JP2985138B2 - Speed control device and numerical control feed speed control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed control device for driving a movable part in a numerically controlled machine tool, an industrial robot, and the like, and a numerically controlled feed speed control method.
In particular, the present invention relates to a sampling control type speed control device and a numerical control feed speed control method for reducing the burden of creating a machining program command, automatically keeping the movement of a drive unit within a movement path error, and reducing mechanical shock. It is.

[0002]

2. Description of the Related Art In a speed control device for controlling the movement of an axis such as a machine tool or an industrial robot, a response delay of a servo used for driving an axis such as an arm, and the inertial force caused by a change in the speed of the machine cause the machine to move. Due to deformation or the like, a path error occurs in which the movement path of the drive unit deviates from the path based on the machining program command. In order to reduce such a path error, a portion having a large curvature (small radius of curvature) is moved at a relatively low speed, and a portion having a small curvature, for example, a portion having a large radius such as an arc or a corner, has a high feed rate. To move.

FIG. 7 shows a speed control device for performing such control.
Shown in This speed controller has a program command
Interpolation mode, for example, linear interpolation mode G01, circular interpolation mode G02, G03, etc., acceleration / deceleration mode ADM, feed speed Vi, movement amount XLi, YLi, ZL in each axis direction.
i or the arc radius R _i , the center coordinates XC _i , YC
_i , ZC _{i and the} like are input. The analysis unit 1 analyzes these machining program commands for each block and creates interpolation data for each block. As interpolation data,
In the linear interpolation mode, the feed rate V for each sampling period, the movement amounts Lx, Ly,
Lz. In the circular interpolation mode, the movement angle Pb per block, the movement angle V per sampling,
p, radius Rb, and the like. The interpolator 9 is an acceleration / deceleration processing unit 10
In cooperation with the above, the amount of movement dX in each axis direction for each sampling period is calculated from the interpolation data for each block analyzed by the analysis unit 1 according to the input acceleration / deceleration mode ADM.
dY and dZ are calculated and output to the servo control unit 8. The servo control unit 8 servo-controls a drive unit such as an arm of each axis for each sampling cycle based on the movement amounts dX, dY, dZ from the interpolator 9.

[0004]

In the above speed control method, in order to determine a feed speed according to a machining shape and perform an appropriate acceleration / deceleration motion, a designer who creates the machining program command requires a machining shape or the like. It is necessary to create a machining program command that appropriately combines a feed speed code, a cutting feed automatic acceleration / deceleration code, etc., while taking into account the problem of creating a machining program command, which requires a great deal of labor. . In addition, it is difficult to automatically determine the normality of the machining program command created in such a manner, and when the designer mistakenly creates the machining program command, the speed control device or the machine may be broken due to malfunction.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the burden of creating a machining program command for a designer who creates the machining program command, and to automatically move the controlled object within an allowable shape error and a limit acceleration (or limit deceleration). An object of the present invention is to provide a speed control device capable of performing sampling control and a numerical control feed speed control method.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an analyzing section for analyzing an input machining program command into interpolation data for each block, and an analysis section for analyzing the interpolation data for each block. , A first interpolator for calculating a first movement amount and a first feed rate in each axis direction for each first sampling period, and a first interpolator for a plurality of sampling periods for the calculated first sampling period.
Movement amount, and a storage unit for storing a first feed speed is the calculated, recognizing the movement trajectory by identifying the curved portion and the corner portion for a first amount of movement of the plurality stored in the storage unit of a shape recognition section that, the corrective feeding speed calculator for calculating the first correction by correcting the feed rate feed rate <br/> acceptable shape erroneous difference in response to the recognized shape, the modified feed rate
An acceleration / deceleration processing unit for calculating a control feed speed such that the acceleration / deceleration is within the limit acceleration of the control object .
And a second interpolator for interpolating the movement amount for each second sampling period from a first movement amount stored in the storage unit and the control feed speed, and interpolating in the second interpolator Previous
On the basis of the movement amount for each serial second sampling period
Provided is a speed control device that servo-controls a control target . The present invention, machining program directive, and erroneous acceptable shape
An input step of inputting the difference and the limit acceleration as parameters, an analysis step of analyzing the input machining program command to obtain interpolation data for each block, and using the interpolation data for each first sampling period. First
A calculating step of calculating a moving amount and a first feed speed of
A storing step of storing a first moving amount and a first feed speed, and a radius of curvature of a moving path based on the stored first moving amount.
A shape recognizing step of calculating the moving shape and calculating the corrected feeding speed used to keep the recognized moving shape within the input allowable shape error by referring to the radius of curvature.
A corrective feeding speed calculating step of calculating distinguishes between irradiation to curved portion and the corner portion, the said corrected feed rate as the target
An acceleration / deceleration processing step of calculating a control feed speed with acceleration / deceleration within the input limit acceleration, and a second sampling period for each second sampling period from the first movement amount and the control feed speed stored in the storage unit. A calculating step of calculating a second movement amount;
An output step of outputting the second movement amount to the control target side. Preferably, the input step includes a step of inputting the allowable shape error and the limit acceleration as parameters. Preferably, the shape recognition step includes a step of calculating a radius of curvature of the movement path from the first movement amount.
The corrected feed speed calculating step includes a step of calculating the corrected feed speed by distinguishing the arc portion and the corner portion with reference to the radius of curvature.

