FIELD OF INVENTION
The present invention relates to a position sensing system for determining the
position of railborne vehicles with respect to certain identified location.
BACKGROUND OF THE INVENTION
Position sensing devices are required for knowing the position of rail borne
vehicles which can be equipment like coke oven machines used in coke oven
plants. The position sensing system can also be used for automatic positioning
of any machine, especially in dusty environments or high temperature.
The knowledge of exact position of the mobile equipment in an industrial
environment has always been a challenging task for the system designer, more
so when the equipment is used in a hot and adverse environment.

There was therefore, a need for providing accurate information about the
position of railborne vehicles like coke oven machines in a coke oven plant.
SUMMARY OF THE INVENTION
The main object of the present invention thus is to provide a system for accurate
position sensing of railborne equipment in a harsh environment, with respect to a
predefined position of the moving equipment.
This and other objects of the present invention are achieved by providing an RF
and IR based system to tag the position of mobile equipment and transmit the
defined position to the connected system over serial link. The industrial harsh
environment demands that the sensor should be so designed that it is able to
sustain high dirt and temperature. Also the space constraint and clearance
available demand that the sensor target arrangement should be as compact as
possible.

In a preferred embodiment the present invention provides a position sensing
system for determining the position of railborne vehicles with respect to a
predefined position, said system comprising: a housing; a sensor unit
encapsulated in said housing, said sensor unit being provided with an RF reader
for transmitting through an RF antenna data of RF tag mounted on the rail track
to said connected system; and means for decoding the transmitted data for
identifying the position of the railborne vehicles.
DETAILED DESCRIPTION
The system design is based on reliable RF ID technology coupled with IR sensor
to give accurate information about the position.
The positions which are to be uniquely identified are tagged with "RF tag". Each
tag has identification number which can be pre programmed. The sensor unit
consists of RF antenna and reader. When the IR sensors are aligned, the RF
reader sends the data of RF tag to the connected system. The connected
system can then decode the data and identify the position of the equipment.

The system can be interface with any auto positioning system to give the
identified position or can assist in computing the target distance.
The position sensing system of the present invention is to be fitted to each of the
mobile machines whose position is to be identified. The tag is to be mounted
along the track at an identifiable position.
The system comprises a housing, RF antenna, RF reader, IR sensor and tag.
The system uses half-duplex RS-232C protocol for communicating with
connected system at a baud rate of 9600 for communicating data containing
information about the position of the equipment. The sensors can assist in
accurate positioning of rail borne vehicles within an accuracy of ± 2 mm in
horizontal and / or vertical direction. The sensors can sustain a temperature of
95° C while communicating data.

WE CLAIM
1. A position sensing system for determining the position of railborne
vehicles with respect to a predefined position, said system comprising:
- a housing;
- a sensor unit encapsulated in said housing, said sensor unit being
provided with an RF reader for transmitting through an RF antenna
data of RF tag mounted on the rail track to said connected system;
and
- means for decoding the transmitted data for identifying the position
of the railborne vehicles.
2. The position sensing system as claimed in claim 1, wherein half-duplex
RS-232-C protocol is provided for communicating with the connected
system at a baud rate of 9600.

3. The position sensing system as claimed in the preceding claims, wherein
means are provided for sending 16 character data containing information
on the position of the railborne vehicles.
4. The position sensing system as claimed in the preceding claims, wherein
the determination of railborne vehicle position by said sensor unit can
achieve an accuracy of ± 2 mm in horizontal and / or vertical directions.
5. The position sensing system as claimed in the preceding claims, wherein
the RF tag is mounted along the rail track at an identifiable position.
5. A position sensing system for determining the position of railborne
vehicles with respect to a predefined position, substantially as herein
described.

The main object of the present invention thus is to provide a system for accurate position sensing of railborne equipment in a harsh environment, with respect to a predefined position of the moving equipment.
This and other objects of the present invention are achieved by providing an RF and IR based system to tag the position of mobile equipment and transmit the defined position to the connected system over serial link. The industrial harsh environment demands that the sensor should be so designed that it is able to
sustain high dirt and temperature. Also the space constraint and clearance
available demand that the sensor target arrangement should be as compact as
possible. In a preferred embodiment the present invention provides a position sensing
system for determining the position of railborne vehicles with respect to a predefined position, said system comprising: a housing; a sensor unit
encapsulated in said housing, said sensor unit being provided with an RF reader
for transmitting through an RF antenna data of RF tag mounted on the rail track
to said connected system; and means for decoding the transmitted data for identifying the position of the railborne vehicles.