JP5824370B2 - Full closed position controller - Google Patents

Description

  The present invention relates to a full-closed position control device, in particular, an incremental detector that directly detects a load-side position to be controlled in a shaft control of a numerically controlled machine, and a multi-rotation absolute position that detects a rotation angle of a drive motor. The present invention relates to a fully-closed position control device for the purpose of configuring an absolute position detection value on a load side from a detector and controlling it according to a position command value.

A fully closed position control device applied to the axis control of a numerically controlled machine controls the load input of the target plant as a control target according to the position command value commanded from the host device by appropriately controlling the control input of the drive motor. To control. Here, when detecting the load position of the target plant, a multi-rotation absolute position detector (hereinafter referred to as a rotary absolute position detector) and an incremental detector (hereinafter referred to as a scale) are used. . The rotary absolute position detector is a motor position detector that is coupled to a drive motor and indirectly detects a load position from the rotation angle of the drive motor. The scale is installed directly on the load and detects the load position. By combining this rotary absolute position detector and the scale respective detection values, the absolute position detection value of the load (hereinafter, referred to as full-closed absolute position detection value x _f) is formed.

Generally, by using a two-phase sine wave output type as a scale, an absolute position within the scale pitch (hereinafter referred to as a scale lower position detection value PL) can be detected by calculation. Figure 4 is a diagram for explaining a conventional construction method of a full-closed absolute position detection value x _f. In the figure, the horizontal axis indicates the load position, and the arrow direction (right direction in the drawing) of the horizontal axis is the + direction of the load position. In the top row, the scale lower position detection value PL and the finally formed fully closed absolute position detection value _xf are shown. Furthermore, the detection value of the rotary absolute position detector (hereinafter, the expression of the motor position detection value x _m and the semi-closed position detection value x _s are used together) is divided in scale pitch units, and the pitch units or more are semi-closed. The upper digit SH and one pitch are expressed as a semi-closed lower position detection value SL.

In the conventional configuration method, using (PL-SL), the full closed upper digit FH is determined by a plurality of determination formulas shown below, and connected to the scale lower position detection value PL to obtain a fully closed absolute position detection value x. _f is constructed. Here, T _OL is a phase alignment allowable pitch and is set in a range of 0 <T _OL <0.5. In this example, T _OL = 0.3 is set.
When −1 <(PL−SL) ≦ − (1−T _OL ): FH = SH + 1 (1)
-(1-T _OL ) <(PL-SL) <-T _OL : FH cannot be set (2)
When -T _OL ≦ (PL−SL) ≦ T _OL : FH = SH (3)
When T _OL <(PL-SL) <(1-T _OL ): FH cannot be set (4)
When (1−T _OL ) ≦ (PL−SL) ≦ 1: FH = SH−1 (5)
It is assumed that PL = SL at a certain initial time point. However, if the shaft operation is repeated thereafter, the backlash between the drive motor and the load, the deflection of the drive system that increases during acceleration / deceleration, and further the thermal displacement The relative displacement (PL-SL) between the scale lower position detection value PL and the semi-closed lower position detection value SL increases and fluctuates.

In FIG. 4, the upper relative relationship (a) shows a numerical relationship in which SL is advanced by 0.25 pitch phase from PL, and is calculated from the semi-closed high-order digit SH according to Equation (3) and Equation (5). create a closed upper digit FH, it connects the this upper digit FH and the scale lower position detection value PL (in combination), constituting the full-closed absolute position detection value x _f. The relative relationship (b) in the middle stage shows a numerical relationship in which SL is delayed by 0.25 pitch phase from PL, and the fully closed absolute position detection value x _f is similarly expressed by Equation (3) and Equation (1). Configure. The lower relative relationship (c) shows a numerical relationship in which SL is delayed by 0.4 pitch from PL. From Formula (2) and Formula (4), it is determined that FH cannot be set in this case. This is a measure for obscuring the determination of whether SL is 0.4 pitch phase behind PL or whether SL is 0.6 pitch phase ahead of PL in the numerical relationship between SL and PL. . Conventionally, the scale is selected so that the scale pitch is set to 5 times the maximum displacement within the drive unit in order to prevent the position detection setting impossible state such as the relative relationship (c) from occurring.

FIG. 5 is a block diagram showing an example of a servo system configuration of a conventional full-closed position control device. The feedback configuration of the position control device 100 is as follows. Subtractor 50 subtracts the full-closed absolute position detection value x _f is the position feedback from the commanded position command value X _C from the upper device (not shown). Position deviation which is the output of which is amplified in the position loop gain Kp fold at the position deviation amplifier 51, the subtractor 52, the motor speed v _m is subtracted, the speed deviation is outputted. The speed deviation is normally proportional-integral amplified by the speed deviation amplifier 53. Expression (6) shows the speed loop gain Gv (note that the proportional gain Gp, the integral gain Gi, and the Laplace transform operator s).
Gv = Gp + (Gi / s) (6)
The output of the speed deviation amplifier 53 becomes the control input u of the target plant P. The control input u is torque controlled (not shown) so as to be equal to the torque generated by the drive motor.

