JPS6383404A - Speed control device for hydraulic actuator - Google Patents

Abstract

PURPOSE:To simplify the construction of the device in the above caption so as to reduce its cost, by computing the deviation data between a detected value a preset value, and driving the pulse motor of a digital valve by a pulse signal whose frequency is proportional to the magnitude of the deviation data. CONSTITUTION:A deviation between the speed data V of an actuator 56 and a preset value Vs is computed, and a pulse signal with frequency corresponding to the above deviation data is output either as CW pulse or as CCW pulse depending on the plus/minus of said deviation data in order to drive the pulse motor of a digital valve 48. The opening/closing of said digital valve 48 regulates the amount of the liquid let to said actuator 56 to control the speed thereof. By the above constitution, the whole feedback loop of the speed control is realized with digital circuits, thus the use of A/D converter or D/A inverter becomes unnecessary, resulting in simplified construction and reduced cost.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a speed control device that controls the drive speed of a hydraulic actuator by regulating fluid using a digital valve, and in particular to a speed control device that controls the drive speed of a hydraulic actuator to a set speed. The present invention relates to a speed control device for a hydraulic actuator that performs feedback control.

(Prior Art) Conventionally, as a conventional speed control device using a digital control method, one shown in FIG. 6, for example, is known.

In FIG. 6, 24 is a digital speed setting device;
The set speed V for driving the actuator 20 is output as, for example, 8-bit digital data. 30 is a rotary encoder that outputs a pulse signal with a frequency proportional to the driving speed of the actuator 20. The pulse signal from the rotary encoder 30 is input to a speed detector 32, and the speed detector 32 outputs a pulse signal with a frequency proportional to the driving speed of the actuator 20. The driving speed V of the actuator 20 is detected from the reciprocal (1/T) and output as 8-bit digital speed data V.

26 is an arithmetic unit, and a digital speed setting device 24
Input the set speed data VS from the speed detector 32 and the detected speed data ■ from the speed detector 32, calculate the deviation Δv=vs−v between the two by digital calculation, and further calculate (Kp・Δv+KifΔVdt) for proportional-integral control, for example. Executes digital operations.

28 is a D/A converter that converts the control data output from the arithmetic unit 26 into an analog signal, amplifies it with the servo amplifier 14, and outputs the analog control signal to the servo valve 16.

(Problems to be Solved by the Invention) However, in the speed control device of a hydraulic actuator using such a conventional servo valve, the operation of the flapper, spool, etc. in the servo valve is affected by minute dust particles. Also, servo valves are complicated to maintain and manage due to the occurrence of sticks, etc. Moreover, servo valves are large and expensive equipment, and furthermore, if you want to perform easy-to-control and highly accurate digital control, you will need a D/A converter, etc. However, there were drawbacks such as the system being expensive and large.

(Means for Solving the Problems) The present invention has been made in view of these conventional problems, and uses a digital valve driven by a pulse motor to convert an electric signal into fluid ■ to generate hydraulic pressure. The object of the present invention is to provide a speed control device for a hydraulic actuator that controls the speed of an actuator, and in particular, to provide a speed control device for a hydraulic actuator that drives a pulse motor of a digital valve using feedback control using digital arithmetic processing. purpose.

In order to achieve this object, the present invention provides a speed control device for a hydraulic actuator that is driven by receiving hydraulic pressure from a fluid pressure source. Speed deviation data is calculated from the detected speed data, and a pulse with a frequency proportional to the magnitude of this deviation data is output to the pulse motor drive circuit as a CW pulse or a CCW pulse depending on the positive/negative of the deviation data, and the pulse of the digital valve is The valve is opened and closed by the drive of a motor, and the drive speed of the hydraulic actuator is feedback-controlled to a set speed.

(Function) According to the configuration of the present invention, the speed setter, the sensor, and the control section of the pulse motor based on the deviation can all be configured with a digital feedback loop, so that the A/D converter and D Since no /A converter is required, the device configuration is simple and cost-effective, and by setting the number of bits of digital data to 8 or 16 bits, extremely accurate speed control can be performed. .

(Embodiment) FIG. 1 is a block diagram showing an embodiment of the present invention using digital operations.

First, the configuration will be explained. 60 is a digital speed setter, which outputs, for example, 8-bit set speed data Vs.

62 is a rotary encoder, and actuator 56
It outputs a pulse signal with a frequency proportional to the driving speed of the motor, and functions as a digital speed sensor. 64 is a speed calculation unit which detects the driving speed of the actuator 56 based on the pulse signal from the rotary encoder 62 and outputs it as, for example, 8-bit detected speed data V.

66 is a pulse frequency calculation unit which inputs the set speed data VS from the digital speed setter 60 and the detected speed data V from the speed calculation unit 64, and calculates the absolute deviation Δ by digital calculation processing which will be explained later. A CW or CCW pulse having a frequency (f>) proportional to the value 1Δ■1 is generated, and the CW pulse is output when the deviation ΔV is positive, and the CCW pulse is output when the deviation ΔV is negative.

46 is a pulse motor drive circuit, and upon receiving the CW pulse from the pulse frequency calculation unit 66, the pulse motor drive circuit 46 rotates the pulse motor 50 provided in the digital valve 48 in steps according to the CW pulse in the CW force direction. The rotation of the pulse motor 50 in directions C to {circle around (2)} drives the variable diaphragm 52 in the direction to open it. When receiving a CCW pulse, the pulse motor 50 is rotated stepwise in the CCW direction according to the CCW pulse, and the rotation of the pulse motor 50 in the CCW direction drives the variable diaphragm 52 in a direction to close it.

Therefore, the digital valve 48 adjusts the working fluid supplied from the fluid pressure source 54 to the actuator 56, which is a hydraulic cylinder or the like, according to the opening degree of the variable throttle 52, and controls the driving speed of the actuator 56.

Here, the CW generated in the pulse frequency calculation unit 66
Between the frequency of the pulse or CCW pulse (f> and the absolute value 1Δv1 of the deviation data, f=−1ΔVI −−
-(1) However, K has a constant relationship, and the larger the absolute value 1ΔV1 of the deviation data, the higher the frequency (f) becomes.

Further, the upper limit frequency of the CW pulse or CCW pulse generated by the pulse frequency calculation unit 66 is determined by the digital valve 4.
The response speed is set to be equal to or less than the maximum response speed of the pulse motor 50 built in the motor 8.

Furthermore, the following relationship holds true between the input frequency to the pulse motor drive circuit 46 and the rotation IX of the pulse motor 50.

X=,/' fdt...(2) However, CW
Let the pulse input frequency be (+) and the CCW input cover pulse frequency =).

That is, the rotation amount X of the pulse motor 50 is the value obtained by integrating the input pulses during the necessary period T=t2-tl.

In addition, C output from the pulse frequency calculation unit 66
The frequency of the W pulse or CCW pulse (f> is the frequency of the (1st
) corresponds to the deviation data ΔV as shown in the equation, so the above equation (2) can be replaced with the following equation (3).

t2 t2.

X=f fdt=f, K l ΔVdt becomes dull, so 1, t2 By controlling the drive, it is possible to obtain the same effect as feedback control based on deviation data.

Furthermore, as the digital valve 48 used in the embodiment shown in FIG. The maximum speed of the pulse motor used for this is 1000pl)S.

FIG. 2 is a block diagram showing a specific example of the speed calculation unit 64 shown in FIG. I'm trying to find out.

In FIG. 2, 68 is a counter that counts the number of pulses output from the rotary encoder 62 at regular intervals, for example, every 250 μs.

70 is a memory such as a RAM that stores eight data Do-D7, and the count value obtained by the counter 68 every 250μ is stored sequentially as [)0 to D7, and the storage of the first eight data is completed. When storing the ninth data, a first-in, first-out storage process is performed in which the first stored data [)0 is erased and the newly obtained ninth data is written.

72 is a pointer counter for controlling the storage of the memory 70, and by receiving a clock every 250μ and incrementing the contents of the counter, addresses AO to A7 of the memory 70 are sequentially designated and data Do to D7 are written. After counting eight clocks and storing data D7, the contents of the pointer are cleared and counting starts again from address AO.

Reference numeral 74 denotes an adder that generates an addition output of the data Do-D7 stored in the memory 70, and performs an addition operation every 250μ in response to a clock, and the output of this adder 74 becomes the detected speed data V.

Next, the processing operation of the embodiment shown in FIG. 2 will be explained with reference to the flowchart shown in FIG.

This flow operates in response to a clock every 250μ, and first, in block 76, the memory 70 is cleared, and in the next block 78, the count value n@n=o of the pointer counter 72 is set.

Next, at block 80, the contents of the counter 68 are read,
In the next block, data [)n is written to address An of the memory 70 specified by An==n.

In the next block 84, the adder 74 outputs the data DO~D.
The detected speed V is calculated from the sum of 7, and the detected speed V is output in block 86.

Then, in block 88, n=n+1 is incremented.
If n=8 has not been reached at determination block 90, the process returns to block 80, and the same process is repeated when the next clock is obtained.

On the other hand, when n=8 is reached, the process returns to block 7B to set n=0 and replace the already stored data [)0 with new data.

In such speed detection processing, the sum of eight pieces of data that have been IJed every 250 microns from the current time up to eight taro clock cycles ago is calculated as the detected speed.

FIG. 4 is a block diagram showing a specific example of the pulse frequency calculation unit 60 of FIG. 1.

