JP4137849B2 - Servo motor control method and apparatus - Google Patents

Description

  The present invention relates to a servo motor control method and apparatus for a servo control system used in a numerical control device for controlling a machine tool, a robot, or the like.

  FIG. 43 shows a general servo motor driving apparatus used in the servo control system. The servo motor drive device receives a rectifier circuit 2 that rectifies the three-phase AC supplied from the three-phase AC power source 1, a smoothing capacitor 3 that smoothes the rectified output of the rectifier circuit 2, and a DC that is smoothed by the smoothing capacitor 3. The semiconductor switching circuit 4 that forms the output part of the PWM circuit that outputs the PWM-converted three-phase alternating current to the AC servo motor 8, and the U-phase and V-phase current values flowing from the semiconductor switching circuit 4 to the AC servo motor 8 are shunted. The current detector 5 detected by the resistor CT, the A / D converter 6 that converts an analog voltage signal proportional to the current value detected by the current detector 5 into a digital signal, and the A / D converter 6 output A digital signal is taken in as a current feedback signal, a predetermined calculation process is performed based on the current feedback value and the speed command value, and each phase PW And a CPU7 for outputting a signal to each phase of the base terminal of the semiconductor switching circuit 4.

  In this specification, a circuit composed of the rectifier circuit 2 and the smoothing capacitor 3 is hereinafter referred to as a converter.

  FIG. 44 shows a general servo control system. The servo control system includes a position control unit 11 that generates a speed command based on a deviation between a position command value output from the NC device 10 and a position feedback value from the motor end or machine end, and a speed command value from the position control unit 11. A speed control unit 12 that generates a current command based on a deviation from the speed feedback value, and a current that generates a current to be applied to the servo motor 8 based on a deviation between the current command value from the speed control unit 12 and the current feedback value based on the shunt resistor CT. And a control unit 13. The servo motor 8 rotationally drives the feed screw 16 by the reduction gear 15 to linearly move the table 17 that is a control object.

  In the case of a semi-closed loop, a motor end detector 18 connected to the servo motor 8 and detecting the rotation speed, rotation angle, and magnetic pole position of the servo motor 8 is used. In the case of a fully closed loop, the linear movement of the table 17 is used. Machine end detectors 19 that detect position are used to obtain feedback signals.

  FIG. 45 shows the current control unit of the AC servo motor. This current control unit limits the q-axis current command value output by the speed control unit 20 to protect the speed control unit 20 that outputs the q-axis current command value and the semiconductor elements that constitute the PWM modulation unit 25 described later. Limiter 21, d-q coordinate conversion unit 22 that converts U-phase and V-phase currents output to AC servomotor 8 into d- and q-axis currents, d-axis current command value and dq coordinate conversion unit 22 is given a deviation from the d-axis current value output, and a current controller 23a that generates a d-axis voltage command so that it is zero, the q-axis current command value output from the speed controller 20 and the dq coordinate. Given a deviation from the q-axis current value output by the converter 22, a current controller 23b that generates a q-axis voltage command so that this deviation becomes zero, and d and q-axis voltages output by the current controllers 23a and 23b Three-phase conversion of command, U, V, W phase voltage command And 3-phase conversion unit 24 for forming, is constituted by a PWM modulator 25 to generate a three-phase alternating current to be output to the AC servo motor 8 from each phase of the voltage command output from the 3-phase conversion unit 24.

  In the configuration as described above, when the NC device 10 outputs the position command value, the position feedback value by the motor end detector 18 in the case of the semi-closed loop and the position feedback value by the machine end detector 19 in the case of the fully closed loop is the position command value. A speed command is generated by the position controller 11 so as to match with the speed controller 12, and a q-axis current command is generated at the speed controller 12 so that the speed command value matches the speed feedback value detected by the motor end detector 18. The The d-axis current command is normally given 0 with respect to the q-axis current command.

  The three-phase alternating current for driving the AC servo motor 8 so as to follow the command is finally generated by the semiconductor switching circuit 4 shown in FIG. 43 according to the q-axis current command and the d-axis current command. PWM modulated and output.

  Next, the operation of the protection function in the conventional servo motor driving apparatus as described above will be described. As described above, when the q-axis current command is generated so as to follow the position command from the NC device 10, if this exceeds the allowable current value of the semiconductor switching circuit 4, the limiter 21 limits the current. Is done.

  In addition, when the ratio of the current command value or the phase current value detected by the current detection unit 5 to the allowable current value exceeds a certain value and a certain time elapses, predetermined alarm processing is performed as an overload alarm. . Further, when the deviation between the position command value given to the position control unit 11 and the position feedback value becomes a value that is more than a certain ratio away from the theoretically calculated deviation, a predetermined alarm process is performed as an excessive deviation difference. Done.

  Also, when a current flowing through each transistor of the semiconductor switching circuit 4 is detected and recognized as an overcurrent, or when a gate cutoff request from a multi-axis drive device or converter unit or NC device is generated The gates of the transistors of the semiconductor switching circuit unit are blocked by hardware.

  In a fully closed loop having the machine end detector 19, the machine end and the motor end coincide with each other and the machine end and the motor end coincide with each other according to the resolution and the number of pulses of the machine end detector 19 and the resolution and the number of pulses of the motor end detector 18. When the difference in the number of pulses that should have been calculated so as to exceed a certain allowable range, a predetermined alarm process is performed as a feedback abnormality.

  The conventional servo motor drive device does not have a function to monitor the current waveform pattern of the current of each phase that flows to the motor output terminal. Therefore, it cannot detect the incorrect connection of the motor output terminal. There is a problem that the operation can only be stopped as a load alarm.

  Further, since it does not have the function of detecting the voltage of each phase applied to the motor output terminal, there is a problem that it is impossible to detect the unconnected motor output terminal or the unconnected converter bus.

  In addition, since there is no function to monitor the gate cutoff signal to the transistor and the type of gate cutoff request signal in the inverter section that controls the current of the servo motor, it is possible to determine the cause of alarms such as excessive deviation and feedback abnormality in more detail There is a problem that cannot be done.

  Also, in the fully closed loop with a machine end detector, if an alarm such as excessive deviation, overload alarm, feedback abnormality, etc. occurs, it does not have a function to determine those factors in more detail, so it does not stop operating There is a problem that it does not get the information and spends a lot of time to clarify the cause.

  Also, when there is an excessive deviation or overload alarm during acceleration / deceleration, etc., there is no means to distinguish whether it occurred because of an insufficient acceleration / deceleration time constant or an abnormal load. If the parameters are readjusted automatically, even if the operation can be continued without stopping the operation, the operation has to be stopped.

  In addition, because the detector model is not determined, if the detector setting by parameter and the communication specification of the actually connected detector are different, a no-signal alarm is generated and the detector and connection cable are not connected. In addition to misjudging it as a failure, there were problems such as prolonged recovery and inability to enter into simple parameter setting mistakes.

  The present invention has been made to solve the above-described problems, suppresses the occurrence of error enlargement alarms and overshoots, allows the system to continue operation without occurrence of error enlargement, and the like. An object of the present invention is to obtain a highly reliable servo motor control method and apparatus.

  In order to achieve the above-described object, in the present invention, a speed command is created based on the deviation between the position command value and the position feedback value, and a current command is created based on the deviation between the created speed command and the speed feedback value. In the servo motor control method in which the servo motor is driven and controlled by the deviation between the created current command and the current command feedback value, and the current command output from the speed control unit is clamped at a predetermined current limit value. If there is a first step of determining whether or not the current command value is clamped at the predetermined current limit value, and if the current command value is clamped at the predetermined current limit value, the position command A second step of limiting the change of the position command per unit time by thinning out, and after the release of the clamp, The position command minute characterized in that it comprises a third step of adding to the position command.

  In the next invention, a speed command is created based on the deviation between the position command value and the position feedback value, a current command is created based on the deviation between the created speed command and the speed feedback value, and the created current command and current command feedback are generated. In the servo motor control method in which the servo motor is driven and controlled by a deviation from the value and the current command output from the speed control unit is clamped at a predetermined current limit value, the current command value is A first step for determining whether or not the current command value is clamped at a predetermined current limit value; and a second step for reducing a position loop gain when the current command value is clamped at a predetermined current limit value; A third step of gradually increasing the position loop gain to the original value when a predetermined constant speed operation is reached after releasing the clamp; Characterized in that it comprises.

  In the next invention, in the above invention, in the second step, the position loop gain is decreased with a predetermined time constant.

  In the next invention, a speed command is created based on the deviation between the position command value and the position feedback value, a current command is created based on the deviation between the created speed command and the speed feedback value, and the created current command and current command feedback are generated. In the servo motor control method in which the servo motor is driven and controlled by a deviation from the value and the current command output from the speed control unit is clamped at a predetermined current limit value, the current command value is A first step for determining whether or not the current command value is clamped, and if the current command value is clamped at a predetermined current limit value, the current position deviation and the rated rotational speed of the motor The position loop gain value when the speed command is equivalent to the motor rated speed is obtained, and the position loop gain is obtained up to the obtained position loop gain value. A second step of reducing the emissions, after the unclamping, it reaches a predetermined constant speed operation, characterized in that it comprises a third step of increasing gradually the original value of the position loop gain.