As described above, the motor speed v _m and the motor position detection value x _m from the rotary absolute position detector coupled to the drive motor in the target plant P, and the two-phase sine wave output x from the scale installed in the load _P is output. Scale position detector 54, the two-phase sine wave output x _P of the scale, and the scale lower position detection value PL, the two-phase sine wave By period count, during incremental significant digit IH (power on or scale pitch units Is cleared). Unit divider 55, a motor position detection value x _m as a semi-closed position detection value x _s, as described above, divided by the scale pitch unit, a semi-closed over pitch unit de upper digit SH, within one pitch semi-closed Output as lower position detection value SL. Position configuration unit 56 configures the scale lower position detection value PL, in semi-closed upper digit SH and semi-closed lower position detection value SL, the full-closed absolute position detection value x _f. Construction operation of full-closed absolute position detection value x _f position configuration unit 56 is as described with reference to FIG. 4 above.

JP 2004-198434 A

  As described above, in the conventional full-closed position control device, the scale pitch is set to 5 times the maximum displacement in the drive unit in order to construct the full-closed absolute position detection value without causing the position detection setting impossible state. It needs to be about. As a result, in the case of a linear shaft, a special and expensive scale having a scale pitch on the order of mm is required, and an inexpensive and general scale having a scale pitch of several μm to several tens of μm can be applied. There wasn't. The problem to be solved by the present invention is that an absolute position detection value on the load side is obtained from a general scale that directly detects the load side position and a rotary absolute position detector that detects the rotation angle of the drive motor. It is to provide a fully closed position control device that can be configured.

  The present invention determines the configuration method of the fully closed absolute position detection value from the relative relationship between the scale lower position detection value and the semi-closed lower position detection value, and determines the position detection value by the determined configuration method as the initial full closed absolute position detection value. In the following, the above-mentioned problem is solved by configuring the fully closed absolute position detection value only with the position information of the scale.

  In addition to the above features, when the power is turned on, a position command value for executing one-way positioning is automatically generated, and semi-closed position control is also executed.

  In the fully closed position control device according to the present invention, an inexpensive and general optical type with a small scale pitch even in a controlled object with large displacement in the drive unit such as play between the drive motor and the load, bending of the drive system and thermal displacement. A fully closed absolute position detection value can be configured by applying a scale.

It is a block diagram which shows the structural example of the full closed position control apparatus which is embodiment of this invention. It is a flowchart explaining the structure operation | movement of a position detection value. It is a flowchart explaining operation | movement of an initial internal function generation part. It is a figure explaining the structure method of the conventional full closed absolute position detected value. It is a block diagram which shows the structure outline | summary of the conventional full closed position control apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a fully closed position control device according to the present invention. Also in this embodiment, as in the prior art, the position deviation is obtained by subtracting the position feedback x from the position command value _Xc . And, since, as in the prior art, the like the position deviation and the motor speed v _m, the speed deviation, the control input u is calculated. However, in the present embodiment, unlike the prior art, the initial position is obtained once at the start of the fully closed position control, and thereafter, the value x _pf obtained by adding the variation amount of the scale position detection value x _I to this initial position is obtained. Used as position feedback x. Note that the scale position detection value x _I, is a position detection value obtained by adding the initial position by connecting the incremental upper digit IH and scale the lower position detection value PL. The initial position is a fully closed absolute position detection value x _f connecting the full closed upper digit FH and the scale lower position detection value PL, or a semi closed state connecting the semi closed upper digit SH and the semi closed lower position detection value SL. One of the position detection value x _S (motor position detection value x _m ) is selected according to the value of PL-SL at the initial stage. Further, in this embodiment, prior to the start of the fully closed position control, one-way positioning for moving the load by an amount exceeding the lost motion of the drive system is also executed in order to reduce the backlash between the drive motor and the load. . Hereinafter, the present embodiment will be described in detail with a focus on such differences from the prior art.

  The initial internal function generator 1 is a part that generates a function that is executed inside the fully closed position control device only once when the power is turned on. More specifically, the initial internal function generator 1 outputs a one-way positioning command for moving the load by a specified amount when the power is turned on. This is done for the purpose of packing backlash between the drive motor and the load in one direction, reducing the deflection of the drive system and minimizing the deviation between PL and SL.

FIG. 3 is a flowchart for explaining the operation of the initial internal function generator 1. In this operation, first, the one-way positioning completion flag Fscf is confirmed (S30). When the power is turned on, the one-way positioning completion flag Fscf is OFF. When Fscf is OFF, the initial internal function generation unit 1 executes the following initial internal function generation according to the value of the sequence counter Sc (S32 to S56).
Sc = 0: A movement command of −20 μm is generated, and Sc = 1 is set (S40, S42).
In response to the movement command of Sc = 1: −20 μm, the position control system using the semi-closed position detection value x _S (= x _m ) as position feedback responds, waits until the movement of −20 μm is completed, Sc = 2 is assumed (S44, S46).
Sc = 2: A movement command of +20 μm is generated, and Sc = 3 is set (S48, S50).
Sc = 3: As in the case of Sc = 1, the process waits until the movement of +20 μm is completed, and when it is completed, Sc = 4 is set (S52, S54).
Sc = 4: The one-way positioning completion flag Fscf is turned ON (S56).
The movement amount of ± 20 μm is selected as an example, and other values may be used as long as the movement amount exceeds the lost motion of the drive system in order to achieve unidirectional positioning.

Command value selector 2 in accordance with the one-way positioning completion flag Fscf, the position command value, the initial internal output or higher-level device of the function generator unit 1 switches from (not shown) to the commanded position command value X _C. When the one-way positioning completion flag Fscf is OFF (one-way positioning is not completed), the command value selector 2 sets the output of the initial internal function generator 1 as a position command value. If unidirectional positioning completion flag Fscf is ON (unidirectional positioning is completed), the command value selector 2 sets the position command value X _C commanded from the host device as a position command value.

The position detection value selector 8, the motor position detection value x _m at the time of unidirectional positioning, a one-way positioning is completed, after the initial position to be described later is output, the full-closed absolute position detection value x _pf, Select and output as position feedback x.

That is, until the one-way positioning is completed, the output from the initial internal function generating unit 1 as a position command, the motor position detection value x _m as a position feedback x, position control using each is performed. When the unidirectional positioning is completed, position control is performed using the position command _Xc output from the host device as the position command and the fully closed absolute position detection value _xpf as the position feedback x. Calculation of the fully closed absolute position detection value x _pf used at this time will be described.

When the one-way positioning completion flag Fscf is switched from OFF to ON, the initial position configuration selection unit 4 confirms the value of (PL-SL) that is the output of the subtractor 3. When (PL-SL) is the above-described formula (1), formula (3), or formula (5), the selection signal SEL1 is output to the first initial position configuration unit 5. In the first initial position configuration unit 5, according to the equation, to determine the full-closed upper digit FH, it connects with the full-closed upper digit FH and the scale lower position detection value PL, constituting the full-closed absolute position detection value x _f The scale offset _OFS is calculated by the following equation.
_{O FS = x f -x I0 ·····} (7)
Here, the scale position detection value x _I is a position detection value obtained by connecting the incremental upper digit IH and the scale lower position detection value PL, and x _I0 is the initial value of the scale position detection value x _I , that is, Fscf is OFF. it means the x _I at the time of initial has been switched to oN from.

On the other hand, when (PL-SL) is the above-mentioned formulas (2) and (4), the conventional absolute position detection configuration method cannot be adopted. The selection signal SEL2 is output to the unit 6. The second initial position configuration unit 6 calculates the scale offset _OFS by the following equation.
O _FS = x _s −x _I0 (8)
Here, the semi-closed position detection value x _s is a position detection value obtained by connecting the semi-closed upper digit SH and the semi-closed lower position detection value SL, and is equal to the motor position detection value x _m .

The unit synthesizer 7 uses the scale lower position detection value PL, the incremental upper digit IH, and the scale offset _OFS calculated by the first or second initial position component to detect the fully closed absolute position according to the present invention. The value x _pf is calculated by the following equation.
x _pf = x _I + O _FS (9)
The output of the unit synthesizer 7 becomes the fully closed absolute position detection value x _{pf according} to the present invention. The initial position configuration selection unit 4 outputs a selection signal SEL1 or SEL2, and then outputs a steady position detection flag Fstd: ON to the position detection value selector 8. Position detection value selector 8, Fstd: a is OFF motor position detection value _{x m,} Fstd: a position feedback amount x to select the full-closed absolute position detection value _{x pf} according ON state present invention.

Here, x _I = x _I0 at the initial time. Therefore, the fully closed absolute position detection value x _pf at the initial time is x _pf = x _I + x _f −x _I0 = x _f (when SEL1 is output) or x _pf = x _I + x _s −x _I0 = x _s ( SEL2 output). On the other hand, SEL1, in SEL2 steady state after output of a _{x I} in the formula (9), equation (7) results in a value different from the _{x I0} in _{(8), x pf = (} x I -x _I0) + _{x f} or _{x pf = (x I -x I0} ) becomes + _{x s.} That is, in the steady state, the fully closed absolute position detection value x _pf is a value obtained by adding the fluctuation amount (x _I −x _I0 ) of the scale position detection value x _{I to} the initial position (x _f or x _s ). .

