JPS607282B2 - Automatic guide device for lifts and trucks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powered vehicle steel guiding device, and more particularly to a wire-following type guiding device for a lift truck or similar vehicle steel.

In cargo handling operations, lift trucks allow operations to remove and store items from closely spaced, non-mobile shelves.

In this case, an operator accompanies the lifting platform of the lift truck and takes out specified items from the mobile loading platform or storage module. In this case, the width of the passage is very narrow;
It can be as long as 4 feet (approximately 120 skins). If the operator does not need to drive the lift truck,
Furthermore, the lift truck can be moved forward while the operator is performing the lifting operation of the platform. Conversely, if the operator must drive the lift truck himself, he would first drive to the destination location and then operate the lift. Those skilled in the art refer to moving forward at the same time as the lifting/lowering operation as "overlapping operation", and by performing this overlapping operation, the productivity per worker can be significantly increased. In many states, occupational safety laws prohibit "overlap" when the operator is driving the lift truck himself. Therefore,
By providing a lift truck guide, not only can the spacing between storage shelves be narrowed, but also labor productivity can be increased by shortening retrieval time. In the prior art, lift truck guide devices are basically divided into two types. The first type guides the lift truck by mechanical means. Upon entering the aisle, the lift truck's loaf fits into the steel tracks attached to each side of the aisle. The operator simply controls the truck's speed, starting and stopping, and the truck is mechanically held in the center of the aisle. Although such mechanical guides are economical and offer some flexibility over the electronic guides described below, they also have some important deficiencies. In mechanical guidance systems, the lift truck maintains its position by experiencing strong reaction forces from the track, so that the wheels are constantly subjected to forces that tend to roll transversely to the track.

This force is always high and can damage the wheels and require constant maintenance as the bolts securing the tracks frequently break.
More lift. When a truck enters a railway trackway, large forces are exerted on it, so that the ends of the track, guide rollers, tracks, shelves, etc. are constantly damaged. In addition, if the operator incorrectly operates the lift truck without properly placing it in the aisle, problems such as damage to the truck's vehicle steel and goods or injury to the operator may occur. Another problem with mechanical guide systems is that the mechanical devices at the end of the passageway are relatively large and take up valuable storage space. Furthermore, dust gets stuck under the racks after the tracks and cannot be easily removed, requiring tedious manual cleaning, which increases the operating costs of the storage facility. The disadvantages of the mechanical guides mentioned above can be overcome by using electronic guides.

In the electronic guide system, a single electric wire is buried under the floor of the storage warehouse, and a positioning unit with a special detector is mounted on the lift truck to guide the lift truck along the buried electric wire. can do. The special lift trucks listed above cost between $50,000 and $750.
At a cost of around $1,000, it is many times the price of a mechanically guided lift truck. The electronic devices described above are fully automated, so the wheels are always automatically controlled. Due to the high cost of electronic lift trucks, the guidance market is currently dominated by mechanical guidance systems. One advantage of the electronic guide system is that it minimizes the time the car is not in operation and reduces maintenance costs due to mechanical failures. The reason for this is that when using an electronic guide device, the lift. This is because the truck is not forced into position by mechanical force, but is steered along the path. If you try to modify a conventional lift truck to install an electronic guide device, you will need to make significant changes to the vehicle steel frame structure to ensure space for installing the steering servo device, or replace the wheels themselves with the guide device. It has been difficult to carry out such modifications in the past, as it has been difficult to carry out such modifications.

The disadvantage was that the above-mentioned modifications would be costly and would easily violate the Automotive Steel Safety Standards (OSHA). The above-mentioned and other disadvantages of prior art guide systems for lift trucks can be overcome by providing a self-powered load carrier with an automatic guide system according to the invention.

The wheels targeted by the present invention have means such as a steering wheel in contact with the ground and a rotatable control cylinder shaft, and the forward direction of the vehicle steel can be determined by manually positioning the steering wheel. It was set up so that The guiding device according to the present invention is provided with a fixed means for determining the course of travel, such as a buried electric wire, on the outside of the pilot, and further provided with an electric motor drive means on a part of the steering cylinder shaft, which responds to the steering control signal. The steering cylinder axis can be rotated. Further detection means are provided for generating an error signal indicative of deviation of the vehicle steel from said path determining means. When the direction control circuit supplies a steering control signal to the electric motor driving means in response to the error signal, the electric motor driving means rotates the steering column shaft so that the tactician moves along the course determining means. make them change direction. In one preferred embodiment, the guidance control system also includes means for manually generating a power steering control signal. The steering control signal provided by the direction control circuit is representative of the error signal if the error signal has a predetermined characteristic, and is representative of the power steering control signal at all other times. As described above, in the present invention, by simply removing the steering wheel (i.e., the handle) from the steering cylinder shaft of the lift truck and attaching the guide device to the end of the steering cylinder shaft, the present invention can be used to replace existing standard lift trucks. A guide device can be attached to the

Next, a detection device is attached to the bottom of the lift truck across the buried electrical wires. Another sensing device is attached to the ground-engaging steering wheel such that the relative angle of the steering wheel to the lift truck is sensed by the electronic guidance device. In "manual" mode, the operator can drive the lift truck by power steering by rotating the steering wheel (or handle) on the guide. At this time, the guide device
The electronic sensing device provides a power steering signal to the directional control circuit in the same manner as the electronic sensing device used when following the lift truck over power lines in the "auto" mode. The operator first manually drives the lift truck to the entrance of the aisle and then pushes the steering wheel (i.e., handle) to change it to the "auto" position. At this time, the guide circuit detects the polarity and sign of the rate of change of the error signal obtained from the buried wire. When the polarity of the error signal and the sign of the rate of change reach a predetermined relationship, the lift truck either crosses the power line and moves away from the power line, or approaches the power line and then moves away from it again. When something is detected by the control circuit, the control circuit automatically turns off the power steering signal and enters a full detector control state. The lift truck is then automatically controlled and follows the electrical wires buried in the path. In a preferred embodiment of the invention, an operator can ride the lift truck and drive the truck directly, for example in an emergency.

