GB2102999A

GB2102999A - Vehicle safety devices

Info

Publication number: GB2102999A
Application number: GB08214695A
Authority: GB
Inventors: Tsuyoshi Tanaka; Kiwamu Yamamoto
Original assignee: Shinko Electric Co Ltd
Current assignee: Shinko Electric Co Ltd
Priority date: 1981-05-22
Filing date: 1982-05-20
Publication date: 1983-02-09
Also published as: GB2102999B; FR2506238A1; DE3219247A1; JPS57187256U

Abstract

A driverless guided vehicle movable along a guide path includes a bumper 13 fixedly mounted on one end of a body of the guided vehicle. The bumper includes a resilient member 15 and a pressure-sensitive switching member 16 disposed outwardly of and fixed relative to the resilient member. The switching member is responsive to external pressure for producing a signal. A control circuit is responsive to the signal from the switching member to de-energize a motor to stop a drive wheel of the guided vehicle. At the same time brakes are also applied to the drive wheels. <IMAGE>

Description

SPECIFICATION Driverless guided vehicle with bumper having emergency stop means Background of the invention Field of the invention This invention relates to a driverIess guided vehicle movable along a guide path and more particularly to such a vehicle having a bumper for preventing damage both to the guided vehicle and an obstacle on the guide path when the former collides against the latter.

Prior art Recently, driverless guided vehicles have been extensively used in many plants and factories. The guided vehicle is moved along a predetermined route or guide path on the floor. There are occasions when an obstacle including a worker inadvertently intrudes into the guide path during the travelling of the guided vehicle. As a result, the guided vehicle often collides the obstacle. It has therefore been desired from a viewpoint of safety to stop the guided vehicle immediately when the guided vehicle collides against the obstacle.

Summary of the invention It is therefore an object of this invention to provide a driverless guided vehicle with a bumper having an emergency stop means whereby upon collision of the guided vehicle against an obstacle on a guide path, the guided vehicle is immediately caused to stop to prevent damage both to the guided vehicle and the obstacle.

According to the prevent invention, there is provided a driveriess guided vehicle movable along a guide path on a floor which vehicle comprises a body having a drive wheel in contact with the floor; a bumper fixedly mounted on one end of the body, the bumper including a resilient member and a pressure-sensitive switching member disposed outwardly of the fixed relative to the resilient member, the switching member being responsive to external pressure for producing a signal; a motor connected to a power source for driving the drive wheel of the guided vehicle; and a control circuit connected to the motor and the power source, the control circuit being responsive to the signal from the switching member to de-energize the motor to stop the drive wheel.

Brief description of the drawings Fig. 1 is a partly-broken, side elevational view of a front portion of a driverless guided vehicle provided in accordance with the present invention; Fig. 2 is a partly-broken, plan view of the front portion of the guided vehicle; Fig. 3 is a plan view of a switching member to be used in a bumper for the guided vehicle; Fig. 4A is a cross-sectional view of the switching member in its off-state; Fig. 4B is a view similar to Fig. 4A but showing the switching member in its on-state; Fig. 5 is a block diagram of a drive control circuitry of the guided vehicle; and Fig. 6 is a schematic side-elevational view of the guided vehicle having a pair of bumpers on opposite ends thereof.

Description of the preferred embodiment Figs. 1 and 2 show a front portion of a driverless guided vehicle 10 movable along a predetermined guide path or route on a horizontal floor 11 in a programmed manner, the guide path comprising a guide line such as electrically detectable guide wire and an optically detectable guide line. The guided vehicle 10 comprises a detector (not shown) for detecting the guide path, a steering means (not shown) responsive to a signal from the detector for steering the guide vehicle to keep it on the guide path, a motor M for driving drive wheels 12, and a program control device (not shown) for applying a signal to a motor drive circuit to drive the guided vehicle in a programmed manner.The guide vehicle 10 comprises free wheels (not shown), and these free wheels and the drive wheels 1 2 are held in rolling engagement with the floor 11.

According to an important aspect of the present invention, a bumper 13 having an emergency stop means is mounted on a front end 1 4a of a generally rectangular body 14 of the guided vehicle 10. The bumper 1 3 comprises a resilient member 15 of a generally square crosssection fixedly secured to the front end 1 4a of the vehicle body 14 and extending horizontally therealong, a pressure-sensitive switching member 1 6 fixedly secured to a front face 1 5a and opposite side faces 15b, 15b of the resilient member 15, and an elastic cover member 1 7 secured to the front end of the vehicle 10 and covering the resilient member 1 5 and the switching member 1 6. The switching member 1 5 has an elongated body and is disposed substantially centrally of the height of the resilient member 1 5. The resilient member 1 5 is made, for example, of sponge. The elastic cover member 1 7 is made, for example, of rubber or synthetic resin.

The pressure-sensitive switching member 1 6 takes the form of a tape switch, and comprises a pair of opposed first and second contacts 1 9 and 20 of an electrically conductive material and an elastic insulating sheath 21 covering the two contacts 1 9 and 20. More specifically, as shown in Fig. 3, the first contact 1 9 is in the form of a strip while the second contact 20 has a corrugated shape. As shown in Figs. 4A and 4B the flexible first and second contacts 1 9 and 20 are disposed in parallel relation to each other and spaced from each other by a small distance G by a pair of insulating spacers 22 and 22 each interposed between the opposed lateral edge portions of the first and second contacts 1 9 and 20.A lead wire 23 is connected to one end of the first contact 19 while another lead wire 24 is connected to one end of the second contact 20.

The lead wires 23 and 24 serve as a positive terminal and a negative terminal, respectively.

Thus, since the first and second contacts 1 9 and 20 are normaily spaced from each other, the switching member 1 6 constitutes a normally open switch, as shown in Fig. 4A.

