JPS6135483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the relative positional relationship between a hanging device of a crane, a suspended load, etc. and a target position on the ground side, and an apparatus used for carrying out the method.

Various technologies have been developed for automatic and unmanned operation of overhead traveling cranes, and it has become possible to control the stopping position in the traveling and traversing directions with considerable accuracy. Therefore, more accurate stopping position control is often required for targets on the ground.
In addition, if the unloading position of the suspended load is not strictly specified, and the approximate position is only fixed (unloading the load onto a movable object such as a truck bed or trolley)
In such cases, control is required to align the desired unloading position with the hanging tool and the hanging load after automatically stopping at a pre-specified position. The following methods are known as means for detecting the relative positional relationship between the crane and the ground target position for performing such control. In other words, a target object on the ground is photographed using a television camera attached to a crane, and the relative position between the television camera and the target object is detected through image information processing. It requires specialized software, lacks versatility, and is expensive. In addition, lighting is often required for photographing, which is troublesome when put into practical use.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a crane position detection method that is highly versatile, highly accurate, and does not require a large-scale device, and a device used to carry out the method. purpose.

First, the optical principle of the present invention will be explained. In Fig. 1, a light emitter T and a light receiver R are placed on a traversing trolley (not shown) of an overhead traveling crane. The locus of the center of gravity of a suspended load, etc. that moves up and down) is installed at a distance of D ₁ and D ₂ from L in the transverse direction, respectively.
The projector T emits a narrow beam of light towards the ground and scans it in the transverse direction. This scanning area is a predetermined range, and this range includes objects that reflect the light beam more fully than other parts. As this object, that is, the position detection sign P, it is possible to use an existing object with a mirror surface, such as a rail, or, conversely, an existing object with a significantly lower reflectance than other parts, or a special mirror object can be used. You can also do it. The light reflected from the marker P is captured by a light receiver R, and the light receiving range of the light receiver R is made slightly wider than the scanning range of the light projector T.
These scanning ranges, light receiving ranges, and furthermore, the lengths of the sign P in the traveling direction (the front and back directions of the drawing) may be appropriately determined depending on the accuracy of automatic stop control and the like.

The scanning means of the light projector T is equipped with means for detecting the scanning direction, for example, means for detecting the scanning angle θ with reference to the scanning area limit on the opposite side of the light receiver R, and the light receiver R is equipped with a means for detecting the scanning angle θ with reference to the scanning range limit on the opposite side of the light receiver R. A means for photoelectrically converting and binarizing the electrical signal output at a predetermined threshold to selectively identify only the light reflected from the sign P;
The value of θ at the time when the reflected light from the sign P is identified and detected is determined from the scanning angle detection means, and this is given to the calculation device, and the separation distance x between the center of gravity locus L and the sign P is calculated using the following equation (1) have them calculate.

x= _D1 -Htan(φ- _φ1 )...(1) However, H: Vertical distance between the emitter, receiver, and sign P _θ1 : Angle between the scanning area limit and the vertical line passing through the emitter T. By readjusting the stop position of the crane in the traverse direction based on x obtained in this manner, desired stop position control can be achieved. For example, when lowering a suspended load to a position where x = A, all you need to do is find the deviation between x and A determined by equation (1) and control the crane's traversal movement to eliminate this deviation.A small lateral movement is sufficient. so it is aligned correctly. Furthermore, if the sign P is to be attached to a suitable location on the loading platform of a truck, all that is required is to position the loading platform at a position where the marker P is within the light beam scanning area of the projector.
Unloading will take place on top. In the latter case, it goes without saying that traverse drive control is performed so that x=0.

Although it is possible to detect the position of the crane using the optical principle described above, if the suspended load is large or relatively close to the ground, the shadow will cause the crane to be far away from the target, that is, the sign P. The camera may fail to capture the reflected light, making it impossible to detect the position. Therefore, in the present invention, as shown in FIG. 2, two floodlights T ₁ and T ₂ are provided on the left and right sides of the hanging fixture, and two signs P ₁ and P ₂ are also provided in the same direction but at different positions.
To prevent position detection from becoming impossible due to blind spots caused by suspended loads. One receiver R may be provided between the emitters T ₁ and T ₂ , or one receiver R may be installed between the receivers R ₁ and R ₂ as shown in FIG.
Provide two.

Furthermore, in the present invention, continuous light is projected and scanned in order to prevent the occurrence of blind spots due to scanning.

Next, the apparatus used to carry out the method of the present invention will be specifically explained based on the drawings. FIG. 4 is a schematic diagram of the device of the present invention, and for convenience of explanation, the light projecting device 1, the sign P
Although only one of each is shown, one projector 1 is provided on each side of the hook 95 as shown in FIGS. 2 and 3. Two signs P are also provided at different positions in the crane traverse direction.