  According to the present invention, if the current command value reaches the current limit value during fast-forward acceleration, the amount of change in the position command per unit time is suppressed, so that overshooting is unlikely to occur as well as the occurrence of an excessive error alarm. A stable and reliable servo control system can be obtained.

  According to the next invention, when the maximum output torque of the servo amplifier is reached during rapid traverse due to the influence of an abnormal load, the position loop gain is decreased only during that time so that the movement of the servo system may be gentle. A reliable servo control system capable of continuing the operation of the system without causing an excessive error or the like can be obtained.

  According to the next invention, when the maximum output torque of the servo amplifier is reached due to the influence of an abnormal load during rapid traverse, the position loop gain is reduced by a certain time constant, so that an error excessive alarm does not occur. A highly reliable servo control system that can continue operation is obtained.

  According to the next invention, when the maximum output torque of the servo amplifier is reached due to an abnormal load during rapid traverse, the position loop gain when the speed command is a value equivalent to the motor rated speed is set to the current droop. Since the speed command is always controlled without exceeding the motor rated speed by calculating from the quantity, a servo control system capable of continuing the system operation without causing an excessive error alarm is obtained.

  Embodiments of the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In the embodiment of the present invention, the same components as those of the above-described conventional example are denoted by the same reference numerals as those of the above-described conventional example, and the description thereof is omitted.

  FIG. 1 shows an embodiment of a servo motor driving apparatus used for carrying out an abnormality detection / diagnosis method for a servo control system according to the present invention. In this servo motor driving device, the current detector 5 for detecting the phase current flowing through the motor output terminal detects the W-phase current in addition to the U-phase and V-phase currents.

  This servo motor driving device has voltage detection circuits 9a, 9b and 9c. The voltage detection circuits 9a, 9b, and 9c divide the voltage between the U phase, the V phase, and the W phase, and output a voltage proportional to the voltage between the phases to the A / D converter 6. The A / D converter 6 converts the voltage detected by the voltage detection circuits 9a, 9b, and 9c into a digital value and outputs the digital signal to the CPU 7.

  FIG. 2 shows a connection diagnosis routine of the motor output terminal in the abnormality detection / diagnosis method of the servo control system according to the present invention. In this connection diagnosis routine, first, after the power is turned on, the q-axis current command Iqa is detected at every sampling period in step S101, and the process proceeds to the next step S102.

In step S102, it is determined whether or not the absolute value is the certain magnitude I _R or the detected q-axis current command IQA, if the absolute value is the certain magnitude I _R or the q-axis current command IQA, acceleration Recognizing that it is being requested, the process proceeds to step S104. On the other hand, if it is not recognized that the acceleration is being requested, the process proceeds to step S103.

  In step S103, it is determined whether or not the acceleration command result flag has already been turned on. If the acceleration command result flag has already been turned on, it is recognized that the first acceleration request has been completed. If there is an incorrect connection in the motor output terminal connection, the first acceleration request will continue until an excessive error or overload alarm occurs, so the acceleration command result flag turns on and the first acceleration request has already been completed. If it is recognized that the normal connection has been made, the connection diagnosis routine is terminated. On the other hand, if the acceleration command result flag has not been turned on, it is recognized that no acceleration command request has been made even after the power is turned on, and the process returns to step S101.

  In step S104, in order to recognize in step S103 that an acceleration command request has occurred after the power is turned on, the acceleration command result flag is turned on, and the process proceeds to the next step S105. In step S105, U-phase, V-phase, and W-phase currents are detected for each sampling period. Note that it is not always necessary to detect the W-phase current, and it is only necessary to detect the current of two of the three phases. Here, the current of all three phases is detected.

  In the next step S106, the detected absolute value of each phase current is compared with the peak value up to the previous time separately on the positive and negative sides of the current polarity. If it is determined from the comparison result that the current value updates the previous peak value or is equivalent, the process proceeds to the next step S107, and if not, the process proceeds to step S109.

  In step S107, the peak value is updated on the positive side and the negative side of the current polarity, or the value marked with the same level value is rewritten as the peak value used for comparison in step S106, and the next step S108 is performed. Proceed with In step S108, the peak value is updated on the positive side and the negative side of the current polarity, or the phase recognition data marked with the same level value is sequentially transferred to memories prepared separately on the positive side and the negative side. And proceed to the next step S109.

  In step S109, when the amount of recognition data stored in the previous step S108 exceeds a certain amount, the process proceeds to the next step S110, and otherwise, the process returns to step S101. In step S110, the current waveform pattern is found from the recognition data stored in step S108, and it is determined whether or not there is a misconnection in the motor output terminal.

  When the acceleration command is a motor forward rotation request, as shown in FIG. 3A, the patterns stored in the order of U, V, and W phases on the basis of the U phase on both the positive and negative sides of the current polarity If it is, it is determined that the normal UVW phase connection is made. On the other hand, if the pattern is U, W, V phase on both the positive and negative sides, there is an erroneous connection that becomes the VWU phase or the WUV phase. It is determined that it has been made.

  When the acceleration command is a motor reverse rotation request, as shown in FIG. 3-2, both the positive and negative sides of the current polarity are stored in the order of U, W, and V phases on the basis of the U phase. If it is, it is determined that a normal UVW phase connection is made, and if it is a U, V, or W phase pattern on both the positive and negative sides, an incorrect connection that results in a VWU phase or a WUV phase is made. It is determined that

  In either case, if the patterns of the recognition data on the positive side and the negative side of the current polarity do not match, it is determined that there is another misconnection. With these determinations, the connection diagnosis routine ends. As a result, the erroneous connection of the motor output terminal is automatically detected, and it is avoided that the motor output terminal is operated in an incorrect state. Further, as described above, after determining the erroneous connection of the UVW phase, the voltage command output phase can be automatically switched by software to continue the operation.

  In this case, the voltage command output phases are interchanged by software processing based on the erroneous connection determination result as shown in FIG. 3 so that the connection is virtually correct. This is one embodiment of a method for automatically optimizing a servo control system according to the present invention.

  FIG. 4 shows a phase voltage detection routine used for connection diagnosis of the motor output terminal and the converter bus in the abnormality detection / diagnosis method of the servo control system according to the present invention. In step S201, each data of the UV phase voltage Vuv, the VW phase voltage Vvw, and the WU phase voltage Vwu detected by the voltage detectors 9a to 9c, converted into a digital signal by the A / D converter 6 and taken into the CPU 7 is obtained. Sampling is performed at predetermined time intervals.

In the next step S202, the switching voltages Vua, Vva, Vwa of each phase are calculated based on the data.
Vua = (Vuv−Vwu) / 3
Vva = (Vvw−Vuv) / 3
Vwa = (Vwu−Vvw) / 3

Since the voltages Vua, Vva, and Vwa calculated in step S202 are switching voltages in the inverter unit and are discrete data, next, in order to make it easy to evaluate the magnitude of the phase voltage, in step S203, the electric machine Using the nominal values of the element inductance L and armature resistance R, the filter is passed through to obtain continuously smooth phase voltages Vu, Vv, Vw.
Vu = R · Vua / (Ls + R)
Vv = R · Vva / (Ls + R)
Vw = R · Vwa / (Ls + R)
s is a Laplace operator.

FIG. 5 shows a motor output terminal connection diagnostic routine in the servo control system abnormality detection / diagnostic method according to the present invention. This motor output terminal connection diagnosis routine, first in step S300, the a i = 1, phase voltage Vi (Vu or Vv, Vw) in step S301 it is determined whether or not a predetermined value or more V _R. If Vi ≧ V _R , the process proceeds to the next step S302.

  In step S302, the phase current Ii (Iu or Iv, Iw) before and after the sampling is detected, and in step S303, it is determined whether or not the phase current Ii is substantially zero. If the phase current Ii is approximately zero, the process proceeds to step S304, where it is determined that the i-phase is not connected.

  Since i = 1 is U phase, i = 2 is V phase, and i = 3 is W phase, step S301 to step S303 are determined as i ≧ 3 in step S305 and in step S306. By updating the detection target phase i by i = i + 1, each phase is performed in the order of the U phase, the V phase, and the W phase. As a result, unconnected motor output terminals are automatically and accurately detected for each of the U phase, V phase, and W phase.

FIG. 6 shows a converter bus connection diagnosis routine in the abnormality detection / diagnosis method of the servo control system according to the present invention. In this converter bus connection diagnosis routine, first in step S401, performs an absolute value is in whether a magnitude I _R or determination of q-axis current command IQA. If the absolute value of the q-axis current command Iqa is greater than or equal to a certain magnitude I _R , the process proceeds to step S402.