In this embodiment, the operator simply pulls out the steering wheel (i.e., handle) to mechanically engage the steering cylinder shaft while electrically disconnecting the control and guidance circuitry. This allows the operator to directly mechanically steer the vehicle without using a guide device. The guiding device according to the invention has a number of advantages.

One advantage is that the initial investment for the user is small.

In addition, since it does not use tracks or loaves unlike mechanical guide devices, the device is less likely to be damaged. Moreover, since the guiding movement is performed electronically, there is no mechanical vibration and no injury to the goods or the operator himself. Because of the precision of the device described above, it is also possible to make the passage narrower than with some mechanical guide devices. Since the storage cabinet equipped with the guide device according to the present invention has no tracks protruding from the floor surface, the floor surface is easy to clean. Based on the invention, the guiding device has all the flexibility of a mechanical guiding device, and the range of operation can be increased by simply extending the buried wire. In the present device, when aligning the lift truck with the automatic guide device, there is no restriction that the lift truck must enter from the entrance side of the passageway.

For example, if a lift truck is fully loaded and visibility is limited, the front view may be limited.
Approximately 1.8 meters) It is possible to detect electric wires from a distance. When a lift truck enters an aisle, it is already aligned with the power lines, so the truck will not hit the shelves or storage areas on either side of the aisle. According to the present invention, the productivity of an operator can be greatly improved. The lift truck is automatically guided into the aisle, allowing the operator to
There is no need to spend much time aligning or maneuvering the truck.
The major advantage of the present guide system over mechanical guide systems and existing state-of-the-art electronic guide systems is that it can quickly and easily replace conventional manual lift trucks without compromising safety standards (06HA). The advantage is that it can be easily converted to an electronic guide device.

This is because the electronic guidance system can be installed on the original lift truck with almost no modification to the original lift truck. Accordingly, one object of the present invention is to provide an electronic guide system that can be installed on conventional lift trucks. Another object of the present invention is to provide an inexpensive electronic guide system for use in lift trucks.

A further object of the present invention is to provide an electronic guide system that can be directly installed in a conventional lift truck. Still another object of the present invention is to provide an electronic guide system for a lift truck that can be operated in a detector control mode, a power steering/hand control mode, and a manual mode in which the guide system is separated. The point is that it provides a distinctive electronic guide device.

Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Please refer to FIGS. 1, 2, 3, and 4.

A basic lift truck 10 for use in the guiding system of the present invention is shown in the figure, although the lift truck 10 is of a conventional type. An electric motor and a storage battery for driving the lift truck are housed in a housing in the rear part 12 of the lift truck. As seen in FIG. 2, the leftmost wheel is a ground-contacting steering wheel 14 which can rotate in a horizontal plane about a vertical jack and is driven by an electric motor within the housing 12. As seen in FIG. 2, a pair of horizontally spaced members 16 extend from the right end of the lift truck, each supporting a pair of ground engaging roller wheels 18. . A fork lift assembly 20 is supported on a vertical rack 22 extending upwardly from the horizontal member 16. The fork lift assembly includes an operator's control room 24 and a control console 26 mounted within the operator room. The operating mechanism for raising and lowering the fork lift according to the operator's operations is the same as that of the conventional system, so it will not be further explained here. The orientation of the steering wheel that engages the ground is determined by the rotation pointer 28 provided on the top surface of the rear housing 12 of the lift truck 1.
Instructions are given so that you can understand at a glance from above 0. The structure described above is the same as the conventional lift truck 10.

To modify the lift truck 10 to be suitable for the guidance system of the present invention, a sensing coil assembly 30 is mounted on the bottom of the lift truck 10 in a symmetrical position between the wheels 14, 18. . A second detector 32 is attached to the top of the rotating pointer 28 to detect the rotation angle of the pointer 28. When the lift truck operates in the detector control mode, the lift truck 10 is operated by the electrode 3 buried under the floor 36.
4 straddle the top. The electric wire 34 is 6. The line driver unit 38 transmits a high frequency signal along the line 34. As will be discussed in more detail below, when the lift truck 10 is operated in the detector control mode, the lift truck straddles the line 34 and picks up the high frequency signals and inputs them into the electronic guide system. The guide system steers the lift truck 10 along a line 34 by rotating the steering wheel 14 by means of an electric motor unit, which will be described in more detail below. A typical example of the arrangement of electric wires is shown in FIG.

FIG. 4 shows a state in which the electric wires 34 are routed through a plurality of storage shelves 40. lift truck lo
is carried into the storage by manipulating it in a manner to be described in detail later, and when it approaches the electric wire 34, the guiding mechanism is set to automatic mode'.
Switch here. When the lift truck crosses or comes relatively close to the wire 34 and then moves away from the wire 34, the guidance system electronically couples the lift truck to the wire 34 and causes the lift truck to move away from the wire 34. The operator can then move the lift truck 10.
It moves forward between the storage shelves 40 until it stops. Figures 6 and 7
The control console 26 will now be described in more detail with reference to the figures.

Control console 26 has a housing 42 containing a steering electric motor 44, a power steering tachometer 46, and printed electronic circuitry 48. The steering wheel 74 is connected to the housing 42
protrudes from the outer surface of A handle 126 is bolted to the outer edge of the steering wheel 74 for convenient hand rotation of the steering wheel 74 (or handle). lift·
The control rod for starting and stopping the truck and the control rod for raising and lowering the fork lift are not shown because they are the same as before. A steering wheel assembly 50 is mounted on a steering cylindrical shaft 52 of the lift truck 10. Traditionally, lift trucks change the angle of the steering wheel 14 engaging the ground by rotating the shaft 52. The shaft 52 has a larger diameter portion 54 to which a steering wheel assembly 60 is attached. The steering wheel assembly 5 includes a steering sprocket gear 56 mounted on a shoulder or large diameter portion 54 on the ratchet 52.