[0007]

In the same manner as in the prior art, the designer creates a machining program command including a feed rate and a movement amount for each axis. The analysis unit analyzes these machining program commands for each block and creates interpolation data for each block. The first interpolator interpolates the amount of movement in each axis direction and the feed speed for each first sampling period based on the interpolation data.
The storage unit stores the amount of movement in each axis direction and the feed speed over a plurality of sampling periods calculated by the first interpolator. The shape recognizing unit recognizes the shape by recognizing the moving shape defined by the moving amount stored in the storage unit into, for example, a corner portion and an arc portion, and outputs shape recognition information. The feed speed calculation unit compares the shape recognition information from the shape recognition unit with the feed speed stored in the storage unit, calculates a corrected feed speed, and replaces the feed speed in the storage unit.
The second interpolator calculates the feed speed such that the moving speed reaching the target speed is within the limit acceleration (or the limit deceleration). The second interpolator performs a servo control of the movement amount and the feed speed in each axis direction stored in the storage unit.
, The amount of movement in each axis direction for each servo cycle is interpolated and output to the control target. A control target such as a servo control unit controls the drive target based on a control command from the second interpolator. The first servo cycle and the second servo cycle may be the same or different.

[0008]

FIG. 1 shows a configuration diagram of a speed control device according to an embodiment of the present invention. This speed control device includes an analysis unit 1, a first interpolator 2, a buffer memory 3 as a storage unit, a shape recognition unit 4, a feed speed calculation unit 5, an acceleration / deceleration processing unit 6, a second interpolator 7, and , A servo controller 8 are connected as shown in the figure. In this embodiment, the analyzing unit 1, the first interpolator 2, the shape recognizing unit 4, the feed speed calculating unit 5, the acceleration / deceleration processing unit 6, and the second interpolator 7 are realized by a microcomputer, The memory 3 is a RAM connected to the microcomputer.

FIGS. 2 and 3 are flowcharts showing the processing contents of the speed control device shown in FIG. A program command creator (designer) separately creates a machining program command using a personal computer or the like. The machining program command includes an interpolation mode, a movement amount in each axis direction, for example, an arc radius, a center coordinate, and a feed speed in the case of the circular interpolation mode. In addition, the creator of the machining program
The allowable maximum error Emax is sent to the feed speed calculating unit 5 in advance, and the limit acceleration (or limit deceleration) ACC is sent to the acceleration / deceleration processing unit 6.
Is set as a parameter. These parameters Emax and ACC can be input together with the machining program command. In this embodiment, however, it is assumed that the parameters are set in advance in the feed speed calculation unit 5 and the acceleration / deceleration processing unit 6 as parameters.