  In step S402, it is determined whether or not any of the calculated phase voltages Vu, Vv, Vw is substantially zero even when the amplifier is recognized as requesting acceleration in step S401. If all of the phase voltages Vu, Vv, and Vw are substantially zero, the process proceeds to step S403 to determine that the converter bus is not connected. Thereby, it is automatically and accurately detected that the converter bus is not connected.

  FIG. 7 shows a gate control circuit of a transistor in the semiconductor switching circuit 4 of the current control unit (inverter unit) used for carrying out the abnormality detection / diagnosis method of the servo control system according to the present invention. This gate control circuit has an overcurrent detector 29 that detects that an overcurrent has flowed through the semiconductor switching circuit 4.

  The CPU 7 receives a signal indicating that an overcurrent has flowed from the overcurrent detector 29 from the latch circuit 30 and a gate-off signal indicating that a gate cutoff request from an amplifier or converter of another axis has occurred from the latch circuit 31 from the NC. The gate-off signal is individually fetched from the latch circuit 32, and the logical product signal of these three signals is inputted from the AND gate 33.

  An AND gate 34 is connected to the gate of the transistor Tr of the semiconductor switching circuit 4, and the AND gate 34 inputs an output signal of the AND gate 33 and a gate on / off signal output from the CPU 7.

  In this gate control circuit, the CPU 7 is activated even when an overcurrent flows through the inverter unit, a gate cutoff request is generated by an amplifier or converter of another axis, or a gate off (gate cutoff) signal is generated from the NC device. Regardless, if the gate-off signal is not output to the AND gate 34 because it is operating normally without detecting any alarm, the outputs of the latch circuits 31 and 32 are confirmed, and the gate cutoff request is based on this. A flag corresponding to the portion where the signal is generated is set, and the number of times that the signal has been generated is stored in the memory for a predetermined period of time. If this number is exceeded, it is determined that the occurrence location is abnormal. As a result, the cause (occurrence location) of occurrence of abnormality in the control system such as excessive error and feedback abnormality is determined.

  FIG. 8 shows a diagnostic routine for the cause of the occurrence of gate interruption in the abnormality detection / diagnosis method of the servo control system according to the present invention. In this diagnostic routine, in step S451, the output state of the gate cutoff for the AND gate 34 is monitored at a predetermined cycle, and in step S452, whether the gate cutoff is being output, that is, whether or not a gate-off signal is being output to the AND gate 34 is determined. Determine.

  If the gate cutoff output is not in progress, the process proceeds to step S453. In step S453, the output state of the latch circuits 31 and 32 for each factor signal is checked. Next, in step S454, the output state of the latch circuits 31 and 32 is reflected in the gate cutoff signal output flag of the CPU 7, and if the gate cutoff signal output flag is on, the process proceeds to step S445, where the gate of the generated factor Counts the number of cutoff outputs (the number of times the gate cutoff signal output flag is turned on for each latch circuit).

  Next, in step S456, the gate cutoff signal output flag is cleared, and in next step S457, it is determined whether or not the count value of the gate cutoff output has reached a predetermined value or more. If the count value of the gate cutoff output reaches a predetermined value or more, the process proceeds to step S458, and an abnormal location (for example, converter or NC device of another axis) that exceeds the allowable number is determined.

  If it is determined in step S452 that the gate cutoff output is being output, the flow advances to step S459 to determine whether or not a predetermined time has passed. If the predetermined time has passed, the flow advances to step S460 to count the gate cutoff output. Clear the value to 0. As a result, the occurrence point of the control system abnormality such as excessive error or feedback abnormality can be understood immediately.

  FIG. 9 shows a wiring diagnosis routine of the feedback cable in the abnormality detection / diagnosis method of the servo control system according to the present invention. This feedback cable wiring diagnosis is applied to the servo control system using the fully closed loop shown in FIG. 44. First, in step S501, the position command value output by the NC device 10 and the machine end detector 19 output. The position feedback value, the speed feedback value output from the motor end detector 18, the current command value output from the speed control unit 12, the current feedback value and their respective polarities are always detected and monitored from the time of power-on.

  In step S502, it is determined whether or not all of these signal values are equal to or greater than a predetermined value. If all of these signal values are equal to or greater than the predetermined value, the process proceeds to step S503. In step S503, it is determined whether or not only the position feedback signal has the reverse polarity. If only the position feedback signal has the reverse polarity, the process proceeds to step S504 to determine that the feedback cable is incorrectly wired. Thereby, erroneous wiring of the feedback cable is automatically and accurately detected.

  FIG. 10 shows a parameter setting diagnosis routine in the abnormality detection / diagnosis method of the servo control system according to the present invention. In the parameter setting diagnosis routine, first, in step S701, it is determined whether or not the polarity of the position feedback signal and the polarity of the position command are the same, and if these polarities are equal, the process proceeds to step S702, and these polarities are determined. If not equal, the process proceeds to step S706.

  In step S702, the number of pulses from the Z phase to the Z phase of the motor end detector 18 is counted, and it is confirmed whether this matches the set motor end detector resolution. If it is determined that this is correct, the process proceeds to the next step S703, and if not, the process proceeds to step S705.

  In step S703, when positioning of a certain feed amount is performed, the number of rotations of the servo motor 8 is calculated from the resolution of the machine end position detector 19 and the number of pulses at that time, and the motor end detector 18 per rotation is calculated. Calculate the number of pulses. In step S704, when this result is X times the actual motor end detector resolution, a setting error of (X = gear ratio / machine end detector resolution / pitch) times the true setting is detected. Check if it is. In step S705, it is determined that the resolution of the motor end detector 18 is abnormal.

  In step S706, it is determined that the feedback cable is incorrectly wired. Thus, when a feedback abnormality occurs at the start-up of the machine, it is distinguished whether this is a machine abnormality (scale abnormality) or a gear ratio, machine end detector resolution, or pitch parameter setting is different.

  FIG. 11 shows the internal configuration of the current control unit used to implement the abnormality detection / diagnosis method of the servo control system according to the present invention. This current control unit corresponds to the current control unit 13 in the general servo control system shown in FIG. 44, and the three-phase conversion unit 26 is added to the conventional current control unit shown in FIG. In addition, a torque calculation unit 27 and a motor position calculation unit 28 are added.

  The three-phase conversion unit 26 performs three-phase conversion on the d and q-axis current command values using the magnetic pole position actually detected from the motor end as an initial value at the beginning of the acceleration / deceleration command, and the three-phase current Ium of the motor model. , Ivm, Iwm. The torque calculator 27 calculates the model output torque Tem from the model three-phase current values Ium, Ivm, Iwm output from the three-phase converter 26 and the torque constant KT.

  The motor position calculation unit 28 calculates the magnetic pole position θrm of the motor model using the model output torque Tem output from the torque calculation unit 27, the nominal value of the inertia, and the number of magnetic poles. Thereafter, the three-phase conversion of the motor model is performed. The motor model output torque Tem is calculated by the following formula using the three-phase current values Ium, Ivm, Iwm and the magnetic pole position θrm.

Tem = √2 / 3 ・ KT ・ {−Ium ・ sinθrm−Ivm ・ sin （θrm-2π / 3）
−Iwm · sin (θrm-2π / 3)}

  A position feedback value θm of the motor model is obtained from the motor model output torque Tem thus calculated. Then, the difference between the position feedback value θm of the motor model obtained as described above and the actual motor end position feedback value θ is monitored, and this difference is kept until immediately before an excessive error or overload alarm occurs. If it is within the allowable range even after the current limit, it is determined that the acceleration / deceleration time constant is insufficient. As a result, an insufficient acceleration / deceleration time constant is recognized.

  In addition, when the difference between the motor model position feedback value θm and the actual motor end position feedback value θ exceeds a certain allowable range, the error between the actual value of the rotor inertia and load inertia and the set value is within the allowable range. If no erroneous gate shutoff occurs, it is determined that this is an overload. Thereby, it is recognized that an overload, that is, an abnormal load exists.

  FIG. 12 shows a diagnostic routine for pursuing the cause when the current is limited in the abnormality detection / diagnosis method of the servo control system according to the present invention. In this diagnosis routine, first, in step S801, the position feedback value θm of the motor model is calculated.

  Next, in step S802, it is determined whether an excessive error or overload alarm has been output. If an excessive error or overload alarm has been output, the process proceeds to step S803, where the current is output until immediately before these alarms occur. It is determined whether or not the restriction has been performed. If the current is limited, the process proceeds to step S804, and it is determined whether or not the difference between the position feedback value θm of the motor model and the actual motor end position feedback θ is within an allowable value. If the difference between the position feedback value θm of the motor model and the actual motor end position feedback θ is within an allowable value, the process proceeds to step S805, where it is determined that the acceleration / deceleration time constant is insufficient.

  On the other hand, if the difference between the position feedback value θm of the motor model and the actual motor end position feedback θ is not within the allowable value, the process proceeds to step S806 to determine whether or not an erroneous gate cutoff or the like has occurred. To do. If no erroneous gate interruption has occurred, the process proceeds to step S807, where it is determined that there is an overload.

