JPS6117755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the length of a multi-stage telescoping boom. For example, in a truck-mounted crane equipped with a multi-stage telescoping boom, it is necessary to detect the boom length as input data for an overload prevention device. Detection of boom length is also essential for automatic cranes equipped with microcomputers, which are being developed recently. By the way, in the conventional boom length detection device, one end of a wire is fixed to the tip boom, and the other end is wound around a rotating drum fixed to the proximal boom, and the rotating drum is rotated according to the amount of expansion and contraction of the boom. The boom length was determined from the output voltage of a potentiometer connected to the rotating drum, and an analog detection signal corresponding to the boom length was obtained. Therefore, if the data processing system is a digital circuit, A/
D (analog/digital) conversion is required, and since measurement is performed using a potentiometer, accuracy is low. Furthermore, there is a risk of obtaining erroneous measurement results due to slack in the wire, problems with the rotation system, etc. There were problems such as the possibility of There are also devices that use a limit switch, but this type can only detect the boom length in stages.

The present invention has been made in view of the above circumstances, and provides a mechanism for directly obtaining digital measurement results using optical technology, and for correcting the positional deviation of the optical system caused by the deflection of the boom. Prepare,
The purpose is to provide a highly accurate and reliable boom length detection device.

The boom length detection device according to the present invention includes a reflector attached to a proper position on one of the tip boom or the base boom constituting a multi-stage telescoping boom, and a light emitter and a light receiver mounted on the other proper position. and a drive circuit for making the light emitting and receiving direction variable relative to the reflector, and a drive circuit that causes the light emitter to emit light intermittently in response to a pulse signal, and an oscillation circuit that generates a clock pulse having a higher frequency than the pulse signal. The circuit includes a circuit for counting the clock pulses, a detector for the load acting on the boom, and a data processing device, and is configured to determine the light emission timing of the light emitter according to each elementary pulse of the pulse signal, and the light emission timing according to each elementary pulse of the pulse signal. The counting circuit is operated in synchronization with the light reception timing of each corresponding light pulse by the light receiver, and the boom length is determined by the data processing device based on the counting result. , the driving means is configured to control the light emitted by the light emitter in the data processing device based on the signal from the detector of the load to reach the light receiver via the reflector.

The present invention will be described in detail below based on drawings showing embodiments thereof. FIG. 1 is a schematic side view of a crane equipped with a boom length detection device according to the present invention, and FIG. 2 is a schematic block diagram showing essential parts of the optical system and control system of the boom length detection device. In the figure, reference numeral 1 denotes a light emitting/receiving unit, which is attached to one side of the proximal boom BB.A case 10 has its front face facing the tip boom TB, and is installed within the case 10 with its light emitting surface facing the front side of the case. A light emitter 11 made of a light emitting diode, a light receiver 12 made of a photodiode or the like mounted with the light receiving surface facing the front side of the case, and a light emitter 11 and a light receiver 12 respectively installed in two holes opened on the front side of the case. One side converts the light emitted from the emitter 11 into a parallel beam and projects it out of the case, and the other side converts the parallel beam incident from outside the case onto the receiver 12. Lenses 11a and 12a that converge to form an image on the light receiving surface of the base end boom BB
One end of the horizontal rotating shaft is fixed to Case 1
Motor 13 fitted on the back of 0 and motor 13
It consists of a potentiometer 14, etc., with a rotor connected to the other end of the rotating shaft.

2 is a reflector 20 made of a corner reflector or the like that reflects incident light and reflected light in the same direction;
This is a reflector consisting of a housing 21 that covers this and has an opening on one side, and is assembled so that the opening of the housing 21 and the incident/reflecting surface of the reflector 20 are on the same side, and the incident/reflecting The surfaces are the lenses 11a and 12a
The tip boom is installed on the side of the TB so that it is directly opposite the TB. For this mounting position, the tip boom
A position where there is no problem in storing the TB in the intermediate boom MB is selected, for example, the side surface of the tip part that suspends the hook HK.

3 is a known moment detector shown as an example of a load detector attached to the rod part of the cylinder CD for raising the boom BM, and is made by connecting a strain gauge with a bridge. Further, 4 is a known boom angle detector, which is attached to the base end boom BB. The above-mentioned light emitter 11 and light receiver 12 are connected via a diode drive circuit 15 and a preamplifier 16, respectively, and the motor 13, potentiometer 14, moment detector 3, and boom angle detector 4 are connected directly to the driver's cab OP. It is connected to a controller 5 placed at a suitable location inside.

