FORM 2
THE PATENT ACT 1970
[39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See section 10 and rule 13]
"PASSIVE KEYLESS ENTRY AND IGNITION SYSTEM USING A SINGLE
ANTENNA IN A VEHICLE"
Name and address of the Applicant:
TATA MOTORS LIMITED, an Indian company having its registered office at
Bombay house, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra,
INDIA.
Nationality: INDIAN
The following specification particularly describes the invention the manner in which it is to be performed.

TECHNICAL FIELD
This disclosure relates to a passive keyless entry and ignition system in a vehicle. More particularly, the disclosure relates to operating vehicle in failsafe condition and determining the location of key fob.
BACKGROUND
Currently, many automobile companies apply push button start system in the vehicles. The push button start system is used while starting the vehicle. The driver of the vehicle carrying a fob, e.g., a smart key capable of bidirectional wireless communications approaches the vehicle. The push button start system authenticates the driver by comparing authentication information e.g., secret code between the vehicle and the fob. Upon completion of authentication, the Electronic Control Unit (ECU) releases the lock of the Electronic Steering Lock Column (ESCL) and enables starting of the vehicle.
Presently, the available passive keyless entry system and push to start function require three internal antennas which are dependent on the size of the vehicle. Further, the hardware required for the passive keyless entry system are three external antennas, an Electronic Control Unit (ECU), a failsafe coil, a push to start button, a ESCL and a base station which is used during failsafe condition i.e. when remote battery get drained. The requirement of the above-mentioned hardware to implement push to start function in failsafe condition increases the manufacturing cost of the vehicle. Further, the hardware occupies a large amount of space in the vehicle.
Further, remote keyless entry devices like key fobs, are used in locking and unlocking doors of the vehicles. Also, the key fobs allow starting the vehicle upon authentication of the key fob by the vehicle. The problem associated with the remote keyless entry device is that there is no method to check the location of the key fob while locking the vehicle or starting the vehicle. Locking keys inside a vehicle is an all too common experience for many drivers.

There is a need to reduce the hardware in the vehicle for passive keyless entry system and provide a system for determining location of a key fob of a vehicle.
OBJECTIVES OF THE DISCLOSURE
One objective of the present invention is to provide a system for low cost passive keyless entry and push to start in a vehicle.
Another objective of the present disclosure is to provide a failsafe system to start the vehicle during the battery drain in the key fob of a vehicle.
Another objective of the present disclosure is to provide a system to determine location of a key fob of vehicle.
Another objective of the present disclosure is to control the locking and starting of the vehicle based on location of key fob.
SUMMARY
The shortcomings of the prior art are overcome and many additional advantages are provided through the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In one embodiment, the present disclosure provides a system to operate key fob of a vehicle in failsafe condition. The system comprises an Electronic Control Unit (ECU and a LF antenna. The ECU is configured to transmit a signal from the vehicle to receive a response signal from the key fob and actuate a Low Frequency (LF) antenna in the vehicle to generate an electric field. The LF antenna generates electric field to supply electric power to a transponder in a fob when the fob is brought close to the LF antenna.
In one embodiment, the present disclosure provides a method for operating a key fob of vehicle in failsafe condition. The method comprises transmitting a signal from the

vehicle to receive a response signal from the key fob. Then, the method comprises determining the absence of response signal from the key fob and actuating a LF antenna to generate an electric field and generating the electric field by the LF antenna to supply electric power to a transponder in the key fob when the key fob is brought close to the LF antenna.
In one embodiment, the present disclosure provides a system to determine location of a key fob of a vehicle. The system comprises a key fob to transmit at least one signal to the vehicle, a Low Frequency (LF) antenna of the vehicle to receive the at least one signal transmitted by the key fob. The system further comprises an Electronic Control Unit (ECU). The ECU is configured to compare the signal strength of the at least one received signal with a predetermined signal strength and performing at least one of determine the key fob to be inside the vehicle upon determining the signal strength to be less than the predetermined signal strength and determine the key fob to be outside the vehicle upon determining the signal strength to be more than the predetermined signal strength.
In one embodiment, the present disclosure provides a method for determining location of a key fob of a vehicle. The method comprises transmitting at least one signal from the key fob to the vehicle, receiving the at least one transmitted signal by a LF antenna of the vehicle, and comparing the signal strength of the at least one received signal with a predetermined signal strength by an Electronic Control Unit (ECU) to determine the location of the key fob. Then the method comprises performing at least one of determining the key fob to be inside the vehicle upon determining the signal strength to be less than the predetermined signal strength and determining the key fob to be outside the vehicle upon determining the signal strength to be more than the predetermined signal strength.
The aforementioned and other features and advantages of the disclosure will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The

detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
The features of the present disclosure are set forth with particularity in the appended claims. The embodiments of the disclosure itself, together with further features and attended advantages, will become apparent from consideration of the following detailed description, taken in conjunction with the accompanying drawings. One or more embodiments of the present disclosure are now described, by way of example only, with reference to the accompanied drawings wherein like reference numerals represent like elements and in which:
Fig. 1 illustrates a schematic block diagram of a vehicle with a single antenna for key less entry and push to start system in accordance with an embodiment of the present disclosure;
Fig. 2 illustrates system for key less entry and push to start system in accordance with an embodiment of the present disclosure;
Fig. 3 illustrates position of a LF antenna in the vehicle in accordance with an embodiment of the present disclosure;
Fig. 4 illustrates a flowchart for operating a key fob of a vehicle in failsafe condition in accordance with an embodiment of the present disclosure;
Fig. 5 illustrates a flowchart for determining location of a key fob of a vehicle in accordance with an embodiment of the present disclosure;

Fig. 6 illustrates schematic diagram of the vehicle showing the internal components in accordance with an embodiment of the present disclosure;
Fig. 7 illustrates block diagram of Passive Start and Entry (PASE) Engine Control Unit (ECU) in accordance with an embodiment of the present disclosure; and
Fig. 8 illustrates energy transmission from the internal antenna to the transponder coil in accordance with an embodiment of the present disclosure.
The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.

Fig. 1 shows a schematic block diagram of a vehicle with a single antenna for key less entry and push to start system in accordance with an embodiment of the present disclosure. The single LF antenna IA creates a Low Frequency (LF) field shown as dotted circles. The LF field covers interior as well as exterior of the vehicle. In an embodiment, the LF antenna covers an area up to approximately 1.5 meters more than vehicle perimeter.
Fig. 2 illustrates position of a LF antenna in a vehicle in accordance with an embodiment of the present disclosure. The system comprises a vehicle 200 with a LF antenna 202, an Electronic Control Unit (ECU) 204 and a memory unit 206. The system also comprises a key fob 208 to operate the vehicle 200. The key fob 208 comprises a transponder 210. The single LF antenna 202 creates LF field for a predefined area. The LF antenna 202 is also configured to send LF challenge to the key fob 208, receive the data from the key fob 208. The LF antenna 202 then sends the received data to the PASE ECU 204 for authentication by comparing the received data with the predefined values stores in the memory unit 206. If the authentication is successful, then the ECU 204 provides the access to operate the vehicle 200 suing the key fob 208. According to one embodiment, the system provides for centre locking and/or unlocking of door of the vehicle under normal mode of operation i.e. when battery of the key fob 208 is charged. When an external switch mounted on door handle of the vehicle 200 is activated, the ECU wakes up and supplies power to the LF antenna 202 located inside the vehicle 200. In an embodiment, the system provides for powering up the transponder 210 of the key fob 208 when battery of the key fob 208 is discharged. In an embodiment, the system also provides for locating the key fob 208 of the vehicle 200 and operating the vehicle 200 based on location of the key fob 208.
Fig. 3 shows a mesh structure with indicates the position of the LF antenna position in the vehicle according to an embodiment of the present disclosure. In an

