JP4712063B2 - Position control device - Google Patents

Description

  The present invention relates to a position control device that drives and controls, for example, a feed shaft with respect to a load machine such as a machine tool, an injection molding machine, and a press machine, and in particular, a position control device that drives one movable part with a plurality of electric motors. It is about.

  When a single load machine (movable part) is driven by a plurality of electric motors, the unbalance of the inertial load of the load machine acting on each electric motor and the unbalance of the disturbance applied to each electric motor or the load machine corresponding to each electric motor As a result, there is a problem that the positions of the load machines corresponding to the plurality of electric motors or the respective electric motors are shifted. When this misalignment occurs, the load machine is distorted and an unreasonable force acts on the load machine, which adversely affects the life of the load machine, particularly the life of the sliding portion. In addition, since the electric motor and the load machine vibrate due to this strain, there is a problem that it is difficult to perform high-precision drive control.

  In order to solve such a problem, conventionally, there has been proposed a technique that eliminates adverse effects due to positional deviation and vibration of each electric motor or a load machine corresponding to each electric motor and realizes highly accurate drive control. For example, in Patent Document 1, one load machine is driven by a plurality of electric motors, and a control compensator for each electric motor generates a control signal based on one position command and a position detection signal of each electric motor. In the compensator, a synchronous compensation signal calculated based on a reference value indicating the average of the positions of a plurality of motors and a deviation signal between each motor is added to a control signal output from the control compensator, and each motor is loaded with a load machine. By generating a drive signal for driving the motor, synchronization of each of the plurality of electric motors is ensured, that is, positional deviation is suppressed.

Japanese Patent Laid-Open No. 7-200062 (page 7, FIG. 1)

  In general, the higher the loop gain of the feedback loop from the position signal of the motor or the load machine driven by the motor to the torque command signal, the higher the control performance can be realized. If it is too much, the stability of the control system is lowered, and the control system shows a vibration response. Furthermore, if the loop gain of the feedback loop is increased, it may diverge. Therefore, it is necessary to adjust the loop gain of the feedback loop to an appropriate value so that the highest possible control performance can be obtained within a range where the control system is stable.

  The technique disclosed in Patent Document 1 adds a synchronous compensator to a control compensator that controls each position signal of a plurality of motors so as to coincide with a position command signal, thereby allowing each motor position shift. Is suppressed. However, the loop gain of the feedback loop from the position of the motor to the torque command signal is a combination of the feedback loop of the position controller and the synchronous compensator, and compared with the case where the synchronous compensator of the feedback loop is not added, Since the gain of the feedback loop is increased by the amount of the compensator, the stability of the control system is lowered. To avoid this, it is necessary to change the gain of the control compensator according to the gain change of the synchronous compensator, and conversely, change the gain of the synchronous compensator according to the gain change of the control compensator. There is a problem that the work until the system is adjusted to an appropriate gain that achieves high control performance within a stable range becomes complicated and requires a long adjustment time.

  The present invention has been made in view of the above, and calculates the gains of the main position control circuit and the sub position control circuit based on a parameter signal input from the outside without reducing the stability of the control system. It is an object of the present invention to provide a position control device that can be changed, facilitates adjustment of the control system, and shortens the adjustment time.

  In order to solve the above-described problems and achieve the object, the position control device of the present invention includes first to n-th motors that drive one load machine by one position command signal, and the first to n-th motors. The first to nth position detectors that detect the position of the load machine and output it as a position signal and drive control of the motors provided to each of the first to nth motors. Main position control circuits for calculating a main torque command signal based on the position command signal and the position signal, respectively. A sub position control circuit that calculates a sub torque command signal based on the position signals output from the first to nth position detectors, and an integrated torque obtained by adding the main torque command signal and the sub torque command signal Matches the command signal A torque control circuit for controlling the torque of the motor, and a control coefficient calculation circuit for calculating and changing control coefficients of the main position control circuit and the sub position control circuit based on a parameter signal input from the outside. It is characterized by that.

  According to the position control device of the present invention, since the control coefficient calculation circuit for calculating and changing the control coefficients of the main position control circuit and the sub position control circuit based on the parameter signal input from the outside is provided, It is possible to calculate and change the control coefficients of the main position control circuit and sub position control circuit without degrading the stability of the system, making it easy to adjust the control system and shortening the adjustment time To do.

