Field of the Invention
The present invention relates to vehicle positioning systems, more particularly a
weigh bridge centring system equipped with plurality of sensors and a method
thereof for determining correct positioning of vehicles on the weigh-bridge.

Background of the Invention

India is an emerging market for business and logistics constitutes an integral
arm of any manufacturing industry. Goods are transported mostly via rail or via
road. Some goods are packed in containers or bags (like cement, food grains,
chemicals etc.) while some are directly loaded in the vehicle (coal, sand, steel
etc.) for transportation. Goods which are directly loaded in the vehicle require
weighment of the entire truck with the material (Gross weight) and without the
material (Tare Weight). Net weight of the goods is determined by subtracting
tare weight from the gross weight. Vehicles are weighed at electronic weigh-
bridges.

In the conventional systems boom barriers are installed at the entrance /exit
gates which is a costly affair. These barriers can only check the presence of
vehicles at the start or end of weighbridge. The system fails if two vehicles
(whose combined length is less than weigh bridge platform length) are
positioned at the platform.

Presently there exists no method to detect a vehicle’s positioning at the weigh
bridge. For weight to be accurately measured and correctly recorded, vehicle
must be positioned at the centre of weighbridge. Due to collusion between the
weigh-bridge operators and drivers, sometimes the vehicles are not properly
positioned at the weigh bridge (i.e. vehicles are standing at the corner with their
front or back tyres placed on the ground instead of platform) or sometime two
vehicles are weighed together. Difference in weight (less or more) leads to loss
in revenue for the industry.

Despite the aforementioned disadvantages pertaining to the conventional
systems , there is an urgent need to provide a weigh-bridge centring system
deployed with photoelectric sensors and a method thereof for alerting vehicles if
not properly positioned at the weigh-bridge.

Summary of the Invention

2

The present invention relates to a weigh-bridge centring system deployed with
thru-beam type emitter receiver photoelectric sensors or diffuse mode sensors and a method thereof foralerting vehicles if not properly positioned at the weigh-bridge.

The system is deployed with three pairs of photoelectric sensors (through beam or diffuse) comprising of
transmitter and receivers mounted on pillars that are adjacent to the weigh
bridge located on the load cell platform. Photoelectric sensors have different
variants. The system uses
a) thru-beam type emitter receiver photoelectric sensorseparated from each other. The emitter transmits directly a light beam to the
receiver. The receiver voltage drops and the switching function is initiated in
case an object interrupts. .
b) Diffuse sensors – The emitters and receivers are located in the same embodiment and the transmitted radidation from the receiver, reflects off the object in front to reach the receiver. Here the target acts as a reflector. The response time of these sensors is less than 1 ms.

The controller analyses the signals from said sensors, processes the same and
controls traffic lights according to the inputs received from sensors. The traffic
lights are driven by a microcontroller unit installed in a circuit board . The
controller connected to a PC running the weighbridge software using RS-232
communication protocol. A LED display screen at the outlet is associated to the
controller to determine the correct positioning of the vehicle by indicating
different colours on the screen.

Objective of the Invention

The main objective of the present invention is to provide a weigh-bridge
centring system deployed with photoelectric sensors and a method thereof for
alerting vehicles if not properly positioned at the weigh-bridge.

Another objective of the present invention is to provide a weigh bridge centring
system deployed with photoelectric sensors that emit strong infrared beam, have
good noise resistance and are strong on dust and dirt.

Still another objective of the present invention is to provide a weigh bridge
system having a controller that analyses the signals from the photoelectric
sensors and performs signal processing over that and controls traffic lights
according to the inputs from sensors.

3

Still another objective of the present invention is to provide a weigh bridge
centring system and a method thereof that employs sensing detection,
overcomes the technical defect of low working efficiency in the prior art, and
can rapidly, effectively and accurately determine the state of vehicle getting on
the weighbridge.

Brief Description of the Drawings

Fig 1 illustrates working of the through beam photoelectric sensors.

Fig 2 illustrates 3D view of the through beam photoelectric receivers and emitters.

Fig 3 illustrates working of diffuse mode photoelectric sensors.

Fig 4 illustrates 3D view of diffuse mode photoelectric sensors

Detailed Description of the Invention

As illustrated in Figs 1-2, the present invention relates to a weigh-bridge
centring system deployed with photoelectric
sensors and a method thereof for alerting vehicles if not properly positioned at
the weigh-bridge.

We can also use Ultrasonic sensors. However, they have a disadvantage of
generating a false signal in a rainy environment.

According to a preferred embodiment of the present invention , the weighbridge
positioning system comprises a weigh bridge , plurality of photoelectric sensors either through beam or diffuse
within the weigh bridge and having transmitter and receivers mounted on pillars
adjacent to the weigh bridge, a controller connected to PC located on the load
cell platform., an analog CMOS processor ASIC present within said sensors , a
microcontroller unit installed in a circuit board and a LED display screen at the
outlet of the weigh bridge associated to the controller.