The operation of the control device shown in FIG. 1 will be described with reference to FIGS. The step S01 analysis unit 1 includes a feeding (moving) speed Vi, a moving amount XLi in the X-axis direction, a moving amount YLi in the Y-axis direction, a moving amount YLi in the Y-axis direction, and a Z-axis direction, such as interpolation modes G01, G02, and G03 as machining program commands created by the designer. The movement amount ZLi, the arc radius Ri, the center coordinates XCi, YCi, ZCi of the arc are input.
The interpolation mode G01 is a linear interpolation mode, G02, G
03 indicates a circular interpolation mode. Although the axial numerical control can control a plurality of axial directions, in this example, X,
The numerical control of the sampling method in the three-axis direction in the Y- and Z-axis directions will be described. The step S02 analysis section 1 analyzes the input machining program command, calculates interpolation data per block, and outputs the calculation results to the first interpolator 2. Steps S03 to S07 The first interpolator 2 calculates the X-axis direction movement amount dX (0) and the Y-axis direction movement amount dY for each first sampling period T1 from the interpolation data per block from the analysis unit 1.
(0), the Z-axis direction movement amount dZ (0), and the combined feed speed V (0) are calculated. These values [dX (0),
dY (0), dZ (0), V (0)] are continuously calculated in the order of the sampling timing. The buffer memory 3 stores these continuously calculated values [dX
(0), dY (0), dZ (0), V (0)] are continuously stored over a plurality of (N) sampling periods. Step S08 When the interpolation results for the N sampling periods are stored in the buffer memory 3, the shape recognizing unit 4 performs the X, Y, and Z-axis directions over the N sampling periods for each first sampling period T1 stored in the buffer memory 3. Movement amount dX (m), d
Y (m) and dZ (m) are read and shape recognition is performed. In this example, shape recognition uses a radius of curvature (or curvature) for a curved portion to identify an arc and a corner.

FIG. 4 shows an arc to be subjected to shape recognition. This arc consists of a center point C, a coordinate point A and a coordinate point B
Is defined by These coordinate points A and B are respectively the movement amounts [dX (n), dY (n), dZ] in the n-th sampling cycle stored in the buffer memory 3.
(N)] and the movement amount [dX (n-1), dY (n-1), dY (n-1) in the (n-1) th sampling period.
dZ (n-1)]. A method for obtaining the radius of curvature of this arc will be described. Assuming that the angle between the points A, C, and B is θ, and the distance between the points A and B is L, when the angle θ is small, the following equation 1 holds.

(Equation 1) By substituting Equation 1, Equation 2 is obtained.

(Equation 2)

The distance L in Equation 2 is represented by Equation 3.

(Equation 3) sin (θ / 2) is obtained as follows. When the two vectors V1 and V2 form an angle θ, the following equation 4 holds.

(Equation 4) In Equation 4, “・” represents a dot product of vectors. Replacing Equation 4 gives Equation 5.

(Equation 5)

From the double angle formula, the following equations (6) and (7) are obtained.

(Equation 6)

(Equation 7) If a = θ / 2, the following equations 8 to 10 are obtained.

(Equation 8)

(Equation 9)

(Equation 10) By substituting Equation 5 into Equation 10, Equation 11 is obtained.

[Equation 11]

The (n-th) read from the buffer memory 3
1) The amount of movement [dX (n
−1), dY (n−1), dZ (n−1)] is calculated as the vector V1 and the movement amount [dX
(N), dY (n), dZ (n)] correspond to the vector V2, the following equations 12 to 14 are obtained.

(Equation 12)

(Equation 13)

[Equation 14] By substituting these equations 12 to 14 into equation 11, sin
(Θ / 2) can be obtained, and the radius of curvature can be obtained.

The shape recognizing unit 4 obtains the radius of curvature of the arc in each part of the shape defined by the continuous moving amount stored in the buffer memory 3 in this manner. When the radius of curvature for a shape defined by adjacent movement amounts in the buffer memory 3 is smaller than a predetermined value, the shape recognition unit 4 regards that portion as a corner portion and the radius of curvature is larger than the set value. In some cases, it is part of an arc having that radius of curvature. As described above, the shape recognition unit 4 shapes the shape recognition data SHAPE in which each part is identified as a corner part and an arc part.
Is calculated. The straight portion is treated as a case where the radius of curvature of the arc is very large.

In step S09, the feed speed calculating unit 5 receives the shape recognition data SHAPE from the shape recognizing unit 4 and the feed speed V (m) in the first sampling cycle stored in the buffer memory 3 and responds to the shape. The maximum speed is calculated, the optimum feed speed V0 (m) for that part is determined, output to the buffer memory 3, and replaced with the combined feed speed V (m) in the first sampling cycle in the buffer memory 3.

As a method of calculating an optimum feed speed according to the shape, the feed speed calculating section 5 calculates an allowable maximum feed speed Fmax for the corner portion based on the following formula 15, and calculates the maximum feed speed Fmax for the arc portion as shown in the following formula 16. The allowable maximum feed speed Fmaxe is calculated based on the maximum feed speed Fmaxe.

(Equation 15) Here, T1 is a first sampling period, ω0 is a servo position loop gain, and Emax is a preset allowable maximum error.

(Equation 16)

The allowable maximum speed Fma thus obtained is
xe and the feed speed V (m) stored in the buffer memory 3
And the maximum allowable speed Fmaxe is equal to the feed speed V
When the value is larger than (m), V (m) is used as it is, so that the contents of the buffer memory 3 are not rewritten. When Fmaxe is smaller than V (m), the feed speed V (m) in the buffer memory 3 is maximum allowable. Replace with the speed Fmaxe.
Thereby, the corrected feed speed V0 (m) is obtained. Therefore, the buffer memory 3 has the first sampling period T
The corrected feed speed V0 (n), the X-axis direction movement amount dX (n), the Y-axis direction movement amount dY (n), and the Z-axis direction movement amount dZ (n) for N sampling periods for 1 are stored. Note that n = 0, 1,..., (N−1).

Step S10: The second interpolator 7 stores the above-mentioned N stored in the buffer memory 3.
Corrected feed rate V0 (n), X,
Movement amounts dX (n), dY (n), dZ in the Y and Z axis directions
Using (n), the movement amounts dXa and dY in the X, Y, and Z axis directions for each second sampling period T2 for performing the servo control.
a and dZa are calculated and output to the servo control unit 8. This second sampling period T2 may be the same as or different from the first sampling period T1 in the first interpolator 2. When the first and second sampling periods are the same, high-speed control is possible, and when they are different, precise control is possible.

Step S11 The corrected feed speed V0 (n) used at this time differs depending on the respective sampling timings, and the speed may greatly change as it is. If the speed change is large, a large impact is generated, which may deteriorate the cutting shape of the cutting surface or damage the speed control device or the tool. In order to prevent such a problem from occurring, the acceleration / deceleration processing unit 6 re-adjusts the feed speed so that the speed change of the corrected feed speed V (0) becomes equal to or less than the limit acceleration (or limit deceleration) ACC.

FIG. 5 is a flowchart showing the acceleration / deceleration processing. Step S21 When the corrected feed speed changes from the speed V1 to the speed V2,
When the speed V2 is higher than the speed V1, acceleration processing is performed,
When the speed V2 is lower than the speed V1, a deceleration process is performed. Describing the acceleration processing in steps S22 to S25 , the speed Va is used as a speed command when the second interpolator 7 calculates the amount of movement in each axis direction for each second sampling period T2. This speed V
The initial value of “a” is the speed V1, and the limit acceleration ACC set in advance as a parameter is added each time the amount of movement is obtained. Va when the speed Va exceeds the speed V2
= V2. In this way, the acceleration processing is performed to linearly increase the corrected feed speed at the limit acceleration ACC. In steps S26 to S28 and S25, the deceleration process is the reverse process of the acceleration process, that is, the deceleration process is performed.
To speed V2. To perform the above processing, the second interpolator 7 reads data in the buffer memory 3 in advance.
When the portion where the target speed changes from the speed V1 to the speed V2 is detected, the combined movement amount is checked from that point, and this value is equal to the travel distance LDCC required to reduce (or accelerate) the speed V1 to the speed V2. The returned position is set as the deceleration (or acceleration) start position.

