JP2653130B2 - Acceleration / deceleration control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration / deceleration control device that controls acceleration or deceleration by continuously changing acceleration in driving a machine tool, a robot arm, or the like. is there.

[Conventional technology]

2. Description of the Related Art Conventionally, when a machine is driven, acceleration and deceleration control is performed so as not to apply a shock or vibration to a mechanical system at the time of starting or stopping. In such acceleration / deceleration control, there is a demand for an S-shaped acceleration / deceleration control system in which acceleration is continuously changed and acceleration or deceleration is performed so as not to exceed a maximum allowable acceleration.

FIG. 9 is a configuration diagram of a conventional acceleration / deceleration control device. In the figure, reference numeral (20) denotes a tracking distance calculation unit that integrates the difference between the command speed and the output speed before smoothing, and calculates the distance between the command position and the current output position, that is, the tracking distance. (twenty one)
Is a deceleration distance calculation unit that calculates the distance traveled while decelerating to zero at the given acceleration from the current output speed before smoothing, that is, the deceleration distance. (22) is an output speed calculation unit. The output speed calculation unit (22) is a first comparator (23) for comparing the command speed and the output speed, and a second comparator for comparing the following distance and the deceleration distance. (24) and a speed calculation unit (25) that calculates the output speed before smoothing based on the comparison and determination results,
And a smoothing filter (26) for smoothing the acceleration and calculating the output speed. Next, the operation of the conventional acceleration / deceleration control device will be described. First, the difference between the command speed before smoothing and the output speed is integrated by the following distance calculation unit (20),
The distance between the command position and the current output position, that is, the following distance is obtained. This is calculated by the following equation (1). That is tracking distance L _i at the sampling time i by using the command speed V _Ci and the last unsmoothed output speed _{V (i-1), L} i = L (i-1) + V Ci -V (i-1) ... (1) However, calculation is performed using L _O = O and V _O = O.

Next, the deceleration distance calculation unit (21) calculates the distance traveled while decelerating from the current output speed to the given acceleration of zero. This is calculated by the following equation (2). That is, the deceleration distance D _i corresponding to the previous output speed V _(i-1) Is calculated by Here, ΔV is an acceleration command value (hereinafter, referred to as an acceleration command value).
Simply referred to as acceleration. ) Is the speed change amount during the sampling period. The acceleration ΔV is a constant determined by the machine to be controlled.

The operation of the pre-smoothing output speed calculator (22) will be described. First, the first comparator (23) compares the command speed V _Ci with the previous output speed before smoothing V _(i-1) , and then the second comparator (24).
Then, when the following distance _Li and the deceleration distance _Di are compared, there are four cases shown in the following (a), (b), (c), and (d).

(A) the command speed V _ci is the last unsmoothed output speed V _(i-1) greater than follow the distance L _i is the deceleration distance D _i is smaller than the case, (b) the command speed V _Ci is the last unsmoothed output speed V _(i-1) greater than follow the distance L _i is the deceleration distance D _i is greater than the case, a small track distance L _i from (c) is the command velocity V _Ci is the last unsmoothed output speed V _(i-1) deceleration distance D _i is greater than the case, a (d) reduced following distance L _i from the command speed V _Ci is the last unsmoothed output speed V _(i-1) is the deceleration distance D _i is smaller than the case.

First, (a) indicates that the command speed V _Ci is the output speed V _(i-1) before smoothing.
Although the vehicle is accelerating because it is larger, the following distance L _i
There output speed smaller than the deceleration distance D _i is directly holds the previous value, wait until the following distance L _i exceeds the deceleration distance D _i.

(B) the commanded velocity V _Ci is greater than the unsmoothed output speed V _(i-1), follow-up distance L _i is in the situation where the acceleration for greater deceleration distance D _i. In this case, the previous output speed before smoothing V
_(i-1) and compares the acceleration value of the acceleration ΔV and a command speed V _Ci, when the acceleration value exceeds the command speed V _Ci outputs a command speed V _Ci as unsmoothed output speed V _i, when not exceeded Represents the acceleration value as the output speed V _i before smoothing.

The case (c) occurs when a short-distance movement command is issued at a high command speed. In this case, although the command speed V _Ci is smaller than the output speed V _(i-1) before smoothing, Tracking distance
L _i is for greater deceleration distance D _i, to accelerate the output speed.
This is the same processing as in the case of (b) described above, where V _(i-1) and ΔV
Is output as the output speed V _i before smoothing. Note that this acceleration, when the follow-up distance L _i is smaller than the deceleration distance D _i, but switched to the deceleration, the processing of the deceleration is the process to be described later (d).

(D) are located in the circumstances to perform deceleration when the command speed V _Ci is smaller than the unsmoothed output speed V _(i-1), and follow-up distance L _i is smaller than the deceleration distance D _i. In this case, in order to decelerate to the commanded position at a constant acceleration and stop, at each sampling time, the acceleration at the next time is obtained using the following distance and the output speed before smoothing at that time, and the output speed before smoothing is calculated. Calculate and output. This is calculated as follows.
That is, when a constant acceleration is unsmoothed output speed from the last unsmoothed output speed V _(i-1) to decelerate to zero, so that the moving distance therebetween is equal to the current of the follow-up distance L _i The acceleration A is calculated using the equation (2). Given by

Therefore, in order to decelerate at a constant acceleration so that the output speed before smoothing becomes zero at the point where the following distance becomes zero, that is, at the point where the command position and the output position match, the next output speed V _i before smoothing becomes Given by Therefore, the output speed before smoothing is calculated by the equation (4) and output.

Finally, the output speed V _i before smoothing is determined by the smoothing filter (26).
Calculates the output speed V _{out i} by smoothing. For example, when the simplest primary filter is used as a smoothing filter,
The output speed V _{out i} can be obtained by equation (5).

V _{out i} = T _S · (V _i + DL _i-1 ) (5) where T _S is a time constant of the given first-order filter. DL _i is the accumulated amount of the primary filter, and (6)
It can be calculated by the formula.

DL _i = V _i −V _{out i} + DL _i−1 (6) With the above-described configuration, an S-shape is applied to the input of the command speed (14) as shown in FIGS. 10 (a) and 10 (b). An output speed (15b) having acceleration / deceleration characteristics and a continuous output acceleration (16b) are provided.

[Problems to be solved by the invention]

Since the conventional acceleration / deceleration control device is configured as described above, the maximum value of the change amount of the acceleration is determined by the maximum allowable acceleration and the time constant of the smoothing filter, and it is difficult to arbitrarily specify the maximum value. Further, the maximum value of the change amount of the acceleration occurs only when the acceleration rises, which is not desirable for the vibration system of the machine. Furthermore, since the filter is used, there is a problem that the stop cannot be performed quickly and the positioning time becomes long.

The present invention has been made in order to solve the above-described problems. In response to a change in the speed command, the acceleration and the change amount of the acceleration are respectively set to be equal to or less than the preset maximum allowable acceleration and the maximum allowable acceleration change amount. It is an object of the present invention to provide an acceleration / deceleration control device having limited acceleration / deceleration characteristics and having the shortest movement time within the range of the limitation.

[Means for solving the problem]

The acceleration / deceleration control device according to the present invention inputs a command speed for each constant sampling period as a first speed, calculates an output speed to accelerate or decelerate to match the first speed, and calculates the output speed. In an acceleration / deceleration control device that outputs a result, a first calculation unit that obtains a first acceleration by taking a difference of a command speed for each sampling cycle, a first acceleration, an allowable change value of the acceleration, a previous output speed, A second calculation for obtaining, from the previous output acceleration, a second speed and a second acceleration that are equal to the commanded speed and the first acceleration, and are equal to or less than the allowable value of the acceleration and equal to or less than the allowable change value of the acceleration, respectively. Unit, the following distance is calculated from the difference between the integrated value of the commanded speed and the integrated value of the previous output speed, and the deceleration distance is calculated from the second speed, the second acceleration, and the allowable value of the acceleration. Following the following distance If so, the second speed and the second acceleration are set as the output speed and the output acceleration. If the following distance is larger than the deceleration distance, the second speed and the second acceleration are corrected so that the deceleration distance is equal to or less than the following distance. And a third calculating unit for respectively obtaining the output speed and the output acceleration.

