JPS604484B2 - Reverse direction guide device for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powered vehicle cocoon guide system, and more particularly to a wire-following guide system for a lift truck.

If a lift truck is used for cargo handling operations, cases and items can be loaded and unloaded from a non-mobile loading platform even when the storage aisle is narrow.

The above-mentioned lift truck is provided with a lifting platform, on which an operator rides along to take out predetermined items from a mobile loading platform or storage module. The operator's cab for the car noodles is attached to the lifting platform, so that the operator can ride on the lifting platform. The passageway is extremely narrow, sometimes only about 47 feet wide. In the guide device described in the application filed by the present applicant in Tokusei No. 51-138558 (Tokukan Sho 53-64357), the title of the invention is "Automatic guide device for lift truck," The operator has three operating modes:
That is, it is provided so that one of a manual mode that does not use a guidance device, a power steering manual control mode, and an automatic guidance mode can be selected. Similar to the "automatic guide device for a lift truck" of the applicant's invention, many self-guided lift trucks have a pair of non-steerable wheels with fixed axles and a wheel that is normally fixed relative to the lift truck's normal direction of travel. and one steerable wheel located at the front.

A detection device for detecting a buried electric wire includes at least a pair of coils spanning the electric wire, and the coil is mounted forward of the fixed axle. The reason why the coil is placed in front of the fixed axle is to ensure stable operation of the servo mechanism. In order to maintain stable operation even when the axle moves backwards, a pair of auxiliary coils must be provided so that when the vehicle moves backwards, the auxiliary coil precedes the non-steered wheels. No. For example, in the car steel disclosed in U.S. Pat. No. 3,667,564 to Schnell, 2
Pairs of control wheels are provided, one pair of the control wheels being mechanically raised and out of engagement with the ground when the wheels move forward, and lowered and engaged with the ground when the wheels move backward. It is set in. Regular steering wheels must be installed so that they do not rotate about the vertical axis when reversing. A detection coil used when reversing the vehicle is also provided to move up and down depending on the direction of movement of the vehicle. However, such a mechanism is rather complicated and inconvenient. Furthermore, there is the problem that when an item placed on the fixed axle, i.e. on the forklift itself, is lowered to the ground, the item collides with a detection coil located at the rear of the axle under the forklift. The above-mentioned drawbacks of the prior art can be overcome with the present invention relating to self-guided car steel.

The Kurumatai according to the present invention automatically follows a travel path provided externally, and has at least one part that engages with the ground.
two steerable guide wheels, a detection means for generating a position error signal representative of the position of the wheel with respect to the traveling path, and a detection means connected to the ground-engaging wheel and receiving a steering control signal to steer the vehicle. and steering circuit means for receiving the position error signal and generating a first steering control signal for controlling the steering motor to automatically cause the axle to follow an external path. In the present invention, an improvement is made to the detector means, which generates a position error signal relative to a virtual detection point at the rear of the vehicle, so that when the vehicle moves backward, the detector means generates a relative position error signal. It is provided to guide the wheel. In a preferred embodiment of the invention, a buried electrical wire carrying electrical current is used as a means to transfer the vehicle steel.

The detection means includes a pair of front detection coils and a pair of rear detection coils, each pair of said coils being normally mounted on the axle so as to straddle said buried electric wire. The voltage produced by each pair of coils is arranged to represent the difference in voltage produced within the two coils contained in each pair. Furthermore, the detector means also contain means for generating a position error signal (V) relative to the virtual detection point according to the following formula: V=(10K)R-KF where R = Output difference between the rear pair of detection coils F = Output difference between the front pair of detection coils K = The distance between the rear detection coil pair and the virtual detection point divided by the distance between the rear detection coil pair and the front detection coil pair Equal constants.

Another less advantageous embodiment is formed by both left and right error coils placed on the left and right sides of the embedded wire on the vehicle steel, and a direction detection coil for detecting the angle of the vehicle steel with respect to the embedded wire. An embodiment can be considered in which a virtual detection point position error signal is generated.

If the angle between the coil and the buried electric wire is 4 mm, the output of the direction detection coil is proportional to the angle of the angle. Additionally, the detector means includes means for generating a position error signal for the virtual detection point according to the following formula: V=L-R+KJ However, K is a constant determined in part by the maximum output of the direction detection coil and the distance between the position detection coil and the virtual detection point, and L and R are the outputs of the left and right error coils, respectively. be.

However, the above embodiment is not very advantageous because it is too sensitive to the straightness of the buried wire. Even the slightest bend in a buried wire can greatly amplify the effect and cause harmful false signals to be generated. Therefore, an object of the present invention is to provide a guide device for a cargo truck driver that has a built-in power, and to be able to guide the freight truck driver even when the axle moves backward without installing a detection coil in front of the truck steel. The point is that it provides a guide device that can be tightened.

Another object of the present invention is to provide a guide device for cargo wheels with built-in power, which detects the position and angle with respect to buried electric wires and generates a position error signal with respect to a virtual detection point in front of the vehicle steel. The main point is to provide a guiding device that can

Objects, features, and advantages of the present invention will become apparent with reference to the following preferred embodiments.

1, 2 and 3 show a lift truck equipped with a guiding device according to the present invention,
The trucks will be made of conventional steel.

