JP2581585B2 - Acceleration / deceleration control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration / deceleration control device for controlling acceleration or deceleration at a constant acceleration in driving a machine tool, a robot arm, etc. In contrast, the present invention relates to an acceleration / deceleration control device capable of accelerating or decelerating at a constant acceleration.

[Prior Art] Conventionally, when a machine is driven, acceleration / 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, a linear acceleration / deceleration control method that accelerates or decelerates at a constant acceleration that does not exceed the maximum allowable acceleration determined by the performance of the driving system and the characteristics of the machine in order to shorten the driving time is desired. I have.

FIG. 7 is a block diagram of a conventional acceleration / deceleration control device disclosed in Japanese Patent Application Laid-Open No. 59-62909. In the figure (1a) (1b) ...
(1n) is n buffer registers, (2) is an adder,
(3) is an accumulator for temporarily storing the addition result,
(4) is the transfer register of the addition result, and (5) is the addition result.
This is a 1 / n divider. Each buffer register (1a) to (1
n) are connected in series, it is input to the first stage of the buffer registers for each sampled as the movement amount command speed V _i of the sampling period (1a). At the same time, the contents of each buffer register are transferred to the next buffer register, and the contents V _(in) of the last buffer register (1n ₎ are added to the adder (2).
Sent to the input.

At sampling time i-1, the content of the transfer register (4) in S _(i-1) Tosureba sampling time i, the output S _i of the adder (2) is _{S i = S (i-1} ) + V i −V _(in) where S ₀ = 0, V ₋ = 0, and the result is stored in the accumulator (3).
1 / n is output by the divider (5) and output. It should be noted that the above-mentioned V _-
= 0 simply represents that the value corresponding to i from 0 to n is 0 _in V _(in) .

From the above, the output speed F _i is Becomes

On the other hand, the addition result S _i of the accumulator (3) is the input of the transfer register sent to (4) and the adder of the next sampling time (2).

With the above configuration, as shown in FIG. 8, output speeds (11a) and (11b) having linear acceleration / deceleration characteristics are given to the inputs of the command speeds (10a) and (10b).

[Problems to be Solved by the Invention] Since the conventional acceleration / deceleration control device is configured as described above, if the sampling period is ΔT, the acceleration / deceleration time constant is constant as T = n · ΔT. Assuming that the command speed is V, the acceleration a is a = V / T, and changes in proportion to the command speed. Therefore, it is necessary to select the time constant T so as to satisfy the maximum allowable acceleration at the maximum command speed. In this case, when the command speed decreases, the drive is performed in a region equal to or less than the maximum allowable acceleration, and the performance of the drive system is maximized. Can not be demonstrated.

Further, in order to perform fine acceleration / deceleration control, it is necessary to select a sampling period ΔT sufficiently smaller than the time constant T, and the number of buffer registers n (= T / ΔT) is required to be large, which complicates the configuration. .

Further, when moving at a command speed V over a short driving distance L, the moving time t = L / V becomes smaller than the time constant T, as shown in FIG. The maximum value of the speed can only rise up to V · t / T, so that there is a problem that the positioning time becomes long.

The present invention has been made to solve the above problems, and has a constant acceleration / deceleration characteristic with respect to a change in command speed, and has a shortest movement time for a short distance movement command. It is an object of the present invention to provide an acceleration / deceleration control device that generates an output speed and realizes fine speed control with quick response.

[Means for Solving the Problems] An acceleration / deceleration control device according to claim 1 of the present invention is a linear acceleration / deceleration control device that linearly accelerates or decelerates at a commanded constant acceleration. A first calculation unit for calculating a follow-up distance between the command position and the current position by integrating a difference between a command speed input from the outside and a current output speed output by the third calculation unit every time; A second calculator for calculating a deceleration distance required for linearly decelerating at the commanded constant acceleration from the current output speed output by the third calculator and stopping, and the command speed and the current speed. The output speed, the following distance, the deceleration distance, and the necessity of acceleration or deceleration are determined using the commanded constant acceleration. There and When decelerating, calculate the output speed based on the deceleration obtained for each sampling cycle so that the moving distance during deceleration from the current output speed at a constant acceleration until the output speed becomes zero becomes equal to the current follow-up distance And a third calculation unit for outputting the result.

The acceleration / deceleration control device according to claim 2 of the present invention is characterized in that a smoothing means for inputting an output speed output by the third calculation unit, smoothing the output speed and outputting the output speed to the outside.
Is added to the acceleration / deceleration control device according to the above.

[Operation] In the present invention, the output speed is calculated by comparing the following distance and the deceleration distance, determining acceleration / deceleration, and accelerating or decelerating the output speed at a specified constant acceleration until it matches the command speed. Therefore, a speed output for accurately moving the moving distance, which is the integral value of the command speed, is generated. Note that this speed output is a speed output that can linearly decelerate to a stop at a commanded stop position at a commanded acceleration and stop at the time of deceleration. Further, even when the moving distance is short, an optimum triangular wave speed output for accelerating and decelerating at the commanded constant acceleration is generated.

Further, the calculated output speed is output through the smoothing means to smooth the acceleration change.

Embodiment 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, FIG. 2 is a flowchart showing a control operation of one embodiment of the acceleration / deceleration control device of the present invention, and FIG. FIG. 2 is a configuration diagram when applied to a control device (hereinafter, referred to as an NC device).

In FIG. 1, reference numeral (20) denotes a tracking distance calculation unit which is a first calculation unit, which integrates a difference between a command speed and an output speed to calculate a distance between a command position and a current output position, that is, a tracking distance. Is what you do. (21) is a deceleration distance calculation unit, which is a second calculation unit, which calculates a distance traveled while decelerating to zero with a given acceleration from the current output speed, that is, a deceleration distance. (22) is an output speed calculation unit which is a third calculation unit. This output speed calculation unit (22) has a first comparator (23) for comparing the command speed and the output speed, and calculates a following distance and a deceleration distance. It comprises a second comparator (24) for comparison and a speed calculator (25) for calculating the output speed based on the result of the comparison.

In FIG. 3, (35) indicates the main control CPU (C
(PU: 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 performing communication between the operator and the CN device. (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 composed of RAM, (4)
4) is a control memory composed of ROM, (45a), (45b) and (45c) are interfaces, (46) is servo output control, (47) is feedback control,
(48) is the drive unit, (49) is the servomotor, (5)
0) 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 procedure for executing the acceleration / deceleration control shown in FIG.
Is stored in

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 2-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 pulses to the interface (45c).

Next, the operation of the acceleration / deceleration control will be described with reference to the flowchart shown in FIG.

A series of control operations shown in FIG. 2 are performed based on an interrupt generated from the interrupt circuit (42), that is, every fixed sampling period ΔT.

In FIG. 2, L _i and D _i are movement amounts of the distance in one sample period, F _i and V _i are movement amounts of the speed in one sample period, and ΔF and Δ
V is a change amount (acceleration) of the speed movement amount in one sample period, and each of these quantities is handled as a dimensionless movement amount. Therefore, it is possible to compare and calculate the magnitude relationship between these quantities for each sample period.

First, when an interrupt occurs, servo CPU (41) reads a command speed V _i 2 from port memory (43) (step
S1).

Next, the difference between the command speed and the output speed is integrated by the tracking distance calculation unit (20) to obtain a distance between the command position and the current output position, that is, a tracking distance. This is calculated by the following equation (1). That is, the following distance L _{i at the} sampling time _i
By using the command speed V _i and the previous output speed _{F (i-1), L} i = L (i-1) + V i -F (i-1) ...... (1) where L ₀ = _0, F _{It is} calculated according to ₀ = 0 (step S2).

Next, the deceleration distance calculation unit (21) calculates the distance traveled while decelerating to zero with the given acceleration from the current output speed. This is calculated by the following equation (2). That is, the deceleration distance D _i corresponding to the previous output speed F _(i-1) (Step S3). Here, ΔF is an acceleration command value (hereinafter, simply referred to as acceleration), and is a speed change amount between sampling cycles. The acceleration ΔF is a constant determined by the machine to be controlled, and is stored in the control memory (44).

The operation of the output speed calculator (22) is indicated by the dotted line (30) in the flowchart of FIG.

That is, first the first comparator (23) compares the command speed V _i and the previous output speed F _(i-1) (step S4), and then at the second comparator (24), following distance L _i is compared with the deceleration distance D _i (step S5 or S6), (a), ( b), (c), (d)
Are divided into four cases. Upon receiving these results, the speed calculation unit (25) performs the operation indicated by the dashed-dotted line (31).

First (a), because the command speed V _i is larger than the output speed F _(i-1), there is a situation where the acceleration, output speed for tracking the distance L _i is smaller than the deceleration distance D _i is the previous value its orゝholds (step S7), and follow-up distance L _i waits until it exceeds the deceleration distance D _i.

(B) the commanded velocity V _i is greater than the output rate F _(i-1),
Since the following distance _Li is larger than the deceleration distance _{Di, the} vehicle is accelerating. In this case, the previous output speed F _(i-1) and acceleration Δ
Sum of F and compares the command speed V _i (step S8), and when the sum value exceeds the command speed V _i, the output speed command speed V _i
Output as F _i (step S9), and is the output speed F _i of the added value when not exceeding (step S10).