According to another embodiment, the system is deployed with three pairs of
photoelectric sensors comprising transmitter and receivers separated from each
other serving as an input for the weigh bridge . Photoelectric sensors have
different variants. The sensors work on +12 to +24 Volts ± 10% Ripple P-P
10% or less DC supply. The sensors are capable of sensing 12mm or more
opaque object . The total current
consumption of receiver and emitter together is less than 30mA. . The sensors have inbuilt

4

Dark ON and Light ON mode and with proper settings to achieve best results
even in dark and dusty environment. The maximum response time of the sensor
is less than 1ms. The sensors are IP67 rated so are suitable for rough
environmental conditions. The analog CMOS processor ASIC provides stable
detection with low power consumption.

The system uses either of
A) a thru-beam type emitter receiver photoelectric sensor wherein
the emitter directly transmits a light beam to the receiver. The receiver voltage
drops at this point and the switching function is initiated in case an object
interrupts. The sensors works on digital logic. In case , no obstacle is present in
front of the receiver, they give a low output. When an obstacle is there, the logic
is reversed.
B) A diffuse mode type photelectric sensors wherein the emitter and the receiver are in the same housing. When an object comes within the sensing range the light is reflected back and the switching function isinititated. They also works on digital logic. When no obstacle is present in front, they give high output. When an obstacle is there, the logic gets reversed.

Using the combination of high/low outputs the vehicle position is
determined on the Weigh Bridge. The controller analyses the signals from said
sensors, processes the same and controls traffic lights according to the inputs
received from sensors. It is powered by 12V ±10% DC supply. The traffic
lights drives different relays driven by a microcontroller unit (MCU) installed in
a circuit board. These are High quality OMRON - G5LA series relays capable
of driving loads upto 10A. The MCU is power up by a 3.3V dc supply which is
supplied using an LDO that converts 12V to 3.3V. The controller connected to a
PC running the weighbridge software using RS-232 communication protocol. A
LED display screen at the outlet is associated to the controller to determine the
correct positioning of the vehicle by indicating different colours on the screen.

According to a another preferred embodiment of the present invention, said
three pairs of photo electric sensors are classified as T1, T2 and T3
(emitters)(1) andR1, R2 and R3(receivers)(2) . T1 and T3 are installed at the
two ends of Weigh Bridge, while the T2 is installed at the center. The
positioning of a vehicle is determined by the following combinations for which
we assume that the vehicle is entering from T1 side and it exits from T3. All the
three sensors are Active when no vehicle is present at the weigh bridge . When
vehicle is entering the Weigh Bridge (let us say it enters from T1), T1 or T1 and
T2 are blocked while T2 and T3 are open. When the vehicle is properly
positioned, T2 is blocked while T1 and T3 are open. When vehicle is exiting,
T3 or both T2 and T3 are blocked.

Table 1

Sensor T1 Sensor T2 Sensor T3 Position Status of Traffic Light
? ? ? No Vehicle On Weigh Bridge
? ? ? Not Correctly Positioned

? ? ? Correctly Positioned
? ? ? Not Correctly Positioned
? ? ? Not Correctly Positioned
? ? ? Not Correctly Positioned. More than one vehicle on WB
? ? ? Not Correctly Positioned
? ? ? Not Correctly Positioned. More than one vehicle on WB

5

A LED display screen determines the correct positioning of the vehicle by
indicating different colours on the screen. In case the light shows Orange color
on the LED screen, it means there is no vehicle on Weigh Bridge, in case of red
light , vehicle is not properly positioned on Weigh Bridge and in case of Green
light , vehicle is properly positioned on weigh bridge. The weigh bridge input is
coupled with the weighing machine and weight cannot be measured/recorded as
long as the light is Red. A trigger is send from the system controller to weigh
machine indicating that the vehicle is correctly positioned and that the weight
can be recorded.

In alternative embodiments the LED display screen can indicate different
colours apart from ones described above.

The invention has been described with respect to a limited number of
embodiments, these should not be construed as limitations on the scope of the
invention, but rather as exemplifications of some of the embodiments. Those
skilled in the art will envision other possible variations, modifications, and
applications that are within the scope of the invention.

CLAIMS:
I CLAIM:

1) A weigh-bridgecentring system comprising of :
- atleast one photoelectric sensors for alerting vehicles
- atleast one controller
if the vehicle is not properly positioned at the weigh-bridge.

2) The system as claimed in claim 1 wherein the
photoelectric sensors emit strong infrared beam and have
good noise resistance and are strong on dust and dirt.

3) The system as claimed in claim 1 wherein the
controller analyses the signals from the photoelectric
sensors and performs signal processing over that and controls traffic lights
according to the inputs from sensors.

3

4) The system as claimed in claim 1 wherein the
weigh bridge
centring system employs sensing detection,
overcomes the technical defect of low working efficiency in the prior art, and
can rapidly, effectively and accurately determine the state of vehicle getting on
the weighbridge.
5)
A method for alerting vehicles if not properly positioned at the weigh-bridge, said method employs sensing detection,
overcomes the technical defect of low working efficiency in the prior art, and
can rapidly, effectively and accurately determine the state of vehicle getting on
the weighbridge.

6) A weigh bridge centerng sytem and method as claimed in any of the preceding claims substantially as herein described with reference to the accompanying drawings