Position control device

Abstract

A position control apparatus for a target device (100) includes: a coefficient calculation unit (10) that performs a temporary operation of the target device (100) to reverse a traveling direction of the target device (100) when backlash compensation is closed, and that calculates a position of the target device (100) on the basis of a position command value (X) at a point in time when a position deviation (DIF) between the position command value (X) and a position detection value (XL) at a load end (104) rapidly increases; calculating an inversion detection coefficient (Mk) for each of the plurality of backlash portions (BLk); a reversal detection unit (12) that operates the target device (100) when the backlash compensation is turned on, and detects the timing at which the load-side transmission torque (tau Lk) is reversed on the basis of the coefficient (Mk), the position command value (X), and the moment of inertia of the entire load (JL); and a compensation value calculation unit (13) that increases or decreases the backlash compensation value (XBLc) at the time when the inversion is detected.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Japanese Patent Application No. 2024-166699, filed on September 25, 2024, the entire contents of which (including the specification, claims, drawings and abstract) are incorporated herein by reference. Technical Field

[0003] This description discloses a position control device for a target device, wherein the torque transmission path extending from the motor has a backlash portion. Background Technology

[0004] Position control devices that control motors to make the position of a target device (plant) (hereinafter referred to as "load position") follow position command values ​​are well known. Such position control devices are used, for example, for axis control of CNC machine tools.

[0005] Position control devices may have a backlash portion in the torque transmission path between the motor and the target device. The backlash portion is a gap or misalignment between torque transmission components. When the direction of movement reverses, this backlash portion becomes a dead zone where torque cannot be transmitted temporarily. This backlash portion causes command following error.

[0006] In view of the above, techniques for reducing command following errors caused by backlash have been proposed. For example, Patent Document 1 discloses a correction device for correcting backlash between a drive gear and a driven gear. This correction device calculates the transmitted torque applied from the drive gear to the driven gear based on position command information. When the sign of this transmitted torque is reversed, the correction device determines that backlash has occurred and corrects the command value to correct the backlash. This technique can reduce command following errors caused by backlash to a certain extent.

[0007] Citation List

[0008] Patent documents

[0009] Patent document 1: JP 2002-366230 A

[0010] Depending on the configuration of the torque transmission path, it may have more than one backlash portion. The prior art device (e.g., disclosed in Patent Document 1) cannot handle situations where the torque transmission path includes multiple backlash portions. As a result, in the prior art device, command following performance deteriorates when the torque transmission path includes multiple backlash portions.

[0011] In view of the above, this description discloses a position control device that can maintain high command following performance even when the torque transmission path includes multiple backlash portions. Summary of the Invention

[0012] This description discloses a position control device for a target device, wherein a motor and a load are connected via a torque transmission path having multiple backlash portions. The position control device includes: a coefficient calculation unit that performs temporary operation of the target device to reverse the direction of travel of the target device when backlash compensation is off, and calculates a reversal detection coefficient for each of the multiple backlash portions based on a position command value at the moment when the position deviation between a position command value and a position detection value at the load end rapidly increases, or based on a speed command value and an acceleration command value at the moment the position deviation rapidly increases; a reversal detection unit that operates the target device when backlash compensation is on, and detects the moment when the load-side transmitted torque of each of the multiple backlash portions reverses based on the reversal detection coefficient, the position command value, and the moment of inertia of the entire load; a compensation value calculation unit that increases or decreases the backlash compensation value at the moment the load-side transmitted torque reverses; and a position control loop unit that controls the position of the motor such that the position detection value at the load end becomes a position command value compensated for by the backlash compensation value.

[0013] In this case, the compensation value calculation unit can add the backlash amount of the k-th backlash portion from the motor to the current backlash compensation value or subtract the backlash amount of the k-th backlash portion from the current backlash compensation value at the moment when the torque transmitted on the load side reverses at the k-th backlash portion.

[0014] The position control loop unit can control the position of the motor to make the absolute value of the position error smaller. The position error is the difference between the compensated position command value and the position feedback value, and the position feedback value can include the sum of the position detection value at the load end and the backlash compensation value.

[0015] The position command value in the temporary operation is indicated by X = X0 + R0 sinθ represents a sine waveform, and the coefficient calculation unit can be based on M. k = (sinθ1 / sinθ k ) J L Calculate the coefficient M corresponding to the k-th backlash portion starting from the motor. k , where θ k θ and J are obtained when the positional deviation increases rapidly due to the k-th back gap portion. L It is the moment of inertia of the entire load.

[0016] The compensation value calculation unit can be based on the equation τ Lk = M k A + τ FCalculate the load-side transmitted torque τ of the k-th backlash section. Lk , where τ Lk For the load side of the k-th backlash section, τ transmits torque. F Let A be the sliding friction torque, and A be the acceleration command value.

[0017] The position command value in the temporary operation is indicated by X = X0 + R0 sinθ represents a sine waveform, and the coefficient calculation unit can be based on equation N. k = sgn(V k ) / A k Calculate the coefficient N corresponding to the k-th backlash portion starting from the motor. k A k This is the acceleration command value when the position deviation increases rapidly due to the k-th backlash portion.

[0018] The compensation value calculation unit can be based on equation r Lk = -A N k + sgn(V) calculates and determines the parameter r Lk Where V is the velocity command value, A is the acceleration command value, sgn is the sign function, and the parameter r is detected and determined. Lk The moment when the positive and negative sides reverse is the moment when the load-side torque reverses at the k-th backlash section.

[0019] According to the technology disclosed in this description, high command-following performance can be maintained even when the torque transmission path includes multiple backlash sections. Attached Figure Description

[0020] Embodiments of this disclosure will be described based on the following figures, wherein:

[0021] Figure 1 This is a block diagram showing the configuration of the position control device;

[0022] Figure 2 This is a schematic diagram of the target device;

[0023] Figure 3 This is a diagram illustrating examples of changes in position command values, acceleration command values, and sliding friction torque;

[0024] Figure 4 It is shown Figure 3 A graph showing the changes in position command value, torque, and position deviation within the range Sa;

[0025] Figure 5 This is a schematic diagram of a target device with a single back gap portion;

[0026] Figure 6 It is shown Figure 5 A graph showing the changes in the position command value and torque of the target device;

[0027] Figure 7 This is a block diagram illustrating another example of a position control device. Detailed Implementation

[0028] The configuration of the position control device will now be described with reference to the accompanying drawings. Figure 1 This is a block diagram showing the configuration of the position control device. Figure 2 This is a schematic diagram of the target device 100. (For example...) Figure 2 As shown, the target device 100 includes a motor 102, a torque transmission path 110, a load terminal 104, and a current control unit 120. The torque output by the motor 102 is transmitted to the load terminal 104 via the torque transmission path 110. The position control device calculates the torque command value τ of the motor 102. m In order to control the position X of the load end 104 according to the position command value X indicated by the upper-level device (not shown). L The current control unit 120 applies a torque command value τ to the motor 102. m The corresponding current. The current control unit 120 may include, for example, an inverter. This position control device can be applied to axis control of CNC machine tools (e.g., machine tools) or robots, and therefore requires system stability and high command following performance.

[0029] like Figure 2 As shown, the torque transmission path 110 of the target device 100 includes multiple (two in the illustrated example) backlash sections BL1 and BL2. Hereinafter, when it is not necessary to distinguish between the multiple backlash sections BL1 and BL2, the subscripts will be omitted, and the multiple backlash sections will be simply referred to as "backlash section BL". Additionally, the k-th backlash section starting from the motor 102 will be denoted as "backlash section BL". k This also applies to other elements.

[0030] The backlash portion BL is the area that experiences gaps or misalignment when the drive direction reverses. Backlash amount X BLk It is the BL of each back gap. k The backlash or offset vector in the drive direction. When the drive direction reverses, a backlash portion (BL) exists, creating a dead zone where motion cannot be temporarily transmitted to the load side, i.e., backlash. The presence of backlash leads to command following error. To illustrate this phenomenon, Figure 2 It shows that only the moment of inertia J Lk and the gap part BL k The model is composed of...

[0031] As described above, the position control device in this example is used for axis control of a CNC machine tool or robot. Typically, the axis to be controlled is connected to a first load end driven in a first axial direction and a second load end driven in a second axial direction. The first and second load ends are then driven with a sinusoidal waveform that has a 90-degree phase difference from each other, thereby driving the axis to be controlled in an arc shape. As an example, the case where the load end 104 is driven with a sinusoidal waveform to drive the axis to be controlled in an arc shape will be described. To drive the load end 104 with a sinusoidal waveform, the position command value X is represented as shown in Equation 1, where R0 is the radius of the arc, X0 is the offset from the center of the arc, ω0 is the angular velocity, and t is time.

[0032] X = X0 + R0 sin(ω0t)

[0033] = X0 + R0 sinθ Equation 1

[0034] A position control device is a computer that physically includes a processor and memory. For example, such a position control device can be configured by combining multiple physically separate computers. The position control device can also be configured as, for example, a numerical control (NC) device.

[0035] From a functional perspective, such as Figure 1 As shown, the position control device is roughly divided into calculating the torque command value τ. m The system includes a position control loop unit 20 and a backlash compensation unit 21. The position control loop unit 20 receives a position command value X from the upstream device. The position control loop unit 20 also receives a load position detection value X. L and motor position detection value X m Load location detection value X L This is the position detection signal provided at the load end 104. Motor position detection value X m It is a signal obtained by converting the signal from the rotation angle detector mounted on the motor 102 into a linear distance.

[0036] By adding the backlash compensation value X output by the backlash compensation unit 21 BLc To compensate for the position command value X. The compensated position command value X c The time derivative is performed by differentiator 51 to generate the velocity feedforward quantity V. fc Additionally, subtractor 50 receives the compensated position command value X. c Subtract the position feedback value X from the middle f It also outputs the position error er. Position feedback value X fThe calculations will be described below. Position error amplifier 52 amplifies the position error er by a factor of the position loop gain Kp. The outputs of differentiator 51 and position error amplifier 52 are added in adder 54 to form a velocity command. Converter 60 converts this velocity command into angular velocity and outputs the resulting angular velocity command value ω. m .

[0037] Motor position detection value X m The time derivative is performed by differentiator 56, and then the resulting value is converted into motor speed ω by converter 19. m Subtractor 55 receives the angular velocity command value ω. m Subtract the motor speed ω m It also outputs the speed error. The speed error is amplified by Gv times by the speed error amplifier 57 (generally a proportional-integral amplifier is used), and the resulting value is used as the torque command value τ. m Output.

[0038] Location feedback value X f By using the backlash compensation value X BLc The value obtained by compensating for the detection value deviation ΔX, which is obtained by measuring the detection value X from the load location. L Subtract the motor position detection value X from the middle m And it is calculated. More specifically, by detecting the value X from the load location. L Subtract the motor position detection value X from the middle m To calculate the detection deviation ΔX, then calculate the backlash compensation value X. BLc The deviation ΔX of the detected value is added. The resulting value is then low-pass filtered by the LPF processing unit 17. The output value of the LPF processing unit 17 is then added to the motor position detection value X. m This generates the position feedback value X. f The position feedback value X is calculated in this way. f The reasons will be described below.

[0039] Next, the backlash compensation unit 21 will be described. Before describing the configuration of the backlash compensation unit 21 in detail, the behavior of the target device 100 during drive direction reversal will be described. Figure 3 This shows the position command value X, the acceleration command value A, and the sliding friction torque τ. F A diagram illustrating examples of changes.

[0040] As described above, in this example, the position command value for sinusoidal motion is X = X0 + R0. sin(θ) is used as input. In this case, the driving direction is reversed at θ = 1 / 2π and θ = 3 / 2π. Additionally, the acceleration command value A is obtained by differentiating the position command value X twice. The acceleration command value A has a waveform with a phase difference of π relative to the position command value X. The sliding friction torque τ... F It is the sliding friction torque required to drive the load.

[0041] In this case, backlashes occur in the ranges Sa and Sb, which are approximately 1 / 2π and 3 / 2π, respectively. (Refer to...) Figures 4 to 6 Describes the load-side transmitted torque τ within the range of Sa. Lk The changes.

[0042] First, such as Figure 5 As shown, the case where the torque transmission path 110 includes a single backlash portion BL1 will be considered. Figure 5 In the middle, J m Indicates the moment of inertia of motor 102, and J L1 Indicates the moment of inertia from the back clearance portion BL1 to the load end 104. Figure 5 In the example, J L1 Equal to the total moment of inertia J L This refers to the moment of inertia of the entire load. Additionally, when the load end 104 moves, it experiences a sliding friction torque τ. F From now on, the left direction of the paper plane will be referred to as the "N direction", and the right direction of the paper plane will be referred to as the "P direction".

[0043] The back gap section BL1 has an output terminal OUT on the N-direction side. N and the output terminal OUT on the P direction side P .exist Figure 5 In the example shown, the input terminal IN and the output terminal OUT N Contact, and with the output terminal OUT P Separation. In Figure 5 In the state shown, when the load end 104 moves in the N direction, the load position detection value X L With motor position detection value X m Consistent, and X L = X m This is valid. On the other hand, when the direction of movement is reversed and the load end 104 moves in the P direction, the motor 102 needs to have a backlash of X. BL1 Over-operation. In other words, X... L = X m + X BL1 It is necessary.

[0044] Therefore, at the moment when the direction of travel of the position command value X reverses, the velocity feedforward amount Vfc Through back clearance velocity V BL Compensation is performed. Backlash velocity V BL For example, it is an impulse response time function, denoted as V. BL = V BL0 e -t÷T Where T is a time constant, and its region is related to the backspace quantity X. BL1 Correspondingly, when the direction of travel reverses, the backlash velocity V can be adjusted according to the direction of reversal. BL Added to velocity feedforward V fc Or from the velocity feedforward quantity V fc Subtract the backlash velocity V BL .

[0045] However, in order to maintain high following performance even after the direction of travel is reversed, torque τ needs to be transmitted on the load side. L1 At the moment of reversal, the execution is rapid and equal to the backlash amount X. BL1 Motor operation. Torque τ transmitted on the load side. L1 From the back gap part B L1 The torque transmitted to the load side. The load side transmits torque τ. L1 Equation 2 below shows that the acceleration command value A is the second derivative of the position command value X.

[0046] τ L1 = J L1 A + τ F Equation 2

[0047] Sliding friction torque τ F The absolute value of τ is independent of velocity and is a constant. Furthermore, the sliding friction torque τ varies between the P and N directions. F The sign is reversed. That is, the sliding friction torque τ F Expressed by Equation 3. In Equation 3, τ FP sgn(i) is a predetermined fixed value, and sgn(i) is the sign function. The sign function is a function that outputs 1 when the independent variable i is positive, -1 when the independent variable i is negative, and 0 when the independent variable i is 0.

[0048] τ F = sgn(V) τ FP Equation 3

[0049] To maintain high tracking performance, the load-side torque τ needs to be transmitted according to Equation 2. L1 The state is used to compensate for the command value. Figure 6 It is shown Figure 5A schematic diagram illustrating the changes in position command value X and torque in target device 100. Figure 6 In the example, make τ F = J L1 For A to hold, θ1 represents the torque τ transmitted on the load side. L1 The moment of reversal.

[0050] Here, when a single back gap portion BL exists, J L = J L 1. This is true. Additionally, it can be determined based on the motor's torque J. m (Constant value) and real-time acceleration / deceleration characteristics make it easy to identify the total moment of inertia J online. L In addition, the sliding friction torque τ F It is pre-measured or identified. Therefore, when a single backlash portion BL exists, it can be determined based on the total moment of inertia J of the load. L Acceleration command value A, and sliding friction torque τ F Easily determine the load-side transmitted torque τ L1 The state.

[0051] On the other hand, such as Figure 2 As shown, when the torque transmission path 110 includes multiple backlash sections BL1 and BL2, it is necessary to determine the load-side transmitted torque τ of each backlash section BL1 and BL2. L1 τ L2 The state is determined, and the backlash compensation value X is changed accordingly. BLc In other words, when the torque transmission path 110 includes multiple backlash sections, the load-side transmitted torque τ of one backlash section BL1 obtained from Equation 2 above is monitored. L1 Insufficient to calculate the appropriate backlash compensation value X BLc Therefore, it is impossible to maintain high command follow-up performance. To address this issue, in this example, multiple backlash sections BL are addressed. k For each of them, determine the torque τ transmitted on the load side. Lk The state of backlash compensation in this example will now be described.

[0052] First, refer to Figure 2 The case where the torque transmission path 110 includes multiple backlash sections BL1 and BL2 is described. Although Figure 2 Only two backlash portions BL are shown, but the following description will assume the existence of n backlash portions BL. Additionally, the k-th backlash portion BL starting from the k-th backlash portion of the motor will be used. k With the next gap section BL k+1 (Or if there is no gap in the BL) k+1The moment of inertia between the load terminals 104 is called the "kth partial moment of inertia J". Lk "The k-th back gap portion BL" k The torque transmitted to the load side is called the "k-th load-side transmitted torque τ". Lk The sliding friction torque τ of the moving load F The sliding friction torque at the load end 104 is always assumed to be the same.

[0053] The torque τ transmitted on the kth load side Lk This can be expressed by equations 4 and 5 below.

[0054] τ Lk = M k A + τ F Equation 4

[0055] M k = J Lk + J Lk+1 + … + J Ln Equation 5

[0056] Therefore, in Figure 2 In the example shown, the first load side transmits torque τ L1 Torque τ transmitted to the second load side L2 The results are given by equations 6 and 7, respectively.

[0057] τ L1 = (J L1 + J L2 ) A + τ F

[0058] = J L A + τ F Equation 6

[0059] τ L2 = J L2 A + τ F Equation 7

[0060] Next, we will consider the backlash compensation value X. BLc When set to 0 (i.e., backlash compensation is turned OFF), the input position command value X indicates a sine wave. In this case, the position command value X is represented as X = X0 + R0. sinθ. Here, when Figure 4When θ is less than θ1, the position command value X indicates travel along the N direction, but the torque τL1 transmitted on the first load side is less than 0. Therefore, the input terminal IN of the first backlash section BL1 and the output terminal OUT on the N direction side are... N Contact. That is, the input terminal IN and the output terminal OUT. N The gap X between S1 It becomes 0.

[0061] Subsequently, when θ > θ1, the torque τ transmitted on the first load side L1 > 0. Therefore, the motor 102 is over-operated, causing the input terminal IN to face the output terminal OUT on the P direction side. P Move. At this time, when the gap X S1 Less than the backlash amount X BL1 At that time, the torque cannot be transmitted to the end side of the first backlash section BL1, which results in insufficient deceleration torque and the load position detection value X. L Overshoot occurs on the N-direction side of the position command value X. Therefore, as Figure 4 As shown in the third row, the positional deviation DIF = X - X L It increases rapidly immediately after angle θ1.

[0062] Similarly, for the second backlash portion BL2, torque τ is transmitted on the second load side. L2 After the angle θ2 reverses from negative to positive, the positional deviation DIF also increases rapidly. Figure 4 θ O The rapid increase in position deviation DIF is due to the sliding friction torque τ. F The delay is caused by drastic changes, not by backlash.

[0063] To reduce the rapid increase in position deviation DIF caused by backlash, at the moment when position deviation DIF increases rapidly (i.e., the k-th load-side transmitted torque τ) Lk (The moment of sign change), the backlash compensation value X to be added to the position command value X. BLc Increase or decrease the k-th back gap portion BL k back clearance X BLk More generally, with the k-th back gap portion BL k Corresponding compensation value X BLck As given by Equation 8.

[0064] Equation 8

[0065] Additionally, the backlash compensation value X is added to the position command value X. BL It is multiple back gap parts BL k compensation value X BLck The sum of these. That is, the backlash compensation value X.BLc As given by Equation 9.

[0066] X BLc = X BLc1 + X BLc2 + … + X BLcn Equation 9

[0067] As can be seen from the above description, in order to calculate the backlash compensation value X BLc It is necessary to know the BL of multiple back gaps. k The load side of each of them transmits torque τ Lk The sign (i.e., positive or negative). However, in order to know the torque τ transmitted on the load side... Lk To determine the sign, we need to know the coefficient M in equation 4. k The value of . As shown in Equation 5, the coefficient M k For the corresponding back gap portion BL k The moment of inertia at the load end 104, and acts as the load-side transmitted torque τ. Lk The inversion detection coefficient.

[0068] To find the coefficient M k In this example, before the target device 100 performs normal operation, the position command value X from Equation 1 is used to temporarily induce sinusoidal motion in the target device 100, and the backlash compensation value X is... BLc Set to 0. In this case, as described above, the torque τ transmitted on the load side is... Lk The moments when the sign changes (i.e., at angles θ1, θ2, ..., θ) n The positional deviation DIF increases rapidly.

[0069] Here, the load side transmits torque τ at angle θ1. L1 Equal to angle θ k Torque τ transmitted on the load side at the location Lk When angles θ1 and θ k The acceleration command values ​​A at the points are represented as A1 and A2 respectively. k When, the following equation 10 is satisfied.

[0070] M1 A1 + τ F = M k A k + τ F

[0071] M1 A1 = M k A k Equation 10

[0072] Furthermore, since the acceleration command value A is obtained by modifying the position command value X = X0 + R0 The value obtained by differentiating sin(θ) twice, therefore A can be calculated as A = -R0ω0 2 sin(ω0t) = - R0ω0 2 · sin(θ). Furthermore, since M1 is the total moment of inertia J L Therefore, equation 10 can be transformed into equation 11.

[0073] J L (- R0ω0 2 sin(θ1)) = M k (- R0ω0 2 sin(θ) k ))

[0074] M k = (sinθ1 / sinθ k ) J L Equation 11

[0075] From Equation 11, it can be seen that the angle θ indicated by the position command value X when the position deviation DIF increases rapidly during the temporary operation can be used as a reference. k Total moment of inertia J L To calculate coefficient M k Therefore, in this example, a temporary operation is performed before the target device 100 operates normally to determine the angle θ at which the position deviation DIF increases rapidly. k Angle θ k Total moment of inertia J L Apply to Equation 11 to calculate the relationship between multiple back gap portions BL k The coefficient M corresponding to each of them k The calculated coefficient M k The coefficients used for inversion detection are stored in the inversion detection unit 12. When the target device 100 performs normal operation, based on the coefficients M... k Calculate the torque τ transmitted on the load side Lk The sign state is determined, and the backlash compensation value X is calculated accordingly. BLc .

[0076] Next, the configuration of the backlash compensation unit 21, constructed based on the above principles, will be described. For example... Figure 1 As shown, the backlash compensation unit 21 includes a coefficient calculation unit 10, a reversal detection unit 12, and a compensation value calculation unit 13. When the calculation flag Ftun is ON, the coefficient calculation unit 10 performs the aforementioned coefficient M calculation.k The calculation flag Ftun is also input to the compensation value calculation unit 13, and when the operation flag Ftun is ON, the compensation value calculation unit 13 outputs 0 as the backlash compensation value X. BLc In other words, when the operation flag Ftun is ON, backlash compensation is OFF.

[0077] The coefficient calculation unit 10 is based on the position command value X and the load position detection value X input when Ftun is ON. L Total moment of inertia J L To calculate coefficient M k Specifically, the coefficient calculation unit 10 is based on the position command value X and the load position detection value X. L The position deviation DIF is calculated. Then, at the moment when the position deviation DIF increases rapidly, the coefficient calculation unit 10 temporarily stores the angle θ indicated by the position command value X. k The moment when the position deviation DIF increases rapidly can be determined, for example, based on the value obtained by differentiating the position deviation DIF over time. That is, the moment when the time derivative of the position deviation DIF exceeds a predetermined threshold can be determined as the moment when the position deviation DIF increases rapidly.

[0078] When it is possible to determine the relationship between multiple back gap sections BL k The corresponding angle θ k At that time, the coefficient calculation unit 10 will calculate the angle θ k Total moment of inertia J L Apply this to Equation 11 to calculate the coefficient M. k Once obtained with multiple back gap sections BL k The corresponding coefficient M k The coefficient calculation unit 10 will then calculate these coefficients M. k The output is sent to the inversion detection unit 12. Furthermore, once multiple coefficients M are calculated... k When the calculation flag Ftun is activated, it will switch from ON to OFF, and the backlash compensation will be switched to ON. The switching of the operation flag Ftun can be performed automatically according to the calculation status in the coefficient calculation unit 10, or it can be performed manually by the operator.

[0079] Inversion detection unit 12 based on coefficient M k Calculate multiple back gaps BL k Torque τ transmitted on the load side at each of them Lk The sign state. Specifically, the reversal detection unit 12 receives the velocity command value V obtained by differentiating the position command value X once, the acceleration command value A obtained by differentiating the position command value X twice, and the sliding friction torque τ. FAs input. In normal operation with backlash compensation ON, the position command value X is not limited to a sinusoidal motion command, and any position command value X for various motions can be input. The reversal detection unit 12 calculates the backlash portion BL based on Equation 4. k The load side of each of them transmits torque τ Lk Then, the inversion detection unit 12 will transmit the obtained torque τ to the load side. Lk The discriminant signal SN obtained by applying the sign function k = sgn(τ Lk The output is sent to the compensation value calculation unit 13. As mentioned above, the sign function sgn(i) is a function that outputs 1 when the independent variable i is positive, -1 when the independent variable i is negative, and 0 when the independent variable i is 0.

[0080] Compensation value calculation unit 13 outputs backlash compensation value X BLc The compensation value calculation unit 13 pre-stores multiple backlash portions BL. k back clearance X BLc Here, as described above, when the calculation flag Ftun is ON, the compensation value calculation unit 13 sets X. BLc =0. On the other hand, when the operation flag Ftun is OFF, the compensation value calculation unit 13 calculates the backlash compensation value X according to equations 8 and 9. BLc In equation 8, when SN k When X > 0, BLck = X BLk And when SN k When ≤ 0, X BLck = 0.

[0081] The backlash compensation value X output from the compensation value calculation unit 13 BLc Add to the position command value X to form the compensated position command value X. c Then, based on the compensated position command value X c To calculate the velocity feedforward V fc The result is that the velocity feedforward V fc Including backlash velocity compensation value V BLc Therefore, even if multiple back gap portions BL exist... k It can also maintain high position tracking performance.

[0082] In addition, such as Figure 1 As shown, in this example, the backlash compensation value X is... BLc Add to load location detection value X L With motor position detection value X mThe deviation between the two values ​​(detection value deviation ΔX) is used to calculate the compensated detection value deviation ΔXc. Then, the motor position detection value X is... m The value obtained by applying the compensated detection deviation ΔXc to the processing in the LPF processing unit 17 is added together to calculate the position feedback value X. f .