  If it is determined in step S803 that the current limit is not performed, the process proceeds to step S809, and the set value of the load inertia of the motor model is investigated. By this diagnostic routine, diagnosis of suitability of acceleration / deceleration time constant and overload determination are performed.

  The method for automatically optimizing the servo control system according to the present invention is implemented by a general servo control system as shown in FIG. 43. When the amplifier power is turned on, the semi-closed loop method and the fully closed loop are used. Of the methods, position control is always performed by a feedback signal from the motor end detector 18 in a semi-closed loop method. At this time, the feedback signal from the machine end detector 19 is also processed at the same time, and it is checked whether the accumulated moving distance by the motor end detector 18 matches the polarity. If the polarities are the same, the control shifts to position control by a fully closed loop system. On the other hand, if the polarities are opposite, the position information accumulated by the machine end detector 19 is inverted and the system is reversed. It automatically shifts to position control by the fully closed loop method without stopping.

  FIG. 13 shows a position control method automatic switching routine in the method for automatically optimizing the servo control system according to the present invention. In step S1001, since the power is turned on, position control by a semi-closed loop method is executed.

  In the next step S1002, it is determined whether or not the cumulative movement distance based on the position command from the NC device 10 has reached a predetermined value (for example, 1 mm), in other words, the designated movement distance has reached the polarity determination distance of the machine end detector 19. It is determined whether or not. If the accumulated movement distance by the position command from the NC device 10 reaches a predetermined value, the process proceeds to step S1002. In step S1003, the accumulated feedback position on the fully closed loop side is compared with the sign of the command accumulated position, in other words, it is checked whether the position feedback amount of the machine end detector 19 matches the position designation polarity. To do. If the polarities match, the process proceeds to step S1005, and if the polarities do not match, the process proceeds to step S1004.

  In step S1004, the cumulative feedback amount generated by the machine end detector 19 is inverted. In step S1005, the feedback signal corresponding to the movement so far is switched to the fully closed loop side, and the position control by the semi-closed loop system is changed to the position control by the fully closed loop system.

  As a result, even when the position feedback amount of the machine end detector 19 does not match the position designation polarity at the time of starting the system, the system state relating to the polarity is automatically optimized and the operation is continued without going down. be able to.

  As described above, the feedback reverse polarity of the automatically detected machine end detector 19 can be stored in the nonvolatile memory, and the position control can be performed with the correct feedback polarity from the first time when the power is turned on next time. However, since there is a possibility that the semi-closed loop method includes a certain amount of error due to mechanical elements such as backlash, it is preferable to add a filter, for example, a first-order delay to the switching.

  The method for automatically optimizing the servo control system according to the present invention executes position control by a fully closed loop method using the machine end detector 19 from the time of turning on the power, and there is a constant error with the feedback amount by the motor end detector 18. The system state can be automatically optimized by reversing the feedback amount up to the present time of the machine end detector 19 when the value exceeds the value.

  FIG. 14 shows an automatic polarity reversal routine in the method for automatically optimizing the servo control system according to the present invention. In step S1101, immediately after the power is turned on, a position control mode by the closed loop method is formed as usual. In the next step S1102, the difference between the fully closed loop feedback position PMA and the semi-closed loop feedback position PMO reaches a preset fully closed loop feedback reverse polarity determination value CER, and the signs are different from each other. Check whether it exists. If the difference reaches the determination value CER and the signs are different from each other, the process proceeds to step S1103.

  In step S1103, the cumulative feedback position on the fully closed loop side is reversed, and the subsequent moving distance is processed as a reverse polarity. As a result, even in this case, even if the polarity of the position feedback amount of the machine end detector 19 is reversed at the time of starting the system, the system state relating to the polarity is automatically optimized, and the operation can be continued without going down. Can do. Also in this case, by storing the automatically detected feedback reverse polarity of the machine end detector 19 in the nonvolatile memory, the position control can be performed with the correct feedback polarity from the first time when the power is turned on next time.

  FIG. 15 shows a servo control system of a dual feedback control system used for carrying out the method for automatically optimizing the servo control system according to the present invention. This servo control system has a control unit 35 that filters a first-order lag on the error between the feedback position by the motor end detector 18 and the feedback position by the machine end detector 19, and the output of the control unit 35 is the actual output. Used as a position feedback amount.

  This dual feedback control is statically a full-closed loop method, a control method that follows the error between the motor end detector 18 and the machine end detector 19 with a certain time constant, and is a control method applied to a low-rigidity machine. It is.

  FIG. 16 shows an automatic polarity reversal routine in the above-described dual feedback control type servo control system. In step S1201, dual feedback control is formed immediately after the power is turned on. At this time, the time constant of the first-order lag filter is set to be larger than the normal parameter setting value.

  In the next step S1202, the difference between the fully closed loop feedback position PMA and the semi closed loop feedback position PMO reaches a preset fully closed loop feedback reverse polarity determination value CER, and the signs are different from each other. Check whether it exists. If the difference reaches the determination value CER and the signs are different from each other, the process proceeds to step S1203. In step S1203, the cumulative feedback position on the fully closed loop side is reversed, and the subsequent moving distance is processed as a reverse polarity.

  In the next step S1204, the primary delay filter time constant of the dual feedback control is returned to the parameter set value, and the operation is continued. As a result, even in this case, even if the polarity of the position feedback amount of the machine end detector 19 is reversed at the time of starting the system, the system state relating to the polarity is automatically optimized, and the operation can be continued without going down. Can do. Also in this case, by storing the automatically detected feedback reverse polarity of the machine end detector 19 in the nonvolatile memory, the position control can be performed with the correct feedback polarity from the first time when the power is turned on next time.

  FIG. 17 shows an embodiment of a servo control system used for carrying out an automatic optimization method for a servo control system according to the present invention. The servo control system includes a control unit 36 that clamps the maximum value of the current command calculated by the speed control unit 12.

  FIG. 18 shows a time constant optimization routine at the time of acceleration / deceleration in the automatic optimization method of the servo control system according to the present invention. First, in step S1501, it is determined whether or not fast-forwarding is currently in progress. If fast-forwarding is in progress, the process advances to step S1502 to sample the current command value In. The sampling of the current command value In is performed at a constant cycle (every several ms) during fast-forwarding.

  Next, in step S1503, the absolute value | In | of the sampled current command value is compared with the maximum value Ip of the current command sampled so far during the current fast-forwarding. If | In | is larger, the process advances to step S1504 to change the maximum value Ip to the current | In |.

  Next, in step S1505, it is determined whether or not the current fast-forward has ended. The term “during fast-forwarding” as used herein means the total time for one movement. When the fast-forwarding is completed, the process proceeds to step S1506. When the fast-forwarding is not completed, the process returns to step S1502 after the sampling period, and the next current command value In is sampled. In step S1506, a ratio β of the maximum value Ip of the current command in the current rapid feed to the maximum current Imax that can be output by the motor drive device such as a servo amplifier is calculated by the following equation.

β = Ip / Imax
In order to set the ideal output ratio to α and the output ratio in the next rapid feed acceleration / deceleration to be close to the ideal output ratio α, the next fast feed will be based on the current fast feed time constant A and the ideal output ratio α and ratio β. The calculation of the constant B is performed by the following formula.

B = A · β / α = A · (Ip / Imax · α)
The acceleration / deceleration time constant B obtained from this calculation result is substituted into A, and the next acceleration / deceleration is performed with this time constant. As a result, every time acceleration / deceleration is performed, the optimal acceleration / deceleration time constant is calculated in real time, and the acceleration / deceleration time constant is automatically optimized, realizing acceleration / deceleration operation in which the stability of the system is not affected by fluctuations in machine load. To do. When the load varies depending on the movement method, such as an unbalance axis, it is necessary to determine the time constant based on the larger current command value depending on the movement direction.

  In general, the change in mechanical load does not show such a large change, so the acceleration / deceleration time constant is determined based on the average value or the peak value of acceleration / deceleration maximum values of several to several tens of times. Also good. Furthermore, since the lubricity of the machine is poor when the power is turned on the first time in the morning and the load is often the largest, the time constant at the time of turning on the power is large, for example, about 50% of Imax, and the time constant is automatically set. It is also possible to pack up.

  FIGS. 19 and 20 show time constant optimization routines that are suitable when the required torque differs depending on the direction of motion, such as an unbalanced shaft. First, in step S1601, it is determined whether or not fast-forwarding is currently in progress. If fast-forwarding is in progress, the process advances to step S1602 to determine the direction of fast-forwarding. If fast forward in the + direction is being performed, the process advances to step S1603. On the other hand, if fast forward in the + direction is not being performed, fast forward in the-direction is performed, and the process advances to step S1611. In step S1603, the current command value In is sampled. The sampling of the current command value In is performed at a constant cycle (every several ms) during fast-forwarding.

  In step S1604, the absolute value | In | of the sampled current command value is compared with the maximum value Ip + of the current command sampled up to the previous time during the current fast-forward. If | In | is larger, the process advances to step S1605 to change the maximum value Ip + to the current | In |.

  Next, in step S1606, it is determined whether or not the current fast-forward has ended. Even during the fast-forwarding referred to here, the total time of one movement is assumed. If the fast-forwarding has been completed, the process proceeds to step S1607. If not, the process returns to step S1603 after the sampling period, and the next current command value In is sampled. In step S1607, the ratio β of the current command maximum value Ip + in the current rapid feed to the maximum current Imax that can be output by a motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip +) / Imax
In order to set the ideal output ratio to α and make the output ratio in the next rapid feed acceleration / deceleration close to the ideal output ratio α, the next fast feed will be based on the current fast feed time constant A + and the ideal output ratio α and ratio β. The calculation of the constant B + is performed by the following formula.

(B +) = (A +) · β / α = (A +) {(Ip +) / Imax · α)}
The acceleration / deceleration time constant B + obtained from the calculation result is substituted into A +, and the next acceleration / deceleration in the + direction is performed with this time constant. In step S1609, the current command value In is sampled. Sampling of the current command value In is also performed at a constant cycle (maximum every several ms) during fast-forwarding.

  In step S1610, the absolute value | In | of the sampled current command value is compared with the maximum value Ip− of the current command sampled up to the previous time during the current fast-forward. If | In | is larger, the process advances to step S1611 to change the maximum value Ip− to the current | In |.

  Next, in step S1612, it is determined whether or not the current fast-forward has ended. Even during the fast-forwarding referred to here, the total time of one movement is assumed. If the fast-forwarding is completed, the process proceeds to step S1613. If not completed, the process returns to step S1609 after the sampling period, and the next current command value In is sampled. In step S1613, the ratio β of the current command maximum value Ip− in the current rapid feed to the maximum current Imax that can be output by the motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip −) / Imax
In order to set the ideal output ratio to α and make the output ratio in the next rapid traverse acceleration / deceleration approach the ideal output ratio α, the next rapid traverse is based on the current rapid feed time constant A-, the ideal output ratio α, and the ratio β. The time constant B- is calculated by the following equation.

(B −) = (A−) · β / α = (A −) {(Ip −) / Imax · α)}
The acceleration / deceleration time constant B- obtained from the calculation result is substituted into A-, and the next-direction acceleration / deceleration is performed with this time constant. As a result, every time acceleration / deceleration is performed, the optimum acceleration / deceleration time constant for each movement direction is calculated individually in real time, and the acceleration / deceleration time constant for each movement direction is automatically optimized individually, and the load on the machine Realizes acceleration / deceleration operation in which the stability of the system is not affected by fluctuations. As a result, the acceleration / deceleration time constant determined so far with the torque required to raise the unbalanced shaft can be reduced when lowered and the machining time can be shortened.

  In mechanical drive, the output torque differs between acceleration and deceleration due to frictional force, and the optimum value of the time constant differs between acceleration and deceleration. Therefore, in this embodiment 10, automatic optimization of the acceleration / deceleration time constant is referred to as acceleration. This is done separately with deceleration.

  21 and 22 show time constant optimization routines in the case where automatic optimization of acceleration / deceleration time constants is performed separately for acceleration and deceleration. First, in step S1701, it is determined whether or not fast-forwarding is currently in progress. If fast-forwarding is in progress, the process proceeds to step S1702. In step S1702, it is determined whether or not the vehicle is accelerating based on a change in speed. If it is accelerating, the process proceeds to step S1704, and if not, the process proceeds to step S1703.

  In step S1703, it is determined whether or not the vehicle is decelerating from the change in speed. If the vehicle is decelerating, the process proceeds to step S1709; otherwise, the process returns to step S1701. In step S1704, the current command value In is sampled. The current command value In is sampled at a constant cycle during fast-forwarding.

  Next, in step S1705, the absolute value | In | of the sampled current command value is compared with the maximum value Ipa of the current command sampled so far during the current fast-forwarding. If | In | is larger, the process proceeds to step S1706, and the maximum value Ipa is changed to the current | In |.

  Next, in step S1707, it is determined whether or not the current fast-forward acceleration has been completed. If the fast-forward acceleration has been completed, the process proceeds to step S1708. If not, the process returns to step S1704 after the sampling period, and the next current command value In is sampled. In step S1708, the ratio β of the maximum value Ipa of the current command in the current rapid feed to the maximum current Imax that can be output by the motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ipa) / Imax
In order to make the ideal output ratio α and make the output ratio in the next fast-forward acceleration / deceleration close to the ideal output ratio α, the next fast-forwarding based on the current fast-forwarding time constant Aa, ideal output ratio α, and ratio β The calculation of the constant Ba is performed by the following formula.

(Ba) = (Aa) · β / α = (Aa) {(Ipa) / Imax · α)}
The acceleration time constant Ba obtained from the calculation result is substituted into Aa, and the next rapid traverse acceleration is performed with this time constant. In step S1709, the current command value In is sampled. The sampling of the current command value In is also performed at a constant cycle during fast-forwarding.

  In step S1710, the absolute value | In | of the sampled current command value is compared with the maximum value Ip− of the current command sampled up to the previous time during the current fast-forward. If | In | is larger, the process advances to step S1711 to change the maximum value Ipb to the current | In |.

  Next, in step S1712, it is determined whether or not the current fast-forward has ended. If the fast-forwarding is completed, the process proceeds to step S1713. If not, the process returns to step S1709 after the sampling period, and the next current command value In is sampled. In step S1713, the ratio β of the current command maximum value Ipb in the current rapid feed to the maximum current Imax that can be output by the motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ipb) / Imax
In order to set the ideal output ratio to α and make the output ratio in the next fast-forward acceleration / deceleration approach the ideal output ratio α, the next fast-forward based on the current fast-forward time constant Ab and the ideal output ratio α and ratio β The calculation of the constant Bb is performed by the following formula.

(Bb) = (Ab) · β / α = (Ab) {(Ipb) / Imax · α)}
The deceleration time constant Bb obtained from the calculation result is substituted into Ab, and the next fast-forward deceleration is performed with this time constant. As a result, every time acceleration / deceleration is performed, the optimum acceleration / deceleration time constant for each acceleration and deceleration is calculated individually in real time, and the time constant for acceleration and the time constant for deceleration are each automatically optimized. Realizes acceleration / deceleration operation in which the stability of the system is not affected by machine load fluctuations.

  23 to 27 show a time constant optimization routine in which automatic optimization of acceleration / deceleration time constant is performed separately for the direction of motion and acceleration and deceleration.

  In step S1801, it is determined whether or not fast-forwarding is performed. If fast-forwarding is not in progress, the process returns to step S1801. If fast-forwarding is in progress, the process advances to steps S1802a to 1802d. In steps S1802a to 1802d, which of the following four types of fast-forwarding is specified. That is, in step S1802a, it is determined whether or not the acceleration is in the + direction. If the acceleration is in the + direction, the process proceeds to step S1803.

  In step S1802b, it is determined whether or not the acceleration is in the negative direction. If the acceleration is in the negative direction, the process proceeds to step S1813. In step S1802c, it is determined whether or not the deceleration is in the + direction. If the deceleration is in the + direction, the process proceeds to step S1823. In step S1802d, it is determined whether or not the deceleration is in the negative direction. If the deceleration is in the negative direction, the process proceeds to step S1833. In step S1803, the current command value In is sampled at a constant period during fast-forwarding.

  In step S1804, the absolute value | In | of the sampled current command value is compared with the maximum value Ip + a of the current command sampled up to the previous time during this fast-forwarding. If | In | is larger, the process advances to step S1805 to change the Ip + a value to the current | In |.

  In step S1806, it is determined whether or not the current fast-forwarding has been completed. If the fast-forwarding is completed, the process proceeds to step S1807. If not completed, the process returns to step S1803 after the sampling period, and the next current command value In is sampled. In step S1807, the ratio β of the current command maximum value Ip + a to the maximum current Imax that can be output by a motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip + a) / Imax
In order to set the ideal output ratio to α and the output ratio in the next fast-forward acceleration / deceleration to be close to α, the next fast-forward time constant B + a is calculated based on the current fast-forward time constant A + a and the ideal output ratio α and ratio β. Do.

(B + a) = (A + a) · β / α
= (A + a) · {(Ip + a) / Imax · α}
The acceleration / deceleration time constant (B + a) obtained from this calculation result is substituted into (A + a), and the next rapid feed + direction acceleration command is created with this time constant. In step S1813, the current command value In is sampled at a constant period during fast-forwarding.

  In step S1814, the absolute value | In | of the sampled current command value is compared with the maximum value Ip-a of the current command sampled until the previous time during the current fast-forward. If | In | is larger, the process proceeds to step S1815, and the Ip-a value is changed to the current | In |.

