|Title of Invention||
"A BI-DIRECTIONAL DRIVERLESS GUIDED VEHICLE"
|Abstract||This invention relates to an automated guided vehicle system. The invention works on the principle of inductive wire guidance. The guide wire is embedded in the floor at a depth of approximately 10 mm. Two sets of tuned coils mounted in the under carriage of the vehicle picks up the high frequency signal transmitted from the guide wire and gives input to the on board controller based on aPLC. The Controller controls two drive wheals on two sides of the vehicle.Differential steering principle is used for tracking and turning. The battery driven vehicle is provided with different types of sensors and safety devices on board.|
|Full Text||This invention relates to a bi-directional driverless guided vehicle.
An automated guided vehicle system comprising of one battery-powered driverless vehicle operated from a PC-based central route controller (CRC) and travelling over a track of approximately 100 mts length has been developed at BHEL corporate R&D. This has been developed as a part of the flexible manufacturing system (FMS) for delivering materials to different machine tools in an un-manned environment of production operation.
An object of this invention is to propose an automated guide vehicle system having increased control over material movement. Another object of this invention is to propose an automated guide vehicle system which has an ability to inter face with a variety of peripheral systems such as automatic/CNC machines, load /unload systems, robots conveyors, automated storage and retrieval systems.
According to the present invention there is provided a bi-directional driverless guided vehicle powered by a battery comprising a motor; a plurality of drive wheels and free wheels; an obstruction sensing means; a differential steering means; an on-board controller, and a Central Route Controller (CRC) for monitoring and communicating the vehicle positioning. A guide wire is embedded in the floor transmitting high frequency signals being picked up by a plurality of tuned coils mounted in the under carriage of the vehicle (AGV) for inputting high frequency signals into the PLC-based on-board controller. The controller monitors and controls the drive wheels based on the picked up high frequency signals, thereby automatically guiding the vehicle over the track.
Further objects and advantages of this invention will be more apparent from the ensuing description made with reference to non limiting exemplary embodiments of the invention represented in the accompanying drawing.,
Fig.1 a schematic of the principle used in an automated g uided vehicle;
Fig. 2 - a schematic of the PLC based on board controller;
Fig. 3 - Obstruction sensing devices on the vehicle.;
Fig. 4 - Schematic of PC based Central Remote Controller
(CRC)'and : '
Big. 5 - Assembly of guided vehicle.
In accordance with this invention, the automated guide vehicle works on the principle of inductive wire guidance (Fig.l). The guide wire (1) is embedded in the floor at a depth of for example 10 mm. Two sets of tuned coils (2) mounted in the under carriage of the vehicle picks up the high frequency signal (3) transmitted from the guidewire (1) and gives inputs to the on-board controller (5) through a signal conditioner (4). The on-board controller is based on a standard PLC (5) and it controls two drive wheels on two sides of the vehicle through drive modules (6) and drive motors (7).Differential steering principle is used for tracking and turning. Traction is from a battery pack. The PLC based on board controller (Fig.2) comprises the Ni-Cad battery pack (8) connected to the inverter (9). The inverter (9) connected to DC Power supply (10) and supplies power to A/D converter (11) and D/A converter (15). Guide sensor
1(12) and guide sensor 2 ( 1 3 ) connected to A/D ccnvei.ter (1l)
which supplies digital signals to the PLC (5), The inverter (9)
connected through a TX former (15) to PLC power supply (17)
and supply power to the PLC (5). Digital output signal from
PLC (5) connected to D/A converter (15) connects and supplies
analogue signals to servo modules (6) which drives the Motors
Ml , M2 (7). IP module (18) provides signal for various functions like emergency and bumper switch, obstruction/ Reset, Bend
and station sensed final stop and ampere/hour meter is fed to
PLC (18) for.processing. The PLC (18) connected to'oIP module
(19) provides for the functions of warning and Head light Horns
and Ho'oter. The; ,~01 P. module (19) also' provides signal to the Brake
contactor ( 20')' which "operates ithe Brakes (21)."Different:,. , types
of sensors and safety decies are. used on-board (Fig.:;3). These .
include IR collision-preventionrsensor consisting of IR scanning.
zone ( inner )(22) and IR scanning zone (outer) (23) fibreopti-c
bumpers (24).) photoelectric sensor for detection of station.