[Action]

In the present invention, the first acceleration is obtained by taking a difference of the commanded speed for each sampling cycle, and the commanded speed and the first speed are obtained from the first acceleration, the allowable change value of the acceleration, the previous output speed, and the previous output acceleration. The second speed and the second acceleration that are equal to the acceleration of 1 and are equal to or less than the allowable value of the acceleration and are equal to or more than the allowable change value of the acceleration are obtained, respectively. And the deceleration distance is calculated from the second speed, the second acceleration, and the allowable value of the acceleration. If the deceleration distance is equal to or less than the following distance, the second speed and the second acceleration are output. If the following distance is larger than the deceleration distance, the second speed and the second acceleration are corrected so that the deceleration distance is equal to or less than the following distance, and the output speed and the output acceleration are obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
Configuration diagram showing details of the speed management calculation unit corresponding to the calculation unit of
FIG. 3 is a configuration diagram showing details of a position management calculation unit corresponding to a third calculation unit, FIG. 4 is a flowchart showing a control operation of the speed management calculation unit, and FIG. 5 is a flowchart showing a control operation of the position management calculation unit. FIG. 6 is a block diagram showing a case where the acceleration / deceleration control device of the present invention is applied to a numerical control device (hereinafter, referred to as an NC device). FIG. 7 is a flowchart showing the operation of a deceleration speed calculation unit. 8 (a) and 8 (b) are waveform diagrams showing the operation characteristics of the present invention.

In FIG. 1, (1) is an acceleration command calculator corresponding to a first calculator for obtaining a first acceleration A ¹ _i , and (2) is a second command calculator.
A speed management calculation unit corresponding to a second calculation unit for calculating the speed V ² _i and the second acceleration A ² _i , and (3) a position corresponding to a third calculation unit for calculating the output speed V _i and the output acceleration A _i. It is a management calculation unit. In FIG. 2, (4) is a tracking speed calculation unit,
(5) is a deceleration calculation unit, (6) is a second comparator,
(7) is a first comparator, and (8) is a speed acceleration calculator. Further, in FIG. 3, (9) is a tracking distance calculation unit,
(10) is a deceleration distance calculation unit, (11) is a third comparator, (1)
2) is a velocity / acceleration correction unit, and (13) is a tracking distance correction unit.

In FIG. 6, (35) is the main control CPU
(Central processing unit) is an arithmetic processing unit that analyzes input information such as NC tape input and manual data input and performs arithmetic control. (36) is a tape reader, and (37) is a CRT display board, which is a setting display board for communicating between the operator and the NC unit. (38) is a main memory. (40) is a servo control for performing machine servo control processing, (41) is a servo CPU, (42) is an interrupt circuit, (43) is a two-port memory constituted by RAM, (44)
Is a control memory composed of ROM, (45a), (45b) and (45c) are interfaces, (46) is a servo output control, (47) is a feedback control, and (48)
Is a drive unit, (49) is a servomotor, and (50) is a detector. Incidentally, L ₁ is the control line, L ₂ is the address lines, L ₃ is a data line.

In the configuration shown in FIG. 3, the execution procedure of the acceleration / deceleration control shown in FIGS. 4 and 5 is stored in the control memory (44) as a control program.

The interrupt circuit (42) generates an interrupt to the servo CPU (41) at a constant sampling period ΔT.

The command speed is created by the main control CPU (35) and transferred to the servo CPU (41) through the two-port memory (43).

The servo CPU (41) reads the command speed in the two-port memory (43) based on the control program in the control memory (44), executes acceleration / deceleration control processing, and calculates the output speed.

Furthermore, the feedback signal of the feedback control (47) is input through the interface (45c), compared with the output speed, the difference is calculated, and the servo is output to the servo output control (46) through the interface (45c). Control processing is also performed.

The servo output control (46) converts the input from the interface (45c) from digital to analog and outputs it to the drive unit (48). The output is amplified by the drive unit (48) and rotates the servomotor (49). The feedback control (47) counts the feedback pulses from the detector (50) and outputs the counted number to the interface (45c).

A series of control operations shown below are performed by the interrupt circuit (42)
Is performed at a constant sampling period ΔT based on an interrupt generated from the above.

First, the calculation contents of the acceleration command calculator (1) for calculating the first acceleration A ¹ _i will be described. First, when an interrupt occurs, the servo CPU (41) reads the command speed V _Ci from the two-port memory (43). Then, the first acceleration A ¹ _i is obtained by the following equation by taking the difference between the previous command speed V _{C (i-1)} and the current command speed V _Ci .

A ¹ _i = V _Ci −V _{C (i−1)} (7) Next, the operation of the speed management calculation unit (2) will be described with reference to the configuration diagram of FIG. 2 and the flowcharts of FIGS. 4 and 7. In the speed management unit (2), the given integrated value of A ¹ _i matches the integrated value of A ² _i calculated by this speed management unit, and
Calculate A ² _i and its integral value V ² _i such that the magnitude of ² _i does not become larger than the maximum allowable acceleration A _{max and} the absolute value of the variation of A ² _i for each sampling period ΔT does not exceed ΔA. I do. _Amax and ΔA are constants determined by the machine to be controlled, and are stored in the control memory (44). Specifically, a difference AL _i between the actual speed and the command speed calculated by the tracking speed calculation unit (4), reduced acceleration speed calculation unit the speed variation AD _i necessary to constant speed (5) Is calculated. The first comparator (7) compares the speed command V _Ci with the previous output speed Vi _-1 and simultaneously the second comparator (6) performs AL _i.
And AD _i are compared with each other, and a second acceleration A ² _i and a second speed V ² _i are obtained by the speed acceleration calculator (8) based on the result of the comparison. Difference AL _i between the actual speed and the command speed is first is calculated by the following equation (step S1).

AL _i = AL _(i-1) + A _Ci -A _(i-1) (8) The contents of the calculation unit (5) for the deceleration speed AD _i are shown in the flowchart of FIG. AD _i is calculated based on the value of the acceleration (AX in FIG. 7) in consideration of the case where the absolute value changes from the previous output acceleration A _{(i-1) in the} direction in which the absolute value increases. That is, if A _i-1 is positive, AX is increased by ΔA, and if A _i-1 is negative, AX is decreased by ΔA (step S3).
1 to S33). As a result, if the absolute value of AX exceeds _Amax , the value is limited (steps S34 to S37). AD _i value is A _i-1
Can be calculated by the following two equations using the sign of (Step S38,
S39).

Subsequently, the first comparator (7) compares the command speed V _Ci with the previous output speed V _(i-1), and if the command speed is smaller,
Enter the acceleration sequence so that the speed becomes constant in the shortest time.
The comparing AL _i and AD _i in the second comparator, towards AL _i enters the larger if the acceleration sequence (step S4). In the acceleration sequence, the second acceleration A ² _i is obtained by adding the maximum allowable acceleration ΔA to the previous output acceleration A _(i−1) . The A _max A ² _i in the case where the result is greater than A _max where
(Steps S8 to S10). In the case of deceleration, the deceleration amount on the basis of the follow-up speed AL _i Ask by Acceleration and minus the value of the expression (11) from the A _i-1 in the same manner is used -A _max as the second acceleration is smaller than -A _max (step S5 to S7). The following speed AL
the absolute value of the difference between the value of _i is less than the allowable acceleration change amount ΔA and previous output acceleration A and _(i-1) and AL _i even when ΔA smaller than, to match the command speed and the second output speed Is determined to be acceptable, and AL _i is used as the second acceleration (step S
3, S11). Finally, the second calculated to the previous output speed V _(i-1)
The second velocity V ² _i is obtained by adding the acceleration A ² _i of
S12).

The operation of the location management calculation unit (3) is described in the block diagram of FIG.
This will be described with reference to the flowchart in FIG. The position management unit (3) compares the second speed V ² _i and the second acceleration A ² _i calculated by the speed management unit (2) with the current output speed.
When used as V _i and acceleration A _i , it is determined whether or not the vehicle can stop at the target position given by the integral value of the speed command V _Ci ,
If it is not possible, modify it to determine V _i and A _i . That is, the distance between the command position and the current output position by tracking distance calculator (9) obtains the (following distance) L _i (step S1
3) In the case of operating at the second speed and acceleration by the deceleration distance calculation unit (10), the distance (deceleration) to be traveled before stopping while satisfying the limitation of the maximum value of the acceleration and the limitation of the maximum change amount. The distance) _Di is obtained (step S14). Then, _Li and _Di are compared by the third comparator (11) (step S17).
_{If i} is smaller, the second speed and acceleration are adopted as the output speed and acceleration (step S18). Otherwise, the stopable speed and acceleration are calculated and set as the output speed and output acceleration (step S19). ~ S29). Further, when the follow-up distance L _i is smaller than ΔA assumes that when the stop is completed, the output speed V _i to 0 (step S15~S1
6). Finally, to end by modifying the value L _i of the follow-up distance to be used for next time (step S30).

Hereinafter, the calculation formula in each calculation unit will be described. In follow-up distance calculator (9), following distance L _i can be calculated by the following equation (step S13).

L _i = L _i−1 + V _Ci −V ² _i (12) In the case of correcting the following distance, the following equation is obtained (step S30).

L _i = L _i−1 + V _Ci −V ⁱ (13) In the deceleration distance calculation unit (10), the calculation formula differs depending on whether or not the minimum acceleration generated before stopping reaches −A _max . The minimum acceleration A _min is obtained by the following equation.

If A _min is greater than -A _max, deceleration distance DL _i is determined by the following equation.

When A _min is smaller than −A _max , the following equation is obtained using n ₁ , n ₂ , and n ₃ as intermediate variables.

n ₁ = (V ² _i + A _max ) / ΔA (16) n ₃ = A _max / ΔA When the result in the third comparator (11) requires correction in the speed / acceleration correction unit (12), the following calculation is performed. In this case, when the acceleration is linearly reduced from the current speed to perform a smooth stop, the magnitude X required for the current acceleration can be calculated by the following equation (step S19).

When the obtained X is included in the range of ± ΔA from the previous output acceleration A _i−1 and is larger than −A _max , the result of Expression (20) is set as the output acceleration A _i . If it is not included in the above range, the value closest to X among the values satisfying the limit is the output acceleration A _i
And then (step S20~S28), calculates the current output speed V _i from the output velocity V _i-1 of A _i and the previous (step S29).

By the operation described above, the operation characteristics of the acceleration / deceleration control device of the present invention can change the acceleration almost linearly as shown in FIGS. In addition, positioning can be performed in the shortest time while limiting the maximum change amount.

8 (a) and 8 (b), (14) is a command speed, (15) is an output speed, and (16) is an output acceleration.

〔The invention's effect〕

As described above, according to the present invention, the first acceleration is obtained by taking the difference of the command speed for each sampling cycle, and the first acceleration, the allowable change value of the acceleration, the previous output speed, and the previous output acceleration are obtained. , A second speed and a second acceleration that are equal to the commanded speed and the first acceleration, and are equal to or less than the allowable value of the acceleration and equal to or less than the allowable change value of the acceleration, respectively. The following distance is calculated from the difference between the speed integral value and the deceleration distance is calculated from the second speed, the second acceleration, and the allowable value of the acceleration. If the deceleration distance is equal to or less than the following distance, the second speed and the second speed are calculated. The acceleration of 2 is an output speed and an output acceleration. If the following distance is larger than the deceleration distance, the second speed and the second acceleration are corrected so that the deceleration distance is equal to or less than the following distance, and the output speed and the output acceleration are obtained. like Acceleration / deceleration control device capable of arbitrarily specifying the maximum amount of change in speed and acceleration, and changing the set value during operation based on the speed command value generated in each sampling cycle. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing details of a speed management calculation unit in FIG. 1, and FIG.
FIG. 4 is a block diagram showing the details of the position management calculation unit in FIG. 1, FIG. 4 is a flowchart showing the operation of the speed management calculation unit, FIG. 5 is a flowchart showing the operation of the position management calculation unit, and FIG. FIG. 7 is a block diagram showing a case where the acceleration / deceleration control device of the present invention is applied to an NC device. FIG. 7 is a flowchart showing the detailed operation of calculating the deceleration speed in FIG. 4, and FIGS. 8 (a) and (b).
FIG. 9 is a waveform diagram showing operation characteristics of the present invention, FIG. 9 is a configuration diagram of a conventional acceleration / deceleration control device, and FIGS. 10 (a) and (b) are waveform diagrams showing operation characteristics of the conventional acceleration / deceleration control device. is there. (1) Acceleration command calculation unit (first calculation unit) (2) Speed management calculation unit (second calculation unit) (3) Position management calculation unit (third calculation unit) . In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A command speed for each fixed sampling period is input as a first speed, an output speed is calculated to be accelerated or decelerated so as to match the first speed, and the calculation result is output. In the acceleration / deceleration control device, a difference between the command speeds in each sampling cycle is calculated as a first
A first calculation unit for determining the acceleration of the first acceleration, the allowable change value of the acceleration, the previous output speed, and the previous output acceleration, and the command speed and the first acceleration, and A second velocity and a second velocity that are less than or equal to an allowable value and equal to or less than an allowable change value of the acceleration.
A second calculating unit for respectively calculating the acceleration of the second speed, the second speed, the second acceleration, and the acceleration of the second acceleration based on the difference between the integrated value of the command speed and the integrated value of the previous output speed. The deceleration distance is calculated from the allowable value, and if the deceleration distance is equal to or less than the following distance, the second deceleration distance is calculated.
The speed and the second acceleration as an output speed and an output acceleration, and if the following distance is larger than the deceleration distance, the second speed and the second acceleration are set so that the deceleration distance is equal to or less than the following distance. A third calculating unit for obtaining the output speed and the output acceleration by correction.