  Next, in step S1816, it is determined whether or not the current fast-forward has ended. If the fast-forwarding is completed, the process proceeds to step S1817. If not completed, the process returns to step S1813 after the sampling period, and the next current command value In is sampled. In step S1817, the ratio β of the current command maximum value Ip-a to the maximum current Imax that can be output by a motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip−a) / Imax
In order to set the ideal output ratio to α and the output ratio in the next fast-forward acceleration / deceleration to be close to α, the next fast-forward time constant B− based on the current rapid feed time constant Aa and the ideal output ratio α and ratio β. Calculate a.

(B−a) = (A−a) · β / α
= (A−a) · {(Ip−a) / Imax · α}
The acceleration / deceleration time constant (Ba) obtained from this calculation result is substituted into (Aa), and the next rapid feed + direction deceleration command is created with this time constant. In step S1823, the current command value In is sampled at a constant period during fast-forwarding.

  In step S1824, the absolute value | In | of the sampled current command value is compared with the maximum value Ipa of the current command sampled up to the previous time during the current fast-forward. If | In | is larger, the process advances to step S1825 to change the Ip + d value to the current | In |.

  Next, in step S1826, it is determined whether or not the current fast-forward has ended. When the fast-forwarding is completed, the process proceeds to step S1827. When the fast-forwarding is not completed, the process returns to step S1823 after the sampling period, and the next current command value In is sampled. In step S1827, the ratio β of the current command maximum value Ipd to the maximum current Imax that can be output by a motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip + d) / Imax
In order to set the ideal output ratio to α and the output ratio in the next fast-forward acceleration / deceleration to be close to α, the next fast-forward time constant B + d is calculated based on the current fast-forward time constant A + d and the ideal output ratio α and ratio β. Do.

(B + d) = (A + d) · β / α
= (A + d) · {(Ip + d) / Imax · α}
The acceleration / deceleration time constant (B + d) obtained from this calculation result is substituted into (A + d), and the next rapid feed + direction deceleration command is created with this time constant. In step S1833, the current command value In is sampled at a constant period during fast-forwarding.

  In step S1834, the absolute value | In | of the sampled current command value is compared with the maximum value Ip-d of the current command sampled up to the previous time during the current fast-forward. If | In | is larger, the process advances to step S1835 to change the Ip-d value to the current | In |.

  Next, in step S1836, it is determined whether or not the current fast-forward has ended. If the fast-forwarding is completed, the process proceeds to step S1837. If not completed, the process returns to step S1833 after the sampling period, and the next current command value In is sampled. In step S1837, the ratio β of the current command maximum value Ip-d to the maximum current Imax that can be output by a motor drive device such as a servo amplifier is calculated by the following equation.

β = (Ip−d) / Imax
In order to set the ideal output ratio to α and the output ratio in the next fast-forward acceleration / deceleration to be close to α, the next fast-forward time constant B− based on the current rapid feed time constant Ad, the ideal output ratio α, and the ratio β. Calculate d.

(Bd) = (Ad) · β / α
= (A−d) · {(Ip−d) / Imax · α}
The acceleration / deceleration time constant (Bd) obtained from the calculation result is substituted into (Ad), and the next rapid feed-direction deceleration command is created with this time constant. As a result, every time acceleration / deceleration is performed, the optimum acceleration / deceleration time constant for each acceleration / deceleration and movement direction is calculated in real time, and acceleration / deceleration operation that does not affect the stability of the system due to mechanical load fluctuations including friction Realize.

  Even if the time constant for acceleration / deceleration is optimized, if the current command value reaches the limit value, the position tracking error due to servo control will be delayed from the ideal value, speed overshoot, or an excessive error alarm will occur. May occur and the system may go down. As a countermeasure against this, the excessive error determination value during rapid feed acceleration / deceleration is made variable to make it difficult to generate an excessive error alarm.

  FIG. 28 shows a routine for changing an excessive error determination value. In step S1901, the excessive error determination value DOD is set to the standard value DB. That is, DOB = DB. The determination method of DB is generally set to about 50% of the ideal droop amount generated during the fast-forward maximum speed (steady state).

  In step S1902, it is determined whether fast-feed acceleration / deceleration is being performed based on the amount of change in the position command value per unit time output from the C device. If fast-acceleration acceleration / deceleration is in progress, the process proceeds to step S1903. If not, the process returns to step S1901. In step S1903, the error excess determination width DOD = DB · a. a is an excessive error tolerance coefficient at the time of acceleration / deceleration, and is set to a> 1, usually about 2.

  In step S1904, an ideal droop amount (position deviation amount) Di with respect to the current command input is calculated. In step S1905, the actual droop amount D at the present time is detected. In step S1906, a difference b between the ideal droop Di and the actual droop amount D is calculated.

  In step S1907, it is determined whether or not the absolute value of the actual droop error b exceeds DOD. If not, the process returns to step S1901 after the elapse of a fixed time, and if it exceeds, the process proceeds to step S1908. In step S1908, an error excessive alarm is generated, an emergency stop state is set, and NC reset is awaited. In step S1909, it is determined whether or not there is an alarm reset request from the NC device (actually an operator input). If there is an alarm reset request, the process proceeds to step S1910. In step S1910, the emergency stop state is canceled, and the process returns to step S1901. As a result, an overspeed alarm is unlikely to occur and a highly reliable servo control system is obtained.

  Although the acceleration / deceleration time constant has been optimized, the servo control position tracking error is delayed from the ideal value due to the current command reaching the limit value. If an error occurs, an excessive error alarm occurs, and the system goes down, the output current (output torque) reaches the maximum value, and it is inevitable that a speed overshoot will occur.

  Normally, if the servo motor rotates at a speed about 1.2 times the specified maximum speed, an overspeed alarm occurs and the system is protected, so the load on the machine increases or suddenly changes. When entering such a mode, an alarm is generated. In order to cope with such a case, the overspeed alarm determination value VOS is changed only during rapid feed acceleration / deceleration so that this alarm does not occur.

  FIG. 29 shows an overspeed alarm determination value change routine. In step S2001, the overspeed alarm determination motor rotational speed VOS is set to the standard value VB. Normally, VB is about 1.2 times the maximum rotation speed of the motor used.

  In step S2004, the actual motor speed V is detected. Next, in step S2005, it is determined whether or not the actual motor speed V exceeds the overspeed alarm determination value VOS. If not, the process returns to step S2001 after elapse of a certain time, and if exceeding, the process proceeds to step S2006.

  In step S2006, an overspeed alarm is generated, an emergency stop state is set, and an NC reset is awaited. In step S2007, it is determined whether or not there is an alarm reset request from the NC device (actually the operator's input). If there is an alarm reset request, the process proceeds to step S2008. In step S2008, the emergency stop state is canceled, and the process returns to step S2001. As a result, an overspeed alarm is unlikely to occur and a highly reliable servo control system is obtained.

FIG. 30 shows an embodiment of the servo control system used for carrying out the method for automatically optimizing the servo control system according to the present invention. This servo control system includes a control unit 37 that clamps the maximum value of the speed command calculated by the position control unit 11. As a result, even when the current limit is reached, the amount of overshoot can be suppressed by clamping the speed command at a constant value V _MAX (about the maximum motor speed 1.2 times).

  In this embodiment, the speed command is clamped only during rapid traverse acceleration / deceleration to suppress the amount of overshoot, without sacrificing the ability to follow a command with a large acceleration, and not affecting high-speed cutting.

  FIG. 31 shows a speed command clamping routine in this embodiment. First, in step S2201, the speed command clamp is released. Next, in step S2202, it is determined whether fast-feed acceleration / deceleration is being performed based on the amount of change in position command per unit time output by the NC device. If acceleration / deceleration is in progress, the process proceeds to step S2203; otherwise, the process returns to step S2201.

In step S2203, since the rapid traverse acceleration / deceleration is being performed, the maximum clamp value of the speed command is set to V _MAX . In step S2204, it is determined whether or not the speed command calculated by the position control exceeds V _MAX . If the speed command exceeds V _MAX , the process proceeds to step S2205. In step S2205, the absolute value of the speed command is output as V _{MAX and the} process returns to step S2201.

  As a result, the maximum speed command is clamped at a constant value only during acceleration / deceleration, so that the time constant setting during rapid traverse acceleration / deceleration is small or the maximum output torque of the servo amplifier is reached due to abnormal loads. Even in such a case, overshoot is less likely to occur.

  In this embodiment, the speed command is clamped only when the current command value reaches the current limit. FIG. 32 shows a speed command clamping routine in this embodiment. In step S2301, the speed command clamp is released, and in step S2302, the current command value In is sampled.

In step S2303, it is determined whether or not the current command value In has reached the current limit value. If the current command value In has reached the current limit value, the process proceeds to step S2304, and if not, the process proceeds to step S2305. In step S2304, the maximum clamp value of the speed command is set to V _MAX .

In step S2305, it is determined whether or not the speed command calculated by the position control exceeds V _MAX . If the speed command exceeds V _MAX , the process proceeds to step S2306. In step S2306, the absolute value of the speed command is output as V _{MAX and the} process returns to step S2301.

  This makes it possible to obtain a stable and highly reliable servo control system that is less likely to cause overshoot even when the time constant setting during rapid traverse acceleration / deceleration is small or the maximum output torque of the servo amplifier is reached due to abnormal loads. .

  In this embodiment, during the fast-forward acceleration, the speed clamp function when the current command value reaches the current limit is further developed, the amount of position droop for overshooting as the speed command is thinned out, and the deceleration time constant from the deceleration start point Add to the distribution.

  FIG. 33 shows the operation flow of this embodiment. In step S2401, it is determined whether fast-forwarding is being performed. If fast-forwarding is in progress, the process proceeds to step S2402. If not, the process returns to step S2401. In step S2402, it is determined whether or not the current command value has reached the current limit. If the current command value has reached the current limit, the process proceeds to step S2403; otherwise, the process returns to step S2401.

In step S2403, clamping the speed command at the motor maximum speed V _MO. Then, the maximum position droop amount D _MAX obtained by calculating the position loop gain from V _MO is compared with the actual droop amount D, and the process of decimating the excess portion of the position droop D _ER from the position command is performed during acceleration. Wait for deceleration. In step S2404, it is determined whether or not the vehicle is decelerating. When deceleration is started, the process proceeds to step S2405. In step S2405, the position command amount D _ER thinned out from the moment when deceleration is started is added during deceleration. The relationship between the speed command and the current command controlled in this way is shown in FIG.

  This makes it possible to obtain a stable and highly reliable servo control system that is less likely to cause overshoot even when the time constant setting during rapid traverse acceleration / deceleration is small or the maximum output torque of the servo amplifier is reached due to abnormal loads. .

  In this embodiment, when the current command value reaches the current limit value during fast-forward acceleration, the position command (command speed) per unit time is reduced, so that overshoot is unlikely to occur and an error excessive alarm is unlikely. Like that. Note that this operation is performed so that the trajectory does not deviate with respect to all axes during the multi-axis interpolation operation.

  FIG. 35 shows an operation flow of this embodiment. In step S2501, it is determined whether fast-forwarding is being performed. If fast-forwarding is in progress, the process proceeds to step S2502, and if not, the process returns to step S2501. In step S2502, it is determined whether or not the current command value has reached the current limit value. If the current command value has reached the current limit value, the process proceeds to step S2503.

  In step S2503, the change amount of the position command per unit time is limited so that the current command of the servo model set in the NC apparatus does not exceed the current control value level. That is, the position command is thinned out. When the current control is released, the position command for the shortage due to thinning is given at a certain time constant or by time distribution, and the absolute position is adjusted. As a result, it is difficult for an overshoot to occur and an error excessive alarm is unlikely to occur.

  In this embodiment, when the maximum output torque of the servo amplifier is reached during rapid traverse due to the abnormal load, the position loop gain of all the axes is reduced only during that time so as not to cause an excessive error.

  FIG. 36 shows the operation flow of this embodiment. In general, the required torque for acceleration is larger than that for deceleration. Therefore, the following description will be focused on acceleration. In step S2601, it is determined whether fast-forwarding is being performed. If fast forward is in progress, the process advances to step S2602. In step S2602, it is determined whether or not the current command value has reached the current limit value. If the current command value has reached the current limit value, the process proceeds to step S2603.

  In step S2603, when the droop amount becomes larger than the ideal value and the NC device lowers the position loop gain of the axis that has reached the current limit of the servo amplifier controller and the current limit is released, the position loop gain is set. If the fixed or constant speed operation is reached during this fast-forwarding, the value is gradually returned to the original value. As a result, if the maximum output torque of the servo amplifier is reached during rapid traverse due to abnormal load, the position loop gain of all axes is reduced only during that time, and the servo system moves more slowly, resulting in excessive errors. Operation can continue without happening.

  In this embodiment, when the maximum output torque of the servo amplifier is reached due to the influence of an abnormal load during rapid traverse, the position loop gain of all axes is reduced by a certain time constant, and the position loop gain at the time when the current limit is released This change is finished, and control is performed with the same gain until the movement is finished. In the next operation, since the rapid feed time constant is changed by the above-described optimization of the acceleration / deceleration time constant, movement starts with the original set position loop gain.

  FIG. 37 shows the operation flow of this embodiment. In general, acceleration requires a larger torque than when decelerating, so here again, the explanation will be focused on acceleration. In step S2701, it is determined whether fast-forwarding is being performed. If fast-forwarding is in progress, the process advances to step S2702.

  In step S2702, it is determined whether or not the current command value has reached the current limit value. If the current command value has reached the current limit value, the process proceeds to step S2703. In step S2703, the droop amount becomes larger than the ideal value, and the NC 10 reduces the position loop gain of the axis that has reached the current limit of the servo amplifier controller with a certain time constant, and when the current limit is released, the position loop is reached. If the gain reaches a fixed or constant speed operation during this rapid traverse, it gradually increases to the original value. As a result, the operation of the system can be continued without causing an excessive error alarm.

  In this embodiment, when the maximum output torque of the servo amplifier is reached due to an abnormal load during rapid traverse, the speed command is a value of V = corresponding to the motor rated speed + α (α is about 2% of the motor rated speed). The position loop gain is calculated from the current droop amount so that the speed command does not always exceed the value of V.

  FIG. 38 shows the operation flow of this embodiment. In general, acceleration requires a larger torque than when decelerating, so here again, the explanation will be focused on acceleration. In step S2801, it is determined whether fast-forwarding is being performed. If fast-forwarding is in progress, the process advances to step S2802.

  In step S2802, it is determined whether or not the current command value has reached the current limit value. If the current command value reaches the current limit value, the process proceeds to step S2803. In step S2803, the droop amount becomes a larger value than the ideal value, and the NC device reduces the position loop gain Kp of the axis that is the current limit of the servo amplifier control unit to a value calculated by the following equation. When the position loop gain Kp reaches a fixed or constant speed operation during this fast-forwarding at the time of release, it gradually increases to the original value.

Kp = (rated motor speed + α) / 60 · D
D is the droop amount.

  Thereby, even in this embodiment, it is possible to continue the operation of the system without generating an excessive error alarm.

  With the progress of absolute positioning and high resolution of detectors used for position feedback, various I / F methods have been used, and it is necessary to use reception lines as much as possible in order to support all these detectors. is there.

  In this embodiment, the type of detector attached by itself is automatically determined at power-on without depending on the setting of the detector by the receiving line and servo parameters corresponding to three different types of detector I / F, and is specified by the parameter. If the detected detector type and the actually connected detector are different, a parameter error alarm is generated.

  The left side of FIG. 39 shows an example of a feedback detection circuit. This feedback detection circuit initially transmits and receives the absolute position by serial communication (RQ and DT) with the incremental detector having the position of the pulse output, the speed control required ABZ phase + the UVW phase for the initial magnetic pole of the synchronous motor, and then This is a circuit that shares three types of input / output circuits: an absolute position detector that performs communication in the A, B, and Z phases and a detector that always performs absolute position data in serial communication (only RQ and DT).

  In FIG. 39, it is the differential input of the A phase, B phase, Z phase, U phase, V phase, and W phase from the upper left side. In this example, the U phase and RQ (serial data request) are combined, and the V phase and DT (serial data line) are combined.

  This feedback detection circuit includes differential receivers 171a to 171f, exclusive circuits 172a to 172f for detecting that a differential input is connected, and an incremental counter (feedback amount creation counter) 173 that is counted by ABZ-phase pulses. The serial request I / F circuit 174 that supports the request part of serial communication, the reception buffer (serial data reception I / F circuit) 175 for storing data from the detector, and the state of the initial magnetic pole UVW phase It has a UVW phase lead port 176 for observing and a phase no signal state read port 177 for observing the no signal state of each phase. As shown in FIG. 40, since the termination resistor is connected to the exclusive circuit, the output is always 1 when the exclusive circuit is open.

  The right side of FIG. 39 shows the state of the read port 177 when three types of detectors are connected. The driver enable line of the serial detector request line is disabled when the power is turned on, and if the detector has normal six input states, information as shown on the right side of FIG. 39 is obtained. This information is compared with the detector model name parameter sent from the NC device, and if they are different, a parameter abnormality alarm is generated.

  FIG. 41 shows this parameter abnormality diagnosis routine. First, in step S2901, all-phase input lines are set, and in next step S2902, the no-signal state is checked.

  In step S2903, the connected detector is determined based on the no-signal state. In step S2904, the detector indicating the detector type name is collated with the connected detector. In step S2905, it is determined whether or not the parameter indicating the detector model name matches the connected detector. If they do not match, the process proceeds to step S2906, where a parameter abnormality alarm is generated and the system is brought down. As a result, when the detector type specified by the parameter is different from the detector actually connected, a parameter abnormality alarm is generated, and the cause of the trouble can be easily pursued.

  In this embodiment, when it is different from the detector specified by the parameter by the above-mentioned automatic discrimination, it is switched to the I / F of the actually connected detector, and the connection state of the detector is automatically optimized.

  FIG. 42 shows an operation flow of this embodiment. First, in step S3001, an all-phase input line is set, and in the next step S3002, a no-signal state is checked. In step S3003, the connected detector is determined based on the no-signal state.

  In step S3004, the detector indicating the detector model name is collated with the connected detector. In step S3005, it is determined whether or not the parameter indicating the detector model name matches the connected detector. If they do not match, the process advances to step S3006, and the transmission / reception unit setting is matched with the I / F of the detector that is determined to be connected. As a result, even if there is a mistake in the parameter setting, a detection circuit adapted to the detector is formed without generating an alarm such as no signal, and the system operates normally.

  As described above, the abnormality detection / diagnosis method and automatic optimization method of the servo control system according to the present invention, and the abnormality detection / diagnosis device and automatic optimization device of the servo control system are numerical values for controlling machine tools, robots, and the like. Useful for control devices and the like.

It is a block diagram which shows one Example of a servomotor drive device. It is a flowchart which shows the connection diagnosis routine of a motor output terminal. It is explanatory drawing which shows the determination result of a misconnection. It is explanatory drawing which shows the determination result of a misconnection. It is a flowchart which shows the phase voltage detection routine used for the connection diagnosis of a motor output terminal and a converter bus-line. It is a flowchart which shows the connection diagnostic routine of a motor output terminal. It is a flowchart which shows the connection diagnostic routine of a converter bus-line. It is a block diagram which shows the gate control circuit of a current control part. It is a flowchart which shows the diagnostic routine of the gate interruption | blocking generation | occurrence | production factor. It is a flowchart which shows the wiring diagnosis routine of a feedback cable. It is a flowchart which shows a parameter setting diagnostic routine. It is a block diagram which shows the internal structure of a current control part. It is a flowchart which shows the diagnostic routine of the cause pursuit at the time of current control. It is a flowchart which shows a position control system automatic switching routine. It is a flowchart which shows a polarity automatic inversion routine. It is a block diagram which shows the servo control system of a dual feedback control system. It is a flowchart which shows the polarity automatic inversion routine in the servo control system of a dual feedback control system. It is a block diagram which shows the Example of a servo control system. It is a flowchart which shows one Example of a time constant optimization routine. It is a flowchart which shows the other Example of time constant optimization routine. It is a flowchart which shows the other Example of time constant optimization routine. It is a flowchart which shows another Example of the time constant optimization routine. It is a flowchart which shows another Example of the time constant optimization routine. It is a flowchart which shows another Example of another time constant optimization routine. It is a flowchart which shows another Example of another time constant optimization routine. It is a flowchart which shows another Example of another time constant optimization routine. It is a flowchart which shows another Example of another time constant optimization routine. It is a flowchart which shows another Example of another time constant optimization routine. It is a flowchart which shows an error excessive determination value change routine. It is a flowchart which shows an overspeed alarm judgment value change routine. It is a block diagram which shows one Example of a servo control system. It is a flowchart which shows one Example of a speed command clamp routine. It is a flowchart which shows the other Example of a speed instruction | command clamp routine. 6 is a flowchart illustrating an example of a speed / position control routine. It is a graph which shows the relationship between a speed command and an electric current command. It is a flowchart which shows the other Example of a speed / position control routine. It is a flowchart which shows another Example of a speed / position control routine. It is a flowchart which shows another one Example of a speed / position control routine. It is a flowchart which shows another another Example of a speed / position control routine. It is a figure which shows the state of a read port when the example of a feedback detection circuit and three types of detectors are connected. It is a circuit diagram which shows an example of an exclusive circuit. It is a flowchart which shows a parameter abnormality diagnosis routine. It is a flowchart which shows the connection state automatic optimization routine of a detector. It is a block diagram which shows the general servomotor drive device used with a servo control system. It is a block diagram which shows a general servo control system. It is a block diagram which shows the electric current control part of an AC servomotor.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 3 phase alternating current power supply, 2 Rectifier circuit, 3 Smoothing capacitor, 4 Semiconductor switching circuit, 5 Current detection part, 6 A / D converter, 7 CPU, 8 AC servo motor, 9a, 9b, 9c Voltage detection circuit, 10 NC Device, 11 Position control unit, 12 Speed control unit, 13 Current control unit, 15 Reduction gear, 16 Feed screw, 17 Table, 18 Motor end detector, 19 Machine end detector, 20 Speed control unit 21 Limiter, 22 d- q coordinate conversion unit 23a, 23b current controller, 24 three-phase conversion unit, 25 PWM modulation unit, 26 three-phase conversion unit, 27 torque calculation unit, 28 motor position calculation unit, 29 overcurrent detector, 30, 31, 32 Latch circuit, 33, 34 AND gate 35, 36, 37 Control unit, 171a to 171f Differential receiver, 172a to 172f Sib circuit, 173 Incremental counter (feedback amount creation counter), 174 Serial request I / F circuit, 175 Receive buffer (serial data reception I / F circuit), 176 UVW phase read port, 177 No signal state read port for each phase.

Claims (6)

A speed command is created based on the deviation between the position command value and the position feedback value, a current command is created based on the deviation between the created speed command and the speed feedback value, and the deviation between the created current command and the current command feedback value is determined. In the servo motor control method for driving and controlling the servo motor and clamping the current command output from the speed control unit with a predetermined current limit value,
A first step of determining whether or not the current command value is clamped at the predetermined current limit value when fast-forwarding is in progress; and
When the current command value of any of the axes is clamped at a predetermined current limit value, an operation to reduce the position loop gain of the axis is performed, and in addition, when interpolation operation of a plurality of axes is in progress A second step of performing an operation of reducing the position loop gain for all the target axes ;
A third step of gradually increasing the position loop gain to the original value when a predetermined constant speed operation is reached after releasing the clamp;
A servo motor control method comprising: 2. The servo motor control method according to claim 1 , wherein in the second step, the position loop gain is decreased with a predetermined time constant. A speed command is created based on the deviation between the position command value and the position feedback value, a current command is created based on the deviation between the created speed command and the speed feedback value, and the deviation between the created current command and the current command feedback value is determined. In the servo motor control method for driving and controlling the servo motor and clamping the current command output from the speed control unit with a predetermined current limit value,
A first step of determining whether or not the current command value is clamped at the predetermined current limit value when fast-forwarding is in progress; and
When the current command value of any of the axes is clamped at a predetermined current limit value, the speed command is set to be equivalent to the motor rated speed for the axis based on the current position deviation and the rated motor speed. When the position loop gain value is obtained and the position loop gain is decreased to the obtained position loop gain value , and in addition, when multiple axes are being interpolated, the operation is performed for all target axes. A second step of performing an operation of decreasing the position loop gain ;
A third step of gradually increasing the position loop gain to the original value when a predetermined constant speed operation is reached after releasing the clamp;
A servo motor control method comprising: A position control unit that creates a speed command based on a deviation between the position command value and the position feedback value; a speed control unit that creates a current command based on a deviation between the created speed command and the speed feedback value; and In a servo motor control device comprising a current control unit that drives and controls the servo motor by deviation from the current command feedback value,
A first control unit for clamping a current command output from the speed control unit with a predetermined current limit value;
When fast-forwarding is in progress, it is determined whether or not the current command value is clamped at the predetermined current limit value by the first control unit, and the current command value of any of the axes is determined to be a predetermined current limit value. If it is clamped by the value, the position loop gain of the relevant axis is reduced . In addition, if multiple axes are being interpolated, the relevant position loop gain is reduced for all target axes. A second control unit that gradually increases the position loop gain to the original value when a predetermined constant speed operation is reached after releasing the clamp;
A servo motor control device comprising: The servo motor control device according to claim 4 , wherein the second control unit decreases the position loop gain with a predetermined time constant. A position control unit that creates a speed command based on a deviation between the position command value and the position feedback value; a speed control unit that creates a current command based on a deviation between the created speed command and the speed feedback value; and In a servo motor control device comprising a current control unit that drives and controls the servo motor by deviation from the current command feedback value,
A first control unit for clamping a current command output from the speed control unit with a predetermined current limit value;
When fast-forwarding is in progress, it is determined whether or not the current command value is clamped at the predetermined current limit value by the first control unit, and the current command value of any of the axes is determined to be a predetermined current limit value. If it is clamped by the value, the position loop gain value when the speed command is equivalent to the motor rated speed is obtained from the current position deviation and the rated motor speed for the relevant axis , and the obtained position loop The position loop gain is reduced to the gain value . In addition, if multiple axes are being interpolated, the position loop gain is reduced for all target axes and the clamp is released. Then, if a predetermined constant speed operation is reached, a second control unit that gradually increases the position loop gain to the original value;
A servo motor control device comprising:

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