Case (c) is generated when performing move command a short distance at a high speed command speed, this time, the command speed V _i is the output speed F _(i-1) Despite the smaller, follow-up distance L _i is for greater deceleration distance D _i, to accelerate the output speed. This is the same process as step 10 described above, and outputs the addition value of F _(i-1) and ΔF as the output rate F _i. 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 _i is the output speed F _(i-1) from small and follow 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, calculate the acceleration at the next time using the following distance and output speed at that time, calculate the output speed, and output it. I do. This is calculated as follows. That is, the previous output speed
F When _{the (i-1)} output speed at a constant acceleration from decelerates until zero, deceleration ΔV in order to move the distance therebetween is equal to the current of the follow-up distance L _i is (2) Using Given by

Therefore, in order to decelerate at a constant acceleration such that the output speed 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 F _i is Given by Therefore, the output speed _Fi is calculated and output according to the equation (4) (step S12).

However, in order to absorb the approximation error of equation (3), L _i is ΔF
It is determined before the process of step S12 that the value becomes smaller (step S11), and in that case, the output speed F _i = L _i is output (step S13).

During the above operation, in steps S4, S5, S6, S8, and S11, if "=" is also determined as "YES", the process proceeds to the next step.

By the above-described operation, the operation characteristics of the acceleration / deceleration control device of the present invention are such that even if command speeds (10a) and (10b) having different magnitudes are input as shown in FIG. As shown in 11a) and (11b), acceleration during acceleration and deceleration is constant. Further, even if the value of the command speed changes arbitrarily with time, the output speed follows the output speed promptly without specifying the acceleration.

Here, it will be described that the operation characteristics shown in FIG. 4 are obtained by the respective processes shown in FIG.

Now, when the command speed Va (10a) is input, the output speed Fa
First, in steps S1, S2, S3 of the flowchart of FIG.
V _i , L _i , and D _i are obtained, and then through steps S4, S5, S8, and S10,
The initial value of Fa is increased by ΔF at every sampling period ΔT from zero (see acceleration period in FIG. 4). Tracking distance L _tp at this time (hereinafter referred to as time) is the sampling time in FIG. 4 t _p is from time t ₀ of the difference between the command speed Va and (10a) and the current output rate Fa (11a) to t _p since the integral value, the time t ₀ ~t between _p, command speed Va and (10a) output speed F
represented by the area of the hatched portion surrounded by a (11a), similarly deceleration distance D _tp is the period from time t ₀ to t _p, is surrounded by a line of zero speed and output speed Fa (11a) It is represented by the area of the dot display part.

In step S8, the output speed Fa (11
It is determined whether a) has reached the command speed Va (10a),
Step S4 from the time t _a of FIG. 4, S5, S8, S9 through output speed Fa (11a) outputs the same value as the command speed Va (10a) (constant speed period of FIG. 4). In this constant velocity period, time t ₀
Obtained in between times t _a from following distance L _ta and deceleration distance D
The value of _ta does not change. In the constant velocity period shown in FIG. 4, the following distance _Lta and the deceleration distance _Dta have the same value.

Next, when the speed command value Va (10a) becomes zero at time t _b, the determination result of step S4 of FIG. 2 becomes NO, the output speed Fa (11
a) is the moving distance from this point (from time t _b to t _{e in} FIG. 4).
It decelerates at a constant acceleration so that the area of the dotted hatched portion) is equal to follow distance Lt _p at time t _b between the output speed Fa and speed zero line before entering the process of stopping. Ie time
t _b Thereafter, step S4 in each sampling period, S6, S11, S1
2, the output speed Fa (11a) is reduced by the deceleration ΔV obtained by the equation (3) and decelerated. When the following distance L _i is smaller than ΔF in step S11,
Finally deceleration at time t _e and outputs all following distance L _i which remains through the step S13 is completed (see deceleration period of FIG. 4).

Also, as shown in FIG. 5, even when a speed command (10) for moving at a high speed over a short distance is input, the output speed outputs an optimal waveform that accelerates and decreases at the specified acceleration value as shown in (11). .

Here, it will be described that the operation characteristics shown in FIG. 5 can be obtained by the respective processes shown in FIG.

