motor connected to the rotating shaft via a gear or a belt or the like, and a two-phase signal A, B and 1 connected to the rotating shaft and shifted by 90 ° in phase. A control device that includes an encoder that outputs a signal C of one rotation pulse and controls the motor by inputting a fixed position stop command to stop the rotating shaft at a fixed position; An up / down counter which receives the output of the multiplier circuit as a count input and is reset by a signal C; and a calculating means for determining the rotational speed of the rotating shaft and the rotational position based on the output of the up / down counter. Comparing means for comparing the rotation speed at the time of inputting the fixed position stop command with a predetermined reference speed serving as a reference for switching the control system; and determining that the rotation speed is higher than the predetermined reference body by the comparison means pressure. When the speed command of the speed control system is set to zero and the speed command means for decelerating the speed of the rotating shaft and the comparing means determine that the rotating speed is equal to or lower than the predetermined reference speed, the rotating shaft is Based on the rotational speed and the rotational position of the position, the position deviation for position control and the position amount to the target point are calculated by assuming that a constant linear smoothing is performed, and these are subjected to a constant linear smoothing process. And position command means for controlling the position of the rotary shaft using the reference value as a reference value. In the first invention and the second invention, the input of the fixed position stop command is arbitrarily input by a program input, a switch or the like as shown in the embodiments described later. [Operation] In the first and second aspects of the present invention, when the rotation speed becomes equal to or lower than a predetermined reference speed serving as a control system switching reference, the speed control is switched to the position control. Are switched after calculating a position deviation for position control and a position command value required for constant inclination straight line smoothing from the speed and the rotational position so that is smoothly continuous. Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 9 is a view showing a conventional fixed position stopping device, wherein (1) is a motor, (2) is a speed detector attached to the motor (1), (3A) is a controller of the motor (1), and (4) ) Is a power line to the motor (1), and (5) is a signal line of the motor speed detector (2). (6), (7) are gears, (8)
Is a main shaft which is a rotary shaft for stopping at a fixed position. (9)
Is an encoder which is a position detector of the spindle (8),
The two-phase signals A and B shifted by 90 ° and the signal C of one pulse per rotation are output. (10) is a cable of the encoder (9). FIG. 1 is a block diagram showing a main part of a fixed position stop control position according to the above embodiment, and FIG. 2 is a circuit diagram of a position control processing unit in FIG. 1. In FIG. Double circuit,
(12) is an up / down counter reset at the rise of the signal C, and (13) is a microcomputer. Here, the outputs A and B of the encoder (9) have four multiplier circuits (11).
After being multiplied by 4, it is counted by an up / down counter (12), and is input to a microcomputer (13) to perform an input arithmetic processing to obtain a rotation speed and the like. FIG. 10 shows waveforms of output signals A, B, and C of the encoder (9), PLS and MNS output from the multiplier circuit (11), and counter values of the up-down counter (12), respectively.
The up / down counter (12) is reset each time the output signal C is sent once per revolution and input. FIG. 11 is a detailed view of the four magnifications (11). In FIG. 1, (14) is a drive circuit. (2
Numeral 0) is an arithmetic means constituted by a microcomputer. (21) comparison means for comparing the rotation speed at the time of the stop command with a predetermined reference speed. (22) is a position control processing unit, the details of which are as shown in FIG. In FIG. 2, reference numeral (23) denotes a constant slope linear smoothing processing unit (24), (25) denotes a switching contact, and comparison means (21).
Is switched by the output of. FIG. 3 is a velocity waveform diagram when a fixed position stop operation is performed, and FIG.
FIG. 5 is a flowchart showing the operation of the above-described apparatus, FIG. 5 is a speed waveform when a stop operation is performed, and FIGS. 6 and 7 are explanatory diagrams showing a part of a part for calculating a position to a target point. . FIG. 8 is a diagram showing input and output when a position command is input to the constant slope linear smoothing circuit (23). As shown in the flowchart of FIG. 4, when the start signal of the home position stop operation is input (S1), it is determined whether or not the control at the time is a speed loop (S2), and as shown in FIG. V when the start signal of the fixed position stop operation is input to
Is higher than the first target speed V1, the contact (24) is closed and the speed command V * is set to zero to perform deceleration control (S3 to S5). When the speed becomes equal to or lower than the first target speed (S3), a position deviation amount (hereinafter referred to as droop) eo from the speed and position at that time and a position amount So to the target stop point are calculated as described in detail below.