Hereinafter, the processing contents will be described by exemplifying the deceleration processing. FIG. 6 is a flowchart showing the deceleration processing. The deceleration distance LDCC is obtained based on the following Expression 17 (step S31).

[Equation 17] Here, Vp is the speed before deceleration, and Ve is the speed after completion of deceleration. The addition moving distance ΔLa and the repetition index i are initialized (step S32). The movement amount La (i) in the i-th sampling cycle is obtained by the following Expression 18 (Step S33).

(Equation 18) The (N-1) th data is read from the buffer memory 3, but the above processing is performed first with the sampling cycle number being larger, and the reading order is (N-1),
(N-3),..., 2, 1, 0. ΣLa is updated by adding the calculated movement amount La (i) in the i-th sampling cycle to the added movement distance ΣLa (step S33). The deceleration distance LDCC is compared with the added moving distance ΣLa (step S34), and when it is smaller than the added moving distance ΣLa, the operation of step S33 is repeated. The processing is completed up to the j-th and the target speed at that time is V1
And Then, assuming that the target speed changes to V2 in the (j−k) -th sampling cycle, the following equation (1) is obtained.
8, the speeds Va and Ve are replaced with the speeds V1 and V2, and the deceleration distance LDCC is obtained by the following equation (19).

[Equation 19]

This will be described more specifically. (J- (k-1))
The movement amount La in the second sampling cycle is calculated. The value of the moving distance La (j- (k-1)) is the deceleration distance L
If it is smaller than DCC, the next (j- (k-2)) th moving distance La (j- (k-2)) is obtained, and these added moving distances ΣLa = La (j- (k-1)) ) + La (j
-(K-2)) and the deceleration distance LDCC. If the deceleration distance LDCC is still larger than the added movement distance ΣLa, the movement distance La (j- (k-3)) in the next (j- (k-3)) th sampling cycle is further obtained.
Is calculated, and the moving distance La is added to the added moving distance ΣLa, and is compared with the deceleration distance LDCC. In this way, the position where the added movement distance ΔLa becomes larger than the deceleration distance LDCC is detected. If the added movement distance ΔLa becomes larger than the deceleration distance LDCC in the (jo) -th sampling cycle, the (jo) -th sampling cycle becomes the deceleration start time.

From the j-th sampling period, (jo)
Until the second sampling period, the speed V of the second interpolator 7
Speed control is performed using the speed V1 as a, and (jo)
The deceleration process is performed from the second sampling cycle. (J-
o) From the second sampling period, based on the speed Va = V1, the limit deceleration ACC is reduced each time interpolation is performed, and when the speed becomes lower than the speed V2, the speed Va = V1.
Let it be 2. In this manner, the deceleration is linearly reduced at the limit deceleration ACC from the (j-o) th sampling period.
In the (J-k) th sampling period, the speed becomes V2.

Step S12 (FIG. 3) The movement amount dX interpolated from the second interpolator 7 as described above.
a, dYa, and dZa are output to the servo control unit 8, and the servo control unit 8 controls the drive target in each axis direction in the second sampling cycle based on the control signal. According to the sampling control based on the control signal described above, the servo control unit 8 can safely drive the drive target within the allowable shape error and the limit acceleration. Although the servo control of this sampling method is performed in the second sampling cycle T2, the second sampling cycle and the first sampling cycle T1 may be the same. As described above, high-speed control is possible in the case of the same sampling period, and precise control is possible in the case of different sampling periods.

As described above, the corrected feed rate and the movement for each sampling cycle having the acceleration / deceleration pattern for operating the drive unit within the allowable shape error according to the cutting shape and accelerating / decelerating the drive unit within the limit acceleration. Since the amount is automatically determined, the creator of the machining program command (designer) decides the amount of movement and feed rate and determines the necessity of acceleration / deceleration while considering the cutting shape when creating the machining program command. This eliminates the necessity, and reduces the work of the designer to create machining program commands. Further, since the designer does not mistakenly determine the acceleration / deceleration pattern, it is possible to prevent the occurrence of a shock or the occurrence of a malfunction such as damaging the tool.