At the rear is a housing 12 containing the electric motor and battery that drives the lift truck. As shown in Figure 2,
The leftmost guide wheel 14 engages the ground and can rotate in a horizontal plane about a vertical axis, said vertical axis being driven by an electric motor inside the housing 12. As shown in FIG. 2, a pair of horizontally separated members 16 are connected to the IJ.
A pair of roller wheels 18 extending from the right end of the foot truck and engaging the ground on fixed axles, each member of which cannot rotate.
have. A forklift assembly 20 is supported on a vertical post 22 extending upwardly from the horizontal member 16. The forklift assembly includes an operator compartment 24,
A control console 26 is contained within the chamber 24 . The operator uses the control mode selection handle 74 to select manual control,
You can select between power control and automatic guidance operation modes. As mentioned above, the operating mechanism in each of the above modes is as follows.
The invention is described in detail in the application No. 57) entitled "Automatic Guide Device for Lift Trucks." The forklift assembly is raised and lowered on the vertical column 22 by an operator's operation, but the method is the same as the conventional lifting technique and will not be described in further detail. The orientation of the guide wheels 14 in contact with the ground is indicated by a rotation pointer 28 on the rear housing 12 of the lift truck 10. The ft-truck described above is of the same type as that used from the subordinate side.

In order to modify the lift truck 10 described above to be compatible with the guide device according to the invention, on the underside of the lift truck, immediately after the guide wheels 14, along the axis of symmetry of the strategist:
An advancement coil assembly or forward sensing coil assembly 30 is provided. The normal forward direction of the sister car 10 is to the left as indicated by the arrow 5 in FIG. Rotation pointer 2
A negative return ring detector 32 is mounted on the rotation pointer 8 to detect the angular position of the rotation pointer 28. A reverse coil assembly, or rear sensing coil assembly 31, is mounted along an axis of symmetry on the underside of the lift truck between the forward sensing coil assembly 30 and the roller wheel 18 having a fixed axle. When operating in automatic guidance mode, lift truck 1 river bed 3
6. Straddle the buried electric wire 34 below. The electric wire 34 has 6. A Hz conductor drive unit 38 is connected to supply a high frequency signal. As will be explained in more detail below, when operating in automatic guidance mode, the lift truck 10 is centered on the buried wire, and the detection coil assembly that straddles the wire picks up signals on the wire to provide an electronic guidance system. send to The guiding device is connected to the guiding wheels 14 by means of an electric motor unit which will be explained below.
to steer the lift truck 10 along the power line 34. A typical arrangement of buried wires 34 is shown in FIG. In the figure, the buried electric wire 34 passes through a plurality of storage shelves 40 and draws a curve. The lift truck is manually maneuvered by power steering into the vicinity of the electrical lines 34 within the storage shed in a manner described in detail below.

When the lift truck 10 approaches the power line 34, the operator switches on the guidance mechanism to switch to autopilot mode. If the lift truck moves away from the power line 34 after crossing over it, or if the lift truck moves relatively close to the power line 34 and attempts to move away from the power line 34 again,
The guide system electronically anchors the lift truck onto the wire and guides it along the storage shelf until the operator stops the lift truck. Next, the electronic detector portion of the guide device will be described in detail with reference to FIGS. 4, 5, and 6. Buried electric wire 3
The electromagnetic field radiated by the alternating current flowing through the sixth
This is indicated by magnetic field lines 156 in the figure. The front coil detector assembly mounted on the lift truck contains left and right reference coils 160, 158 and left and right error coils 162, 164. The distinction between right and left is determined in Fig. 4 when looking in the forward direction indicated by the arrow, and in Fig. 6, when the observer stands behind the coil and faces in the forward direction (left). You can decide based on what you see. Reference coils 158, 160' are approximately 1
The coils are spaced approximately 9.5 inches (7.5 inches) apart, so that each coil is spaced approximately 9.5 skins (3.75 inches) horizontally from the buried wire. Error coils 162, 164
are spaced approximately 37 skins (14.5 inches) apart from each other, so there is a horizontal distance of approximately 18.4 cm (7 inches) from buried power lines.
．． 25 inches) spaced apart. The rear detection coil assembly 31 is located about 60c from the front detection coil assembly 30 (
2 feet) and contains left and right detection coils 35, 33 spaced approximately 7.5 inches apart from each other on either side of the buried wire. That is, each coil is spaced approximately 3.75 inches horizontally from the wire. The rear detection coil assembly is located approximately 2.4 skins (8 feet) in front of the virtual detection point 29. Then the fourth
See diagram. It is now assumed that the strategist has moved off the guide path and that the axis of symmetry 34' of the vehicle steel, indicated by the broken line in FIG. The manner in which the guide device according to the invention generates an error signal when the driver is traveling in the forward direction, ie in the direction of arrow 5, is detailed below, and is described in detail in the applicant's above-mentioned “Lift・It is also detailed in ``Automatic Guidance Device for Trucks''. However, when the vehicle moves backward, the positional error (V) between the virtual detection points 29 and 29', which are located a certain distance behind the rear detector, is given by the following formula based on geometric considerations. It will be done.
V=R-(F-R) stage V=(10DV/DS)R-device where: F=error in front detector 30, i.e. coil 160
and 158 output difference R = error in rear detector 31, i.e., difference in outputs of coils 35 and 33 ○v = distance between rear detection coil assembly 31 and virtual detection point 29 Ds = detection coil assembly For example, if detectors 30 and 31 are 60c (2 feet) apart and the virtual detection point is 3 skins (10 feet) behind rear detection coil assembly 30, then the distance ratio K is 10/2=5, so the virtual detector signal is 6 times the rear detector signal minus 5 times the front detector signal.

Since the error signal is given as the difference between two large numbers, the detector characteristics must be extremely accurate.

For example, if 5% nonlinearity exists in the characteristics of the rear detector, nonlinearity of 5×5:25% appears in the virtual detector output. Since a change in the detection sensitivity of the detector appears as a change in the loop gain, linearity of the detector characteristics is an important factor for stable and accurate servo operation. When the detector sensitivity is increased, a problem arises in that noise signals from the drive motor are easily picked up. In order to obtain a coil that has excellent linearity and reproducibility and is difficult to pick up noise signals, it is preferable to use a highly rigid sandwich structure as shown in FIG. coil 1
58 etc. are horizontally mounted on the printed circuit board by lead wires 159. Each lead wire of the coil is connected to each other by a printed circuit, and the connection method will be described later. On the side of the substrate 157 opposite the coil is a rubber sheet approximately 0.32 arc (1'8 inch) thick, approximately 0.015 arc (0.006 inch) thick.
5 arc x 17.7 ka (2 inch x 7 inch) plate piece 163 of mu-metal with a thickness of about 0.32 arc (1/2 inch)
An assembly containing a piece of cold rolled steel sheet 165 8 inches thick is secured. The mu-metal plate piece 163 terminates near the inside of the detection coil, thereby providing a low reluctance horizontal return path for the magnetic field lines 156 emanating from the buried guide wire 34. The presence of the return path increases the detector output and reduces the response to noise signals from the steel drive motor. Furthermore, the action of the mu-metal linearizes the detector characteristics and reduces the variation in the detector characteristics due to the steel track components. This effect of Mu-metal is extremely important because the extent to which the magnetic field lines emanating from buried power lines are distorted by the steel parts of the truck is different at the front and rear of the truck. Nonlinearities in the detector characteristics resulting from front and back misalignment appear greatly magnified in the final virtual detector characteristics. Furthermore, by using mu-metal, a very thin detector assembly can be obtained. In one embodiment, the detection coil is a 5 hHy radio frequency choke coil.

Both detector assemblies 30 and 31 have the above configuration. The operation of the guide device according to the invention will now be described in more detail with reference to FIGS. 7A and 7B. Opposite phase output RF from right reference coil 158 and left reference coil 160
and -LF are applied to the negative and positive input terminals of summing junction 104, respectively, through independent variable gain transconductance amplifiers 102, 101. The output from the summing junction 104 is applied to the input of an automatic gain controlled rectifying amplifier 106 via a 6.2 arc Hz filter 05. The output of automatic gain control rectifying amplifier 106 is applied to the DC gain control input terminals of variable gain transconductance amplifiers 101 and 102. The outputs of amplifiers 101 and 102 are proportional to the gain controlled DC input. When such a loop circuit is used, the gains of the amplifiers 101 and 102 are controlled so that the sum of the outputs of the left and right reference coils becomes
can be made to have a constant value at the output terminal of. As described above, the difference between the left and right reference coil outputs becomes less sensitive to the distance from the buried electric wire 34, and linearity is improved. Similar to the front detector, the opposite phase outputs LR and RR of the left and right detection coils 35 and 33 of the rear detector are also applied to the negative and positive inputs of the summing junction 109 via variable gain transconductance amplifiers 108 and 107, respectively. be done. Output LR+RR from summing junction 109
is applied to an automatic gain control rectifying amplifier 111 through a 6.2 Hz band filter 110. The output of the automatic gain control rectifying amplifier 111 is connected to the switching "contact" 1.12 of a one-circuit two-contact electronic switch. Switch 112 is operated by wheel direction detection logic 114. When the vehicle is moving backwards, the equivalent bushing point 112 is connected to the DC gain control input terminals of the transconductance amplifiers 107, 108 to supply the output of the automatic gain control rectifying amplifier 111 thereto. When the car is moving forward, the output of the automatic gain control rectifying amplifier is connected to the gain control input terminals of a pair of transconductance amplifiers 100 and 103. Amplifier 100' is left error coil 164
The output of the right error coil 16 is supplied to the amplifier 103.
2 outputs are provided. The output signals LF○, RF0 from amplifiers 100, 103 are applied to the negative and positive inputs of summing junction 109, respectively. switch 112
When in the forward mode, amplifiers 107 and 108 are not supplied with DC gain control current, they are actually disconnected, and summing junction 109 is supplied with only the LF○ and -RFO signals. Conversely, when the switch 112 is in the reverse mode side, no DC gain control current is supplied to the amplifiers 100 and 103, and the amplifiers are actually cut off and the L
Only the R and one RR signals are applied to junction 109. The purpose of providing a loop containing the band filter 110 and the automatic gain control rectifying amplifier 111 is to
As in the case of 02, the gain of each amplifier is adjusted to keep the sum of the left and right detection coil signals applied to the junction 109 at a constant value at the output terminal of the Obijo filter 110. The outputs RF and -LF of amplifiers 102, 101 are also applied to the input terminal of subtraction junction 113, whose output LF
-RF is applied to the input of transconductance amplifier 115. The output of transconductance amplifier 115 is applied to summing point 116. The summing junction 116 has the effect of amplifying its output to five times (xK) the input.

The negative and positive inputs of summing junction 109 are further applied to a second subtracting junction 117 whose output is fed to a transconductance amplifier 118 .

The output of transconductance amplifier 118 is RR-LR in reverse mode and RFO-LF in forward mode 0.
O, but said output is also fed to one of the inputs of summing junction 116. The output of amplifier 118 is also fed to another summing junction 119. The other input to summing junction 119 is a CMOS electronic switch 120 which is connected to the output of summing junction 116. The above switch is closed in reverse mode,
Open in forward mode. As mentioned above, in reverse mode, the output of the summing junctions 1 1 9 is given by the formula {(RR-LR)
+(LF-RF)} x50(RR-LR)=6(RR
-LR)-5(RF-LF) of the rear detector signal
It can be seen that the value obtained by subtracting 5 times the forward detector signal from this value is obtained.

In this example, the distance from the rear detector to the virtual detection point is five times the spacing between detector assemblies 30 and 31. When calculating the difference signal, instead of subtracting RF-LF from the RR-LR signal, perform an equivalent operation, that is, RR-LR plus LF-LF.
Add RF.