  Embodiments of a position control device according to 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, the main position control circuit is described as a first position control circuit, and the sub position control circuit is described as a second position control circuit. Accordingly, the main torque command signal will be described as a first torque command signal, and the auxiliary torque command signal will be described as a second torque command signal.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a position control apparatus according to an embodiment of the present invention. In FIG. 1, in the present embodiment, the same movable part of one load machine 10 is driven by two electric motors 101 and 201 for ease of explanation. However, one movable part has three or more movable parts. The same applies to the case of driving with an electric motor. This embodiment is an example in which two ball screws 10a and 10b that slide a sliding table are driven by two electric motors 101 and 201 as the same movable part. The position detectors 102 and 202 detect the current values of 10 positions of the load machine corresponding to each of the electric motors 101 and 201 or each of the electric motors 101 and 201. In the present embodiment, the positions of the electric motors 101 and 201 are detected. It is an example in the case of detecting.

First, the overall operation of the embodiment shown in FIG. 1 will be described. The first drive control circuit 103 and the second drive control circuit 203 are configured to drive and control each of the two electric motors 101 and 201 that drive one load machine 10. A first position control circuit (main position control circuit) 104 inside the first drive control circuit 103 is a motor 101 that is detected by a position command signal R that indicates a target position of the load machine 10 and a position detector 102. The first torque command signal (main torque command signal) TR11 is calculated on the basis of the position signal P1 representing the current position. The second position control circuit (sub position control circuit) 105 is a second torque command signal (sub torque command signal) based on the position signals P1, P2 of the electric motors 101, 201 detected by the position detection circuits 102, 202. TR12 is calculated. The torque control circuit 106 controls the torque of the electric motor 101 so as to coincide with a torque command signal (integrated torque command signal) TR1 obtained by adding the second torque command signal TR12 to the first torque command signal TR11. Gain calculating circuit (control coefficient calculation circuit) 107, based on the parameter signal α inputted from the outside, a first position control circuit 104 calculates the control coefficient of the second position control circuit 105, each of the control coefficients Are set in the first position control circuit 104 and the second position control circuit 105. Since the operation of the second drive control circuit 203 is the same as that of the first drive control 103, the description thereof is omitted. The parameter signal α input from the outside is a parameter common to all drive control circuits (drive control circuits 103 and 203) for driving the load machine 10, and in the drive control circuit 105, the position signal P1 to the main torque command signal TR11. The main normalized feedback loop obtained by dividing the loop gain of the feedback loop by the equivalent load inertia J1 acting on the electric motor 101, and the sub loop obtained by dividing the feedback loop gain from the position signal P1 to the sub torque command signal TR12 by the equivalent inertia load J1. This parameter adjusts the normalized feedback loop gain. In the drive control circuit 205, the main normalized feedback loop obtained by dividing the loop gain of the feedback loop from the position signal P2 to the main torque command signal TR21 by the equivalent load inertia J2 acting on the electric motor 201, and the auxiliary torque from the position signal P2. This parameter adjusts the subnormalized feedback loop gain obtained by dividing the feedback loop gain up to the command signal TR22 by the equivalent inertia load J2.

Next, the principle of the effect obtained by the embodiment will be described. The first position control circuit 104 receives the position command signal R and the position signal P ₁ detected by the position detector 103 as input, and uses a position differential gain K _v , a position proportional gain K _p , and a position integral gain K _i. the PID (proportional-integral-derivative) operation expressed by the following equation, the deviation between the position signals P ₁ and the position command signal R is for calculating a first torque command signal T _R11 to decrease.

When driving one load machine with a plurality of electric motors, when a disturbance torque having a different magnitude is applied to the plurality of electric motors or the load machine, for example, the disturbance torque Td1 is applied only to the electric motor 101 or the load machine corresponding to the electric motor 101. think of. In this case, the position signal P1 of the motor 101, by the effect of disturbance torque, Ri is Na large delay with respect to the position command signal R, the tracking error becomes large. On the other hand, the position signal P2 of the motor 102 to which no disturbance torque is applied is affected by Td1 due to the physical interference of the load machine 10, but here, if this physical interference is ignored, the position signal P2 becomes the position command signal R. Follow up without delay. For this reason, positional deviation occurs in the position signals P1 and P2 of the electric motors 101 and 102.

The second position control circuit 105 is for suppressing the positional deviation as described above. The second position control circuit 105 receives the position signals P ₁ and P ₂ of the electric motor 101 and the electric motor 201 and inputs the average of the position signals P ₁ and P ₂ . Based on the difference (P ₀ −P ₁ ) between the position P ₀ and the position signal P ₁ of the electric motor 101, the following equation is used by using the positional deviation differential gain C _v , the positional deviation proportional gain C _p , and the positional deviation integral gain C _i. in the PID operation represented, the position signal _{P 1} of the electric motor 101 for calculating a second torque command signal _{T R12} to approach the average position _{P 0.}

Two electric motors that drive one load machine 10 caused by disturbance torque or the like by adding the second torque command signal _TR12 calculated by the equation (2) to the first torque command signal _TR11. It is possible to suppress misalignment of 101 and 201. When the case where the disturbance torque _{T d1} is applied to the example, the position signal _{P 1} of the electric motor 101 by the disturbance torque _{T d1} is delayed with respect to the mean position _{P 0,} the second position control circuit 105 advances the position signals _{P 1} a second torque command signal _{T R12} calculated such that, the position signal _{P 2} of the motor 201 is advanced with respect to the mean position _{P 0,} the second position control circuit 205 first to delay position signal _{P 2} 2 torque command signal _TR22 is calculated. Thereby, even if the position signals P ₁ and P ₂ are displaced due to the disturbance torque T _d1 , the second position control circuits 105 and 205 control the position signals P ₁ and P ₂ so as to approach the average position P ₀ , respectively. Therefore, the displacement is suppressed.

