US3826380A

US3826380A - Arrangement in cranes to determine the deviation of the hoisting device of the crane from a defined vertical line

Info

Publication number: US3826380A
Application number: US00350623A
Authority: US
Inventors: B Lenander; B Ling
Original assignee: ASEA AB
Current assignee: ABB Norden Holding AB
Priority date: 1972-04-14
Filing date: 1973-04-12
Publication date: 1974-07-30
Anticipated expiration: 1991-07-30
Also published as: GB1422013A; SE361869B; JPS4916153A; NL7305071A; DE2316810A1

Abstract

To determine the deviation of the hoisting device of a crane from a vertical line, a light emitting arrangement is placed on the crane which emits a wide beam of light downwardly. Within this beam, the hook or other hoisting device has an upwardly directed reflector. There is also on the crane a detector unit which receives the light reflected from the reflector and emits a signal which indicates the deviation of the hoisting device from the vertical.

Description

United States Patent [191 Lenander et al.

in] 3,826,380 [451 July 30, 1974 ARRANGEMENT IN CRANES TO DETERMINE THE DEVIATION OF THE HOISTING DEVICE OF THE CRANE FROM A DEFINED VERTICAL LINE [75] Inventors: Bo Lenander; Bernt Ling, both of Vasteras, Sweden Assignee: Almanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden Apr. 12, 1973 Appl. No.: 350,623

[22] Filed:

[30] Foreign Application Priority Data Apr. 14, 1972 Sweden 4859/72 [52] U.S. Cl 212/125, 212/11, 340/282 [51] Int. Cl. B66c 19/00 [58] Field of Search... 212/10, 21,11, 39 R, 39 MS,

[56] References Cited UNITED STATES PATENTS 2,948,890 8/1960 Barth et a1. 340/282 X 3,517,830 6/1970 Virkkala 212/21 X 3,544,988 12/1970 Astheimer 340/282 3,750,130 7/1973 Lute 340/267 C Primary Examiner-Richard A. Schacher Assistant Examiner.1ames L. Rowland 57 ABSTRACT To determine the deviation of the hoisting device of a crane from a vertical line, a light emitting arrangement is placed on "the crane which emits a wide beam of light downwardly. Within this beam, the hook or other hoisting device has an upwardly directed reflector. There is also on the crane a detector unit which receives the light reflected from the reflector and emits a signal which indicates the deviation of the hoisting device from the vertical.

12 Claims, 6 Drawing Figures PATENTEDJULBOISM SHEET 1 BF 3 Fi'g/ BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arrangement for cranes to determine the deviation of the hoisting device of the crane from a defined vertical line.

2. The Prior Art When goods are being loaded with the help of cranes, for various reasons undesirable oscillations of the hoisting device of the crane, to which the load is attached during hoisting and transport, occur. These oscillations may be of a magnitude of :t 500 mm and have a duration of sec, which considerably increases the time required for a loading or unloading cycle since the load cannot be lowered until the oscillations fall below a certain amplitude. When stacking containers, for example, the oscillation amplitude must in certain cases be less than i 25 mm.

It is therefore extremely important to reduce or even a completely eliminate these oscillations during the travelling stage of the crane so that, when the crane is in the desired final position, the movements of the hoisting device have been reduced to an acceptable level for a hoisting or lowering movement. The time required for a work phase can therefore be kept to a minimum. In order to achieve this reduction of the oscillations, measuring equipment is required to record parameters such as oscillation amplitude, the speed of the hoisting device in relation to the crane trolley, cable length, and other variables, and such measuring equipment must be rapid, accurate and reliable.

SUMMARY OF THE INVENTION The object of the present invention is to provide a means, with the help of which parameters of a described oscillating sequence can be measured and which can be utilized to control a system for reducing such oscillations.

The arrangement according to the invention'is characterized in the fact that the crane carries an arrangement for emitting downwardly a light beam of considerable width, within the field of which lies an upwardly reflecting device carried by the gripping device or hook. The crane also has a detector unit composed of a lens and a light sensitive member in the path of the upwardly reflected light and responsive to changes in the direction of light to indicate deviation from the vertical line.