Adjustment semi-fixed resistors are provided to eliminate variations in the detection coil output and circuit gain. In forward mode, a signal RFO-LFO corresponding to the difference between left and right error coils 162, 164 is applied to the output of addition degree point 119. A signal obtained by radiating the sum of the left and right reference coil signals LF and RF is used as a reference signal for the synchronous detector 180.
The operation of the synchronous detector will be described later. The traveling direction of the wheels is determined by the armature voltage of the drive motor and the forward/reverse switch 121.
It can be determined from.

See also FIG. 13. Even if a command is issued to reverse the direction of travel of the wheels, due to the inertia of the car body, the car copper will continue to move in the original direction for a while. During that time, the armature voltage is reversed. The driver's actual direction of travel is detected by wheel direction detection logic circuit 114. Logic circuit 1 above
The output of the fourteen logic latch circuits 124 becomes a truth value only when the wheel is moving in the commanded direction. To avoid unnecessary power being dissipated by the steering motors when the wheels are stationary, an operational time-out circuit 12 is activated under the control of the vehicle direction detection logic circuit 114.
2 closes the electronic CMOS switch 123 and sends the steering control signal only when the movement of the carfish is confirmed by the armature voltage.

The timeout circuit switches immediately when entering the operating state, but operates after a delay of 19 seconds when turning off the guide circuit. The output of the Obijo filter 105 is the inverting amplifier 1.
72 and one arm of potentiometer 174.

The output of the inverting amplifier 172 is labeled with the symbol "1 (LF + RF)". The above output is potentiometer 174
is connected to the other arm of the The movable point of the potentiometer 174 is mechanically connected to the guide wheel 14 that engages the ground. The above connected state is potentiometer 17
4 and the electric motor 44 by a broken line. Therefore, the angle of the guide wheel 14 is reflected in the position of the movable contact of the potentiometer 174. 1 and 2, the detector 32 mounted on the rotary pointer 28 provided at the front of the housing 12 of the lift truck is comprised of the potentiometer 174 and a mechanical It is a connection. When the guide wheel 14 is rotated all the way to the right, the movable contact of the potentiometer 174 moves to the signal 1 (LF 1 R).
Move to the position where it receives F). When the guide wheel is rotated fully to the left, the movable dovetail point of the potentiometer 174 comes to the opposite position and receives a signal (LF + RF). The signal obtained from the movable rock is used as a negative return signal, so FB
If we decide to entrust this FB signal to the addition junction point 119
is applied to The output signal from the summing junction 119 is "R-L+FB", where R-L is 6(RR-LR)-5(RF-LF) in reverse mode and RFO-LFO in forward mode. . This signal is applied to the input terminal of operational amplifier 176. The output signal R−L−FB of the amplifier 176 passes through the loop gain adjustment resistor 178 and enters the negative input terminal of the synchronous detector 180.

The amplified reference signal obtained at the output of amplifier 172 - (
LF+RF) enters the other input terminal of the synchronous detector 180. A synchronous detector has the function of detecting a signal component that is in phase with the reference signal. That is, the phase difference between the reference signal and the error signal is 18
00, the synchronous detector will output the error signal R.
-L+FB is integrated, and the phase difference between the reference signal and error signal is 1.
If the number is 800 or more, the synchronous detector outputs an error signal R-L+.
Invert and integrate FB. In this way, spurious noise signals are averaged to zero. Synchronous detector 180
The output of is a DC signal whose magnitude represents the magnitude of the position error of the lift truck 10 and whose polarity represents which side of the lift truck 10 is relative to the buried power line. The above output is 5H to remove high frequency pulses.
Passed through a Z low pass filter 84, the output of the filter 184 is advanced in phase by about 60 degrees through a 0.1-1.2 day Z phase shift filter to prevent feedback loop oscillations. The output of the phase shift filter 86 is one circuit two-contact electronic switch 188.
connected to two terminals. The other terminal of switch 188 is connected to power steering tachometer 46, which is pivoted by steering wheel 74.

The output of the phase shift filter 86 is further connected to an allowable logic circuit (ena
blelogic) 1 90' is supplied. The other input of the tolerance logic circuit 190 is connected to the output of a signal amplitude detector 192 whose input is provided by the inverting amplifier 172 . The role of the acceptance logic circuit 190 is to determine whether or not the guiding device has detected a buried electric wire.

The output of the signal amplitude detector 192 acts as a threshold signal,
The above threshold signal is simply an amplified reference signal -(LF+RF). This function value signal and the phase shift filter 186
The output signal of the tolerance logic circuit 19 determines whether the signal has sufficient strength to guide the guide circuit, and the sign of the rate of change and polarity of the error signal determines whether or not the lift signal is strong enough to guide the guide circuit. It is determined whether the truck 10 has once crossed the electric wire and is moving away from the electric wire, or whether the truck 10 has once approached the electric wire sufficiently and is moving away from the electric wire again. Next, referring to FIG. 10, reference signal -(LF+
RF) The drawing shows (L'+R') and the error signal L-R.
A waveform diagram of is drawn with respect to the position of the buried electric wire 34.