The switching member 1 6 is attached to the resilient member 1 5 with the second contact 20 of a corrugated shape disposed outwardly of the first contact 1 9. The second contact 20 is so elastic that when the switching element 1 6 is subjected to external pressure in the direction indicated by an arrow in Fig. 4B, the second contact 20 is flexed into contact with the first contact 19 to turn on the switching member 16.

As shown in Fig. 2, the lead wire 23 is connected to a positive terminal of a battery 26 via a relay 27 while the lead wire 24 is coupled to a negative terminal of the battery 26. When the switching member 1 6 is turned on or closed, the relay 7 is activated to apply a signal to a motor drive circuit to de-energize the motor for the drive wheels 12. Upon activation of the relay 7, a braking action is imparted to the drive wheels 12 as described later.

Fig. 5 shows a block diagram of a drive control circuitry of the guided vehicle 10. A control circuit 30 includes the relay 1 7. The control circuit 30, the motor M and a magnetic brake means 31 are connected to a battery. The switching member 16, when turned on, applies a signal to the control circuit 30 whereupon a signal is fed from the control circuit 30 to the motor M to de-energize it to stop the drive wheels. Also, the control circuit 30 is responsive to the signal from the switching member 1 6 for activating a magnetic brake means 31 to apply a braking action to the drive wheels 12.

The operation of the guided vehicle 10 will now be described.

First, program switches of the program control device are operated to preselect a guide path or route along which the guided vehicle 10 is to be moved in a programmed manner. A start switch for the guided vehicle 10 is then operated so that the motor M is powered to drive the drive wheels 12 for rotation. When an obstacle 33, which may be a man, intrudes into the guide path during the travelling of the guided vehicle 10 therealong, the bumper is brought into contact with the obstacle 33.Upon collision of the guided vehicle 10 against the obstacle 33, the switching member 1 6 is subjected through the elastic cover member 1 7 to an external pressure exerted by the obstacle 33, so that the second contact 20 of the switching member 16 is flexed into engagement with the coacting first contact 19, thereby turning on the switching member 1 6. Upon activation of the switching member 16, the motor M is deenergized through the control circuit 30 to stop the drive wheels 12.Simultaneously with the deenergization of the motor M, the magnetic brake means 31 is activated to apply a braking action to the drive wheel 1 2. Thus, upon collision of the guided vehicle 10 against the obstacle 33, the motor M ceases to drive the drive wheels 12, and simultaneously the magnetic brake means positively brakes the drive wheels 1 2 to stop the guided vehicle 10 without delay. Although the guided vehicle 10 advances slightly after it has collided against the obstacle 33, the resilient member 1 5 suitably absorbs the shock developed to prevent both the guided vehicle 10 and the obstacle 33 from being subjected to damage.

While the guided vehicle 10 according to this invention has been specifically shown and described herein, the invention itself is not to be restricted by the exact showing of the drawings or the description thereof. For example, the bumper 1 3 may be attached only to the rear end of the vehicle body 14, and also two bumpers 13 and 1 3 may by attached to the front and rear ends of the vehicle body 14, respectively as shown in Fig.

6. Further, the switching member 16 may comprise a pressure-sensitive conductive rubber whose electrical conductivity is varied in response to an external pressure applied thereto. Further, the switching member 1 6 may be attached to the outer surface of the cover member 1 7.

Claims

1. A bumper for a driverless guided vehicle movable along a guide path which bumper comprises, a resilient member extending along and attached to one end of a body of the guided vehicle, and a pressure-sensitive switching member disposed outwardly and fixed relative to said resilient member, said switching member being activated when subjected to external pressure.

2. A bumper according to claim 1, further comprising an elastic cover member, said switching member being attached to the outer end face of said resilient member, said cover member being secured to the one end of the guided vehicle and covering said resilient member and said switching member.

3. A bumper according to claim 1 or claim 2, in which said switching member comprises an elongated body and extends horizontally along the outer end face of said resilient member.

4. A bumper according to claim 3, in which said switching member comprises a pair of flexible first and second contacts extending along the length thereof in parallel opposed relation, and a sheath of an elastic insulating material covering said first and second contacts, said first and second contacts being spaced from each other generally horizontally.

5. A bumper according to claim 4, in which said first contact is in the form of a strip, said second contact being of a corrugated shape and being disposed outwardly of said first contact, said first and second contacts being spaced from each other by a pair of insulating spacers each interposed between the opposed lateral edge portions of said first and second contacts.

6. A driverless guided vehicle movable along a guide path on a floor which vehicle comprises, a body having a drive wheel in contact with the floor, a bumper fixedly mounted on one end of the body, said bumper including a resilient member, and a pressure-sensitive switching member disposed outwardly of and fixed relative to said resilient member, said switching member being responsive to external pressure for producing a signal, a motor connected to a power source for driving the drive wheel of the guided vehicle, and a control circuit connected to said motor and said power source, said control circuit being responsive to said signal from said switching member to de-energize said motor to stop the drive wheel.

7. A driverless guided vehicle according to claim 6, further comprising a brake means for braking the drive wheel, said control circuit being responsive to said signal from said switching member to activate said brake means to brake the drive wheel.

8. A driveless guided vehicle according to claim 6, in which said brake means is a magnetic brake.

9. A driveless guided vehicle according to claim 1 , further comprising a second bumper fixedly mounted on the other end of the vehicle body, said second bumper being identical in construction to said first-mentioned bumper.

10. A bumper for a driverless guided vehicle constructed and arranged substantially as hereinbefore described and with reference to the accompanying drawings.

11. A driverless guided vehicle constructed and arranged substantially as hereinbefore described and with reference to the accompanying drawings.