RU1785993C - Weight oscillation stabilizer - Google Patents

Abstract

The invention relates to hoisting and transport machinery. SUMMARY OF THE INVENTION: the load is suspended by a mechanism for moving the truck at one point by four ropes, forming a square or rhombus in plan, the ropes are wound on four drums. According to the signals of the load acceleration sensors, one or another drum is turned on, which stabilizes the oscillations of the load. 5 ill .:

Description

The invention relates to hoisting-and-transport machinery, in particular to devices for limiting vibrations of a load transported by a truck, as well as for accurately moving loads to small distances, for example, when setting the load in place.

A known system for stabilizing the angular movement of a ballistic missile.

Control systems for the normal and lateral movement of a ballistic missile are known.

A known system of angular stabilization of a spacecraft.

The above systems are used to control aircraft and are not intended for use in material handling equipment.

Closest to the proposed technical solution (prototype) is a device in which control actions are applied to a truck for moving a truck. The disadvantage of this method and device is the significant inertia of the truck and drive, which reduces the effectiveness (i.e., stability and accuracy) of load stabilization.

SUMMARY OF THE INVENTION that the load is suspended not on one, but on four ropes connected together at the load securing point, the ropes pairwise forming two mutually perpendicular vertical planes. In the absence of a difference in the tension forces of the ropes lying in one PLANE Rna Rnv 0 (FIG. 1), Spret

prideful expression

Rna + Rnv + P 0. (1)

where Rna is the tension force of the rope Za;

Rnv is the tension force of the rope Sv;

P-weight of cargo;

O is the load securing point.

Moreover, the ropes Za and Zv lie in the same vertical plane. When the difference in the tension forces of the ropes of one vertical PLANE / RNA / / RCP / & About (figure 2), there is a horizontal component of the forces Ru, defined from the expression

Ria + Rnv + R Ru,. (2)

fe

H |

09

ABOUT

CH

H

With

where Fy is the horizontal component of the forces, which is used as a control action (control force):

and / are the angles of deviation of the ropes from the horizontal plane.

In order for the ropes to form two vertical mutually perpendicular planes, the drums of the winches on which the ropes are wound are placed to form a quadrangle with mutually perpendicular diagonals in plan view. The drums of each of the four winches are driven by separate electric motors.

To control the electric drive, a control system is used, including a load acceleration sensor, capable of creating a difference in the tension of the ropes in one vertical plane, for which the control system is made in the form of a closed two-channel automatic control system, each of which channels controls the motors of two winches, the drums of which are located so that the ropes wound on them lie in one vertical plane, i.e. in plan they form one of the diagonals of the quadrangle with mutually perpendicular diagonals.

Load acceleration sensors are designed to measure linear perturbations in the horizontal plane acting on the load being controlled. Sensors can be of either a direct type (e.g., accelerometers) or an indirect type (e.g., perturbations acting on the load are calculated through the difference in the tension of the ropes). Optical or induction sensors can also be used to remotely measure load parameters. The principle of operation and the design of the sensors for accelerating the movement of the load can be any and are not essential; it is possible to constructively combine sensors operating on different axes in one device. To store and implement the control law, a conversion device is used, which can be, for example, an operational amplifier, a passive correction circuit or a digital control device, for example, a computer in which the control law is embedded. The design and operation of the converter device are not essential.

If it is necessary to accurately move the load a small distance l (l d). where

- the distance between the projections of the winch drums of one channel on a horizontal plane, when such movement is difficult to achieve by the movement mechanism of the truck, then any of the links in the control system may include a control device that can thus act on the electric drives of the winches so that as a result 0 Then the rope was wound on one drum and synchronously with it the rope was wound from the drum of the same channel. The result is a horizontal position of the load. The control device may be structurally

5 is taken outside the device, which includes, or can be made in one unit with the latter, for example, the control device is made in the form of a remote control located at the crane operator or

0 A computer, which is a converter device, also functions as a control device. One of the simplest options. The implementation of the control device may be a manual control panel,

5, which includes two potentiometers with a midpoint, the displacement of the movable contacts of which can generate the required mismatch signals, which are perceived by the converter as a static error. An actuator connected to directly control the operation of the winches is connected to the output of the converter device. For instance,

5, it may be some thyristor or relay circuit controlling the operation of the electric drive in accordance with the signals removed from the converter device. Working principle and

0 actuator design can be any. Structurally, it can be made as a separate device, or it can be combined with a converter device or with

5 electric winches.

The executive body of the control system are winches driven by an electric drive.

In FIG. 1 shows a vector diagram of forces in the absence of disturbances and control; in phip2, a vector diagram illustrating how the control force Fy occurs; in Fig.3 is an example of the construction of the mechanical part

5 stabilizers of cargo fluctuations Dolgopolov; Fig. 4 is an example of a control system; figure 5 - operation of the device in the mode of precise movement of the cargo.

Fig. 3 shows an example of the construction of the mechanical part of the Dolgopolov load vibration stabilizer. which consists of four winches 1a, 16,1b, 1g, mounted on a load moving mechanism 2 (for example, on a trolley) so that the winch drums in plan form a quadrangle with mutually perpendicular diagonals (for example, square, rhombus, etc. .). Four ropes 3 are lowered from the winch drums, connected together at the load securing point 4. To drive the winch 1, four reversible electric motors (ED) 5 are used, which are controlled in pairs by a closed two-channel control system, an example of which is shown in FIG. 4 , which consists of a load acceleration sensor (DU) 6, a conversion device (PU) 7, an actuator (DUT) 8, the output of which is connected to the ED 5, which drive the actuator (BUT), which are caustic 1, the control object (G U) for control of this system is the load 4, which affect the disturbance f. To adjust the control law depending on the change in the length of the ropes 3, we use the feedback between IO 1 and PU 7. For the exact movement of the load by a small distance I (K d), where d is the distance between the projections of the winch drums of one channel on the horizontal the plane of Fig. 3, the control unit 7 may include a control unit (UC) 9 capable of generating a mismatch signal proportional to the required offset and opposite in sign in magnitude. In the simplest case, UE 9 may be two potentiometers with a midpoint.

Now consider the operation of the stabilizer of the oscillations of the load. The state of the stabilizer in the absence of external disturbances f and control actions Fy is illustrated by the vector diagram in Fig. 1 and formula (1).

When a disturbance f appears, it is measured by the remote control b (Fig. 4) and supplies a signal proportional to the disturbance f to the input of the control unit 7, which converts this signal in accordance with the control law incorporated in it and supplies this converted signal to the input of the control device 8, which creates a voltage difference on the windings of the ED 5, corresponding to the signal received at the input of the DUT 8. This voltage difference on the windings of the ED 5 leads to a difference in the torques on the shafts of the latter, which is transmitted to the drums of the corresponding hoists HO 1. The difference in the moments on the shafts of the winch leads to a difference in the tension of the ropes (Fig. 2), which can be determined by the formula

/ FH3 / - / FHB / -, (3)

where Ma, Mb are torques on the drums of winches 1a and 1c;

Ra, Re are the radii of the winch drums 1a and 1c.

Since in this case Ra Re R, then formula (3) can be written as / s / / s / Ma-Mv Ma-Ma f.)

/ Gna / - / gnv / --- B-- (4J

Now, using the vector diagram (Fig. 2) and formula (2), we find the magnitude of the control action Fy:

Fy - FH8 + FHB + P, (2) where Fy is the control action resulting from the difference in the rope tension forces; p is the weight (gravity) of the cargo.

We project all the forces on the axis of the action of the force Fy.

/ Fy / / РНЛ COS а - / Рнв / COS в, (5)

where a, / 3 are the angles between the ropes of the winches 1a, 1c and the horizontal plane.

Since the angles a and ft are almost equal, expression (5) can be written in the form / Fy / / FHa / - cos a - / FHB / cos a «

(/ Рна / - / Рнв /) COSa, (6)

Substituting formula (4) into expression (6), we obtain

35

1g , Ma MV / F / CQS a

Thus, we obtain the dependence of the magnitude of the control action / Fy / on the difference of moments on the drums

winches 1. Obviously, to create such a difference of moments, it is enough to change only the magnitude of the currents flowing in the windings of the electric drives of the winch drives, which is not

requires the movement of mechanical components, which increases the speed and, consequently, the stabilization efficiency.

If it is necessary to accurately move the load to a small distance I, where I d (d. Is the distance between the winches of the same channel of Fig. 3), when the desired accuracy is difficult to achieve by moving the carriage CU (9) (Fig. 4) forms a mismatch signal

input to the LN 7. This signal can be generated in various ways: manually or automatically, can be transmitted via communication channels, etc. In the simplest case, the signal can be formed by displacing the base of the potentiometer in CC 9. V

As a result of the control unit 7, it seems that a constant disturbance acts on the load and to compensate it, the control system generates a control action Fy directed towards the required movement and proportional to its value. Since the disturbing action, which this control action Fy, as it were, hinders, is virtually absent, the difference in the moments on the winch drums leads to a change in the lengths of the ropes of one channel, and, consequently, to the horizontal movement of the load. In Fig. 5, the solid lines show the position of the ropes 3 of one channel and the load 4 before the start of movements, the dotted line shows the position after moving by a predetermined distance I, smaller than the distance d between the winch drums of one channel. The arrows show the directions of rotation of the winch drums (1a and 1c) of one channel to create this movement.

Formula a isobreten and a stabilizer of oscillations of a load suspended from a moving mechanism of a truck containing

an electric drive mounted on a moving mechanism, including a reversible electric motor, a control system for the latter, including load acceleration sensors, distinguishing also by the fact that the drive additionally includes three electric motors and associated with the latter and the main winch, the drums of which placed with their formation in terms of a quadrangle with mutually perpendicular diagonals, the ropes are connected together at the point of attachment of the load, and the drive control system is made closed two-channel Second, each of its channels further comprises

a conversion device connected to an acceleration sensor, an associated actuating device cooperating with two winches.

Figure 1

Fig. 2 ph. 3 rope length

FIG. 4.

Fzh5.