  Next, the transfer characteristic of the feedback loop will be described with reference to FIG. FIG. 2 shows one motor 101 out of two motors that drive one load machine 10 and a drive circuit 103 that drives and controls the motor 101, and 11 shows the load of the load machine 10 in FIG. Of the inertia, it is the load inertia that acts on the electric motor 101 and means the equivalent load inertia that the electric motor 101 drives equivalently.

2, the electric motor the transfer characteristic of the feedback loop from the position signals P ₁ of 101 to the torque command signal T _R1, equivalent load inertia normalized feedback divided by J ₁ loop transfer characteristic G ₁ acting on the electric motor 101 _(s) Is a first normalized feedback loop transfer characteristic G ₁₁ (s) obtained by dividing the transfer characteristic of the first feedback loop from the position signal P ₁ to the first torque command signal TR ₁₁ by J ₁ , and the position signal P It is represented by the sum of the transfer characteristic of the second feedback loop from ₁ to the second torque command signal T _R12 and the second normalized feedback loop transfer characteristic G ₁₂ (s) divided by J ₁ (G ₁ (S) = G ₁₁ (s) + G ₁₂ (s)).

Although it is possible to suppress the positional deviation of the position signal P _1, P ₂ and adding a second position control circuit, (5) as indicated equation, the torque command signal from the position signal P ₁ of the electric motor 101 T _Since the normalized feedback loop gain up to _R1 becomes W _k + W _{c and} increases by the amount of the second position control circuit added, the stability of the control system decreases. Therefore, adding a second position control circuit to the drive control circuit 103, in consideration of the follow-up characteristics of the position signal P ₁ with respect to the position command R, the positional shift suppressing effect of the position signal P ₁ and P _2, further control system It is necessary to reset the gains of the first position control circuit and the second control circuit again so that becomes stable.

Therefore, in this embodiment, on the basis of one parameter signal externally input alpha, first to normalize the feedback loop gain of the position signal P ₁ of the electric motor 101 to the torque command signal T _R1 becomes a constant value 1 The distribution of the normalized feedback loop gain W _k and the second normalized feedback loop gain W _c is changed, and the position control circuit 104 and the second position control circuit 10 are changed based on the respective normalized feedback loop gains. The PID gain is calculated and changed.

Next, the operation of the gain calculation circuit 107 will be described. As shown in the equations (7) and (8), the gain calculation circuit 107 represents the first normalized gain W _k as a product of a constant value W ₀ and an externally input parameter signal α. The normalized gain W _c of 2 is expressed by the product of a constant value W ₀ and the complement of the parameter signal α to 1, and the parameter signal α input from the outside is changed to thereby change the first normalized feedback loop gain W W _k and W _c are calculated so that the sum of _k and the second normalized feedback loop gain W _c becomes a constant value W ₀ .

Here, the constant value W ₀ is appropriate for the control system to achieve high performance in a stable range when the second position control circuit is not provided, that is, when the parameter signal α input from the outside is 0. If the set normalized feedback loop gain is used, the control system normalized feedback loop gain is constant at W ₀ regardless of the value of the parameter signal α, so that the stability of the control system is maintained. The Since the normalized feedback loop gain needs to be positive, the adjustment range of the parameter signal α is in the range of 0 to less than 1. Further, as the parameter signal α is increased, the position signals P ₁ and P ₂ of the electric motors 101 and 201 are closer to the average value P ₀ thereof, and the effect of suppressing the positional deviation becomes stronger. The command followability of the average value P ₀ of the position signals P ₁ and P ₂ of the electric motors 101 and 201 with respect to the position command signal R when added is reduced. Therefore, the parameter signal α may be adjusted in the range of about 0 to 0.5.

  As a result of the above, due to the effects of the gain calculation circuits (control coefficient calculation circuits) 107 and 108, the parameter signal α is changed from 0 based on the loop gain of the normalized feedback loop when the parameter signal α input from the outside is set to 0. It is possible to suppress the displacement of the position signals of the electric motors 101 and 201 without impairing the stability of the control system by simple adjustment that is simply increased.

  In the present embodiment, the position detection circuits 102 and 202 detect the positions of the electric motors 101 and 201, but the position detection circuit detects the position of the load machine 10 driven by the electric motors 101 and 201. May be.

  Further, the position signal input to the first position control circuit is the position of the electric motor, and the position signal input to the second position control circuit is the position of the load machine 10 driven by the electric motors 101 and 201. In addition, the position signals input to the first position control circuit and the second position control circuit may be different.

  As described above, according to the position control device of the present embodiment, the gains (control coefficients) of the first position control circuit and the second position control circuit are calculated based on the parameter signal input from the outside. Since a gain calculation circuit for changing to a calculation result is provided, it is possible to calculate and change the gains of the first position control circuit and the second position control circuit, thereby facilitating adjustment of the control system. At the same time, adjustment time can be shortened.

  Further, according to the position control device of the present embodiment, the gain calculation circuit drives and controls the loop gain of the feedback loop from the position signal to the first main torque command signal based on the parameter signal input from the outside. A first normalized feedback loop gain divided by the inertial load of the load machine acting on the electric motor driven by the circuit, and a second normalization obtained by dividing the feedback loop gain from the position signal to the second torque command signal by the inertial load. Since the control coefficients of the first main position control circuit and the second sub position control circuit are calculated and changed so that the sum with the feedback loop gain becomes a predetermined constant value, the stability of the control system is lowered. The gains of the first position control circuit and the second position control circuit can be calculated and changed without any change.

  Furthermore, according to the position control apparatus of the present embodiment, the gain calculation circuit is configured so that the first feedback loop of the feedback loop from the position signal to the first torque command signal is based on a parameter signal input from the outside. The first position control circuit and the second sub position so that the sum of the transfer characteristic and the second feedback loop transfer characteristic of the feedback loop from the position signal to the second sub torque command signal becomes a predetermined constant value. Since the control coefficient of the control circuit is calculated and changed, it is possible to calculate and change the gains of the first position control circuit and the second position control circuit while keeping the control system more stable.

  As described above, the position control device according to the present invention is optimal for a position control device that drives a movable part such as a feed shaft with a plurality of electric motors, such as a machine tool, an injection molding machine, and a press machine, which are load machines. It is a thing.

It is a block diagram which shows the position control apparatus by embodiment of this invention. FIG. 2 is a block diagram showing an extracted portion related to a first drive control circuit in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Load machine 11 Equivalent load inertia which acts on 1st electric motor 101 1st electric motor 102 1st position detection circuit 103 1st drive control circuit 104,204 1st position control circuit (main position control circuit)
105, 205 Second position control circuit (sub-position control circuit)
106, 206 Torque control circuit 107, 207 Gain calculation circuit (control coefficient calculation circuit)
201 Second electric motor 202 Second position detection circuit 203 Second drive control circuit

Claims (2)

The outputs from the first to drive one of the load machine by one of the position command signal and the motor of the n, the position of the mechanical load provided from the first to each of the motors of the n as the detected position signal 1 to n-th position detectors, and first to n-th drive control circuits that are provided in each of the first to n-th electric motors and drive-control the electric motors,
The first to n-th drive control circuits each include at least one of proportional, integral, and differential operations based on the position command signal and the position signals of the first to n-th motors, respectively. A main position control circuit for calculating a main torque command signal for each of the first to n-th motors by a control operation;
On the basis of all position signals output from the first to n-th position detectors, a sub-torque for each of the first to n-th motors by a control operation including at least one of proportional, integral and differential operations. A sub position control circuit for calculating a command signal;
A torque control circuit for controlling the torque of each of the first to n-th motors so as to coincide with an integrated torque command signal obtained by adding the main torque command signal and the sub torque command signal;
Based on one parameter signal representing the effect of suppressing the shift of the position signal corresponding to the first to n-th electric motors, a loop gain of a feedback loop from the position signal to the main torque command signal is determined in the drive control circuit. A main normalized feedback loop gain divided by the inertia load of the load machine acting on the motor driven by the motor, and a subnormal obtained by dividing the loop gain of the feedback loop from the position signal to the sub torque command signal by the inertia load. The main normalized feedback loop gain and the subnormalized feedback loop gain are determined so that the distribution is changed while the sum of the normalized feedback loop gain is a predetermined constant value, and multiplication is performed using the main normalized feedback loop gain as an element. It performs an operation of a control factor of the proportional-integral-derivative operation of the main position control circuit based, based on the multiplication and the secondary normalized feedback loop gain elements A control coefficient calculation circuit for performing calculation of the control coefficient of the proportional-integral-derivative operation of the secondary position control circuit,
A position control device comprising: Wherein said control coefficient operation circuit according to claim 1, characterized in that the control system the predetermined constant value only the main position control circuit and the main normalized feedback loop gain when adjusted to be stable Position control device.

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