If, in accordance with the device according to the invention, all active and sensitive parts of the measuring equipment are placed on the crane and the hoisting device only comprises passive, compact, easily-handled element having no direct contact with the active part of the equipment, considerable advantages are gained in comparison with an arrangement in which the detector unit is placed on the hoisting device. This would, for instance, require special signal wiring between the crane and the hoisting device. Special regulations would then apply since this signal wiring would run in the vicinity of high-voltage cables. Such signal wiring is subject to dirt and wind and must therefore be provided with some form of stabilizer to prevent it from being blown in among the hoisting cables of the crane and also to gather it up when the hoisting cables are shortened. There must also be some form of container on the hoisting device for this purpose, which takes up considerable space. Equipment on the hoisting device is also likely to become dirty. Furthermore, additional equipment on the hoisting device requires more space and increases the weight and a measuring unit placed on the hoisting device therefore limits the range of application, for example to handling containers, so that the hoisting device can be constructed to cater for specific requirements.

BRIEF DESCRIPTION OF THE DRAWINGS The device according to the present invention will be further described with reference to the accompanying drawings, in which FIG. 1 shows a crane with trolley and hoisting device on which the device according .to the invention is placed,

FIG. 2 shows in detail the ray path of the detector unit included in the device according to the invention,

FIGS. 3a and 3b show the principle of a retroreflector,

FIG. 4 is a diagram of the light-sensitive surface of the photo-detector and FIG. 5 shows an example of an evaluation device included in the device according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows atrolley l2 movable in the directions 11 on a crane beam 10. A hoisting device 14 is suspended from the trolley 12 by means of cables 13. A load may be applied on the hoisting device 14, to be hoisted and transported. The device according to the invention comprises an active unit 15 arranged on the lower side of the trolley 12, and a passive unit in the form of a retroreflector 16 arranged on the upper side of the hoisting device 14.

The main parts of the active unit 15 constitute a light emitter 17, a collecting lens 18 and a detector 19, as can be seen in FIG. 2.

The function of a retroreflector can be seen in.FlGS. 3a and 3b. A retroreflector 16 consists of three similar reflecting

surfaces

20, 21 and 22, in the same configuration as the corners of a cube. A light ray 24 reflected by the retroreflector is always parallel to the light ray 23 falling on the retroreflector 16 and the reflected light ray 24 leaves the retroreflector 16 at a point diagonally opposite the point of entry. The retroreflector 16 can be rotated about arbitrarily directed axes of totation through its point without altering the distance between the approaching and reflected light rays.

The operation of the device according to the invention will now be described with referenceto FIGS. 1, 2, 4 and 5.

The light emitter 17, the optical axis of which is suitably arranged to coincide with the optical axis of the lens 18, the mid-point normal to the light sensitive surface of the detector 19, and with the vertical line 25 for the hoisting device 14 when this is in its rest position, emits a diverging light bundle 26 in the direction of the hoisting device 14, whereupon some of the light 26 emitted is reflected by the retroreflector 16 towards the active unit 15, parallel to the rays approaching the retroreflector 16. The reflected light falls on the collecting lens 18 arranged immediately above the light emitter 17. The lens 18 breaks down the light falling on it on the light-sensitive horizontal surface 27 of the detector 19.

The light emitter 17 has preferably such divergence that it covers the area within which the retroreflector 16 is expected to move and the diameter of the lens 18 is preferably twice as'large, or even more, than that of the retroreflector 16 so that all light which comes into contact with the retroreflector 16 will be thrown back through the lens 18 and projected on the detector 19 The light emitter 17 preferably consists of a light diode which is fed by pulses from an oscillator 30. Pulsing is used in order to easily distinguish between light received by the detector 19 from the retroreflector 16 and other irrelevant light.

The detector 19 preferably consists of a linear photodetector having two axes with the ability to sense the focal point of the projected light, thus making good focus'singof the light on the detector 19 unnecessary.

An example of such a detector is UDT SC/25, produced by United Detector Technology, Inc., US.

The mentioned photo-detector UDT SC/25 has a light-sensitive surface 27, as can be seen in FIG. 4. On this surface 27 two

axes

28, 29 are marked, to one of which output signals obtained from the photo-detector are related.

When the retroreflector 16 (that is, the hoisting device 14) has moved a distance X from the vertical line 25 with an angle of oscillation a, the focal point of the light projected by the lens 18 onto the light-sensitive surface 27 of the detector 19 becomes displaced.

If theline length in question is equal to S and the projection of the line length on the vertical line 25 is equal to S, then when a l (in practice a 2.5")

tan a X/S X/S and when the distance between the lens 18 and the detector is Z, then 0 tan a Y/Z which gives Thus, if the line length S can be measured continuously and if the distance Z between the lens 18 and the detector 19 is constant and known, the output signals fromthe detector 19, after evaluation, can be used as input signals for a control system which controls the relative movement between the hoisting device 14 and the trolley 12.

The line length S is measured continuously by a potentiometer unit, for example, (not shown) arranged on the trolley 12.

When UDT SC/25 is used as detector 19, two output signals are obtained in the form of voltages U, and U the magnitudes of these depending on the deviation of the focal point of the light falling on the detector surface 27 from one of the

axes

28 or 29. In order to obtain a direct measurement of the deviation Y of the focal point, the signal U,/( U, U is obtained, or the signal U /(U, U,). The position of the vertical line 25 then corresponds to U, U

Signals

31 and 32 obtained from the detector 19 are conveyed to

filters

33 and 34, respectively and

amplifiers

35 and 36, respectively, after which the pure signals U, and U, are obtained. Both the signals U, and U, are supplied to an amplifier 37 and added to give the signal U, U This latter signal, together with one of the signals U, or U,, in this case U,, is supplied to a di- 4 vider 38, thus producing the signal It, U,/(U, U,,) where k, is a constant dependent on the divider. The signal k, U,/(U, U is supplied, together with a signal U,,,, to an amplifier 39. The signal U now has the value k, l/2, that is, it represents the signal k, U,/ (U, U when U, U

that is, the deviation X 0.

By the indicated addition a signal It, Y is obtained from the summator 39 where Y is the deviation of the focal point of the light falling on the detector 19 from the mid-point of the detector 19 and k, is a constant.

Signal k Y is supplied to a multiplicator 40, together with the momentary value of the line length, whereupon'a signal It, S Y is obtained.

A signal is thus obtained which directly carries information concerning the deviation of the hoisting device 14 from the vertical line 25, and which can be supplied to a member controlling the relative movement between trolley 12 and hoisting device 14.

The summation signal U, U, is preferably used for other purposes also.

The signal U, -.l- U, can also be used to control the output intensity of the light emitter 17, that is the light diode, when conditions such as variation in line length and weather cause the signals U, U to differ on different occasions.

In order to adjust the output capacity of the light diode to said variations, the signal U, U, is fed together with a reference signal U to an amplifier 41, the output signal of which constitutes the difference between said signals. This difference, together with the pulse train from the oscillator 30, controls the output capacity of the light diode.

The summation signal U, +U is alsoused to detect whether the necessary light strength is being obtained on the surface 27 of the detector 19 by supplying the signal U, U, to a level indicator 42 which in turn may be connected to a signal or indicating device 43, thus preventing false output signals from the device caused by mishaps such as temporary blocking of the retroreflector 16 by dirt or the like.

As mentioned earlier, the light emitter may comprise a light diode, in which case HAFO lA65 is extremely suitable.

Amplifiers may suitably be SL 8018.

The multiplicator and divider may be Nexus 4552, for example and the level detector ASEA QDGU 105.

The device described above is not, of course, limited to the embodiment shown, but may be constructed in many ways within the scope of the following claims.

We claim:

1. in a crane, having a hoisting device suspended therefrom, means to determine the deviation of the hoisting device (14) from a defined vertical line (25), which comprises a light emitter (17) on the crane, a light reflector (16) on the hoisting device (14) and a detector unit (18, 19, 31-43) on the crane, the light emitter (17) including means to direct diverging light (26) towards the hoisting device (14) so that the light covers a presumed area of movement for the hoisting device (14), the reflector (16) including means to refleet light falling upon it towards the detector unit (18, 19, 31-43), and the detector unit (18, 19, 31-43) including means responsive to such light falling upon it to detect deviations of the hoisting device (14) from said vertical line and to detect the direction of 4. In a crane according to claim 3, the light reflector (16) comprising a retroreflector.

5. In a crane according to claim 2, the lens system (18) having a horizontal aperture which is at least twice as large as the horizontal extension of the light reflector (16).

6. In a crane according to claim 2, the photo-detector (19) having a light-sensitive surface includes means to emit signals (31, 32) which constitute a gauge of the deviation of the focal point of the light converging on the light-sensitive surface (27) from a defined axis (28) on the light-sensitive surface (27 7. In a crane according to claim 6, the axis (28) defined on the light-sensitive surface (27) of the photodetector (19) constituting the normal for said vertical line (25).

8. In a crane according to claim 1, the presumed area of movement for the hoisting device (14) comprising said vertical line (25).

9. In a crane according to claim 1, said vertical line (25) coinciding with the optical axis of the light emitter (17).

10. In a crane according to claim 9 the optical axes of the light emitter (17) and the lens system (18) being coincident.

11. In a crane, having a hoisting device suspended therefrom, means to determine the deviation of the hoisting device (14) from a defined vertical line (25), which comprises a light emitter (17) on the crane, a light reflector (16) on the hoisting device (14) and a detector unit (18, 19, 31-43) on the crane, the light emitter (17) including means to direct diverging light (26) towards the hoisting device (14) so that the light covers a predetermined area of movement of the housing device (14), the reflector (16) including means to reflect light falling upon it towards the detector unit (18, 19, 31-43), means for measuring the length of lines (13) running between the crane and said hoisting device, said detector unit (18, 19, 31-43) comprising an evaluating device (31-43) arranged to emit an output signal proportional to the deviation of the hoisting device from said vertical line (25) and proportional to the direction of said deviation.

12. In a crane, having a hoisting device suspended therefrom, means to determine the deviation of the hoisting device (14) from a defined vertical line (25), which comprises a light emitter (17) on the crane, a light reflector (16) on the hoisting device (14) and a detector unit (18, 19, 31-43) on the crane, the light emitter (17) including means to direct diverging light (26) towards the hoisting device (14) so that the light covers a predetermined area of movement for the hoisting device (14), the reflector (16) including means to reflect light falling upon it towards the detector unit (18, 19, 31-43), said detector unit (18, 19, 31-43) comprising an evaluating device (31-37, 41) arranted to produce output signals for controlling the output intensity of said light emitter (17).

Claims

1. In a crane, having a hoisting device suspended therefrom, means to determine the deviation of the hoisting device (14) from a defined vertical line (25), which comprises a light emitter (17) on the crane, a light reflector (16) on the hoisting device (14) and a detector unit (18, 19, 31-43) on the crane, the light emitter (17) including means to direct diverging light (26) towards the hoisting device (14) so that the light covers a presumed area of movement for the hoisting device (14), the reflector (16) including means to reflect light falling upon it towards the detector unit (18, 19, 31-43), and the detector unit (18, 19, 31-43) including means responsive to such light falling upon it to detect deviations of the hoisting device (14) from said vertical line (25) and to detect the direction of such deviation.

2. In a crane according to claim 1, the detector unit (18, 19, 31-43) comprising lens system (18) and a photo-detector (19), the lens system (18) projecting light falling upon it on to the light-sensitive surface (27) of the photodetector (19).

3. In a crane according to claim 1, the light reflector (16) reflecting light parallel to the light falling upon it.

4. In a crane according to claim 3, the light reflector (16) comprising a retroreflector.

6. In a crane according to claim 2, the photo-detector (19) having a light-sensitive surface includes means to emit signals (31, 32) which constitute a gauge of the deviation of the focal point of the light converging on the light-sensitive surface (27) from a defined axis (28) on the light-sensitive surface (27).

7. In a crane according to claim 6, the axis (28) defined on the light-sensitive surface (27) of the photo-detector (19) constituting the normal for said vertical line (25).