The sprocket gear 56 has a reduced diameter on the opposite side of the shoulder 54, and a rotatable pulley 60 is fitted into this reduced diameter portion 58. Pulley 6 rests completely on the small diameter portion 58 of the steering sprocket gear 56. A clutch boss 62 is then mounted on the shaft 52 and positioned next to the 4 inch diameter section 58 of the sprocket gear 56. The left end of the clutch boss 62 is provided with a large recess, as seen in FIG. 7, containing a cylindrical coupling village 66 that engages the shaft 52. The coupling member 66 is attached to the reduced diameter portion 58 of the sprocket gear 56 by a bolt 68 passing through the clutch boss 62. Axis 5
A hexagonal nut is fitted into the left end of 2 and serves to contact the left end of the coupling member 66 and hold the steering wheel assembly 50 in position in contact with the shoulder 54 of the shaft 52, as seen in FIG. do. Although not shown in FIG. 7, the sprocket gear 56 and the connecting member 66 are fixed to the shaft 52 and rotate together with the shaft. Because of the bolt 68, the clutch boss 62 also rotates with the shaft 52. Clutch boss 62 is cylindrical and has a reduced diameter portion 72 that forms a shoulder 80 at the left end of clutch boss 62, as seen in FIG.

A steering wheel 74 is ironed onto the clutch boss 62. The left end of the steering wheel 74 in FIG. 7 has a recess 76 in rotational and sliding contact with a boss shoulder 80. The steering wheel 74 further has a small diameter recess 78, the diameter of which is smaller than the clutch boss 6.
It is slightly larger than the diameter of the small portion 72 of No. 2.
The reduced diameter recess 78 of the steering wheel 74 forms a shoulder 79 which adjoins a boss shoulder 80 . Thus, the steering wheel 74 is provided to prevent it from falling off the clutch boss 62. The axial recess of the steering wheel 74 further has a reduced diameter portion 82 which rotationally and dynamically contacts the surface of the reduced diameter portion 72 of the clutch boss 62. As shown in FIG. 7, a switch plate 84 is bolted (not shown) to the right end of the steering wheel 74. The diameter of the switch plate 84 is the same as that of the steering wheel 74.
is approximately 2'3 of the diameter of the pulley 60 and sprocket gear 56. As shown in FIG. 7, a ball pawl support 86 is provided on the outer periphery of the pulley 60 and on its left side.
When the support body 86 is mounted, the support body 86 has an internal recess in which the ball 88 is placed.

As seen in FIG. 7, the pole 88 is prevented from sliding upwardly by a leaf spring 90 attached to the pulley by a suitable mounting bracket (not shown). A ball pawl support 86, a pawl 88, and a spring 90 protrude from a gate 92 in the switch plate 84.
As shown in FIG. 7, there is a plate-shaped pawl village 94 on the outer periphery of the right end of the steering wheel 74. The plate pawl member 94 has two holes 96 and 98 which alternately engage the balls 88 depending on the longitudinal position of the steering wheel pulleys on the opposite shafts 52. Still referring to FIG. 13, it can be seen that the pulley 60 includes a pair of metal studs 100.

The pair of dowels are separated by 180 degrees and are pushed into the recess of the pulley 60. Ai〈gi 10
01 protrudes from the side of the steering wheel side of the pulley 60 and is arranged with a radius such that it can be received in a recess inside the steering wheel 74 (not shown). As briefly mentioned above, in certain modes of operation of the lift truck 10, an operator may be mounted on the guiding device to provide direct manual mechanical maneuvering.

To do so, the operator simply pulls the steering wheel 74 to the left as seen in FIG. That is, the steering wheel may be pulled out toward the operator so that shoulder 79 of the steering wheel engages shoulder 80' of the clutch boss. To rotationally lock the steering wheel 74 to the clutch boss 62, the steering wheel shoulder 79 has an axial recess 104.
It has five pins 102 which are iron-coupled with each other. The recessed portion 104
is parallel to axis 52. Pin 102 projects from steering wheel shoulder 79 into large diameter recess 76 . Each pin 102 is elastically held in position by a spring 106 at one end. The spring 106 is iron-fitted to a large portion of the seat of each recess 108, and the other end of each spring 106 is connected to the switch plate 8.
It is fixed at 4. The pins 102 are radially spaced apart within the steering wheel 74 by 720 spacings. Clutch boss opposite protruding pin 102. Six recesses 110 are provided on the circumference of the shoulder 80 to receive the protruding ends of the pins 102. The recesses 110 are arranged at intervals of about 60 degrees. Because the five pins 102 and six recesses 110 are arranged in this manner, the steering wheel 74 and clutch boss 62 are almost immediately rotated when the steering wheel 74 is pulled out along the axis 52. can be engaged.

This is because in order to force one of the pins 102 into one of the recesses 110 and effectively lock the steering wheel 74 and the shaft 52, it is only necessary to apply a rotational displacement of about 1. . In order to longitudinally lock the steering wheel 14 to the clutch boss 62, the outer ring of the steering wheel 74 is provided with a locking pin 112, said pin 112 being able to slide in a hole 114 in the steering wheel 74. .

The hole 114 extends into a large diameter recess 76 and the pin 112 is always forced out of the hole 114 by a compression spring 116 held in the hole 114 by a screw 118 on the outer circumference of the steering wheel 74. Is receiving. Because the button 120 is secured to the pin 112 by a screw 122, the pin 112 is provided so that it does not fully exit the hole. The button 120 projects horizontally from the steering wheel 74 within a horizontal hole 124, as seen in FIG. However, in the manual steering position without a guide, the inner end of the pin 112 contacts the small diameter shoulder 124 at the outermost end of the clutch boss 62. Steering wheel 74 is locked in a manual position without guides to prevent vertical movement. Steering wheel 74 is
To return to the ``auto'' or ``manual'' positions, the operator must lift the button 122 to move the pin 112 back into the hole 114 and out of the shoulder 124. A sprocket chain 128 is attached to the sprocket gear 56, and the sprocket chain 128 is connected to the sprocket gear 56.
As best shown in FIG. 6, the chain 128 is engaged with a sprocket gear 1301 on the rotating shaft of the steering electric motor 44.