A trolley 93 is installed on the main girder 92 of the crane 90 to run on the runway 91.
A hook 95 is moored to the wire wound around the hoisting drum 94 to lift the suspended load 9.
6 can be raised and lowered. This trolley 93
A light projecting device 1 and a light receiving device 2 are installed at a predetermined distance apart. The projecting and receiving devices 1 and 2 do not necessarily need to be installed at the same height, nor do they need to be installed at the same position in the traveling direction (front and back directions in the drawing). These differences can be dealt with in the arithmetic processing process for geometrically determining x in the above-mentioned equation (1). However, for convenience of explanation, it is assumed here that the mounting positions of the light projecting device 1 and the light receiving device 2 differ only in the transverse direction. It goes without saying that the method of the present invention can be carried out even if the light projecting device and the light receiving devices 1 and 2 are installed at the same position.

FIG. 5 is a front view of the light projection device 1, and FIG. 6 is a bottom view thereof. The projector 1 includes a light beam generator 10 using a laser beam generator, a rotating mirror 11 as a light beam scanner, and the like. That is, a light beam generator 10 is mounted outside one end of the housing 12 with the beam head facing the other end of the housing, and a plane mirror 11b is mounted on a horizontal shaft 11a rotatably provided in the housing 12 in the beam traveling direction. A rotating mirror 11 is disposed, and the front end of the horizontal shaft 11a extends through the housing 12, and a rod-shaped cam follower 13 is fixed to this end. A motor 14 is installed inside the housing at a position outside the light beam passage area, and its output shaft protrudes toward the front side of the housing. There is a narrow plate-shaped reference plate 16.
Both are attached to rotate in conjunction with the output shaft. The cam 15 is mounted with a disk eccentrically mounted, and when the cam follower 13 in sliding contact with the cam 15 is pushed down to the lowest position as shown in FIG. θ ₁ from the vertical line to the side opposite to the light receiving device 2
It is reflected by the plane mirror 11b in the direction of the scanning area limit (angular position from the scanning reference angular position) opposite to the scanning reference angular position. The light beam is reflected in the direction of θ=θm), and the reference plate 1
6 is positioned so that a predetermined signal can be obtained when the light beam is directed toward the scanning reference angular position. That is, a metal proximity switch (a photo interrupter may be used) 17 is provided in the rotation range of the reference plate 16 to detect its passage.
For example, the rising point of the pulse signal of the switch 17 obtained by passing through the reference plate 16 is used as a detection reference for the projection scanning direction of the light beam.

The light receiving device 2 consists of a light receiving device 21 equipped with a photoelectric conversion function such as a photodiode, an optical system 22 for focusing light onto the device, and the light receiving range φ is θ.
= 0 to θm is determined so as to cover the light projection scanning area corresponding to θm.

FIG. 7 is a block diagram of the main parts of the electric circuit of this device. Reference numeral 31 is a counter connected to count clock pulses generated by the high frequency oscillator 30. The output of the metal proximity switch 17 is given to the counter 31 as a reset and counting start signal. The output of the light receiver 21 is processed by a binarization circuit 32 in which a predetermined threshold is set so that only a signal of a predetermined level becomes a high level output, and this output is given to a counter 31 as a counting stop signal. It is structured as follows. Note that the binarization circuit may be constructed by a combination of a comparator and a one-shot multi-channel circuit whose output is used as a trigger signal. These circuits are mounted, for example, in the housing 12 or the like together with other control circuits. However, it is not necessary to arrange all of the components, equipment, and circuits on the crane, and some of them may be arranged in a ground operator's room or the like.

8A to 8D are time charts for explaining the operation of the circuit of FIG. 7. As shown in FIG. 8A, as the reference plate 16 rotates, a pulse signal _P17 is generated from the switch 17 once per rotation of the cam. FIG. 8B shows the output of the light receiver 21. As mentioned above, since there are signs P with sufficiently high reflectivity compared to other signs placed in the light projection scanning area on the ground side, the receiver output peaks when the reflection from the sign P occurs. The light beam changes as follows, and while the cam 15 and reference plate 16 make one rotation, the light beam changes as
Since it makes one round trip between .about..theta.m, the above peak appears twice during one cycle of the pulse signal _P17 . By setting the threshold value of the binarization circuit 32 to an appropriate value in advance, the portion corresponding to the reflection from the marker P is converted into a pulse signal as shown in FIG.
The counter ₃₁ stops counting. Therefore, the counter 31 is as shown in FIG.
As shown in the figure, the time clock pulses from the rising edge of the pulse signal P ₁₇ to the rising edge of the pulse signal P ₃₂ are counted, and the counting result is read to the arithmetic unit 33 as information specifying θ, that is, specifying the light projection scanning direction. It turns out. Note that although the pulse signal P ₃₂ is emitted twice in one cycle of the pulse signal P ₁ A ₇ , the second pulse, that is, the pulse when the light beam moves backward, has no effect on the counting of the counter 31.

