GB1586018A

GB1586018A - Arrangements for controlling trackless vehicles

Info

Publication number: GB1586018A
Application number: GB16447/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-08-25
Filing date: 1978-04-26
Publication date: 1981-03-11
Also published as: DE2738337A1; SE7805998L

Description

(54) IMPROVEMENTS IN OR RELATING TO ARRANGEMENTS FOR CONTROLLING TRACKLESS VEHICLES (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to arrangements for controlling a plurality of trackless vehicles.

When operating several vehicles which are guided automatically one behind another by means of a common guide cable laid on or in their path of travel, there is the danger that one vehicle may crash into the preceding vehicle because of different speeds of travel or because of faults which may occur.

According to the present invention there is provided a system comprising a guide cable, a plurality of trackless vehicles which are automatically guided one behind another by the guide cable which is laid on or in their path of travel, the system further comprising an information cable is laid beside the guide cable, each vehicle carrying an inductive sensor which is associated with the information cable and in which signals are induced by information current flowing in the information cable, there being several block stations distributed along the length of the guide -cable and the information cable where no information can be transmitted to the sensors because of a lateral displacement of the information cable relative to the guide cable or as a consequence of magnetic screening which only affects the information cable.

The invention will be further described by way of example with reference to the accompanying drawing which is a diagrammatic representation of one embodiment of the invention.

In the system shown in the drawing, 1 denotes a guide cable which is used to guide a plurality of trackless vehicles, only two vehicles of which are shown at 2 and 3 in the drawing, on their path which is fixed by the guide cable, so that the vehicles maintain as short a distance as possible from the guide cable. Alternating current flows through the guide cable 1 with a frequency of approximately 10 kHz and produces a cylindrical magnetic field which is concentric with the guide cable. Disposed slightly above the guide cable on the underneath side of the vehicles are inductive sensors in which voltages, which depend upon the respective lateral distance from the guide cable 1 according to size and direction, are introduced by the magnetic field. German Offenlegungsschrift 2 521 571 discloses a device, comprising three pairs of coils, for guiding a trackless vehicle, this device enabling the vehicle to have slight lateral deviations from the guide cable even when the path of travel, fixed by the guide cable, is very curved.

To enable several vehicles to travel automatically on one and the same guide cable and in the same direction of travel as indicated by an arrow 4 in the drawing, an information cable 5 is laid on or in the path of travel beside the guide cable 1 but at a slight lateral distance therefrom. If the guide cable 1 and the information cable 5 lie very close to one another (a few cms apart), then undesired coupling between the two cables occurs when long paths are involved. In this case, suitable filters are provided at block stations for separating longitudinal and transverse guidance frequencies. If this is not desirable, then adequate space must be left between the two cables. The information cable 5 is supplied with signals from a transmitter 6 which serves to guide the vehicles 2, 3 longitudinally, the magnetic field of the current, which field surrounds the information cable 5, being picked up by sensors (not shown) on the respective vehicles. Information concerning a desired speed which is to be maintained in each case can thereby be transmitted.

The path of travel of the vehicles, fixed by the guide cable 1, is interrupted by three block stations denoted by 7, 8 and 9 in the drawing.

The block stations 7, 8 and 9 are provided where the distance between the information cable 5 and the guide cable 1 is so great that the magnetic field of the information cable can no longer be detected there by the sensors of the vehicle guided on the guide cable 1, and that, as a consequence, a vehicle which arrives at a block station no longer receives any desired speed information there and is therefore stopped at the beginning A of the individual block stations.

The block station 9 is formed by the information cable 5 being screened by a sleeve made of ferromagnetic material throughout the length of this block station so that the magnetic field arising from the information cable cannot reach the sensor of a vehicle which arrives at the block station 9 and the vehicle therefore is stopped at the beginning of the block station 9.

Each of the vehicles 2, 3 carries a small computer which is in the form of a microprocessor and evaluates the desired speed information derived from signals from the information cable 5. In addition, a central computer ZSR is provided which is connected to the information cable 5, but especially also to the guide cable 1. When one of the vehicles arrives at one of the block stations, not only is the vehicle stopped, but at the same time a a signal is sent from the vehicle to the central computer ZSR through the guide cable 1, this signal informing the central computer of the pertinent vehicle number and the block station number. This computer examines whether the path section as far as the next block station is free and, if so, gives the vehicle by way of the guide cable 1 a command to continue its travel. Thereupon, in the microprocessor of the vehicle, a programme is started which prescribes a desired speed until the block station is left, the longitudinal guidance signals of the information cable 5 being able to be received again at the end E of the block Station. These processes occur so quickly that the vehicles are not even arrested if the track section is free, but continue their travel immediately because of the command to travel from the central computer ZSR. It is possible, for example at slow travel points, for the desired speed to be able to be prescribed by the microprocessor even over a specific length of path or even until the next block station is reached.

If, in the direction of travel, switch points, loading points or unloading points or other specific track items follow after a block station, the central computer ZSR sends signals over the information cable 5 to the microprocessor, which then allows the appropriate programmes to be operated, such signals initiating the pertinent commands for a switch point departure, for example to the right, for stopping and positioning, for example after 25 metres, etc., together with the command to travel.

In a preferred embodiment, each of the vehicles may contain a section counter which is set to 0 when a loop 10, serving as the starting point, is crossed. As long as the path sections between the block stations are not selected so as to be too short, a rough measurement of the path is in fact adequate to show the vehicle which block station it has just reached.

A high degree of safety in a longitudinal guidance system can be achieved by the arrangement of the invention. This safety results from the fact that the vehicles are periodically stopped at the block stations without any active elements being necessary therefor. Continued travel is only possible on the basis of a command from the central computer ZSR. If the longitudinal guidance signals fail, all the vehicles guided on the guide cable 1 are immediately stopped. A fault in the central computer ZSR causes each of the vehicles to continue travelling as far as the next block station and to stop there.

If, for example, stationary transmitters (for example ultrasonic fixed transmitters) are used for positioning the vehicles at loading points, it is readily possible for the central computer ZSR also to actuate these transmitters.

The beginning A or the end E of a block station may be used as the mark for destinction braking or for any other functions.

WHAT WE CLAIM IS: 1. A system comprising a guide cable, a plurality of trackless vehicles which are auto matically guided one behind another by way of the guide cable which is laid on or in their path of travel, the system further comprising an information cable laid beside the guide cable, each vehicle carrying an inductive sensor which is associated with the information cable and in which signals are induced by information current flowing in the information cable, there being several block stations distributed along the length of the guide cable and the information cable where no information can be transmitted to the sensors because of a lateral displacement of the information cable relative to the guide cable or as a consequence of magnetic screening which only affects the information cable.

2. A system as claimed in claim 1, in which a microprocessor is disposed on each vehicle and a common central computer forming part of the system is provided for all the vehicles, by means of which computer the paths between successive block stations can be monitored.

3. A system as claimed in claim 1 or 2, in which the vehicles have automatically applied braking devices which come into operation when one of the block stations is reached.

4. A system as claimed in claim 2 or 3, in which the central computer is connected to the guide cable for passing on information concerning the magnitude of a desired speed.

5. A system as claimed in any of claims 1

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. that, as a consequence, a vehicle which arrives at a block station no longer receives any desired speed information there and is therefore stopped at the beginning A of the individual block stations. The block station 9 is formed by the information cable 5 being screened by a sleeve made of ferromagnetic material throughout the length of this block station so that the magnetic field arising from the information cable cannot reach the sensor of a vehicle which arrives at the block station 9 and the vehicle therefore is stopped at the beginning of the block station 9. Each of the vehicles 2, 3 carries a small computer which is in the form of a microprocessor and evaluates the desired speed information derived from signals from the information cable 5. In addition, a central computer ZSR is provided which is connected to the information cable 5, but especially also to the guide cable 1. When one of the vehicles arrives at one of the block stations, not only is the vehicle stopped, but at the same time a a signal is sent from the vehicle to the central computer ZSR through the guide cable 1, this signal informing the central computer of the pertinent vehicle number and the block station number. This computer examines whether the path section as far as the next block station is free and, if so, gives the vehicle by way of the guide cable 1 a command to continue its travel. Thereupon, in the microprocessor of the vehicle, a programme is started which prescribes a desired speed until the block station is left, the longitudinal guidance signals of the information cable 5 being able to be received again at the end E of the block Station. These processes occur so quickly that the vehicles are not even arrested if the track section is free, but continue their travel immediately because of the command to travel from the central computer ZSR. It is possible, for example at slow travel points, for the desired speed to be able to be prescribed by the microprocessor even over a specific length of path or even until the next block station is reached. If, in the direction of travel, switch points, loading points or unloading points or other specific track items follow after a block station, the central computer ZSR sends signals over the information cable 5 to the microprocessor, which then allows the appropriate programmes to be operated, such signals initiating the pertinent commands for a switch point departure, for example to the right, for stopping and positioning, for example after 25 metres, etc., together with the command to travel. In a preferred embodiment, each of the vehicles may contain a section counter which is set to 0 when a loop 10, serving as the starting point, is crossed. As long as the path sections between the block stations are not selected so as to be too short, a rough measurement of the path is in fact adequate to show the vehicle which block station it has just reached. A high degree of safety in a longitudinal guidance system can be achieved by the arrangement of the invention. This safety results from the fact that the vehicles are periodically stopped at the block stations without any active elements being necessary therefor. Continued travel is only possible on the basis of a command from the central computer ZSR. If the longitudinal guidance signals fail, all the vehicles guided on the guide cable 1 are immediately stopped. A fault in the central computer ZSR causes each of the vehicles to continue travelling as far as the next block station and to stop there. If, for example, stationary transmitters (for example ultrasonic fixed transmitters) are used for positioning the vehicles at loading points, it is readily possible for the central computer ZSR also to actuate these transmitters. The beginning A or the end E of a block station may be used as the mark for destinction braking or for any other functions. WHAT WE CLAIM IS:

1. A system comprising a guide cable, a plurality of trackless vehicles which are auto matically guided one behind another by way of the guide cable which is laid on or in their path of travel, the system further comprising an information cable laid beside the guide cable, each vehicle carrying an inductive sensor which is associated with the information cable and in which signals are induced by information current flowing in the information cable, there being several block stations distributed along the length of the guide cable and the information cable where no information can be transmitted to the sensors because of a lateral displacement of the information cable relative to the guide cable or as a consequence of magnetic screening which only affects the information cable.

5. A system as claimed in any of claims 1

to 4, in which each of the vehicles contains a .section counter which is set to 0 when an induction loop disposed at the beginning of the path of travel is crossed.

6. A system constructed and arranged and adapted to operate substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawing.