JPH0320119B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle traveling system, and more particularly to a traveling control method for an unmanned vehicle such as a forklift truck, which is useful for cargo handling work in warehouses, factories, etc.

Generally, unmanned cargo handling equipment is used to carry out cargo handling operations under adverse conditions, such as in freezers. In this case, in order to automatically drive an unmanned vehicle, there are systems that control the accelerator, brakes, steering, and cargo handling from the ground side.

According to this method, a guide wire is placed on the ground, and the vehicle is guided in the direction of the destination by switching the signals supplied to the guide wire, while the self-propelled vehicle performs predetermined steering control. . In addition, to control the accelerator, brake, and cargo handling, transmitting coils and receiving coils are installed on the ground, and signals are transmitted by guided radio through the vehicle's transmitting and receiving antennas. Furthermore, the accurate stopping or shifting position of an unmanned vehicle can be determined by installing a position detection coil on the ground, by using a lead contact and a magnet, or by using a position sensor using an electromagnetic or optical sensor. FIGS. 1 and 2 show typical system configuration examples of such a vehicle guidance device. FIG. 1 shows the corresponding arrangement relationship between a plurality of stations and a vehicle, and FIG. This figure shows the specific structural relationship between the vehicle and the station when the vehicle is viewed from direction A.

In FIGS. 1 and 2, 1 is a guided vehicle such as a forklift, and 2 is a guiding cable laid on the ground or underground. 3a and 3b are steering coils, 4a is a transmission coil on the vehicle side, and 4b is a reception coil on the vehicle side. Each of the stations ST1, ST2, and ST3 on the ground is provided with a transmitting coil 5a and a receiving coil 5b, respectively. Control signals are supplied to the induction cable 2 and the transmitting/receiving coils 5a and 5b from signal power sources (not shown) each having a predetermined frequency. Vehicle 1 includes a transmitting circuit,
A first control unit 6 consisting of a receiving circuit and various other circuits for performing other necessary operations is mounted, and on the ground side there are a transmitting circuit for supplying a predetermined frequency signal to the transmitting coil 5a, and a receiving coil 5.
A second control unit 7 is provided, which includes a receiving circuit for receiving the signal b and other circuits for performing other necessary operational controls.

In such a conventional vehicle guidance system, a self-propelled vehicle learns the positional relationship of the self-propelled vehicle through a proximity switch 10 installed at each station and a set of transmitting/receiving coils, and detects the position using these proximity switches. A series of controls such as turning off the power, stopping the vehicle, and starting the vehicle are performed by transmitting and receiving signals and predetermined signals via the transmitting and receiving coils. Further, as a signal transmission function, predetermined command signals such as predetermined acceleration commands, deceleration commands, control commands, etc. are given to the self-propelled vehicle 1 from the control unit 7 on the ground side via the transmission coil 5a,
A response signal from the self-propelled vehicle 1 is sent to each command signal from the transmitting coil 4a→receiving coil 5b→control unit 7.
The operation mode of the self-propelled vehicle 1 is managed on the ground side by determining the response signal to the command signal received along the route.

In such a conventional device, steering control is performed while guiding the vehicle in the direction of the destination point by switching the signal supplied to the guidance cable 2. The self-propelled vehicle 1 is driven by an electric motor or an engine. Further, as a steering function, as is well known, when a current of a predetermined frequency is passed through the induction cable 2 buried in the floor surface, an induced magnetic field is generated. This magnetic field is converted into voltage by a steering coil, and this voltage drives a servo motor, etc., thereby guiding the self-propelled vehicle along the guidance cable.

In the conventional travel control method that performs such predetermined operations, the time chart in Figure 3 shows the operation mode during transmission of predetermined signals between the self-propelled vehicle 1 side and the ground side. In this time chart, A to C show the operating states of each part provided on the ground side, and D and E show the operating states of the first control unit mounted on the self-propelled vehicle 1. Moreover, in FIG. 3, _t1 to _t4 indicate time.