A V-belt 132 is looped around a corresponding V-groove of pulley 60 to connect pulley 60 to a pulley 134 having a similar V-groove at the end of the axis of rotation of tachometer 46. As will be explained in more detail below, when the control console 26 is operating in automatic mode, i.e. detector mode,
The steering wheel 74 is pushed all the way back on the shaft 52. That is, it is pushed to the far right in FIG.
Assuming that the lift truck 10 straddles the buried line 34, when the steering wheel 74 is in this position, the light emitting diode 1 for indicating the electronic device
36 lights up on the top surface of the console 43. In this way, an "automatic" operation is indicated. Assuming that the detection circuit has "detected" the buried wire, the electronic guidance circuit will independently detect the steering electric motor 44 after one day in the "auto" mode.
is operated, and the steering cylindrical shaft 52 is moved by the sprocket chain 128 and sprocket gear 56. However, until the wire is "detected," the operator must
Pilot 0. If the operator wishes to operate the lift truck 10 himself, he can stop the steering wheel 74 at the pawl 94.
All you have to do is bring it to the intermediate position shown by the hole 98.

The detector control of the steering circuit is decoupled, and the output of the power steering tachometer 46 goes directly into the steering control circuit to provide a directional control signal to the steering electric motor 44.
As steering wheel 74 and pulley 60 rotate, V-belt 132 causes pulley 134 to rotate and generate an electrical signal. The magnitude of this signal represents the planned rotational speed of the steering electric motor 44. Steering motor 44 then rotates steering column shaft 52 via sprocket gears 130, 56 and sprocket chain 128 to change the direction of travel of lift truck 10 by the desired amount. In the power steering manual control mode, ie, the "manual" mode, the indicator lamp on the top surface of the console displays "manual" by the light emitting diode 138. As mentioned above, in the manual mode without a guide device, the operator pulls the steering wheel 74 all the way forward on the shaft 52 so that the steering wheel 7
4 and the shaft 52 are directly mechanically connected.

An indicator diode 140 labeled "0.R." illuminates to indicate that the lift truck is fully mechanically steered. Next, referring to Figure 8, the guide mode
Explain the operation of the switch.

Two pushbutton switches 144 and 146 are mounted in holes provided in one leg 143 of the L-shaped bracket 142. The pushbutton is located on the leg 143 of the bracket 142.
and protrudes into the space formed by 145. 8th
As shown, switches 144 and 146 are vertically aligned, with switch 146 at the bottom. The end of one leg of elbow actuator 148 is rotatably mounted to the top of bracket leg 145 about axis 150 . Actuator 148 rotates within the space enclosed by the bracket legs. Actuator 148
The other leg of is mounted in contact with the actuating plate of the steering wheel assembly 50. The upper part of the elbow portion 164 of the actuator 148 is connected to the switch 14 as shown in FIG. 8 when the actuator 148 is rotated clockwise.
It is arranged so as to contact the push button No. 4. Elbow part 15
The lower portion of 4 is positioned to contact the push button of switch 146 when actuator 148 is further rotated clockwise as shown in FIG. The actuator 148 rotates clockwise when the switch plate 84 moves downward as seen in FIG. 8, that is, moves to the right as seen in FIG. As the actuator 148 rotates clockwise, the switch 144 is first closed, and as the switch plate 84 further moves in the same direction, the switch 146 is activated. The switch 146 is a one-circuit, two-contact switch that controls switching between manual mode and automatic mode. The switch 144 is also a one-circuit, two-contact switch that is normally open and functions to cut off the power supply to the guide device when the operator selects the manual mode in which the guide device is not used. Next, with reference to FIGS. 9, 10, and 14, the electronic device section of the guide device according to the present invention will be explained in detail.

The electromagnetic field created by the alternating current passing through the buried wire 34 is distributed radially along the lines, as shown by magnetic field lines 156 in FIG. The magnetic coil detector included in the lift truck 10 includes left and right reference coils 160, 158.
and left and right error coils 164, 162. left,
The distinction on the right is specified in Figure 14 assuming that the observer is looking at the coil from behind the page, and in Figure 9 it is assumed that the observer is standing behind the coil and looking in the direction of travel (to the left). It is specified as Reference coil 158, 16 rivers or approx. 20
．． Because they are placed 3 togs (approximately 8 inches) apart, buried wires 3
The horizontal distance from 4 will be 10.1 skins (4 inches) apart. The error coils 162, 164 are approximately 35.
5 skins (approximately 14 inches) apart, so buried electrical wires 3
4 would be approximately 17.7 skins (7 inches) apart horizontally. Referring to FIG. 15, the coil assembly is shown in further detail.

Like coil 158 shown, all coils are mounted horizontally on printed circuit board 157 by leads 159. The coil leads are connected to each other by a printed circuit board as described below. On the side of the substrate 157 opposite to the coil, there is a rubber sheet 161 with a thickness of about 0.32 inches (1/8 inch) and a thickness of about 5.08 inches (2 inches).
Width, approximately 0.015 skin (0.006 inch) thick
A sheet assembly consisting of metal plate 163, approximately 1/8 inch thick cold rolled steel billet i65, is firmly crimped. Mu metal piece 163 serves to provide a low reluctance horizontal return magnetic circuit for passing the magnetic flux formed by guide wire 34. In this way very thin detectors can be obtained. In one embodiment, 5 mm radio frequency choke coils are used as detection coils. One end of each coil is connected to circuit ground potential, while the other lead wire connection is is performed as follows: Coil 162 (output "L") and coil 164 (output "R") are wound in opposite phases to each other, and the ungrounded leads are connected to their outputs (L, -R). ) is connected to the summing junction 166'.

Since the phases are shifted by 1800, the sum of the above two signals is expressed as LR. The outputs from the two reference coils 158, 160, R', are summed at a summing junction 168, the output of the summing junction being labeled "L+R" in the figure.

The output L'+R' is connected to the inputs of operational amplifier 170 and inverting amplifier 172, as well as to one arm of potentiometer 174. The output of inverting amplifier 172, labeled "L'+R'", is connected to the other arm of potentiometer 174. The movable contacts of the potentiometer 174 are mechanically connected to the ground engaging steering wheel 14. The above-mentioned mechanical connection is indicated in FIG. 9 by a dashed line leading to the electric motor M. The angular position of the steering wheel 14 is therefore reflected in the position of the movable contact of the potentiometer 174. Includes a mechanical connection shown in dashed line connected to electric motor 44 and potentiometer 174.
Rotation pointer 28 on the back of the lift truck housing 12
It forms the substance of the detection device 32 mounted on the top. When the steering wheel 14 is turned all the way to the right, the movable contact of the potentiometer 174 moves to receive the signal -(L+R').

When the steering wheel 14 is turned fully to the left, the movable contact of the potentiometer 174 moves to the opposite end (L+R).
) signals will be received. Since the output signal from the movable contact of the potentiometer is a negative feedback signal, it will be written as FB. This FB signal is applied to summing junction 166 for subtraction. The output signal of summing junction 166 is therefore LR-FB. The output signal is then applied to the input terminal of operational amplifier 176. Operational amplifier 1
The output signal L-R-FB of 76 is connected to the loop gain adjustment resistor 1.
78 and enters one input terminal of the synchronous detector 180.
Amplified signal L′+R obtained from the output of operational amplifier 170
′ is also 6. Synchronous detector 18 through Hz filter 82
0 is applied to another input. Synchronous detector 18 detects an output signal that is in phase with the reference signal. That is, when the phase difference between the reference signal and the error signal is 1800 or less, the synchronous detector 180G integrates the error signal LR-FB. On the other hand, if the phase difference between the reference number and the error signal is 1800 or more, the synchronous detector 180 inverts and integrates the error signal LR-FB. In this way, the noise signal is averaged and canceled. The output of the synchronous detector 180 is a DC signal whose magnitude indicates the magnitude of the error in the position of the lift truck 10 and whose polarity indicates which side of the wire the lift truck 10 is on. This output signal is passed through a 5 Hz low pass filter 84 to remove high frequency pulses, and then passed through a 0.1-0.2 Hz phase shift filter 86 to about 6 Hz.
A phase lead of 0.00 is given to prevent oscillation of the negative feedback loop.

The output of the phase shift filter i86 enters a one-circuit, two-contact electronic switch 188. The other terminal of switch 188 is connected to power steering tachometer 46.

The output of phase shift filter 1 86 is an enable logic circuit (enab).
(le logic circuit) 1901 is also applied. The other input of the tolerance logic circuit 190 is supplied from an amplitude detector 192, and the input to the amplitude detector 192 is 6. It is supplied from the Matsuhi filter 82. The purpose of the tolerance logic circuit 190 is to know when the guiding device has "sense" a buried wire 34.

The output of the amplitude detector 192 is simply amplified reference signal L'+R', but is a function value signal (thresholds).
Acts as i-law al). This threshold signal 220 and
Based on the phase shift filter signal 186, the permissive logic circuit 19
0 detects whether the magnitude of the signal is sufficient to move the circuit 190 to the next step and, judging from the rate of change and polarity of the error signal, sends the signal to the lift truck 10. It is detected whether the lift truck 10 has already crossed the power line and is moving away from the power line, or whether the lift truck 10 has come very close to the power line and is moving away from the power line. Next, referring to Figure 10,
The reference signal R' and the error signal L-R are shown relative to the distance from the embedded wire 34.

As can be readily seen from the figure, there is a slight dip in the amplitude of the reference signal when the lift truck 10 straddles the buried wire at the exact center. The error signal indicates zero when lift truck 10 straddles electrical wire 34 exactly in the middle. When the error signal and the reference signal are on the same side of the horizontal axis, the two signals are in phase; on the other hand, when the two signals are on opposite sides of the horizontal axis, they are out of phase. When the lift truck 10 crosses the power line,
The polarity of the output of synchronous detector 180 changes from one side to the other, and the error signal approaches zero. In such a state, the enable logic circuit 190 is triggered and the electronic switch 18
8 is activated, and the output of the phase shift filter 186 is added to the summing junction 1.
is applied to the positive input terminal of 94. Until the above conditions are met, the tolerance logic circuit 190 connects the power steering tachometer 46 to the positive input terminal of the summing junction 194. A manual-automatic changeover switch 146 is also connected to the enable logic circuit 190, and when the operator manually operates the switch 146 while the steering wheel 74 is in the intermediate position, the electronic switch 188 is actuated to switch the power on and off. A steering tachometer 46 can follow the summing junction 194. The permissive logic circuit 19 also activates the "auto" indicator lamp 13 when the phase shift filter 86 is connected to the summing junction 194 via the switch 188.
It has the function of lighting 6. The output of summing junction 194 is applied to pulse width modulated power supply driver circuit 196 .

The output of power supply drive circuit 196 is a series of pulse signals, the width of which is proportional to the magnitude of the error signal, and the polarity of the pulses equal to the polarity of the output signal of synchronous detector 180. The polarity of the pulses therefore changes depending on which side of the buried wire 34 the lift truck 10 is on. One output lead of power supply drive circuit 196 is connected directly to electric motor 44 . The other output lead is connected to motor 44 through a low resistance 198. The electronic tachometer 200 has three input terminals, and these terminals are connected to the power supply drive circuit 1.
96 is connected to the motor 44 to detect both the voltage drop across the motor 44 and the voltage drop across the resistor 198. Electric motor 44 effectively acts like a generator. That is, by knowing the magnitude of the voltage drop due to resistive losses in the armature, and by knowing the current in the motor that appears as a voltage drop across resistor 198,
The magnitude of the back electromotive force generated by the electric motor 44 can be calculated. The above information is calculated analogously within the electronic tachometer to produce a negative feedback signal, which is subtracted at summing junction 194. This negative machine return signal functions to prevent oscillation of the motor due to overshoot. It is believed that without the damping effect of the negative feedback signal described above, oscillation would occur due to the main negative feedback loop through potentiometer 174. Next, the circuit of FIG. 9 will be explained in more detail with reference to FIGS. 11 and 12.

Parts that are identical to those shown in FIG. 9 are enclosed in dashed lines and generally have the same reference numerals as in FIG. The L'+R' reference signal is applied to the input of amplifier 170. Differential amplifier 1701
6 in Figure 9. The filter is connected to operate as a filter corresponding to the Hz filter. The output of amplifier 170 is applied to one input terminal of second differential amplifier 180. The second differential amplifier is wired to act as a synchronous detector. The output of the synchronous detector 180 is 5Hz
It is applied to the filter 184. The above-mentioned 5-day filter consists of a capacitor connected between the output of the synchronous detector 180 and the circuit ground potential. Note that some components of the circuits described below are connected to circuit ground potential, while other components are connected to signal ground potential. The reason for this is as shown in the lower circuit of Figure 11.
This is because power supply circuit 202 has a -12 volt output relative to circuit ground and a 15 volt output connected to signal ground. The output of the low-pass filter 184 is connected to the differential amplifier 20.
4, and the other input of the differential amplifier is connected to the output of the phase shift filter 186.