exemplary embodiment, the LF antenna 202 is placed on floor console in interior of the vehicle 200. A person skilled in the art would understand that the LF antenna 202 can be located at other location in the vehicle. The LF antenna 202 transmits the LF challenge User Identification (UID) to the key fob 208 in which secret code, random number and received signal strength indicator (RSSI) strength are embedded. The UID transmitted by the LF antenna 202 is compared with UID of the key fob 208. If the comparison is valid, then UID or the key fob 208 transmits the RF signal to the ECU 204 including UID tag, vehicle identification details and RSSI strength.
Fig. 4 illustrates a flowchart for operating a key fob of a vehicle in failsafe condition in accordance with an embodiment of the present disclosure. The method is configured to communicate with the key fob 208 in a situation where an emergency start is required. For example, in a situation where a battery of the key fob 208 is discharged, the method allows the series of processes of starting the vehicle 200 to be performed when a driver brings the key fob 208 close to a specific location in the vehicle 200. The process for starting the vehicle comprises providing power supply to a transponder, secret code authentication, start-up authorization, etc.
The method comprises transmitting a signal from the vehicle 200 to receive a response signal from the key fob 208 at step 402. Upon challenge being sent to the UID or key fob 208 from the LF antenna 202, if Radio Frequency (RF) signal is not received by the ECU 204 from the UID or the key fob 208, i.e., then the ECU 204 understands either the battery of the key fob 208 has been drained or UID remote is not the antenna range. In such a case, the ECU 204 determines the absence of response signal from the key fob 208 and actuates the LF antenna 202 to generate an electric field at step 404. Now, when a driver of the vehicle 200 brings the key fob 208 close to the LF antenna 202 of the present invention, then the LF antenna 202 generates a suitable electric field, and thereby electrical power is supplied to the transponder 210 in the key fob 208 at step 406.
In an exemplary embodiment, the LF antenna 202 may be mounted on the inside of a receiving portion at the bottom of a centre area between a driver's seat and a front

passenger's seat, for e.g. on the inside of a package tray. In this embodiment, the driver performs an emergency start by positioning the key fob 208 inside the package tray and operating a push start button.
Fig. 5 illustrates a flowchart for determining location of a key fob of a vehicle in accordance with an embodiment of the present disclosure. The method for determining location of the key fob 208 is used to prevent driver of the vehicle 200 to inadvertently lock the key fob 208 inside the vehicle 200. Also, the method is used to prevent the driver to start the vehicle 200 when the driver does not have the key fob 208. .In an embodiment, the vehicle 200 transmits at least one signal from the key fob 208 to the vehicle 200 at step 502. The transmitted signal is received by the LF antenna 202 of the vehicle 200 at step 504. The ECU 204 in communication with the LF antenna 202 then compares strength of the received signal with predetermined signal strength at step 506. Based on the comparison, if the signal strength is more than the predetermined signal strength, the key fob 208 is determined to be outside the vehicle at step 508. In the alternative, if the signal strength is less than the predetermined signal strength, the key fob 208 is determined to be inside the vehicle 200 at step 510.
Thus, if driver of the vehicle 200 tries to start the vehicle 200 without carrying the key fob 208, then a message will be displayed on dashboard of the vehicle 200 informing that key fob 208 cannot be found. Similarly, if the driver tries to lock the vehicle 200 leaving the key fob 208 inside the vehicle 200, then the driver is not allowed to lock the vehicle 200.
Fig. 6 illustrates the vehicle with range covered by the LF antenna 202 inside and outside the vehicle 200. Fig. 7 shows a system block of Passive Start and Entry (PASE) Engine Control Unit (ECU) in the vehicle 200. The ECU 204 controls the door actuator control for opening if the UID is at a predefined distance and the identification data such as UID tag, vehicle identification details and RSSI strength are matched with the predefined values stored in the memory unit 206. The system uses a controller area network (CAN) to communicate with the Engine Management System (EMS). The

system receives the authentication data from the UID or remote key using the LF antenna 202, compares the data with the predefined values. If both the data matches, then the ECU 204 actuates the door actuator control for unlocking of the doors. When the push to start button is pressed by a driver of the vehicle 200 to activate the ignition (IGN), actuator and engine start functioning, then the ECU 204 comes out of the sleep mode into normal mode of operation and activates the single LF antenna 202. The LF antenna 202 creates a LF field which covers the cabin area of the vehicle.
Fig. 8 shows energy transmission from the LF antenna 202 to the transponder 210 of the key fob 208. Upon powering up the failsafe transponder 210 in the key fob 208, the key fob 208 starts LF communication with the LF antenna 202. The data transmitted by the key fob 208 is received by the ECU 204 through the LF antenna 202. If the comparison performed by the ECU 204 between the received data and predefined data stored in the memory unit 206 is matched, then the ECU 204 allows the user to crank the vehicle 202.
In one embodiment, during the failsafe condition the key fob 208 has to be kept in the slot provided inside the floor console area where the LF antenna 202 is fixed. The LF antenna 202 gets powered up and creates the LF field which is passed though the transponder 210 inside the key fob 208 to provide the power for the transponder 210.
The advantages with the single antenna for key less entry and push to start system are that there is no need of the external antennas as used in the conventional vehicles. Also, the extra internal antennas, failsafe antenna coil inside the switch, base station for failsafe functionality and drivers inside the ECU which are driving the external antenna are not required. The system of the present disclosure saves a lot of hardware, which reduces the cost of manufacturing. Thus, the outcome is a low cost passive keyless entry and push to start function in vehicles such as cars.
Also, the passive keyless entry and push to start along with the failsafe with a single antenna does not require the external antennas, failsafe immobilizer coil and failsafe base station as used in the conventional vehicles.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.
In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

We claim:
1. A system to operate a key fob of a vehicle in failsafe condition comprising:
an Electronic Control Unit (ECU) to:
transmit a signal from the vehicle to receive a response signal from the key fob; and
actuate a Low Frequency (LF) antenna in the vehicle to generate an electric field;
the LF antenna generates electric field to supply electric power to a transponder in a fob when the fob is brought close to the LF antenna.
2. The system as claimed in claim 1, wherein the LF antenna is further configured to communicate with the transponder of the key fob for authentication of the fob.
3. The system as claimed in claim 1, wherein the LF antenna is placed on floor console in interior of the vehicle.
4. A method for operating a key fob of vehicle in failsafe condition comprising:
transmitting a signal from the vehicle to receive a response signal from the key fob;
determining the absence of response signal from the key fob and actuating a LF antenna to generate an electric field; and
generating the electric field by the LF antenna to supply electric power to a transponder in the key fob when the key fob is brought close to the LF antenna.
5. The method as claimed in claim 4, wherein the LF antenna is placed on floor console in interior of the vehicle.
6. A system to determine location of a key fob of a vehicle comprising:
a key fob to transmit at least one signal to the vehicle;

a Low Frequency (LF) antenna of the vehicle to receive the at least one
signal transmitted by the key fob; and
an Electronic Control Unit (ECU) configured to:
compare the signal strength of the at least one received signal with a predetermined signal strength and performing at least one of:
determine the key fob to be inside the vehicle upon determining the signal strength to be less than the predetermined signal strength; and
determine the key fob to be outside the vehicle upon determining the signal strength to be more than the predetermined signal strength.
7. The system as claimed in claim 6, wherein the LF antenna is placed on floor console in interior of the vehicle.
8. The system as claimed in claim 6, wherein the LF antenna is further configured to communicate with the transponder of the key fob for authentication of the fob.
9. The method as claimed inn claim 6, wherein the ECU prevents starting of the vehicle upon determining the key fob to be outside the vehicle.
10. The method as claimed inn claim 6, wherein the ECU prevents locking of the vehicle upon determining the key fob to be inside the vehicle.
11. A method for determining location of a key fob of a vehicle comprising:
transmitting at least one signal from the key fob to the vehicle;
receiving the at least one transmitted signal by a LF antenna of the vehicle; and
comparing the signal strength of the at least one received signal with a predetermined signal strength by an Electronic Control Unit (ECU) and performing at least one of:

determining the key fob to be inside the vehicle upon determining the signal strength to be less than the predetermined signal strength; and
determining the key fob to be outside the vehicle upon determining the signal strength to be more than the predetermined signal strength.
12. The method as claimed in claim 11 further comprising, wherein communicating by a LF antenna with the transponder of the key fob for authentication of the fob.
13. The method as claimed inn claim 11, wherein starting of the vehicle is prevented upon determining the key fob to be outside the vehicle.
14. The method as claimed inn claim 11, wherein locking of the vehicle is prevented upon determining the key fob to be inside the vehicle.