[0083] Here, the position feedback value X is expressed as α times the input of the LPF processing unit 17 (where 0 ≤ α ≤ 1) when the output of the LPF processing unit 17 is expressed as α times the input of the LPF processing unit 17. f This can be represented by Equation 12.

[0084] X f = α{(X L - X m ) + X BLc} + X m

[0085] = X L + (1 - α)( X m - X L ) + α X BLc Equation 12

[0086] Here, if (X) m - X L ) equals X BLc Therefore, a position control system can be implemented, where X c = X m and X c = X L + X BLc (i.e., X = X) L All conditions are met. This ensures high position tracking performance. Therefore, even when using the position command value X and the backlash compensation value X... BLc The sum of the compensated position command values ​​X c The load position detection value X is used as input to configure the fully enclosed position control system. L The backlash compensation value X will not depend on the direction of travel. BLc The physical offset.

[0087] Furthermore, in this example, the backlash compensation value X BLc This applies to the position command value X, not the speed command value. Therefore, the response error of the speed control system can be compensated for by the response action of the position control system. As a result, for the backlash portion of the operation, the load position detection value X of the target device 100 can be reduced. L The following error relative to the position command value X.

[0088] Next, another embodiment will be explained. In the above description, the load-side transmitted torque τ is based on Equation 4. Lk The calculation results determine the switching and multiple back gap sections BL k Corresponding compensation value X BLck At that moment. However, it is not always necessary to calculate the load-side transmitted torque τ. Lk Determine the switching compensation value X BLck At that moment.

[0089] That is, by substituting Equations 3 and 11 into Equation 4, the torque τ transmitted on the load side is... Lk It can be converted into Equation 13.

[0090] τ LK = J L (sinθ1 / sinθ k ) A + τ FP Equation 13 sgn(V)

[0091] Here, when the target device 100 performs a temporary operation and the backlash compensation value X BLc When set to 0, the result is that at angle θ1 corresponding to the moment when the sign of the transmitted torque reverses, the transmitted torque τ on the first load side... L1 = 0. The velocity command value V1 at this angle θ1 is V1 = R0. ω0 cos θ1, and the acceleration command value A1 is A1 = -R0 ω0 2 sinθ1. Substituting these equations into equation 13 yields equation 14.

[0092]

[0093] Equation 14

[0094] Furthermore, simplifying Equation 14 yields Equation 15.

[0095] Equation 15

[0096] Substituting Equation 15 into Equation 13 and rearranging the results, we get Equation 16.

[0097] Equation 16

[0098] Here, τ FP It is a predetermined fixed value, and its sign is always positive. Therefore, the load-side transmitted torque τ is determined.Lk Whether it is positive or negative determines the parameter r shown in equation 17. Lk Is it positive or negative?

[0099] Equation 17

[0100] Here, A k = -R0 ω0 2 sinθ k And from Figure 4 We know that sgn(ω0 cosθ1) = sgn(V1) = sgn(V k Substituting these into Equation 17 and rearranging the result gives Equation 18.

[0101] Equation 18

[0102] The definite parameter r in equation 18 Lk The moment of positive and negative reversal can be regarded as multiple back gap parts BL k The load side of each of them transmits torque τ Lk The moment when the positive and negative reverse.

[0103] In this case, coefficient calculation unit 10 calculates the coefficient N shown in equation 19. k The result is then output to the inversion detection unit 12 as the inversion detection coefficient.

[0104] N k = sgn(V k ) / A k Equation 19

[0105] In addition, the inversion detection unit 12 calculates and determines the parameter r according to Equation 18. Lk The inversion detection unit 12 also determines the parameter r. Lk Apply the sign function and use the result as the deterministic signal SN. k = sgn(r Lk Output. The compensation value calculation unit 13 calculates the compensation value according to the determined signal SN. k Change the backlash compensation value X BLc .

[0106] Even under these circumstances, the load-side transmitted torque τ can be correctly determined. Lk The timing of the reversal allows for the appropriate increase or decrease of the backlash compensation value X. BLc As a result, even with multiple back gap portions BL... k It can also maintain high position tracking performance.

[0107] The above configuration is merely an example, and any other configuration can be used as long as the configuration of claim 1 is satisfied. For example, the back gap portion BL k The number is not specifically limited, as long as there are two or more. Calculate the position feedback value X. f The processing can also be changed. For example, in Figure 1 In the example, although the position feedback value X f By measuring the motor position detection value X m Obtained through addition and subtraction, but, as Figure 7 As shown, the position feedback value X f Alternatively, the motor position detection value X can be used instead of the actual position value. m For input.

[0108] Reference Symbol List

[0109] 10: Coefficient calculation unit, 12: Reversal detection unit, 13: Compensation value calculation unit, 17: LPF processing unit, 19, 60: Converter, 20: Position control loop unit, 21: Backlash compensation unit, 50, 55: Subtractor, 51, 56: Differentiator, 52: Position error amplifier, 54: Adder, 57: Speed ​​error amplifier, 100: Target device, 102: Motor, 104: Load end, 110: Torque transmission path, 120: Current control unit, A: Acceleration command value, BL: Backlash portion, DIF: Position deviation, Ftun: Calculation flag, IN: Input end, J L Total moment of inertia, J Lk : The kth partial moment of inertia, J m Motor inertia, M k N k : coefficient, OUT N Output terminal, OUT P Output terminal, SN k : Confirmation signal, X: Position command value, X BLc : Backlash compensation value, X BLk : Backlash amount, X L : Load location detection value, X c : Compensated position command value, X f Location feedback value, X m Motor position detection value, τ F : Sliding friction torque, τ Lk τ represents the torque transmitted on the k-th load side. m Torque command value.

Claims

1. A position control device for a target device, wherein a motor and a load end in the target device are connected via a torque transmission path having a plurality of backlash portions, the position control device comprising: The coefficient calculation unit, which is: A temporary operation is performed on the target device to reverse its direction of travel while backlash compensation is disabled, and Based on the position command value at the moment when the position deviation between the position command value and the position detection value at the load end rapidly increases, or based on the velocity command value and acceleration command value at the moment when the position deviation rapidly increases, calculate the reversal detection coefficient of each of the plurality of back gap portions; The inversion detection unit, which: The target device is operated when the backlash compensation is enabled, and Based on the reversal detection coefficient, the position command value, and the moment of inertia of the entire load, the moment when the load-side transmitted torque reverses in each of the plurality of backlash portions is detected. The compensation value calculation unit increases or decreases the backlash compensation value at the moment when the torque transmitted on the load side reverses. The position control loop unit controls the position of the motor so that the position detection value at the load end becomes a position command value compensated by the backlash compensation value.

2. The position control device according to claim 1, characterized in that, At the moment when the torque transmitted on the load side reverses at the k-th backlash portion starting from the motor, the compensation value calculation unit adds the backlash amount of the k-th backlash portion to the current backlash compensation value or subtracts the backlash amount of the k-th backlash portion from the current backlash compensation value.

3. The position control device according to claim 2, characterized in that, The position control loop unit controls the position of the motor to reduce the absolute value of the position error, which is the difference between the compensated position command value and the position feedback value. The position feedback value includes the sum of the position detection value of the load end and the backlash compensation value.

4. The position control device according to any one of claims 1 to 3, characterized in that, The position command value in the temporary operation is indicated by X = X0 + R0 sinθ represents a sine wave, and The coefficient calculation unit is based on M k = (sinθ1 / sinθ k ) J L Calculate the coefficient M corresponding to the k-th backlash portion starting from the motor. k , where θ k θ is obtained when the position deviation increases rapidly due to the k-th back gap portion, and J is obtained when the position deviation increases rapidly. L Let be the moment of inertia of the entire load.

5. The position control device according to claim 4, characterized in that, The compensation value calculation unit is based on equation τ Lk = M k A + τ F Calculate the load-side transmitted torque τ in the k-th backlash section. Lk , where τ Lk For transmitting torque to the load side in the k-th backlash section, τ F Let A be the sliding friction torque, and A be the acceleration command value.

6. The position control device according to any one of claims 1 to 5, characterized in that, The position command value in the temporary operation is indicated by = X0 + R0 sinθ represents a sine wave, and The coefficient calculation unit is based on equation N. k = sgn(V k ) / A k Calculate the coefficient N corresponding to the k-th backlash portion starting from the motor. k , where A k This is the acceleration command value when the position deviation increases rapidly due to the k-th backlash portion.

7. The position control device according to claim 6, characterized in that, The compensation value calculation unit: Based on equation r Lk = -A N k + sgn(V) calculates and determines the parameter r Lk Where V is the velocity command value, A is the acceleration command value, and sgn is the sign function, and Detect the determined parameter r Lk The moment when the positive and negative values ​​reverse is the moment when the load-side transmitted torque reverses at the kth backlash portion.

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