In FIG. 4, 92 is a subtracter, which calculates the deviation Δ between the set speed data VS obtained from the digital speed setter 60 and the detected speed data ■ obtained from the speed calculation unit 64.
Calculate V as ΔV=Vs-V.

94 is a digital comparator, and 8 from the subtracter
It determines whether the difference data Δ■ is positive or negative, and generates a torque output at +Δ■ and a torque output at −ΔV.

Reference numerals 96 and 98 are repeat type subtracters, which become operational upon receiving the torque output from the digital comparator 94 side, and receive setting data G from the GAINHU regulator 100.
Subtract the deviation data ΔV obtained by the subtractor 94 from AIN,
This subtraction operation is repeated until the subtraction result becomes less than or equal to zero.

The operation of the repeat subtracters 96, 98 is based on digital comparators 102, 104 and inverters 106.98. '108
controlled by

That is, the digital comparators 102 and 104 monitor whether the subtraction result of the repeat type subtracter 96 or 98 becomes less than or equal to zero, and until the result becomes less than or equal to zero, the outputs of the digital comparators 102 and 104 remain at the trubel level. is inverted by inverters 106 and 108, and commands repeat type subtracters 96 and 98 to repeat the subtraction operation.

When the subtraction result is less than zero, the digital comparator 9
The outputs of 6 and 98 rise to the torque level, inhibiting repetition of subtraction and applying a reset.

Furthermore, the outputs of the digital comparators 102 and 104 are given to the one-shot multis 110 and 112, which are triggered by the torque output of the digital comparators 102゜'104, and the one-shot multi 110 outputs one CW pulse, and the one-shot multis 110 and 112 output one CW pulse. Multi 112 is CCW
Outputs one pulse.

The operation cycle of the pulse frequency calculation unit shown in FIG. 7 is performed by a clock of about 5 μs, and therefore the maximum speed of the pulse motor is 1000 pps (1 mS).
This results in sufficiently high-speed processing.

Next, the control processing of the pulse frequency calculation unit shown in FIG. 4 will be explained with reference to the flowchart shown in FIG.

First, a determination block 120 checks whether or not the speed has been set. When the speed has been set, the process proceeds to block 122, where a predetermined GAIN value is set. This GAIN
If we select a sufficiently large value for the deviation ΔV, for example, if the maximum deviation ΔV obtained by feedback control is 50, then GAIN = 50, which is about 10 times that value.
Set to 0. However, GAIN is finally adjusted to the smallest value within the range in which the feedback loop operates stably.

Next, in block 124, the deviation ΔV is calculated, and if the deviation △■ is rarely positive, the process proceeds to block 130. In block 130, the deviation Δ■n at that time is subtracted from the first shift of GAIN, and the next judgment block is executed. Check whether the subtraction result is less than or equal to zero.

If the subtraction result is greater than or equal to zero, then in block 136 the counter n is
is incremented, the process returns to block 124 to find the deviation ΔVn1 when receiving the next clock, subtracts the subtraction result in block 130 from the previous subtraction result, and checks in judgment block 312 whether it is less than or equal to zero.

Then, when it is determined in block 132 that the subtraction result is less than zero, the process proceeds to block 134, where the CW pulse is reduced to 1.
output one.

To explain specifically, since the initial detected speed V is 10, the maximum deviation ΔV = 50, and in this case,
In order to make the subtraction result less than or equal to zero, since GAIN=500, the subtraction cycle must be repeated 10 times. That is, when ΔV=50, for example, if one subtraction cycle is 100 μs, the CW pulse is 1
One signal is output every 0X'lOOμs=1ms, and the pulse motor is controlled at the maximum speed.

Next, the detection speed increases and, for example, the deviation ΔVn becomes ΔVn=4.
If it drops to 0, there will be 13 subtraction cycles where the subtraction result is less than zero, and the CW pulse will be 13x100μs.
One signal is output every = 1.3 ms, and as the deviation decreases, the driving speed of the pulse motor decreases.

When the deviation △vn=o, the subtraction result will not become less than zero no matter how many times it is repeated, so the output of the CW pulse will stop, and the rotational position of the pulse motor will be determined by the moderation of the CW pulse up to that point, that is, the integral value. The actuator is driven at a constant speed (set speed VS) by the hydraulic pressure determined by .

On the other hand, when the deviation ΔVn calculated in block 124 is negative, the process proceeds to block 138, in which the deviation Δvn is similarly subtracted from GAIN, and the subtraction cycle is repeated until the subtraction result becomes less than or equal to zero in determination block 140. If it becomes less than zero, the process goes to block 142, in which case the CC
One W pulse will be output.

The detected speed calculation unit 64 in FIG. 1 calculates the speed by counting the number of pulses obtained from the rotary encoder 62, but it detects the period T of the pulses from the rotary encoder 62 and calculates its reciprocal (1 /T) may be used to detect the speed.

Furthermore, the numerical values described in the above (e) are merely examples, and the present invention is not limited to these numerical values.

Furthermore, in the pulse frequency calculation unit shown in FIG.
Two pulse generation sections consisting of a repeat subtracter, a digital comparator, and a one-shot multi are provided independently for CW pulses and CCW pulses, but this pulse generation section is used as one system, and the output of the one-shot multi is input to the multiplexer. and convert this multiplexer to the deviation data Δ
CW pulse or CC by switching based on the positive or negative of
A W pulse may be output.

(Effects of the Invention) As explained above, according to the present invention, a pulse signal of a frequency corresponding to the deviation data between the set speed data and the actuator speed data detected by the sensor is converted into a CW pulse or a CW pulse according to the positive/negative of the deviation data. The pulse motor of the digital valve is outputted as a CCW pulse, and the speed is controlled by adjusting the fluid flow to the actuator by opening and closing the valve by driving the pulse motor, so the feedback loop for speed control is entirely implemented in a digital circuit. Since no A/D converter or D/A converter is required, the device configuration can be simplified and costs can be reduced.

Furthermore, the accuracy of speed control using a digital feedback loop can be easily increased by increasing the number of bits of digital data handled.

On the other hand, as an effect specific to the embodiment, the pulse frequency calculation unit determines the pulse frequency by the number of subtraction recycles in which the deviation data at that time is repeatedly subtracted from the preset GAIN value until the result becomes zero. By repeating a simple calculation cycle called subtraction, it is possible to generate a CW pulse or CC~■ pulse with a frequency proportional to the deviation data.For example, when the pulse frequency teaching calculation unit is controlled by a program, processing is extremely simple. Moreover, a sufficient RIM degree can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an embodiment of the speed calculation unit in FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the speed calculation unit in FIG. A flowchart showing the processing, FIG. 4 is a block diagram showing an embodiment of the pulse frequency calculation unit in FIG. 1, and FIG.
FIG. 6 is a flowchart showing the arithmetic processing shown in the figure, and FIG. 6 is a block diagram showing a conventional example. 48: Digital valve 50: Pulse motor 52: Variable throttle 54: Fluid pressure source 60: Digital speed setter 62: Rotary encoder 64: Speed calculation unit 66: Pulse frequency calculation unit 68: Counter 70: Memory 72: Pointer counter 74 : Adder 92: Subtractor 94.102, 104: Digital comparator 94.
98: Repeat type wc calculator 106.108: Inverter

Claims (5)

[Claims] (1) In a speed control device for a hydraulic actuator that is driven by receiving hydraulic pressure supply from a fluid pressure source, the fluid pressure source for the hydraulic actuator is driven by opening and closing a valve according to the rotation amount and rotation direction of a pulse motor. a digital valve that adjusts the amount of fluid from the hydraulic actuator; a detection means that outputs a pulse signal with a frequency proportional to the driving speed of the hydraulic actuator; a speed calculation means for calculating and outputting digital speed data; a digital speed setting means for setting the driving speed of the hydraulic actuator using a digital signal; and a pulse frequency calculation means for calculating deviation data from the digitally detected speed data and outputting a pulse having a frequency proportional to the magnitude of the deviation data as a CW pulse or a CCW pulse depending on the sign of the deviation data. Features: Speed control device for hydraulic actuators. (2) The speed calculation means includes pulse number calculation means for calculating speed data based on the number of pulses per fixed time of the pulse signal obtained from the detection means. The speed control device for a hydraulic actuator according to item 1. (3) The pulse number calculation means includes a counter that counts the number of pulses obtained from the detection means at regular intervals, and a plurality of storage areas that store the counting results of the counter, and stores the counting results of the counter first in, first out. A patent characterized in that the invention comprises a storage means for sequentially storing data according to the above-mentioned counter, and an addition means for reading and adding up and outputting all the counting results stored in a plurality of storage areas of the storage means every counting cycle of the counter. A speed control device for a hydraulic actuator according to claim 2. (4) The hydraulic actuator according to claim 1, wherein the speed calculation means includes calculation means for calculating speed data from the reciprocal of the period of the pulse signal obtained from the detection means. speed control device. (5) The pulse frequency calculation means includes a subtraction means for detecting deviation data by subtracting the digital setting speed data and the digital detection speed data, and converting the deviation data obtained by the subtraction means from preset GAIN data. a repeat type subtraction means that performs subtraction and repeats the subtraction operation until the subtraction result becomes less than or equal to zero, and a CW pulse of 1 if the deviation data is positive when the subtraction result of the repeat type subtraction means becomes less than or equal to zero; 2. The speed control device for a hydraulic actuator according to claim 1, further comprising pulse generating means for outputting one CW pulse if the deviation data is negative.