The embodiment described above is an exemplification, and various modifications may be made in practicing the present invention in addition to those described above. For example, even if each of the configurations shown in FIG. 1 is realized using one microcomputer,
The same performance and effects as described above can be obtained even by using a plurality of microprocessors.

[0027]

As described above, according to the present invention, the corrected feed rate and the moving amount for each sampling cycle within the allowable shape error and the limit acceleration can be obtained even by the machining program command created by the designer in the same manner as before. Is automatically calculated, and servo control of an appropriate sampling method can be performed using these control amounts. In addition, it is not necessary to create a complicated machining program command, and it is possible to prevent creation of an erroneous machining program command, thereby preventing malfunction of the speed control device. Further, since the interpolation mode is not used for shape determination, even when the circular motion is performed by the continuation of the minute linear interpolation, it can be correctly recognized as the circular arc. In addition, it can support free-form surfaces other than arcs.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a numerical control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the numerical control device of FIG. 1;

FIG. 3 is a flowchart showing an operation of the numerical control device of FIG. 1;

FIG. 4 is a diagram showing an arc for performing shape recognition according to the embodiment of the present invention.

FIG. 5 is a flowchart illustrating an acceleration / deceleration process according to the embodiment of the present invention.

FIG. 6 is a processing flowchart for determining a deceleration distance according to the embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional numerical control device.

[Explanation of symbols]

1. Analysis unit 2. First interpolator 3. Buffer memory 4. Shape recognition unit 5. Feed speed calculation unit 6.
Acceleration / deceleration processing section, 7 second interpolator, 8 servo control section. Applicant Toshiba Machine Co., Ltd.Attorney Takahisa Sato

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-106808 (JP, A) JP-A-63-106809 (JP, A) JP-A-63-265306 (JP, A) JP-A-2- 219107 (JP, A) JP-A-2-137006 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G05B 19/416 G05B 19/4103

Claims (2)

(57) [Claims] An analyzing section for analyzing an input machining program command into interpolation data for each block; and a first section in each axis direction for each first sampling period from the interpolation data for each block. first moving amount over multiple sampling periods regarding the movement amount and the first interpolator for calculating a first feed speed, the first sampling period the calculated, and the calculated
A storage unit which issued storing the first feed rate for the first movement of the plurality stored in said storage unit
Recognizing the shape recognizing unit movement shape curved portion and the corner portion identified and, feeding the first at the permissive shape erroneous difference in response to the recognized shape
A corrective feeding speed calculator for calculating a corrected and correct feed speed speed Ri, acceleration and deceleration within the limit acceleration of the controlled object the corrective feeding speed
And calculating the control feed speed so that the acceleration and deceleration processing section, interpolation to the amount of movement of each first second sampling period from the movement amount and the stored in the calculated said storage unit and the control feed speed second and a interpolator, the second sampling cycle obtained by interpolating in the second interpolator to
Servo-controls the controlled object based on the amount of movement for each period .
That the speed control device. 2. A machining program directive, and erroneous acceptable shape
An input step of inputting the difference and the limit acceleration as parameters; an analyzing step of analyzing the input machining program command to obtain interpolation data for each block; and a first sampling cycle using the interpolation data. Calculating a first movement amount and a first feed speed, storing a first movement amount and a first feed speed, and calculating a movement path from the stored first movement amount . Calculate radius of curvature
A shape recognizing step of recognizing a moving shape, and correcting the corrected feed speed used for keeping the recognized moving shape within the input allowable shape error by a curvature of half.
A corrected feed speed calculating step of calculating a curve portion and a corner portion separately with reference to a diameter, and an acceleration / deceleration for calculating a control feed speed by an acceleration / deceleration within the input limit acceleration with the corrected feed speed as a target A processing step; a calculating step of calculating a second moving amount for each second sampling period from the first moving amount stored in the storage unit and the control feed speed; and a second moving amount. And an output step of outputting to the control object side a numerically controlled feed speed control method.