The phase shift filter 86 is an RC parallel circuit forming a negative feedback path of the amplifier 204. The output of differential amplifier 170 is also provided to amplitude detector 192 .

The amplitude detector 192 includes an input resistor 206, a diode 208, and a differential amplifier 210. The input resistor 206 is connected to the cathode of the diode 208, and the anode is connected to the input terminal of the amplifier 210. ing. The other input of amplifier 210 is connected to circuit ground through resistor 212 and further connected to diode 2 through capacitor 214.
It is connected to the anode of 08. The anode of diode 208 is biased through resistor 216 to 112 volts. The output signal of amplifier 210, which may be referred to as a dark value signal, is provided to tolerance logic circuit 190 through conductor 220. The "manual" terminal of the one-circuit, two-contact switch 146 is connected to a conductor 2201.

The movable contact of switch 146 is connected to circuit ground. Therefore, when the switch 146 is in the "manual" position, the conductor 22 is grounded and no voltage signal is applied to the allowable logic circuit 19, as if no voltage signal was being generated. Become. Both the state in which no threshold signal is generated as described above and the state in which the conducting wire 202 is grounded will be referred to as a logic zero state herein. Conductor 220 is connected to the input terminal of inverting amplifier 222 and the output of inverting amplifier 222 is wired to one input of NOR gate 224 .

The output of NOR gate 224 is connected to second NOR gate 226
, the control terminal of CMOS switch 228 , and the input terminal of inverting amplifier 230 . NO
applied to the other input terminal of R gate 224. The other input terminal of NOR gate 224 is connected to the output terminal of NOR gate 226. The output of the inverting amplifier 230 is connected to the resistor 23
2 to the base of an NPN transistor 234. The emitter of the transistor 234 is grounded. A light emitting diode 138 is inserted in series between the 124 volt power supply and the collector of transistor 234. The output of the inverting amplifier 230 is also connected to a control terminal of a first MOS switch 236 whose input is supplied from the output of the power steering tachometer 46 . The outputs of CMOS switches 228 and 236 are both supplied to one input terminal of a differential amplifier 238.
The other input of NOR gate 226 is supplied with the output of exclusive OR gate 240 .

As will be explained in detail later, the output of the exclusive OR gate 240 determines whether the rate of change and polarity sign of the error signal after synchronous detection match and the logic circuit should be "operated". , is a signal indicating whether or not the guide device is in a state where it has detected a buried line. As previously discussed, if switch 146 is in "manual" mode and no threshold signal is present on conductor 220, NOR gate 224
A logic 1 is entered in the corresponding input state.

NOR gates 224 and 226 then act as flip-flop circuits, with NOR gates 224 and 226 acting as flip-flop circuits, with
Input 1 entering the R gate 224 becomes the IJ set signal when no guiding device is used. As a result, the output of NOR gate 224 will be a logic zero and the output of NOR gate 226 will be a logic one, regardless of the state of the output of exclusive OR gate 240. When a logic zero appears at the output of NOR gate 224, transistor 234 becomes conductive and light emitting diode 138 is turned on.
lights up. A logic zero appearing at the output of the NOR gate 224 opens CMOS switch 228 while CMOS switch 236 closes due to inverting amplifier 230.
CMOS switch 228 opens and CMOS switch 23
6 closes, the power steering tachometer 46
The output of is applied to the input of differential amplifier 238. The output of amplifier 238 can also be thought of as a speed command, effectively acting as a steering control signal to the motor.
The direction of rotation of the motor changes depending on the polarity of the signal. When switch 146 is turned to the "manual" position as shown in FIG.
The output of 2 becomes a logic zero. Now, it is assumed that the output of the exclusive OR gate 240 is also logical, indicating that the sign of the rate of change and the sign of the polarity of the error signal after synchronous detection are different signs, and that the output of the NOR gate 224 is Assuming that the output remains a logic zero, NOR gate 22
The output of 6 becomes logic 1. In this case switch 146
Even when in the "auto" position, the lift truck continues to operate in power steering mode until the rate of change and polarity of the error signal are of the same sign. When the rate of change of the error signal and the suitability have the same sign, the output of exclusive OR gate 240 becomes a logic one and the output of NOR gate 226 becomes a logic zero. When both input terminals of the NOR gate 224 are logic zero, the output of the NOR gate 224 is a logic one.
, and latches the flip-flop. When a logic 1 appears at the output of NOR gate 224, CMOS switch 228 becomes conductive and CMOS switch 236 becomes non-conductive.

At this time, the light emitting diode 138 controlled by the output of the inverting amplifier 230 is turned off. At this time, the guidance control input signal picked up by the detection Z output coil is input to the amplifier 238, and the lift truck is automatically operated. To know the polarity and rate of change of the error signal,
The output of differential amplifier 204 is applied to the input of amplifier 242.

The other input of the amplifier 242 is grounded to the chassis;
The output is applied to one input terminal of exclusive OR gate 240. The output of differential amplifier 204 is also applied to one input terminal of differential amplifier 244 and, via resistor 246, to the other input terminal of differential amplifier 244. The other input terminal is connected to circuit ground via a capacitor 248. The output of the differential amplifier 244 is an exclusive OR
is applied to the other input terminal of gate 240. The output of the amplifier 242 represents the characteristic of the output of the differential amplifier 204, and the output of the amplifier 244 represents the rate of change of the output of the amplifier 204. When lift truck 10 approaches buried power line 34 sufficiently close, a threshold signal appears at the output of amplifier 210. At this time, two amplifiers 242 and 24
4 and exclusive OR gate 240 determines whether the sign of the rate of change of the error signal is the same as the sign of the polarity and the lift truck 10 is moving away from the power line. When the rate of change and the polarity of the error signal are of the same sign, the output of exclusive OR gate 240 becomes a logic one. It should be noted that the guided flip-flop comprised of NOR gates 224 and 226 is effectively a latching flip-flop.