FIG. 5 shows an example in which the command speed V becomes zero during the acceleration period. When the command speed V is input, the output speed F
First, in steps S1, S2, S3 of the flowchart of FIG.
V _i , L _i , and D _i are obtained, and then through steps S4, S5, S8, and S10,
From the initial value of F, it increases by ΔF every sampling period ΔT. When the command speed V becomes zero at a time t _b, this time t _b
Is the following distance L _tb (the area of the hatched portion between the command speed V and the output speed F between times t _{0 and} t _{b in} FIG. 5) is the deceleration distance
Since it is larger than D _tb (the area of the dot display portion between the zero speed line and the output speed F at the same time as above), the output speed further increases by ΔF through steps S4 and S6 to S10.

When the output speed F is increased, the (2) for the deceleration distance D so as to obtain an increase from the equation, the determination result of step S6 at time t _c is NO, and thereafter the deceleration period of the Figure 4 Similarly to the operation, the output speed is reduced by the deceleration .DELTA.V obtained by the equation (3) through steps S4, S6, S11 and S12, and the output speed is reduced. When the following distance L _i is smaller than ΔF in step S11, the end step S13
Output all of the follow-up distance L _i that remains through the to complete the deceleration at time t _e. In this case the moving distance from the time t _b until the reduction end time t _e (broken line hatched portion area between the line of output speed F and the velocity zero between the fifth view of the time t _b ~t _e) at time t _b Following distance L
Processed to be equal to _tb .

Here, the relationship between the command acceleration ΔF and the deceleration ΔV will be described.

In the above acceleration period, the acceleration can be unconditionally increased by increasing the acceleration ΔF, but at the time of deceleration, it is necessary to adjust the distance from the deceleration at a constant acceleration to the stop to the command value. It is necessary to calculate the deceleration ΔV according to the equation (3) in accordance with the following equation: This ΔV is the deceleration (ie, the deceleration at the time of deceleration at a constant acceleration such that the movement distance (the area of the hatched portion in FIG. 4) during the deceleration period in FIG. (A change amount of the output speed), and when the following distance L at the time of the start of deceleration is equal to the deceleration distance D at that time, it becomes equal to the given command acceleration ΔF. However, in normal control characteristics, the following distance L is often slightly larger than the deceleration distance D, and in this case, ΔV is slightly smaller than ΔF.

In the above embodiment, the function of the output speed calculation unit is to accelerate or decelerate the output speed at a constant acceleration.
As shown in the figure, a simple smoothing filter (60) may be provided at the output end of the output speed.

[Effect of the Invention] As described above, the present invention obtains a following distance and a deceleration distance from a command speed, an acceleration, and an output speed, determines acceleration / deceleration using these, and accelerates / decelerates at a specified constant acceleration. Therefore, there is an effect that an acceleration / deceleration control device that maximizes the efficiency of the drive system and generates a fine and smooth velocity waveform that enables high-speed and high-accuracy position control can be obtained.

Further, by outputting the calculated output speed through the smoothing means, the change in acceleration can be made smooth, and the impact and vibration applied to the driven machine can be suppressed low.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flowchart showing a control operation of an embodiment of the acceleration / deceleration control device of the present invention, and FIG.
FIG. 4 and FIG. 5 are waveform diagrams showing operating characteristics of the present invention, FIG. 6 is a structural diagram of an output speed calculating section showing another embodiment of the present invention, FIG. FIG. 1 is a configuration diagram of a conventional acceleration / deceleration control device, and FIGS. 8 and 9 are waveform diagrams showing operation characteristics of the conventional acceleration / deceleration control device. In the figure, (20) is a following distance calculation unit (first calculation unit), (21) is a deceleration distance calculation unit (second calculation unit), (2)
2) is an output speed calculator (third calculator). In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] A linear acceleration / deceleration control device for linearly accelerating or decelerating at a commanded constant acceleration, wherein a command speed inputted from outside and a third calculating unit output the signal every fixed sampling period. A first calculation unit that calculates a follow-up distance between the command position and the current position by integrating the difference between the current output speed and the current output speed. A second calculation unit that calculates a deceleration distance required for linearly decelerating and stopping at a constant acceleration, and using the command speed, the current output speed, the following distance, the deceleration distance, and the commanded constant acceleration. It is necessary to determine whether acceleration or deceleration is necessary or not. When accelerating or decelerating, the output speed accelerates or decelerates at the commanded constant acceleration, and when decelerating, the output speed at a constant acceleration from the current output speed. But And a third calculation unit that calculates and outputs an output speed based on the deceleration obtained for each sampling cycle so that the moving distance during deceleration until the current speed becomes equal to the current following distance. Acceleration / deceleration control device. 2. The acceleration / deceleration device according to claim 1, further comprising a smoothing means for inputting an output speed output from said third calculation unit, smoothing the output speed, and outputting the output speed to the outside.