As can be readily seen from the figure, the amplitude of the reference signal is
When the truck comes directly over the buried power lines, it creates a slight depression. On the other hand, the error signal indicates that the lift truck
It passes zero when it comes directly above . When the error signal and the reference signal are on the same side of the machine axis, these signals are in phase, and when they are on opposite sides of the horizontal axis, they are out of phase.
When lift truck 10 attempts to cross a power line, the output signal of the synchronous detector changes from one polarity to the other and the error signal approaches zero. When the above state occurs, the trigger of the allowable logic circuit 190 is pulled and the electronic switch 18
8 is activated to connect the output of phase shift filter 86 to the positive input of summing junction 194 . On the other hand, until the output signal of the synchronous detector reaches the above state, the allowable logic circuit 1
90 connects a power steering tachometer to the positive input of summing junction 194. The manual one-shot changeover switch 146 is also connected to the allowable logic circuit 1901,
The operator can manually toggle switch 188 to connect the power steering tachometer to summing junction 194 when steering handle 74 is in the intermediate position. In addition, switch 188 adds phase shift filter 186 to summing junction 194.
If A is in the position connected to A, the permissive logic circuit 190 turns on the "AUTO" indicator lamp 136. Addition junction 1
The output of 94 is applied to a pulse width modulated power drive circuit 196. The output of the power drive circuit 196 is a series of pulses, the pulse width of which is proportional to the magnitude of the error signal, and the polarity of which corresponds to the polarity of the output signal of the synchronous detector 180. That is, the output pulse of the power drive circuit 196. Extremely low weight
It varies depending on which side of the buried wire 34 the track 10 is on. One output lead of power drive circuit 196 is connected directly to electric motor 44 . The other output lead is connected to the motor through a low resistance 198. The electronic tachometer 200 has three input terminals, which are connected to the power drive circuit 196 and the output circuit of the electric motor 44 to detect voltage drops across both the electric motor 44 and the resistor 198. . The electric motor 44 actually acts like a generator. By knowing how much of the voltage drop across the motor is due to resistance losses in the armature, if the value of the current flowing into the motor from the voltage drop across resistor 198 is known, , the magnitude of the back electromotive force generated inside the motor 44 can be calculated. The above information is calculated analogously within the electronic tachometer and produces a negative feedback signal that is subtracted at junction 194. The motor is braked by the negative feedback signal to prevent oscillation due to overshoot. This overshoot can occur due to the main negative feedback loop through potentiometer 174 if the negative feedback signal is not used. Next, referring to Figures 8 and 9,
The circuits shown in FIGS. A and 7B will be explained in more detail.

Parts that are the same as those shown in FIGS. 7A and 7B are enclosed in broken lines and given the same reference numerals. Reference signal 1 (LF 1R
F) is applied to one input terminal of a synchronous detector 180 that acts as a synchronous detection circuit. The output of the synchronous detector 180 is a 5Hz low-pass filter consisting of a capacitor connected to the output of the synchronous detector and the circuit ground potential, and a resistor connected to the output of the synchronous detector and the signal ground potential. 84. Note that some of the circuit components described below are connected to circuit ground potential while others are connected to signal ground potential. The reason for this is as shown at the bottom of FIG.
This is because the circuit supplies an output of 112V with respect to the circuit ground potential, and the output terminal of 15V is connected to the signal ground potential. The output of low pass filter 184 is applied to one input terminal of differential amplifier 204.

The other input terminal of the differential amplifier 204 is supplied with the output of a phase shift filter 86, and the phase shift filter 86 is composed of a parallel RC circuit inserted into the negative feedback path of the amplifier 204. The output of the inverting amplifier circuit IT2 is sent to the amplitude detector 19.
2 is also applied.

The amplitude detector 192 includes an input resistor 206 connected to the cathode of a diode 208 whose anode is connected to the input terminal of a differential amplifier 210. The other input terminal of amplifier 210 is connected to circuit ground potential via resistor 212;
Furthermore, it is connected to the anode of the diode 208 via a capacitor 214. A resistor 21 is connected to the anode of the diode 208.
A bias of 12 volts is applied through 6. The output signal of amplifier 210 can be considered to be a threshold signal, and the output signal of conductor 2
20 to allow logic circuit 190'. 1
The “manual” side terminal of the circuit 2 contact switch 146 is connected to the conductor 22
The river is connected.

The movable contact of switch 146 is connected to circuit ground potential. Therefore, when switch 146 is turned to the "manual" position,
Conductor 220 is grounded, and the dark value signal is no longer provided to the permissive logic circuit as if the dark value signal were not occurring. As shown above, the state where the function value signal is not generated, and
Both states in which the function value signal is asserted will be referred to as logic zero states in the following discussion. The conductor 22 is connected to the input of an inverting amplifier 222 whose output is fed to one input of a NOR gate 224 .
The output of the NOR gate is supplied to one input of OR gate 226 and also to the control input of CMOS switch 228 and the input of inverting amplifier 230. Above NO
The NOR gate 22 is connected to the other input terminal of the R gate 224.
6 outputs are provided. The output of inverting amplifier 230 is connected to the base of NPN transistor 234 via resistor 232. The emitter of the transistor is connected to the circuit ground point. A light emitting diode 138 is connected in series between the positive 24 volt power supply and the collector of the transistor 234.
is inserted. The output of the inverting amplifier 230 is also
It is connected to the control input terminal of the S switch 236, and the CM
The OS switch input is provided from the output of the power steering tachometer 46.

The outputs of CMOS switches 228 and 236 are combined and applied to the input of differential amplifier 238. NOR gate 22
The other input of 6 is provided from the output of exclusive OR gate 240.

As will be explained in more detail later, the output of the OR gate 240 determines whether the rate of change and sign of the polarity of the error signal after passing through the synchronous detector are in a combination that should "turn on" the logic circuit. , is a signal indicating whether the combination is such that the guide device captures the buried electric wire 34 and automatically follows it. As previously mentioned, when switch 146 is in manual mode or when there is no threshold signal on conductor 220, a logic 1 appears on the corresponding input terminal of NOR gate 224.

In this case, NOR gates 224 and 226 are flipflops. When a logic 1 signal from the inverting amplifier 222 is applied to the NOR gate 224, the guide device is in a reset state in which it is not activated. As a result, NOR
The output of gate 224 is a logic zero, and NOR gate 22
The output of 6 is a logic 1 regardless of the output of exclusive OR gate 240. A logic zero signal on NOR gate 224 causes transistor 234 to conduct and light emitting diode 138 to illuminate. The above logic zero signal opens CMOS switch 228. Furthermore, since there is an inverting amplifier 230, the CMOS switch 2
36 closes. The CMOS switch 228 opens and the CM
When OS switch 236 is closed, the output of power steering tachometer 46 is applied to the input of differential amplifier 238.

The output of amplifier 238 may be a speed command or, in effect, a maneuver control signal to the electric motor. The polarity of the signal determines the direction of rotation of the motor. When switch 146 is turned to the "eye movement" position as shown in FIG. 8, a threshold signal appears on conductor 220 and the output of inverting amplifier 222 becomes a logic zero.

Assume that the rate of change and the sign of the polarity of the synchronously detected error signal are not equal, and that the output of the exclusive OR gate 240 is also a logic zero, and that the output of the NOR gate 224 also remains a logic zero. Assuming that, NOR gate 22
The output of 6 becomes logic 1. In this case switch 146
Even when the lift truck is in the "auto" position, it continues to operate in power steering manual control mode until the sign and polarity of the rate of change of the synchronous detection error signal are equal. When the sign of the rate of change of the synchronously detected error signal and the characteristic become equal, the output of the exclusive OR gate 240 becomes logic 1 and NO.
The output of R gate 226 will be a logic zero. NOR gate 2
If a logic zero enters two inputs of 24 at the same time, the output is a logic 1.
, and the flip-flop is latched. When the output of the NOR gate becomes a logic 1, CMOS switch 228 becomes conductive and CMOS switch 236 becomes non-conductive.

The light emitting diode 138 receiving the control signal from the inverting amplifier 230 is also turned off. In this case, the guidance control input signal obtained from the detection coil is applied to the input of amplifier 238. The lift truck 10 is thus automatically steered. The output of the amplifier 204 is applied to one input terminal of the amplifier 242 in order to know the polarity and rate of change of the error signal, and the other input terminal of the amplifier 242 is grounded. The output of amplifier 242 is applied to exclusive OR gate 240'. The output of amplifier 204 is also applied to one input terminal of differential amplifier 244 and further applied to the other input terminal of differential amplifier 244 via resistor 246 . The second input terminal is also connected to circuit ground potential via a capacitor 248. The output of amplifier 244 is connected to the other input terminal of exclusive OR gate 240. The output of amplifier 242 represents the polarity of the output of amplifier 204, and the output of amplifier 244 represents the rate of change of the same signal. Once the value signal is generated, two amplifiers 242, 244 and an exclusive OR gate 240 examine the sign of the rate of change and polarity of the error signal to determine whether the lift truck 10 is moving away from the wire. is detected.If the sign of the change rate and polarity of the error signal match,
The output of exclusive OR gate 240 becomes a logic one. The guided flip-flop containing NOR gates 224, 226 effectively acts as a latch flip-flop.

Once flip-flop 224 is in automatic mode, the signal appearing at the output of inverting amplifier 222 changes state to indicate whether switch 146 has been flipped to "manual" mode or the threshold signal has disappeared. The original state will not be restored unless some event is detected. Dark value signal exists and switch 14
6 is in the auto position, no matter how the output of exclusive OR gate 240 changes, the state of the flip-flop does not change. In the event that the dark value signal is somehow lost, the output of NOR gate 224 is passed through series RC circuit 246 to alert the operator that the state of the guiding flip-flop has changed. It is applied to a NAND gate 248 such that a logic zero is a truth value.

The input terminal of the NAND gate 248 is suitably connected to 112
The bolt is biased. NAND gate 2
The other input terminal of NAND gate 248 is connected to the auto-J contact of switch 146 and is applied to light emitting diode 136 through resistor 250.
It is connected to the base of a PN transistor 252, whose emitter is connected to circuit ground potential and whose collector is connected to a positive 24 volt power supply in series with the warning lamp. In operation, the input signal provided from switch 146 to NAND gate 248 is a logic zero.

If the guide flip-flop is reset for some reason and the output of the NOR gate 224 becomes a logic zero, the NA
The output of ND gate 248 becomes a logic one, transistor 252 becomes conductive, and alarm device 254 is activated. In the event of a power failure, amplifier 256 activates alarm device 254. One input terminal of the amplifier 256 is connected to the 112 volt power supply via a diode 258, and the output terminal is connected to the base of the transistor 252 via a resistor 260. Next, refer to FIG.

The speed command signal from amplifier 238 is output to comparator 262.
and the corresponding input terminal of the second comparator 264. The output of amplifier 262 is applied to an exclusive OR gate 266, an input of an inverting amplifier 268, and then through a parallel diode and resistor circuit 270 to one input terminal of amplifier 272. The input to amplifier 272 is connected through a capacitor 274 to circuit ground potential. The output of inverting amplifier 268 enters amplifier 278 through a resistor-diode parallel circuit 276 similar to 270. The input to amplifier 278 is connected through a capacitor 280 to circuit ground potential. The amplifier 272,2
The other input terminal of 78 is connected to a 112 volt power source. The output of amplifier 278 is NPN transistor 28
Connected to the base of 2.

The collector of the transistor 282 is connected to the outside of a PNP transistor 286 via a resistor 284. The external emitter of transistor 286 is connected directly to the 124 volt power supply for the motor. The above transistor 286
The base of is forward biased from a 124 volt supply through a suitable resistor. The output of amplifier 272 is connected to the base of NPN transistor 288.

The collector of the above NPN transistor 288 is the resistor 29
0 to the collector of PNP transistor 292. The emitter of transistor 292 is
It is connected directly to the 4 volt supply, and the base is biased to the 124 volt supply or otherwise through appropriate resistors. The bases of transistors 286 and 292 are connected to the collector of PNP transistor 294, and the emitter of transistor 294 is connected to circuit ground potential. To control the direction of current to motor 44, the collector of transistor 286 is connected to the base of PNP transistor 296, and the emitter of transistor 296 is connected to the 124 volt power supply.

The collector of transistor 296 is connected to the collector of NPN transistor 300 through junction 298. The base and emitter of transistor 300 are connected to the emitter of transistor 288 and junction 302, respectively.
The emitter of transistor 282 is NPN transistor 3
04, the emitter of transistor 304 is connected to junction 302, and the collector is connected to junction 306. The collector of transistor 292 is connected to the base of PNP transistor 308 and PNP transistor 3
The 08 emitter is connected to a 124 volt battery power source for the motor.

The collector of transistor 308 is connected to junction 306. The junction point 302 is a resistance line 3 with a very low value.
It is connected to the negative side terminal of the motor power supply via 10. One end of motor 44 passes through junction 298 and resistor 19
8 to junction 306. The output of exclusive OR gate 266 is applied to one input of NOR gate 314.

The output of the NOR gate 314 is applied to a combination 316 of an inverting amplifier and an operational amplifier, said combination 316 being N
It has the effect of turning OR gate 314 into a 200 microsecond monostable multipiperator. NOR gate 314
, effectively the output of the multipipulator, is applied to the base of PNP transistor 294 via an inverting amplifier 318. When any of the inputs of NOR gate 314 becomes a logic 1, the output of the NOR gate becomes a logic zero, transistor 294 becomes conductive, and transistor 286 becomes conductive.
, 292 are forward biased.

When transistors 286 and 292 are forward biased, the bases and emitters of the transistors 296 and 308 are shorted, respectively.
becomes non-conductive and the motor stops rotating. If all inputs to NOR gate 314 are logic zeros, its output will be a logic one and transistors 286 and 292 will be nonconductive. Assuming that the output of amplifier 262 becomes a logic 1, the output of amplifier 272 causes transistor 288 to conduct, such that the bases of PNP transistor 308 and NPN transistor 300 are connected to resistor 29, for example about 6000 Ω.
The transistors 308 and 30 are connected through 0 and are conductive.

In this case, a 24 volt battery power supply, transistor 30
8, resistor 198, motor 44, transistor 300,
A current path is opened through resistor 310 and the negative terminal of the battery. Therefore, the motor rotates in a direction determined by the current direction. Similarly, amplifier 262
Assuming that the output of becomes a value equivalent to a logical zero,
Each of the above transistors becomes non-conductive, and instead, transistor 28 passes through inverting amplifier 268 and amplifier 278.
2, 304, and 296 conduct and supply current to motor 44. However, the current flows in the opposite direction to that in the above case, and the motor rotates in the opposite direction. As mentioned above, the direction of rotation of the motor changes depending on the polarity of the output of amplifier 262. As detailed below, the polarity of the output signal of amplifier 262 is determined by the polarity of the speed command from amplifier 238 and electronic tachometer 2.
It is determined by the polarity of the output of 00. Electronic tachometer 2 as previously described in connection with FIGS. 7A and 7B.
00 is connected in parallel to the motor and resistor 198.

As shown in FIG.
20 and 322, and each of the aforementioned conductors is connected to point 298, the junction of the motor and resistor 198, and point 306, respectively. Conductors 312, 320, and 322 provide three inputs to electronic tachometer 200. The electronic tachometer 200 includes a differential amplifier 324 whose input is connected to the motor and whose output is connected to the other input terminals of the amplifiers 262 and 264 that are not connected to the output of the amplifier 238. Connected to the terminal. As above,
The outputs of amplifiers 262 and 264 are connected to exclusive OR gate 266
is applied to the input of The exclusive OR gate acts as a controlled inverting amplifier, and the output of the controlled inverting amplifier is such that when the speed command signal and the tachometer output signal have the same polarity and the absolute value of the speed command signal is greater than the absolute value of the tachometer output signal. becomes a logical zero. If the polarities of the two signals are opposite, the output of OR gate 266 will be a logic zero. Under other conditions, the output of OR gate 266 will be a logic 1 and motor 44 will stop. The minimum time interval for motor 44 to stop is approximately 200 French seconds. The value of the upper limit time interval is determined by the circuit constants of the multipipulator circuit 316. The length of time that motor 44 is energized is determined by the time it takes for the output signal from electronic tachometer 200 to match the speed command from amplifier 238.
To prevent the pair of transistors 296 and 300 or 308 and 304 from conducting at the same time, a parallel circuit of resistors and diodes 276 and 270 and capacitors 280 and 2 are used.
．． 74 is inserted so that when the polarity of the speed command signal changes, all the power transistors become non-conductive and then another pair becomes conductive. Differential amplifier 326
The two input terminals of the resistor 31 are connected in parallel and act as a torque limiting detector.

The torque limiting detector functions to turn off the power to the electric motor when something becomes entangled with the guide wheel and a current flows to the extent that it causes a failure in the electric motor. If the voltage appearing across resistor 310 increases and exceeds the predetermined value,
The output of the amplifier 326 is a voltage of a magnitude that can be considered a logic 1, and the output is applied to the input of the NOR gate 314. This logic 1 signal cuts the current flowing to the motor. Similarly, a power outage signal from amplifier 256 is applied to NOR gate 3 1 4 to stop the motor when the power supply to the guide circuit fails. Next, the first
1 and 12, a modified embodiment of the reverse guide device according to the invention is shown.

In the embodiment described above, the rear detection coil is not used, and instead, the angle detection coil 125 is arranged near the middle of the left and right reference coils 160 and 158. Angle detection coil 1
25 is similar to the long ferrite core coils sometimes used in antenna coils for portable radios and portable radio direction finders. The coil 125 is placed at a position directly above the buried electric wire 34 in the normal case at the bottom of the car steel. Now, assuming that the strategist is placed exactly above the wire 34, but the direction is shifted by an angle with respect to the wire, the output of the coil 125 will be A sinJ. Here, A is the maximum value of the coil output. It should be noted that when the value of ◇ is very small, the sine of ◇ is equal to the sine of ◇. If the virtual detection point 29' is located behind the fixed axle of the vehicle steel and the vehicle engineer makes an angle of 0 with the buried electric wire 34, the virtual detection point 29' is at a distance d from the electric wire.
It is assumed that there is a deviation by

The distance between the center of the angle detection coil 125 and the virtual detection point is D
p, then the error d is approximately DpSi due to geometric considerations.
It is given in nma. That is, ASinoid A sin? is the output of the coil 125 itself, and since the sky is a constant, the error signal 'arc' can be rewritten.

Here, ◯ indicates the output of the coil 125. A normal position error signal obtained from coils 162, 164 is added to the above error signal. The position error signal represents a distance error between the vehicle steel and the buried electric wire. Therefore, if the outputs of the error coils 162 and 164 are R and L, the error signal finally obtained is R-L+K◇. Then the 12th
See diagram. The circuit of FIG. 12 is derived from the circuit of FIG. 7A with circuit elements 107, 108, 113, 115, 116, 12
0 is omitted. Furthermore, the gain control signals for amplifiers 100 and 103 are provided directly from automatic gain control rectifying amplifier 111 rather than from the terminals of switch 112. The output of angle sensing coil 125 enters a transconductance amplifier 126 whose output is applied to the positive input of summing junction 109 and the positive input of summing junction 117. Therefore, when the switch 112 is turned to the forward mode side, the output of the amplifier 118 becomes RFO-LFO, and when the switch 112 is turned to the reverse mode side, the output of the amplifier 118 becomes RFO-LFO.
26, the output of amplifier 118 is R
FO-LFO+KO. Similar to the embodiment shown in FIG. 7A, the output of amplifier 118 is provided to summing junction 119 and is combined with feedback signal FB at junction 119. The output of junction 119 is routed to switch 123 as in the embodiment of FIG. 7A. As mentioned at the beginning of this specification, the embodiment described above has some disadvantages over the embodiment shown in FIG. 7A because it is more sensitive to the straightness of buried wires. Even a slight bend in the wire can significantly magnify the effect and create a harmful error signal. The above effect can be somewhat reduced by increasing the length of the coil 125 and applying it only to an axle with a relatively small wheelbase. The reason for this is that the projection distance Dp becomes small and the magnification for magnifying the non-straightness of the buried electric wire does not become very large.
The above can be clearly understood, apart from the fact that it is a constant. Therefore, if Dp is reduced by some method, the effect resulting from the non-straightness of the buried electric wire will be reduced. Although the present invention has been described in detail with reference to embodiments, it is obvious that changes and modifications may be made without departing from the scope of the invention.

[Brief explanation of the drawing]

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. FIG. 3 is a plan view of a buried wire guideway for a lift truck according to the present invention.
FIG. 4 is a schematic diagram showing the arrangement of detection coils in the embodiment shown in FIG. FIG. 5 is an enlarged, partially exploded, partially cross-sectional, enlarged elevational view of one of the detector assemblies in accordance with the present invention.
FIG. 6 is a schematic enlarged view showing one example of the arrangement of detection coils according to the present invention. 7A and 78 are both schematic configuration diagrams showing the electronic guide device of the present invention. FIGS. 8 and 9 are both schematic diagrams showing in more detail the circuits shown as configuration diagrams in FIGS. 7A and 7B. Figure 10 shows
7A and 7B are output waveform diagrams of the front detector coil of the guide device shown in FIGS. 7A and 7B; FIG. FIG. 11 is a plan view showing another coil arrangement according to the second embodiment of the invention. FIG. 12 is a diagram of a circuit adapted to the second embodiment of the present invention by modifying the configuration diagram shown in FIG. 7. Figure 13 shows 7A,
7B is a schematic diagram showing details of the direction detection logic portion of the circuit of FIG. 7B; FIG. 14... Guide wheel, 30... Front detection coil assembly, 31... Rear detection coil assembly, 44... Maneuver drive motor. FIG. l FIG. 2 FIG. 4 FIG. 3 FIG. 5 FIG. 6 FIG. 7A FIG. 78 FIG. 8 FIG. 9 FIG. 10 FIG. ll FIG. 12 FIG. l3

Claims (1)

[Scope of Claims] 1. A self-guided vehicle of the type that automatically advances along an external path formed by buried electric wires, comprising at least one
A self-guiding vehicle comprising two ground steering wheels and a steering drive device attached to the ground steering wheels for steering the vehicle in response to a steering control signal, wherein the signal output from the buried electric wire is connected to a pair of ground steering wheels. a front detector that detects with a detection coil and generates a position detection signal, and is installed at the rear of the vehicle at a certain distance from the front detector, and detects the position by detecting the signal output from the buried electric wire with a pair of detection coils. A rear detector that generates a signal, and a position detection signal generated from the front detector and a position detection signal generated from the rear detector when the vehicle moves backward, and the following formula V=(1+K)R is used. -KF [However, R = difference in the output of the rear detection coil pair, F = difference in the output of the front detection coil pair, and K = rear detection coil pair and virtual detection for the distance between the front detection coil pair and the rear detection coil pair. A vehicle characterized in that it has a steering control circuit that outputs a steering control signal based on a position error signal (V) represented by a constant equal to the ratio of the distance to a point. 2. The vehicle according to claim 1, which has a pair of wheels on a fixed axle in addition to at least one ground steering wheel, and a front detector pair and a rear detector pair are fixed to the steering wheel. The rear detector is mounted on the vehicle body between the axles so that it is closer to the fixed axle, and in the formula for calculating the signal (V), the rear detector is A vehicle characterized in that a distance ratio (K) between a pair of detection coils and a virtual detection point is greater than 1. 3. A self-guided vehicle according to claim 2, wherein the forward and backward detectors have separate automatic gain control amplifiers to reduce errors caused by variations in vertical distance to the path. Featured vehicles.