Deceleration and acceleration at bends are actuated by on-board
electromagnetic sensors. The vehicle can be used continuously
for one shift with full payload before the batteries need
The vehicle has built in safety features for obstruction
sensing in the direction of travel through IR sensors and
fibre optic bumpers. On sensing the obstruction the vehicle slows
down and emits an audio signal. If the obstruction is removed the
vehicle resumes its full speed. If obstruction is not cleared
and it is sensed by the closer range of the IR sensor or by the
fibre optic bumper it stops instantaneously. In such cases, the
vehicle has to be reset after removing obstruction for it to resume its travel. In addition to the above the vehicle is provided with four locking type emergency switches for stopping it in case of emergency. The vehicle also gives a warning through an audio alarm and revolving lamp while in motion., The vehicle stops instantaneously on rare occurrence of deviating from the guide path. All the electronic and electrical equipment are provided with suitable protection devices.
The routing of the vehicle is done from a central route controller-(CRC) . (Fig.'4). This is. connected to keypads available at each of the .stations enroute to facilitate calling, sending and-freeing of the vehicle.M inimum distance path is-automatically selected by route control program and different segments of the guidewire are energized in the appropriate sequence. The position of the vehicle is monitored from the CRG and is also communicated to each station through LED display.
This vehicle may be integrated into the flexible manufacturing system (FMS) wherein it works under the FMS master computer and carries materials between different machine tools. The chassis of the vehicle (Fig.5) is fabricated from rolled steel angles and channels (25) and is capable of carrying the rated payload, the electrical sub-assemblies and the battery. The suspension (26) provided in the body allows the vehicle to travel on uneven surfaces. Two Harmonic drive wheels (26) driven by two independent DC motors (7) are mounted at the center and two free wheels ( 27,28) are mounted at the front (27) and rear (28) of the chassis. Normal speed of the vehicle is automatically reduced while negotiating a bend. The DC motors (7)
are controlled by the PLC (5) through the drive cards. Differential
starring principle i used for tracking and turning. The vehicle is capable of moving on an inclined surface.
The invention described hereinabove is in relation to a non- limiting embodiment and as defined by the accompanying claims .
1. A bi-directional driverless automated guided vehicle (AGV) powered by a battery (8) the vehicle comprising a motor (7); a plurality of drive wheels (26) and free wheels (27,28); an obstruction sensing means (22,23,24); a differential steering means; an on-board controller (5), and a Central Route Controller (CRC) for monitoring and communicating the vehicle positioning, characterized in that a guide wire (1) is embedded in the floor transmitting high frequency signals being picked up by a plurality of tuned coils (2) mounted in the under carriage of the vehicle (AGV) for inputting high frequency signals into the PLC-based on-board controller (5), and in that the controller (5) controlling said plurality of drive wheels (26) based on said picked up high frequency signals, thereby automatically guiding the vehicle over the track.
2. The vehicle as claimed in claim 1, wherein said on-board controller (5) has a D.C power supply source (10) and a power supply source (17).
3. The vehicle as claimed in claim 1, wherein said tuned coils (2) transmitting said high frequency signals via a signal conditioner (4) to said on-board controller (5).
4. The vehicle as claimed in claim 1, wherein said on-board controller (5) having a plurality of servo modules (6) for controlling said plurality of drive wheels (26).
5. The vehicle as claimed in claim 1, wherein said on board controller (5) having a plurality of signal converter (11,15) connected to a plurality of guide sensors (12,13).
6. The vehicle as claimed in claim 1, wherein said obstruction sensing means (22,23,24) having an IR scanning zone inner (22), and an IR scanning zone outer (23).
7. The vehicle as claimed in claim 1, wherein said plurality of signal converters (11,15) are A/D converter (11) and D/A converter (15) for conversion of analogue/digital and digital/analogue signals.
8. A bi-directional driverless guided vehicle (AGV) powered by a battery as substantially herein described and illustrated with reference to the accompanying drawings.
|Indian Patent Application Number||1745/DEL/1995|
|PG Journal Number||39/2010|
|Date of Filing||22-Sep-1995|
|Name of Patentee||BHARAT HEAVY ELECTRICALS LTD.|
|Applicant Address||BHEL HOUSE, SIRI FORT, NEW DLEHI-110049, INDIA.|
|PCT International Classification Number||B62D 1/24|
|PCT International Application Number||N/A|
|PCT International Filing date|