FIG. 2 is a flowchart for sequentially explaining the configuration operation of the position detection value in the present embodiment. For each position detection cycle, first, the two-phase sine wave output x _P of the scale, and the scale lower position detection value PL, computes the incremental upper digit IH (S10). Then, the normal position detecting flag Fstd: The steady state before the OFF (OFF at S12), the motor position detection value _{x m,} and semi-closed upper digit SH, calculates a semi-closed lower position detection value SL (S14). In the steady state before the one-way position complete before: In (Fscf OFF at OFF, S16), the motor position detection value _{x m} is selected to the position feedback amount x. In this state, semi-closed position control is executed.

Unidirectional positioning completion: in (Fscf at ON, S16 ON) cycle, if the SEL1 is valid, _{O FS} is calculated by Equation (7) (S22). Conversely, SEL1 is if invalid (SEL2 is enabled), _{O FS} is calculated by the equation (8) (S20). If either step S20 or step S22 is executed, the steady position detection flag Fstd is switched ON (S24).

Subsequently, x _pf is calculated according to Equation (9), and is output as position feedback x (S26, S28). In the first stage, since xI = xI0, x = x _pf = x _f or x = x _pf = x _s . The first position feedback x = x _pf = x _f or x _s means an initial position.

Also in the next cycle, the calculation of PL and IH (S10) is performed, and then the steady position detection flag Fstd is confirmed (S12). In the cycle after SEL1 or SEL2 is output once, since the steady position detection flag Fstd is ON, the process proceeds to steps S26 and S28. In steps S26 and S28, x _pf is calculated according to equation (9), and output as position feedback x = x _pf . Here, at this stage, _{x I,} because they are updated from the initial value _{x I0, x pf = (x} I -x I0) + x f or _{x pf = (x I -x I0} ) becomes + _{x s.} That is, the change amount of the scale position detection value x _I (x _I −x _I0 ) is added to the position detection value of the one-way positioning completion cycle to form the fully closed absolute position detection value x _pf according to the present embodiment, The position feedback amount x.

  As described above, in the fully closed position control apparatus according to the present invention, the deviation between the scale lower position detection value PL and the semi-closed lower position detection value SL is obtained by executing the one-way positioning internally when the power is turned on. In accordance with the size of the deviation, the reference value for detecting the fully closed absolute position is selected from PL or SL. Furthermore, during steady operation in which the deviation between PL and SL increases due to backlash of each part of the drive system or bending due to rigidity, only the amount of change in the scale position detection value is added to the selected reference value, so that it is fully closed. Configure absolute position detection value.

  DESCRIPTION OF SYMBOLS 1 Initial internal function generation part, 2 Command value selector, 3 Subtractor, 4 Initial position structure selection part, 5 1st initial position structure part, 6 2nd initial position structure part, 7 Unit composition part, 8 Position detection Value selector, 10 Position control device (Embodiment of the present invention), 50 Subtractor, 51 Position deviation amplifier, 52 Subtractor, 53 Speed deviation amplifier, 54 Scale position detector, 55 Unit divider, 56 Position component, 100 Position control device (conventional example), 200 target plant.

Claims (2)

In a fully closed position control device of a numerical control machine that drives a servo motor according to a position command value and controls the position of a target plant,
A first initial position configuration unit that configures an initial position detection value with reference to a detection value of an incremental detector that directly detects a load position at the start of full closed position control;
A second initial position configuration unit that configures an initial position detection value based on a motor position detection value of a motor position detector that detects a rotation angle of the servo motor at the start of full-closed position control;
An initial position configuration selection unit that selects one of the first and second initial position configuration units at the start of full closed position control;
Full-closed absolute position detection is the sum of the initial position detection value calculated by the selected initial position component and the amount of fluctuation of the detection value at the incremental detector from the start of the full-closed position control. A unit synthesizer that operates as a value;
When performing fully closed position control, the fully closed absolute position detection value is used as a position feedback amount ,
The initial position configuration selection unit is configured to determine the first and second positions based on a difference value between a position within the scale pitch detected by the incremental detector and a position within the scale pitch detected by the motor position detector. Selecting one of the second initial position components;
A fully-closed position control device for numerical control machines. The fully closed position control device according to claim 1 , further comprising:
Prior to the start of the full-closed position control, an initial internal function generator that commands unidirectional positioning;
A command value selector that selects a position command value commanded by the host device during the full-closed position control, and a command value selector that selects the initial internal function generator command value as the position command value during the one-way positioning execution;
A position detection value selector that selects the motor position detection value at the time of the one-way positioning execution, and the full-closed absolute position detection value at the time of the full-closed position control, respectively, as a position feedback amount;
A fully-closed position control device comprising:

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