Once flip-flop 224 is placed in the "auto" mode, the state of the flip-flop will not reset unless the output signal state of inverting amplifier 222 changes. A change in the state of the output signal of inverting amplifier 222 occurs due to either switch 146 being engaged in the "manual" mode or the threshold signal disappearing. If the dark value signal is present and switch 146 is in the "auto" position, no change in the output of exclusive OR gate 240 will change the state of the flip-flop. If the dark value signal disappears for some reason, the operator can
N to give a warning that the state of the flop has changed.
The output of OR gate 224 is applied through an RC series circuit 246 to one input terminal of a NAND gate 248 whose truth value is a logic zero.

A suitable bias voltage of 112 volts is applied to the input terminal of the NAND gate 248. NAND
The other input of the gate is connected to the auto side terminal of the switch 146 and also via a resistor 250 to the light emitting diode 1.
It is also connected to 36. The output of NAND gate 248 is N
It is connected to the base of the PN transistor 252, is grounded to the emitter of the transistor 252, is grounded to the circuit ground point, and is further connected to the collector via the warning lamp 254 in series.
Connected to volt power supply. In operation, the input provided from switch 146 to NAND gate 248 is a logic zero. When the output of NOR gate 224 also changes to a logic zero, indicating that the guide flip-flop has reset for some reason, the output of NAND gate 248 becomes a logic one, which activates warning lamp 254 via transistor 252. Light. In the event of a power supply failure, an amplifier 256 activates a warning lamp 254.One input terminal of the amplifier is connected to a 112 volt power supply via a diode 258, and the output of the amplifier is connected via a resistor 260 to a transistor. It is connected to the base of 252.
Next, refer to FIG. 12.

The speed command output signal of amplifier 238 is output to comparator 262.
and the corresponding input terminal of the second comparator 264. The output of amplifier 262 is exclusive O
One input terminal of R gate 266 and inverting amplifier 268
It is also applied to the 0 input of the amplifier 272 via a parallel circuit 270 of a diode and a resistor. The input to amplifier 272 is connected to circuit ground via capacitor 274. The output of the inverting amplifier 268 is
It is connected to one input of an amplifier 278 through a parallel diode and resistor circuit 276 similar to circuit 270. The input to the amplifier 278 is connected to circuit ground via a capacitor 280. The other input terminals of amplifiers 272, 278 are connected to a 112 volt power supply. Amplifier 27
The output of 8 is connected to the base of NPN transistor 282.

The collector of the transistor 282 is connected to the outside of a PNP transistor 286 through a resistor 284, and the emitter of the transistor 286 is directly connected to a +24 volt motor power supply. The base of transistor 286 is biased in the normal direction from the 124 volt power supply through a suitable resistor. The output of amplifier 272 is connected to the base of NPN transistor 288.

The collector of transistor 288 is connected through a resistor 290 to the collector of PNP transistor 292, and the emitter of transistor 292 is connected directly to the 124 volt motor power supply. The base of transistor 292 is biased in the negative direction from the 124 volt power supply through a suitable resistor. The bases of transistors 286 and 292 are also both connected to the collector of NPN transistor 294;
The emitter of transistor 294 is connected to circuit ground. To control the direction of current supplied to the motor, the collector of transistor 286 is connected to the base of a PNP transistor 296, whose emitter is connected to the 124 volt motor power supply.

The collector of transistor 296 is connected to junction 298 and N.P.
Connected to the collector of N transistor 300. The base and emitter of transistor 300 are connected to the collector of transistor 288 and junction 302, respectively. The emitter of transistor 282 is NPN transistor 304
is connected to the base of the transistor 304 and connected to the emitter junction 302 of the transistor 304, and the collector is connected to the junction 302.
Connected to 06. The collector of transistor 292 is P
It is connected to the base of an NP transistor 308, whose emitter is connected to a 124 volt motor battery power source.

The collector of transistor 308 is connected to junction 306. Junction point 302 is connected to the negative terminal of the motor battery power supply via a resistance wire 310 having a very small resistance value in series. One of the motor 44 inputs is coupled to junction 298 and the other is connected to junction 306 through resistor 198. The output of exclusive OR gate 266 is applied to one input of NOR gate 374.

The output of NOR gate 374 is applied to a combination of an inverting amplifier and an operational amplifier designated by reference numeral 316. The above combination 316 transforms the NOR gate 374 into a monostable multipipelator with a delay time of 200 microseconds. The output of NOR gate 374, which is effectively equal to the output of the multipipulator, is applied to the base of NPN transistor 294 via inverting amplifier 318. N
When any of the input terminals of OR gate 374 becomes a logic one, the output of the NOR gate becomes a logic zero, causing transistor 294 to conduct and forward bias transistors 286 and 292.

When the transistors 286 and 292 are forward biased and conductive, the bases and emitters of the transistors 296 and 308 are shorted, respectively, and the transistors are nonconductive and the motor does not rotate. If all inputs to NOR gate 374 are at logic zero, the output of NOR gate 374 will be at logic one and transistors 286 and 292 will be non-conducting. Assuming now that the output of amplifier 262 is a logic 1, the output of amplifier 272 makes transistor 288 conductive and connects the bases of PNP transistor 308 and NPN transistor 300 through a resistor 290, e.g. 308,30
0 becomes conductive.

In this way, from a 24 volt battery the transistor 30
8, it can be seen that current flows through resistor 198, motor 44, transistor 300, and resistor 310 to the negative electrode of the battery. At this time, the motor rotates in a predetermined direction according to the direction in which the current flows. Similarly, amplifier 262
When the output of transistors 288, 308,
300 becomes non-conductive, and the inverting amplifier 268 and amplifier 27
Transistors 282, 304, and 296 conduct through transistors 8 to supply current to motor 44. However, since the direction of the current is reversed, the direction of rotation of the motor is also reversed. As described above, the polarity of the output of amplifier 262 determines the direction of rotation of the motor. As discussed in more detail below, the polarity of the output signal of amplifier 262 depends on the polarity of the speed command of amplifier 238 and the output of electronic tachometer 200. As already explained in connection with FIG. 9, the electronic tachometer 200
4 and resistor 198 in parallel.