Next, the speed loop flag is reset, the position loop flag is set (S6), and the position control process shown in FIG. 2 is performed (S7). Hereinafter, a method of calculating the droop eo and the position amount So to the target stop point will be described. Since the up / down counter (12) is reset at the rising edge of the pulse of the signal C (see FIG. 11), the up / down counter (12) indicates a relative position where that point is zero. At the moment when switching from the speed loop to the position loop, read the count value of the counter (12),
This value is assumed to be X, and if it is assumed to be zero in order to simplify the target, the position Xo to the target point is Xo = 2π (1-x / 4No) [rad] (No: pulse number of one rotation of encoder) ( 4; 4 times multiple). Next, in the constant inclination straight line smoothing process (23), the position amount is calculated by a constant inclination linear acceleration / deceleration pattern up to the target at the time of switching from the speed loop to the position loop. The target point is set to 0 [rad] for simplicity. In FIG. 5 and FIG. 6, deceleration; a [rad / s 2] switching point speed; Vo [rad / s] switching point position; Xo [rad]. a · to = 0 ∴to = Vo / a Therefore, the position S before the stop is S = 1/2 · Vo · to = Vo2 / 2a On the other hand, when the position quantity So to the target point is obtained, Since the difference between the switching points is xo and the target point is a rotating body, it is repeated every 2π, so So = 2πi + Xoi: integer. Next, the deviation droop of the position loop is calculated to smoothly switch the speed command. Let droop be e,
Assuming that the gain of the position loop is kp, e × kp = V * droop eo for smoothly switching the speed command is expressed as eo × kp = Vo∴eo = Vo / kp, and droop eo is the target position amount So. Become a part. Therefore, as shown in FIG. 7, So is required to be equal to or greater than the position S until the vehicle simply stops. If it is less than that, it returns too much and is not preferable. S ≦ So−eo = 2πi + Xo−eo ∴i ≧ 1/2 · (S + eo−Xo) The minimum value i that satisfies this equation is io, and the round-up is represented by INT. Io = INT [(S + eo−Xo) / 2π] = INT [(Vo * / 2a + Vo / kp-Xo) × 1 / 2π] So = 2πio + Xo Therefore, when switching from speed loop to position loop, droop: Vo / kp Position command: So-eo = Xo-Vo / k + 2π × After setting INT [(Vo2 / 2a + Vo / kp−Xo) × 1 / 2π], after switching, the position command is input to the constant linear smoothing circuit (23), and smoothing processing is performed as shown in FIG. . The signal is sent out as the output reference signal of the constant slope linear smoothing circuit (23), and is calculated by the arithmetic means (20).
Is returned through the differentiator (14) to determine the difference between them. And the difference is the integrator (1
The control signal is transmitted as a control signal through 5), the position loop gain (16) and the contact (25), and the drive circuit (14) drives and controls the motor (1) based on the control signal. In the above-described embodiment, the case where the gears are connected by a gear has been described. However, a belt may be used, and the detector of the main shaft position may be directly connected. You may connect. [Effects of the Invention] As described above, according to the present invention, when the rotation speed of the rotating shaft becomes equal to or less than a predetermined reference speed serving as a reference for switching the control system, based on the rotating speed of the rotating shaft and its rotation position, The position deviation for position control and the position amount to the target point are calculated and calculated on the assumption that a straight line with a constant slope is performed, and a straight line smoothing process with a fixed slope is performed on these. Since the position is controlled and the rotating shaft is stopped at the fixed position, the switching of the speed command is performed smoothly.In addition, the position is controlled with the shortest movement amount below the reference speed, and the time of unnecessary acceleration / deceleration Therefore, fixed position stop control can be performed in a very short time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a main part of a fixed position stop control device according to one embodiment of the present invention, FIG. 2 is a block diagram of a position control processing unit in FIG. 1, FIG. FIG. 4 is a velocity waveform diagram at the time of a fixed position stop operation, FIG. 4 is a flowchart showing the operation of the apparatus of FIG. 1, FIG. 5 is a velocity waveform diagram at the time of deceleration, and FIGS. FIG. 8 is a smoothing waveform diagram. FIG. 9 is a block diagram showing an entire position stopping device according to one embodiment of the present invention. FIG. 10 is a signal processing waveform diagram of the four multiplier circuit and the up / down counter, and FIG. 11 is a detailed circuit diagram of the four multiplier circuit. In the figure, (9) is an encoder, (11) is a quadruple circuit, (12) is an up-down counter, (13) is a microcomputer, (14) is a drive circuit, (20) is arithmetic means,
(21) is comparison means, and (22) is command means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Continuation of the front page (56) References JP-A-59-91514 (JP, A) JP-A-60-147812 (JP, A) JP-A-54-181 (JP, A) JP-A-57-75752 (JP) , A) JP-A-61-194508 (JP, A) JP-A-55-65046 (JP, A) JP-A-61-168405 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB G05D 3/12 G05D 3/00 B23Q 15/22

Claims (1)

(57) [Claims] A motor for driving a rotating shaft; and a rotation detector for outputting a pulse train signal and a one-pulse signal per rotation according to rotation of the rotating shaft. A control device for stopping the shaft at a fixed position, a means for determining a rotation speed and a rotation position of the rotation shaft based on an output signal of the rotation detector, and a reference for switching between the rotation speed of the circuit shaft and a control system. Means for comparing with a predetermined reference speed; and in the comparison, when it is determined that the rotation speed of the rotation shaft is higher than the predetermined reference speed, means for reducing the rotation speed of the rotation shaft. In the comparison, when it is determined that the rotation speed of the rotation shaft is equal to or less than the predetermined reference speed, a position control position deviation and a target point are determined based on the rotation speed of the rotation shaft and its rotation position. The position amount up to is calculated by assuming that a straight line with a constant slope is calculated, a straight line smoothing process with a fixed slope is performed on these, and the position of the rotation axis is controlled using the reference value as a reference value, and the rotation axis is calculated. Means for stopping at a fixed position. 2. A motor connected to the rotating shaft via a gear or a belt, and a two-phase signal A,
A control device for controlling the motor in response to the input of a fixed position stop command to stop the rotating shaft at a fixed position. A multiplication circuit, an output of the multiplication circuit is input as a count input, an up / down counter reset by the signal C, and a rotation speed of a rotating shaft is obtained based on an output of the up / down counter. Computing means for determining the rotational position thereof; comparing means for comparing the rotational speed at the time of inputting the stop command with a predetermined reference speed serving as a reference for switching the control system; Speed command means for reducing the speed of the rotating shaft by setting the speed command of the speed control system to zero when it is determined that the speed is higher than the speed; When it is determined that the speed is equal to or less than the fixed reference speed, it is assumed that the position control position deviation and the position amount to the target point are subjected to a constant linear smoothing based on the rotation speed and the rotation position of the rotating shaft. And a position command means for controlling the position of the rotation axis by performing a straight line smoothing process with a constant slope and using the smoothing process as a reference value.