The controller 5 includes a central processing unit (CPU), read-only memory ROM, and random access memory.
It is equipped with a microcomputer 50 consisting of RAM and the like. This microcomputer 50 not only functions as a data processing device in the apparatus of the present invention, as will be described later, but also functions as a center for overload operation prevention and other crane automatic operation control. 51 is a pulse oscillator which emits a relatively low frequency pulse signal _P1 as shown in FIG.
The signal is inputted to the reset terminal of the circuit and the diode drive circuit 15. Diode drive circuit 1
5 drives the light emitter ₁₁ while the pulse signal P1 is at a high level, that is, while the elementary pulse is input, so that the light emitter 11 emits light intermittently.
Therefore, the light emitted from the light emitter 11 is transmitted through the lens 11.
a, the light becomes a parallel light beam and reaches the reflector 20, where it is reflected and reaches the lens 12a, where it is converged and reaches the light receiver 12. Since the light emitter 11 emits light intermittently as described above, the light receiver 12 receives pulsed light. This light pulse is photoelectrically converted by the light receiver, and then sent to the preamplifier 1.
6, the signal is amplified and input to the waveform shaping circuit 53 of the controller 5. The waveform shaping circuit 53 shapes the input signal to produce a pulse signal P ₂ having elementary pulses corresponding to each of the above optical pulses, as shown in FIG.
This is input to the stop terminal of the counter 52, and the gate 5 is controlled to open and close by the CPU.
It is configured to be imported into the CPU through step 4.

55 is an ultra-high frequency oscillator that emits an ultra-high frequency clock pulse CLK as shown in FIG.
The clock pulse CLK outputted by this is configured to be counted by a counter 52. The counter 52 starts counting as soon as it returns to zero when the reset terminal becomes high level, and stops counting when the stop terminal becomes high level.

When the CPU receives the fact that the stop terminal has become high level through the gate 54, the CPU reads through the gate 56 the contents of the counter when counting is stopped, that is, the clock pulse count value.

A display 57 is connected to the CPU via a gate 58 whose opening and closing are controlled by the CPU, and digitally displays the boom length calculated by the CPU based on the clock pulse count value. The principle of measuring boom length is as follows. That is, the light emitted from the light emitter 11 by each elementary pulse of the pulse signal P ₁ travels twice the distance l from the light emitter 11 or the light receiver 12 to the reflector 20, and then reaches the light receiver 12. The pulse signal reaches
Each elementary pulse of P ₁ and the corresponding pulse signal P ₂
The speed of light is v between the rising timing and the elementary pulse of
Then, there is a delay of time t expressed as t=2l/v. As described above, the counter 52 measures the time from the time when the input signal to the reset terminal, that is, the pulse signal _P1 , becomes high level to the time when the input signal to the stop terminal, that is, the pulse signal _P2 , becomes high level. During time t, clock pulses CLK are counted as shown in FIG. 3D. Therefore, if the count value of the counter 52 is n and the period of the clock pulse is s, the relationship t=n/s holds, so l can be found as l=nv/2s.
Based on this principle, the CPU sequentially reads s, v, and n given in advance in the ROM from the counter 52.
According to the arithmetic program in the ROM based on
nv/2s is calculated, and the value of l is displayed on the display 57 as the boom length, and is also stored in a RAM or the like for other automatic controls. If the boom length needs to be determined as the distance from the pivot point of the base boom BB to the center of the sheave at the tip of the tip boom TB, an appropriate value may be added to the value of l above.

Reference numeral 59 denotes an analog switch, and the output terminals of the potentiometer 14, moment detector 3, and boom angle detector 5 are connected to the input terminal, and the three input signals are alternately controlled by the CPU. The signal is input to an A/D converter 60. The output signal of the A/D converter 60 is
The CPU passes through the gate 61 which is controlled to open and close by the CPU.
It is configured to be read into. 62 is a motor drive circuit interposed as an interface between the CPU and the motor 13. A motor drive signal issued from the CPU is supplied to a motor drive circuit 62 via a gate 63 that is controlled to open and close by the CPU, and this circuit 62 drives the motor 13 forward or reverse depending on the content of the motor drive signal. It is set as. The CPU reads the output signal of the moment detector 3 via the A/D converter 60 at regular intervals under the control of the analog switch 59, and sequentially
While storing it in RAM, if the pulse signal P ₂ is not input to the CPU for a long time than the period T of the pulse signal P ₁ (or P ₂ ) given in advance, the output signal of the moment detector 3 at that time M ₀ is read and compared in magnitude with the output signal M ₁ of the moment detector 3 previously stored in the RAM.
If the value of M ₁ is larger than the value of M ₀ , the boom BM is deflected due to the increase in moment, which prevents the light emitted from the emitter 11 from reaching the receiver 12 . Assuming that a positional shift has occurred in the optical system, the CPU issues a motor drive signal to rotate the motor 13 in the forward rotation direction shown by the arrow, and as a result, the optical axis of the light emitted from the light emitter 11 changes due to the deflection of the boom. The reflected light is directed toward the reflector 20, which has moved downward, and the light receiver 12 can again receive the reflected light. The motor drive signal is continued until a pulse signal _P2 of a predetermined level is obtained. Conversely, if the value of M ₀ is larger than the value of M ₁ , it is assumed that the moment has decreased and the deflection has decreased.
The CPU continues to issue a motor drive signal to rotate the motor 13 in the reverse direction until a pulse signal _P2 of a predetermined level is obtained. In addition, potentiometer 14
The output signal of the boom angle detector 4 is also taken into the CPU via the A/D converter 60, but the output of the potentiometer 14 is the rotation angle of the potentiometer 14 accompanying the rotation of the motor 13, that is, the boom
It is used as data to calculate the amount of deflection of BM,
Together with the signal from the boom angle detector 4 and the calculated value of the boom length, it is used to calculate the actual working radius, etc.

The device of the present invention configured as described above starts operating by supplying power to the controller 5, etc., and the pulse oscillator 51
The light emitter 11 emits light intermittently in synchronization with the pulse signal _P1 generated by the light emitter 11. Then, this light is received as a light pulse by the light receiver via the reflector 20, and a pulse signal _P2 is obtained. Since the counter 52 operates as described above, the CPU sequentially reads the counted value, calculates the boom length, which changes every moment as the boom extends and contracts, according to the above-mentioned formula, and displays the calculation result on the display 57. On the other hand, it is used for actual working radius and other calculations, and as data for automatic operation control. If deflection occurs in the boom BM due to extension of the boom BM or increase in load, the displacement of the optical system is corrected by rotating the case 10 by the motor 13, and the measurement of the boom length can be continued without any problem. become.

In the case of the apparatus of the present invention constructed and operated as described above, since there are almost no moving parts, the occurrence of failures is reduced and durability is improved. Furthermore, since light is used to measure the boom length and digital data is obtained, there is an advantage that the accuracy and reliability of the measured data is extremely high. Furthermore, since the device of the present invention is provided with a means for correcting the positional deviation of the optical system due to changes in the load on the boom, it is possible to correct the positional deviation of the optical system due to changes in the load on the boom. , or even if light from the outside enters, stable measurements can always be performed. Furthermore, since the amount of deflection of the boom can also be determined, it becomes possible to accurately detect the boom angle by adding the amount of deflection of the boom to the output signal of the boom angle detector.

In the above-described embodiment, the counting control of the counter 52 is performed at each rising edge of the pulse signals P ₁ and P ₂ , but each falling edge may be used. Further, in the above embodiment, the emitter and receiver are rotated together with the case 10 by the motor 13, but only one of the emitter or the receiver is rotated to correct the positional deviation of the optical system. Good too. Furthermore, the light emitting/receiving unit 1 is attached to the tip boom TB, and the reflector 2 is attached to the tip boom TB.
Of course, it is also possible to attach them to the proximal boom BM, respectively, and reverse the positional relationship with the above-mentioned embodiment.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic side view of a crane showing the mounting position of the light emitting/receiving unit, etc., Fig. 2 is a schematic block diagram of the device of the present invention, and Fig. 3 A to D are explanatory diagrams of the operation of the controller. 1... Light emitting/receiving unit, 2... Reflector, 5...
Controller, 11... Emitter, 12... Light receiver, 13
...Motor, 50 ...Microcomputer, 5
1...Pulse oscillator, 52...Counter, 55...
...Ultra high frequency oscillator.

Claims (1)

[Claims] 1. Attach a reflector to an appropriate location on one of the tip boom or base boom that constitutes a multi-stage telescoping boom, and attach a light emitter and a light receiver to the appropriate locations on the other end, and place a light emitter or light receiver at a relative position between the light emitter or light receiver and the reflector. A drive circuit that is attached with a drive means that makes the direction of light emission and reception variable, and that causes the light emitter to emit light intermittently using a pulse signal, an oscillation circuit that generates a clock pulse with a higher frequency than the pulse signal, and a count of the clock pulses. a circuit, a detector for a load acting on the boom, and a data processing device, the timing for emitting light from a light emitter according to each elementary pulse of the pulse signal;
The counting circuit is operated in synchronization with the light emission timing of each corresponding light pulse by the light receiver, and the boom length is determined by the data processing device based on the counting result. If the data processor is unable to transmit the light, the data processing device is configured to control the driving means based on the signal from the detector of the load so that the light emitted by the light emitter is directed to the light receiver via the reflector. A boom length detection device characterized by: