SU1530823A1 - Electrohydraulic follow-up drive - Google Patents

Abstract

The invention can be used in the following systems of industrial robots and manipulators. The purpose of the invention is to improve the accuracy and stability of the electro-hydraulic follower drive. One positive input of the third adder (C) 27 is connected to a constant voltage source 28, the other to the output of the second block (B) 21 multiplication. The output of the second B 29 division is connected to the second input B 18. The differentiating link 33 is connected with deceleration by the input to the output of the error meter, the output is connected to the input B 31, connected in series with the fifth B 32, the output of which is connected to the positive input C 3. The input is divisible B 29 through link 30 is connected to the output of meter 1. Second input B 22 is connected to output B 31. Output C 3 is connected to input of amplifier 4 via B 34, second input B 32 is connected to output B 17, second input B 34 is connected to output C 27. The inputs of the divider B 29, 31 are connected to the output of C 27. This circuit provides Invariance to the variables of the moment of inertia and the moment of viscous friction, taking into account the leakage of the working fluid. 1 il.

Description

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The invention relates to hydraulics and can be used in the following systems of industrial robots and manipulators.

The purpose of the invention is to increase accuracy and stability.

The drawing shows a structural diagram of an electro-hydraulic follower drive.

The drive contains a meter connected in series 1 mismatch, aperiodic link 2 of the second order and the first adder 3 connected to the series-connected amplifier 4, the drive 5 of the regulator (not shown) of the pump 6 connected by hydraulic lines 7 and 8 a gearbox (not shown), whose shaft JO is connected to the control object 11 and sensors 12 and 13 of the position and speed, respectively, and torque sensors (not in the drawing; -,: - en), the pressure differential sensor 14 in series 7 and 8, the second adder 15, the integrator 16 the first dividing unit 17 and the first multiplying unit 18, the output of which is connected to the second positive input of the first adder 3, as well as the temperature sensor 19 connected in series, the first nonlinear unit 20, the second multiplying unit 21 and the third the multiplication unit 22, the output of which is connected to the third positive input of the first adder 3, and the output of the position sensor 12 is connected to the second negative input of the error meter 1, the first positive input of which is connected to the output of the sensor commands (not shown), the output of speed sensor 13 is connected to the input of the divider of the first division block 17, through the fourth multiplication unit 23 to the second negative input of the second adder 15, and through the relay moment 24 with zero neutral point to the third the negative input of the second adder 15, the fourth negative input of which is connected to the output of the torque sensor, the second input of the second multiplication unit 21 through the second nonlinear block 25 is connected to the output of the pressure sensor 26, and the second input of the fourth multiplication unit 23 is connected to the output of the second block 21 multiply. In addition, it contains

Q

5 0 5 0 about 5 Q

five

hence the connected Tpeiiin adder 27, the second positive input of which is connected to the output of the constant voltage source 28, and its first positive input to the output of the second multiplication unit 21 and the second division unit 29, the output of which is connected to the second input of the first multiplication unit 18, also serially connected differential block 30 with deceleration, the input of which is connected to the output of the error meter 1, the third division unit 31 and the fifth multiplication unit 32, the output of which is connected to the fourth positive input the first adder 3, the second input of the divisible second dividing unit 29 through the differentiating link, 33 with the second order slowing down is connected to the output of the error meter 1, and its first divider input is connected to the third adder 27, the second input of the third multiplication unit 22 is connected the third block 3J division, the output of the first adder 3 through the sixth multiplication unit 34 is connected to the input of the amplifier 4, the second input of the fifth multiplication unit 32 is connected to the output of the first division block 17, the second input of the sixth multiplication unit 34 is output m third adder 27, and the second input of the third divider dividing unit 31 - with an output of the third adder 27.

In addition, there are the following notations in the drawing: oL, and - equivalent

Significantly, the position signals of the shaft 10 from the command setpoint and from the position sensor 12 are the signal of the speed sensor 13; M is the torque on the shaft 10, p is the signal from the pressure differential sensor 14 in hydrolines 8 and 7; RD, is the signal of the torque sensor, is the magnitude of the error (drive error).

Electro-hydraulic follower drive works as follows.

Signal. after correction, through amplifier 4 enters the drive 5 of the regulator of pump 6, which, creating a flow of working fluid in hydrolines 8 and 7, acts on the hydraulic motor 9, which changes the position of the adjustment object 11, reducing the mismatch between the input

signal oif. and signal. 11 p sensor

1 position. To eliminate the negative effect of variable torque

51

the inertia of the control object 11 and the moment of viscous friction on the quality performance of the entire drive in the service correction circuit, including a second-order aperiodic link 2, a differentiating link 33 with a second-order slowdown and a slowing differentiator 30. Moreover, the gains of the differentiating links 30 and 33 vary depending on the change in the moment of inertia of the object 11 and are regulated by 1 and the coefficient of viscous friction.

The transfer function of the electro-hydraulic servo drive in the open position can be represented as

: Y (P) W. (P) W, (P) W, JP) W, (P

 (.1) where W (p) p is the transfer function

drive {

- respectively, the transfer function of the amplifier

W (P)

4 and pump regulator 6j

- transfer function of the correction circuit;

Wjj - transfer function

hydraulic transmissions

consisting of a pump 6 and a hydraulic motor 9. The moment developed by the hydraulic motor 9, taking into account the moments of dry and viscous friction, is described by the ratio

M

um

 WjP M / ip +, + M ,,, + T, w.

(2)

- coefficient of viscous friction; - the moment of dry friction J - the moment of inertia of the rotating parts of the hydraulic motor 9 and the object 11, reduced to the hydraulic motor shaft 10.

Taking into account expression (2) and the leakage ratio of the working fluid LjVO, the transfer function V P takes the form (/ prc formation W (P) M is assumed to be zero

TR

and., (P)

with (t)

R (t)

t is the angle of rotation of the regulator of the pump 6; ip - gear ratio of hydraulic motor gearbox 9j

to -. .

., W,

,, g,

R |

V

- characteristic volumes of the pump 5 and hydraulic motor 9;

- proportionality coefficients;

- rotation speed of pump 6,

- the volume of the working fluid in the hydroline 7 (or 8 of the pump and in the cavity of the pump 6 pump;

- total moment of inertia of rotating parts of hydromo (3)

45

ngm (P)

35/9 and the adjustment object 11;

P is a symbol of differentiation. The transfer function parameters are variable if

.

0 variables are T and Cr. As a result, the dynamic properties of the electro-hydraulic follower drive significantly change as I and K- vary over a wide range. In some cases, even the loss of stability of his work is possible.

If the dynamic properties of the electro-hydraulic follower drive remain unchanged, it is necessary to stabilize all parameters of the transfer function W (p). For this is a correction circuit with a transfer function.

where Tj and Tj are some fixed time constants that can be selected based on the dynamic properties of the drive.

The parameters of the transfer function W (p) must be adjusted to the values of the moment of inertia I and the coefficient K, taking into account those of Kyiflero. The transfer function W (P) taking into account expressions (1), (2) and (4) takes the form

(Pl WJP) W, (P) W. (P) W (P)

TO

) W, (P) (t p + 1) (T, P + 1) P

From the expression (3) it can be seen that all parameters of the transfer function V (P) remain constant, which means that the dynamic properties and quality indicators of the whole electro-hydraulic follower drive as a whole, i.e. the accuracy and stability of the drive does not depend on the change in I and Kj.

The correction W (P) is performed using a second-order aperiodic link 2 with a transfer function

2

W, P

/ Ultrasound

(+ 1 (TUR + 1)

differentiating link 30 with slowing down and differentiating link 33 with slowing down the second order respectively with transfer functions of the form

W ,, (P)

 P + -1) (m. P + 1)

33

t

  O (Tj, P + 1) 45

At the same time, the gains of the first and second inputs of the first adder 3 connected with link 2 and block 18 are single, the gain of the third input connected to block 22 is equal to V / K, and the fourth input connected to block 32 is equal to L ,.

The first and fifth blocks 18, 32 multiplications are used to set the parameters for the current value of I. Dp parameter settings for the current value of K. use v, (r)

with the second and third blocks 29. Lenin, as well as the third and sixth pole; Glossary 22, 34 multiplied.

If the signal proportional to I is formed at the output of the first division block 17, the signal proportional to K is generated at the output of the second multiplication unit 21

at

at the source output signal

28 constant voltage

proportional to W ,, then taking into account

The first input of the third adder 27 has the gain L.J, and its second input is a single, transfer function) has the form (4). (The first input of the adder 27 is connected to block 21, and the second to the source 28).

A signal proportional to I is formed as follows.

According to expression (2), the value of I is determined from the ratio

J (M / ip - Meter - KgipU) dt ipW

(6) The torque sensor signal is

M W ,, iP

PM 40

45

thirty

The fourth negative input of the second adder 15 has a gain of 1, its second negative input is a wuxi factor; 1 ip / W; and the third (negative), 35 gain factor 1 / V. At the second input of the fourth block 23, the signal diminishes, the pth is K ;, and the relay element 24 with zero ng neutral point is described by the expression JM sign UJ. Then on the output of the second adder 15 is formed with P -l-4 (V | ip) - i K w / Wj-j M, T} MiFn (α) | W. I6 integrator transfer function

Ws looks like

w ,, (P) and on his

Kg2; p - -v (it

output signal is generated j (/ ip - jMcTpfsipnU

f

Dividing this signal in block 7 dividing by the signal U, at its output we get the signal T (see expression (b)). The fluid viscosity can be determined using the expression

55

G-ssb

Cr (RR „) - K (TG,)

Where

and T - corresponding to current

pressure values of the fluid and its temperature,

Pd and Tjj are respectively the nominal values of the pressure of the fluid and its temperature; VISCOSITY of the fluid at P,,

and t;

Kp and K are constant coefficients characterizing the change in viscosity, respectively, from changes in pressure and temperature.

A view similar to expression (7) has a coefficient of viscous friction.

to (P- "rft V

(eight)

where K is the coefficient of viscosity tpe

with RO and T.

If we assume that the sensors 19 26 of temperature and pressure are installed in the working area and measure accordingly the temperature T and the pressure of the fluid in which the moving parts of the hydraulic motor 9 (and, possibly, the gearbox with control object P) and the first and second nonlinear blocks 20, 25 respectively implement functional zevig)

simoshy

V К е, then at the input of the second multiplication unit 21 a signal is formed that is proportional to the value of Kg (see Expression (8). Nonlinear blocks can be realized, for example, by using a device that performs a piecewise linear approximation of nonlinearity. Thus, proposed

drive is provided invariant-.

ness to variable moment of inertia

drive and the moment of viscous friction, taking into account the leakage of the working fluid, which is aimed at improving the accuracy and stability of the drive in a wide range of variation of these values.

Claims (1)

Invention Formula Electro-hydraulic servo drive containing sequentially connected discrepancy meter, second-order aperiodic link and the first adder connected to the output from the serially connected booster and the drive of the regulating organ of the pump connected by hydroli- position sensors , tO 15 20 with zo five 0 five Q speeds and moment /, as well as L 3 ifx of differential pressure dp and gtstsro.tpchh, connected to a series-connected second adder, integrator, first division unit and first multiplication unit, the output of which is connected to the positive input of the first adder, a source of constant voltage and a temperature sensor connected in series, a first non-linear unit, a second multiplication unit and a third multiplication unit, the output of which is connected to the positive input of the first adder, the output of the position sensor being connected to the negative The input of the error meter, the positive input of which is connected to the output of the sensor, the output of the speed sensor is connected to the input of the divider of the first dividing unit, through the fourth multiplication unit with the second negative input of the second adder, and through the relay element to the third negative input of the second adder, the fourth negative input of which is connected to the torque sensor, the second input of the second multiplication unit is connected via the second nonlinearity block to the output of the pressure sensor / t, and the second input of the fourth block connects With the output of the second multiplication unit, characterized in that, in order to increase accuracy and stability, it is equipped with a third adder, a second and a third division block, a differentiating link with deceleration, a differentiating link with deceleration of the second order, and also fifth and the sixth multiplication units, with one positive input of the third adder connected to a constant voltage source, and the other to the output of the second multiplication unit, the output of the second division block connected to the second input of the first multiplication unit, the differential The decelerating link is connected by an input to the output of the error meter, and the output is connected to the input of a divisible third division unit, connected in series with the fifth multiplication unit, the output of which is connected to the positive input of the first adder, and the input of the splittable second division unit through differentiating link by slowing down the second order is connected to the h; ho omg-rasstn153082312 The second input of the third block with the output of the first dividing unit, multiplied by the third to second input of the sixth multiplication unit of its dividing unit, the output of the first sum — with the output of the third adder, and the input to the amplifier’s input the divider of the second and third blocks; the sixth multiplication block; the second division — with the output of the third sum — the input of the fifth multiplier block.