The count contents of the counter 31 read by the arithmetic unit 33 as described above are calculated according to the equation (1) above or the mathematical equation given by the geometrical relationship determined according to the layout of the light projecting device 1 and the light receiving device 2. The separation distance x between the center of gravity locus L of the hanging tool 95 and hanging load 96, which is used as a position reference, and the sign P is calculated, and this is given to the control circuit 34 of the traverse drive motor to determine the required distance determined by the relative relationship with the sign P. The motor is driven and stopped for control such as lowering a suspended load to a certain position.

Then, as shown in FIG. 3, the projectors T ₁ , T ₂ , 2
If there are two light receivers R ₁ and R ₂ , and two signs P ₁ and P ₂ , it is sufficient to install two circuits as shown in Figure 7. If there is only one R, a signal for specifying the scanning angle reference position of both projectors T ₁ and T ₂ (the above-mentioned pulse signal
_P17 ) is emitted by 180 degrees, and by providing a gate using this signal or a signal created based on these signals, the signal from the receiver R can be transmitted to the emitter.
It is necessary to separate the light emitted from T ₁ and T ₂ respectively. As a result, even if one sign enters a blind spot due to the hanging load and is no longer detected by receiver R, the reflected light from the other sign will be reflected from the other projector on the other side of the hanging device. is obtained, and position detection is not impossible. In the case of Figure 3, which has two emitters and two receivers and two markers, the emitters are adjusted based on the accuracy of the stop position control in the traveling and traversing directions on the crane side, which is unrelated to the target on the ground.
The light emission scanning area of T ₁ (or T ₂ ) includes the marker P ₁ (or P ₂ ), and therefore the light receiving range of the receiver R ₁ (or R ₂ ) includes the marker P ₁ (or P ₂ ). The relative positions of the marks P ₁ and P ₂ are determined in consideration of the maximum dimension of the suspended load. In this case, the relative position of the crane and the sign is calculated based on the data of the two sets of light emitters and receivers, and the position is determined by averaging the two. Further, when the reflected light from one of the signs is not received due to a hanging load, relative position calculation is performed based on only one set of data.

As described above, the present invention is a method for specifying the position of a marker by an optically simple method of one-dimensional projection scanning of a light beam. Although it is possible to detect the position of the device, the device can be constructed at a low cost. Moreover, since no special software is required for the arithmetic unit 33, and there are no special restrictions on the installation of ground-side targets, the system can be applied to any location.

Furthermore, even if the suspended load is large or located close to the ground, the presence of two projectors and two signs makes it possible to detect the position by eliminating the effects of blind spots due to the suspended load. Furthermore, since the continuous light is projected toward the sign, there is no inconvenience such as when the light is not reflected from the sign sometimes, which is the case when the light is projected intermittently.

The scanner that enables such continuous light projection is equipped with a rotational position detector of the cam 15 consisting of a reference plate 16, a metal proximity switch 17, etc., so that the scanning direction of the light projection can be accurately detected and the position can be detected. The present invention has excellent effects such as high accuracy. It goes without saying that the present invention can be applied not only to the detection of the position in the transverse direction but also to the detection of the position in the running direction.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the optical principle, Figs. 2 and 3 are explanatory diagrams of the method of the present invention, Fig. 4 is a schematic configuration diagram of the apparatus of the present invention, Fig. 5 is a front view of the light projecting device, and Fig. 6 is a bottom view, FIG. 7 is a block diagram of the main part of the electric circuit of the device of the present invention, and FIGS. 8A to 8D are time charts for explaining its operation. T, T ₁ , T ₂ ... Emitter, R, R ₁ , R ₂ ... Light receiver, 1 ... Light projector, 2 ... Light receiver, 10 ...
Light beam generator, 11... Rotating mirror, 14... Motor, 15... Cam, 16... Reference plate, 17... Metal proximity switch, 21... Light receiver, 31... Counter, 33... Arithmetic device . 〓〓〓〓

Claims (1)

[Scope of Claims] 1. One floodlight is provided on each side of the hanging device on the crane, and two signs are provided below the crane at different positions in the same direction as the floodlight, and the floodlight indicates that the crane is While continuous one-dimensional light projection scanning within a predetermined range including the signs from top to bottom, the crane receives the reflected light from the light projection scanning area, and when the reflected light that should be obtained from each sign is received. 1. A method for detecting a position of a crane, comprising: detecting a scanning direction of light emitted from the vehicle; and determining a relative position of the crane with respect to each sign based on the detection result. 2. One light beam generator is installed on each side of the lifting device on the crane, and the light beams emitted by each light beam generator are continuously projected downward in a one-dimensional manner within different ranges. A scanner for scanning, a light receiver arranged to receive reflected light from a sign in a light projection scanning area of each light beam and having a photoelectric conversion function, and a light projection scanning direction detection means of the scanner; The scanner includes an eccentric disc cam, a cam follower in sliding contact with the cam follower, a mirror connected to the cam follower and reflecting a light beam emitted by a light beam generator, and a rotational position detector for the eccentric disc cam. and is configured to determine the relative position of the crane with respect to the object that has emitted the reflected light based on the detection result of the light projection scanning direction when the receiver receives the reflected light of a predetermined intensity. Position sensing device.