Now, as shown in Figure 1, the self-propelled vehicle 1 is at the station.
Assuming that the self-propelled vehicle ₁ is to be guided from station _{ST 1} to station ST ₃ , first, at point t ₁ in FIG. Send to. This command signal _S1 is received on the self-propelled vehicle side through a route from coil 5a (5b) to receiving antenna coil 4a (4b). The first control unit 6 decodes the content of _the received signal _S5 shown in FIG.
or control the brake circuit (not shown) to generate signal S ₅
If the instruction code is "3rd forward speed", the accelerator is operated via the accelerator circuit to bring the vehicle speed to 3rd forward speed. In this way, if the self-propelled vehicle 1 operates the accelerator to the "3rd forward speed" position based on the command signal transmitted from the ground side, then the self-propelled vehicle 1 determines that time t ₃ is reached by the self-propelled vehicle.
The second control unit 7 on the ground side transmits a third response signal _S4 based on the response signal _S4 .
If the received output signal _S2 in FIG. B matches the command code of "3rd forward speed", a starting command is immediately given to the self-propelled vehicle to start and accelerate. In addition, the signal in Figure 3 C
_S3 indicates that the self-propelled vehicle 1 is at station _ST1 .

In such an operation mode during transmission, there is almost no problem when starting a self-propelled vehicle, but for example, when a self-propelled vehicle is moved to an intermediate station during acceleration control,
In ST ₂ , switch the vehicle speed command signal from "3rd speed command" to "2nd speed command", and set the station to "2nd speed command".
This becomes a problem when driving towards the ST ₃ side. That is, the station ST ₂ is located midway through the travel, and is in an accelerating state. Therefore, in the corresponding positional relationship between the transmitting and receiving coils 5a and 5b on the ground side and the transmitting and receiving coils 4a and 4b on the self-propelled vehicle side, for example, only a part of the transmitting and receiving coils on the self-propelled vehicle are on the ground side. In such a case, the output signal level of the receiving coil that receives the command signal or the response signal will be extremely reduced, and the receiving coil will be unable to receive the command signal or the response signal. If reception is lost in this way, the self-propelled vehicle will continue to drive to the target point, station ST ₃ , at its maximum speed of 3rd forward speed, resulting in an overshoot where the vehicle passes the target point. The braking operation itself becomes very unstable. More importantly, even if the correspondence positions of the coils on the self-propelled vehicle side and the ground side are such that reception is possible, since the self-propelled vehicle is in an accelerating state, the condition of the floor surface and cargo Furthermore, the signal level of the received output fluctuates greatly depending on the state of the vehicle speed, etc., and the signal is not accurately transmitted to the other party, making the transmission operation itself extremely unstable, such as erroneous operation of the accelerator position or misunderstanding of the response signal. The problem is that the vehicle becomes unstable and highly accurate driving control cannot be performed.

The present invention has been made in view of the above points, and its purpose is to repeat communication between the ground side and the self-propelled vehicle a required number of times in accordance with the command signal when the self-propelled vehicle is not in a state or there is no response signal at all. A driving control method for an unmanned vehicle that eliminates runaway behavior of a self-propelled vehicle and increases safety by immediately stopping the self-propelled vehicle by immediately interrupting the signal supplied to the induction cable in the case of an unmanned vehicle. The goal is to provide the following.

A driving control method for an unmanned vehicle according to an embodiment of the present invention will be described below with reference to FIGS. 4 to 7.

FIG. 4 shows a circuit configuration on the self-propelled vehicle side used in the traveling control method of the present invention, where 9 is an operation control unit which inputs the received signal of the receiving circuit 8a, and 10 is a steering coil (also called a pick-up coil). ) The guidance signals 3a and 3b are input, and predetermined steering control is performed according to these guidance signals, and output signals of "1" and "0", which mean the presence/absence of the guidance signals, are sent to the operation control section 9. This is a steering control circuit that inputs to the operation control unit 9;
Steering control circuit 10, accelerator operation circuit 1
1 and the brake operation circuit 12 constitute a first control unit 6.

FIG. 5 shows the circuit configuration of the second control unit 7 provided on the ground side, where 13 is a control command section, 14
a is a transmitting circuit, 14b is a receiving circuit, and 15 is a transmitting/receiving switching circuit. In addition, as shown by the dotted line in FIG.
It is also possible to use two loop coils to provide both transmitting and receiving functions.

FIG. 6 shows a more specific circuit configuration of the control command unit 13, in which 16 is a demodulation circuit that receives the received output signal of the reception circuit 14b, and 17 is a demodulation signal S ₇ from the demodulation circuit 16 and the vehicle speed. A determination circuit that determines whether the setting signal _S8 of the setting device 18 matches or does not match, 1
9 is a mismatch counter, and 20 is a preset setting device for setting a preset value.The mismatch counter 19 sequentially inputs and counts the judgment signal _S9 (signal indicating mismatch) from the judgment circuit 17, and counts the counted value until the preset value is reached. When it matches the value, it is automatically reset to 0, and the output signal _S11 is given to the switch operation circuit 21, which will be described below. 21 is the output signal _S11 of the discrepancy counter 19 or the output signal from the determination circuit 17
The switch operating circuit 21 is activated by _S9 , and the switch operating circuit 21 turns off the switch circuit 22 to cut off the signal supply from the signal source 23 to the induction cable 2.

In the above configuration, when the self-propelled vehicle 1 is stopped on the station ST ₁ and starts toward the station ST ₃ as shown in FIG. 1, the self-propelled vehicle 1 receives the position signal as shown in FIG. is transmitted from the transmitting circuit 8a to the ground side through the transmitting antenna 4a, so this position signal is sent to the receiving coil 5b on the ground side in FIG.
It is received through the route of the control command unit 13 and detects and confirms that the self-propelled vehicle 1 is located at the station _ST1 .

During such operation, the frequencies f ₁ and f 2 are predefined so _that the ground-side transmitting/receiving circuit 14a or 14b separately transmits or receives two different frequencies f ₁ and f ₂ , and The transmitting/receiving circuits 14a, 14b are switched between transmitting and receiving in a predetermined timing mode in accordance with a program command from the control command section 13.

The steering function is the main function of the self-propelled vehicle 1, and as shown in Figure 4, when a current of a predetermined frequency is passed through the induction cable 2 buried in the floor, an induced magnetic field is generated around the induction cable 2. . This magnetic field is converted into voltage by a pair of steering coils 3a and 3b sandwiching an induction cable 2, and the voltage level generated in both steering coils is inputted to a steering control circuit 10 having a differential amplifier etc. to control a steering motor, for example, a servo motor. to drive.
When the servo motor is driven, the direction of the front wheels changes and the midpoint of the pair of steering coils 3a and 3b becomes directly above the induction cable 2, and the output difference of the differential amplifier becomes zero, and the servo motor stops rotating, creating a balanced state. becomes. When the vehicle approaches a curve, this balance is disrupted and the vehicle repeats the above-mentioned actions and travels automatically.

Further, the steering control circuit 10 emits a signal "1" if there is an input voltage from the steering coils 3a, 3b, and, on the contrary, emits a signal "0" if there is no input voltage. Steering control circuit 1
When a signal "1" is input from 0 to the operation control section 9, the operation control section 9 determines and confirms that the prescribed steering control is being performed, and when a signal "0" is input, an abnormality is detected. It is determined that the time is right and the brake circuit 12 is controlled to bring the self-propelled vehicle to an emergency stop.

This embodiment, which performs the above-mentioned predetermined operations, will be described in detail with reference to the time chart of FIG. 7, particularly regarding the transmission mode during driving, which has been a problem with the conventional device.

In the time chart of Fig. 7, A to D indicate the operation mode of each part installed on the ground side, and similarly E and F.
1 shows the operation mode of the first control unit 6 mounted on the self-propelled vehicle. Self-driving cars are now stations
It is assumed that the vehicle is started and accelerated from ST ₁ toward station ST ₃ and rapidly approaches station ST ₂ at the maximum speed of "3rd forward speed."
If a position sensor is installed at station ST ₂ , the signal from this position sensor is used to determine that the self-propelled vehicle has arrived at the station ST ₂ at the control command unit 13 on the ground side shown in Fig. 6. confirm.
In addition, if the type does not have a position sensor and uses one set of loop coils for both transmission and reception as shown in Fig. 5, a command signal from the control command section 13 on the ground side can already be sent to the loop coil of station _ST2 . is selected, and the loop coil, transmission/reception switching circuit 15, and control command section 13 shown in FIG. 5 are connected to each other. Therefore, when a self-propelled vehicle enters an area where reception is possible at one end of the loop coil of station ST ₂ , a predetermined signal is transmitted from the self-propelled vehicle to the control command unit 13 on the ground side, and this reception output and ST ₂
The determination circuit 17 of the control command unit 13 determines and confirms that the self-propelled vehicle has reached the station ST ₂ under the AND condition that the loop coil is selected.

When it is confirmed that the self-propelled vehicle has reached station ST ₂ through the steps described above, the control command unit 13 on the ground side first changes the vehicle speed command from "3rd forward speed" at time _t1 in Figure 7. In order to switch to "forward 2nd speed", the vehicle speed command signal S _1a for "forward 2nd speed" (Fig. 7-A
) shown in FIG.
Send via the following route. Note that when the vehicle speed command signal for "2nd forward speed" is transmitted, the control command unit 13 in FIG. Time the response time. Therefore, the vehicle speed command signal for "2nd forward speed" transmitted through the above path is received through the path of receiving coil 4b -> receiving circuit 8b -> operation control unit 9 shown in _FIG . If the command code (shown in Fig. A predetermined command signal is given, the accelerator operation circuit 11 operates the accelerator position of the self-propelled vehicle to the "2nd forward speed" position, and a signal S _4a (shown in E in Fig. 7) indicating that the accelerator operation is completed is generated. ) in Fig. 4 from the operation control unit 9 → transmission circuit 8a → transmission coil 4a
It is transmitted to the ground side through the route. This response signal
S _4a is received and demodulated from the reception circuit 14b in FIG. 6 to the demodulation circuit 16, and this received output S _2a (shown as B in FIG. It is determined whether the vehicle speed command signal matches the vehicle speed command signal for "2nd speed". If it is determined that the received output S _2a and the vehicle speed command signal do not match based on the determination result, a discrepancy signal shown at time t ₄ in FIG. 7-C is generated.
S _6a is input to the discrepancy counter 19 and counted. Note that since the clock circuit 24 in FIG. 6 starts timing at the same time as the vehicle speed command is transmitted as described above, the clock circuit ₂₄ in FIG. stop it,
If the time until the response signal is received is within a preset time, the clock circuit 24 is reset to prepare for the next time measurement. Now, if it is determined that there is a mismatch, the control command unit ₁₃ in FIG.
(shown at time _t5 in FIG. 7-A) is given to the self-propelled vehicle to cause it to perform a predetermined accelerator operation. If the response signal from the self-propelled vehicle side to this vehicle speed command signal S _1b is the S _4b signal shown at time t ₇ in Fig. 7-E, then
At the same time as stopping the clock circuit 24,
It is determined whether the received output signal S _2b and the vehicle speed command signal S _1b correspond to the response signal S _4b shown between times t ₇ and _{t 8} in FIG. 7, and whether they match or do not match. If this judgment result does not match, a discrepancy signal S _6b (shown in Fig. 7-C) is output to the discrepancy counter 19 to advance the count, and in parallel with this operation, the control command unit 13 again sends a signal that is the same as the previous one. The vehicle speed command signal S _1c (shown as A in Figure 7) is sent to the self-propelled vehicle to cause it to perform a predetermined accelerator operation, and the response signal from the self-propelled vehicle is matched or mismatched with the vehicle speed command signal. be monitored and judged. Therefore, the sixth
If the preset value of the mismatch counter 19 is set to "3" on the side of the control command unit 13 in the figure, the third mismatch signal _S6c (shown as C in FIG. 7) is input to the mismatch counter 19. At the time of counting, the mismatch counter 19 sends a signal to the switch operation circuit 21 to indicate that the signal source 23 of the induction cable should be cut off, and at the same time, the mismatch counter 19
is reset and returns to the initial value "0". Since the cutoff command signal is sent to the switch operation circuit 21, the switch circuit 22 is circuited by the signal from the operation circuit 21, and the signal source 23 is cut off.
When the signal current flowing through the induction cable is cut off in this way, the self-propelled vehicle side generates 10 Since the servo motor (not shown) is driven via the steering control circuit 10 of The self-propelled vehicle is immediately stopped by sending out a signal "0" indicating that the vehicle is running and giving an emergency stop command signal to the brake operation circuit 12 via the operation control unit 9.

The above explanation applies even if the corresponding positional relationship between the transmitting-receiving coil of the self-propelled vehicle and the transmitting-receiving coil (or loop coil) on the ground side is within the receivable area.
When the received output fluctuates greatly due to noise, etc., and the vehicle speed command signal and even the response signal are not accurately transmitted to the other party, or when an accident occurs on the self-propelled vehicle and the specified accelerator operation in response to the vehicle speed command signal is not performed correctly. This is an explanation of the operation in abnormal situations, such as when there is no accelerator or no accelerator operation is performed. An explanation will be given of the operation in an abnormal situation where the corresponding positional relationship with the receiver is not in the predetermined positional relationship and reception is not possible at all. As mentioned above, when the required vehicle speed command signal is transmitted to the self-propelled vehicle, the clock circuit 2 in FIG.
In step 4, clock signals are sequentially input and the time required until a response signal is received from the self-propelled vehicle is measured. At the time of such measurement, the signal transmission time, the operation time such as accelerator operation, etc. are data that is known in advance at the design stage, so the required time is known data and can be set arbitrarily. Therefore, if there is no response signal from the self-propelled vehicle within the required time set by the clock circuit 24 in FIG.
A signal source 23 cutoff command signal is sent to forcefully cut off the signal source 23 of the induction cable 2. In addition, when shutting off the signal source 23 to bring the self-propelled vehicle to an emergency stop, it is not done by simply receiving the first "unreceivable" judgment signal as in the above method, but by detecting the unreceivable signal several times. It can be done at the same time. This method has the advantage of avoiding unnecessary emergency stops and increasing the reliability of the system itself.

As explained above, the present invention transmits and receives a command signal from the ground side and a return signal from the self-propelled vehicle to the ground side a required number of times, and determines whether these signals match or differ by the control command unit on the ground side. However, in parallel with this operation, the time required from the time the command signal is transmitted until the response signal is received is monitored, and the self-propelled vehicle is controlled based on this determination result. Therefore,
According to the present invention, even in the event of an abnormality in which reception is not possible or the received output signal level fluctuates greatly and the signal is not accurately transmitted to the other party, the self-propelled vehicle is immediately stopped, thereby preventing runaway due to erroneous operation. Problems such as not being able to stop at the target point can be resolved all at once.
It enables safe driving of self-propelled vehicles, and its effects are great.

[Brief explanation of the drawing]

Fig. 1 is a side view showing the conventional driving control method for an unmanned vehicle, Fig. 2 is a front cross-sectional view thereof, Fig. 3 is a time chart of the conventional control method, and Fig. 4 is the driving control method of the present invention. FIG. 5 is a block diagram of the control unit on the side of the self-propelled vehicle used, FIG. 5 is a block diagram of the control unit on the ground side used in the travel control method of the present invention, and FIG. 6 shows further essential parts of the control unit of FIG. 5. The block diagram, FIG. 7, is a time chart of the control method of the present invention. 1...Self-propelled vehicle, 2...Induction cable, 4a, 5
a...Transmission coil, 4b, 5b...Reception coil,
6...First control unit, 7...Second control unit, 8a, 14a...Transmission circuit, 8b, 14
b... Receiving circuit, 9... Operation control unit, 11... Accelerator circuit, 12... Brake circuit, 13... Control command unit, 15... Transmission/reception switching circuit, 16... Demodulation circuit, 17... Judgment circuit , 19... Discrepancy counter, 21... Switch operation circuit, 22... Switch circuit, 23... Signal source.

Claims (1)

[Claims] 1. Guides the vehicle based on a guidance cable laid along the traveling course, and communicates between the self-propelled vehicle and the ground side via transmitting/receiving coils installed at each station on the traveling course. In a vehicle control device that controls a running vehicle, there is a condition in which a response signal from the self-propelled vehicle in response to a command signal from the ground side control unit does not match the command signal multiple times, and a condition in which the response signal and the command are If there is a discrepancy with the signal, the control unit on the ground side sends the command signal again, and the condition is set that the time required from the time the command signal is sent until the response signal is received is longer than the set time. A method for controlling the running of an unmanned vehicle, characterized in that, as a condition, the running of the self-propelled vehicle is stopped.