As shown in FIG. 12, the above-mentioned wiring is performed by conducting wires 312, 320, and 322 connected to the junction 298, the junction between the motor 44 and the resistor 198, and the junction 306, respectively. Conductors 312, 320, and 322 provide three inputs to electronic tachometer 200. Above electronic tachometer 2
00 contains a differential amplifier 324, the differential amplifier 32
4 is supplied from a conductor connected to the motor, and the output is supplied from amplifier 2 of the input terminals of amplifiers 262 and 264.
It is connected to the input terminal on the side not connected to 38. As previously mentioned, the outputs of amplifiers 262, 264 are exclusive O
Provided to the input of R gate 266. Exclusive OR gate 2
66 acts as a controlled inverting amplifier, and when the speed command signal and the tachometer output signal are of the same polarity and the absolute value of the speed command signal is greater than the absolute value of the tachometer output signal, the exclusive OR gate 266 is activated. The output becomes a logic zero. If the polarities of the above two signals are opposite, OR
The output of gate 266 will be a logic zero. In all other conditions, the output of OR gate 266 will be a logic 1 and motor 44 will not rotate. The minimum time that current to motor 44 is cut off is approximately 200 microseconds, the value of which is determined by the internal circuit constants of multipipulator 316. The time that motor 44 is energized is determined by the time it takes for the output signal of electronic tachometer 200 to match the speed command signal from amplifier 238. To prevent a pair of power transistors connected in series with each other, such as transistors 296 and 300, 308 and 304, from conducting at the same time, parallel circuits of resistors and diodes 276, 270 connect corresponding capacitors 280, 2.
74 so that when the polarity of the speed command signal changes, all the power transistors become non-conductive before any set of power transistors becomes conductive. A resistor 310 is inserted in parallel between the two inputs of the differential amplifier 326 and acts as a torque limiting detector, so that if something becomes entangled with the steering wheel mechanism and a large overload current flows through the electric motor, the electric motor It acts to cut off the conduction to.

If the voltage appearing across resistor 310 exceeds the predetermined value, the output of amplifier 326 will reach a logic one signal value and that output value will be applied to one input terminal of NOR gate 374. This logic 1 signal causes current to the motor to be cut off. Similarly, when a power failure signal from the output of amplifier 256 is applied to one input terminal of NOR gate 374, current to motor 44 is cut off when power to the guide circuit is removed. Although the embodiments have been described in detail above with reference to the drawings for clarity of understanding, certain changes may be made without departing from the spirit of the invention as set forth in the claims. You should pay attention to this point.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a lift truck containing a guiding device according to the invention. FIG. 2 is a side elevational view of a lift truck containing a guiding device according to the present invention. 3 is a top plan view of the lift truck shown in FIG. 2; FIG. FIG. 4 is a plan view of the embedded electric wire guideway according to the present invention. FIG. 5 is a vertical sectional view of a portion of the embedded electric wire shown in FIG. 4. FIG. 6 is an enlarged partially cutaway perspective view of the control console of the guide device according to the present invention. FIG. 7 is an enlarged partial elevation cross-sectional view of a steering wheel assembly according to the present invention. 8 is a partially exploded, enlarged perspective view of the mechanical switch components of the steering wheel assembly shown in FIG. 7; FIG. FIG. 9 is a schematic block diagram of the electronic control circuit of the guide device according to the invention. FIG. 10 is a waveform diagram of the detection coil output of the guide device shown in FIG. 9. 11 and 12 are detailed schematic diagrams of the circuit shown as a block diagram in FIG. 9. FIG. 13 shows the steering wheel assembly shown in FIG. 7 rotated 90 degrees from the position shown in FIG. 7. FIG. 3 is an enlarged cross-sectional elevational view of the steering pulley. FIG. 14 is an enlarged schematic diagram showing the arrangement of detection coils according to the present invention. FIG. 15 is an enlarged cross-sectional view of the detection coil assembly shown in FIG. 14. 14
... Steering wheel, 30 ... Detection coil assembly, 34 ... Buried electric wire, 44 ... Electric motor, 46 ... Power steering tachometer. FIG. l FIG. 2 FIG. 3 FIG. 4 FIG. 5 FIG. 6 FIG. 7 FIG. 8 FIG. 9 FIG. 10 FIG. ll FIG. ! 2 FIG. l3 FIG. l4 FIG. l5

Claims (1)

[Scope of Claims] 1. An automatic guide device for instructing a powered vehicle to proceed along an external taxiway, wherein the vehicle has at least one ground steering vehicle and a ground steering wheel in the direction of the vehicle's course. This type has a rotatable handwheel for manually pointing the vehicle, and the guidance device has a manual mode and an automatic mode, and detects the vehicle's position and direction of travel based on signals generated by the external guideway. a vehicle-mounted detection device that emits an error signal indicating a deviation between the vehicle and a predetermined course of travel; a manually operable signal generator that generates a power steering control signal; a signal generating device containing an electronic tachometer that generates a power steering control signal proportional to the rotational speed of the steering wheel;
An actuator that directs the vehicle in a course direction in response to a supplied control signal, and an actuator that receives an error signal generated from the vehicle-mounted detection device, detects the polarity and sign of the rate of change of the error signal, and detects the sign of the polarity and rate of change of the error signal. a permissible logic circuit that generates a permissible output signal when the sign of the polarity and the sign of the rate of change have the same sign; an automatic guidance system, comprising: a selector circuit having a switch circuit that operates to transmit an error signal to an external guideway; 2. In the automatic guidance device according to claim 1, the selector circuit is electrically isolated from the actuator, and at the same time, the position of the ground steering wheel can be mechanically and directly manually controlled by the handwheel. Device characterized in that it has a manual device. 3. In the automatic guidance system according to claim 1, the actuator comprises: a ground steering wheel electric motor; and a tachometer feedback device that detects the voltage drop due to the electric motor and the current flowing through the electric motor, and indicates the response of the electric motor to the actuator control signal. An apparatus comprising an electronic tachometer for generating a signal, and a device for removing a tachometer feedback signal from the actuator control signal and supplying the actuator control signal from which the tachometer feedback signal has been removed to the electric motor.