FORM 2
THE PATENT ACT 1970 [39 OF 1970]
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
[See section 10; rule 13]
“SYSTEM AND METHOD FOR LOGGING OF DISTANCE TRAVELLED BY VEHICLE IF MALFUNCTION IS DETECTED”
Name of the Applicant: Tata Motors Limited; Bombay House, 24 Homi Mody
Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India.
Nationality: Indian
The following specification particularly describes the invention and the manner in which it is to be performed

TECHNICAL FIELD
This disclosure relates to logging of distance travelled by vehicle in case of emission system malfunction.
BACKGROUND AND PRIOR ART
On-Board Diagnostic (OBD) – I compliance in vehicle requires that any malfunction in emission system of the vehicle that causes increase in emission should be indicated on the malfunction indicator lamp (MIL) also the distance travelled by the vehicle in such conditions should be logged by the ECU.
In order to log this distance inside the ECU memory one has to use non-volatile memories as this distance data should be available even after vehicle power is removed and restored from OFF to ON.
There are a number of types of non-volatile memory (NVM) media available that can be programmed multiple times. Examples of such media include electronic memory, such as flash electronically-erasable programmable read-only memory (EEPROM) devices. Such media, however, typically wear out after a certain number of write/erase cycles. Flash EEPROM devices, for instance, are typically rated to endure between 10,000 and 100,000 write/erase cycles, after which the devices become unreliable.
This novel methodology explains how to increase the reliability of the storing capacity of the EEPROM memory
According to a prior art, Sprouse, et al. teaches a method for extending the endurance of non-volatile memory using data encoding. One or more data bits are encoded into a larger number of non-volatile memory bit patterns such that changes to the data bits are distributed across fewer changes per non-volatile memory bit. Non-volatile memory endurance is extended since more changes to the data values are possible than can be supported by underlying changes to individual non-volatile memory bits.
Pinto, et al. teaches methods for writing to non-volatile memories for increased endurance. A relatively small memory is made up of a number of individually-accessible

write segments, each made up of a single memory cell or a small number of cells. A count is encoded so that it is distributed across a number of fields, each associated with one of the write segments. As the count is incremented, only a single field is changed, and these changes are evenly distributed across the fields. The changed field is then written to the corresponding segment, while the other write segments are unchanged. Consequently, the number of rewrites to a given write segment is decreased, and the lifetime correspondingly increased, by a factor corresponding to the number of write segments used.
Maletsky, et al. teaches counting beyond endurance limits of non-volatile memories, the storage cells in a non-volatile memory are subdivided into two groups, one for the implementation of a rotary counter that keeps track of the less significant part of the count and another for a binary counter that keeps track of the more significant part of the count. The rotary counter implements a counting method that maximizes the count that can be obtained before the endurance limit of the memory is reached by making sure that each change of state of each cell is recorded as one count and that all cells in the rotary counter experience two change of state in every cycle. The binary counter records the number of cycles the rotary counter has gone through.
SUMMARY OF THE DISCLOSURE
A method of reliable logging of distance travelled by vehicle in ECU if malfunction in emission system is detected is described in the disclosure. The malfunction is detected by the ECU with its interface between the sensors and actuators of the system. Once the malfunction is detected the ECU starts logging distance travelled by vehicle in case of malfunction. This distance travelled is derived from the vehicle speed fan-out from instrument cluster. A separate sensor is not utilized for this purpose. Thus the cost of overall system is reduced.
This distance travelled is logged in terms of km in non volatile memory of EEPROM. Distance is logged to the resolution of m also. The endurance counter is also maintained for every EEPROM cell thus keeping a log of the endurance. Once the endurance of a particular cell is reached the location in non volatile memory is shifted to the next. Thus

completely using the cell and shifting to next location only when required. When power is switched off the values stored in EEPROM in previous Ignition cycle are read and added with the current Ignition cycle values of distance in 100m, km and current endurance counter. This can be read on a standard diagnostic connecter through an external device. Thus, a reliable, efficient and cost benefit method is provided for logging distance travelled by vehicle if malfunction is detected.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Referring now to the drawings wherein the illustrations are for the purpose of demonstrating a preferred embodiment of the disclosure only, and not for the purpose of limiting the same
Figure 1 shows block diagram of system for logging distance travelled by vehicle in case of emission system malfunction.
Figure 2 shows the flow chart of strategy for reading of distance travelled by vehicle in ECU in case of emission system malfunction.
Figure 3 shows the flowchart of calculation of actual distance travelled by vehicle in case of malfunction and logging in EEPROM.
Figure 4 shows the EEPROM memory MAP.
DETAILED DESCRIPTION
The primary embodiment of the present disclosure is a system to log distance travelled by a vehicle during emission system malfunction comprises sensors and actuators of emission system (3) connected to an Engine Control Unit (ECU) (9) to detect malfunctioning of emission system; vehicle speed sensor (1) connected to the ECU (9) via instrument cluster (2) to detect vehicle speed; and Engine Control Unit (ECU) (9) comprising central processing unit (CPU) (7) to calculate the distance travelled by the vehicle using the vehicle speed and log the distance travelled into non-volatile memory (11) upon detecting malfunction of the emission system, logging location in the nonvolatile memory is shifted based on endurance counter value of each memory cell.

In yet another embodiment of the present disclosure the ECU is connected with an indicator lamp (4), said lamp glows to indicate the malfunctioning of the emission system.
In still another embodiment of the present disclosure the ECU is connected with on-board diagnostic (OBD) (5) connector to communicate data logged in the memory to external devices.
In still another embodiment of the present disclosure the non-volatile memory is selected from a group comprising of EPROM (Erasable Programmable Read Only Memory), EEPROM (Electronically Erasable Programmable Read Only Memory), flash memory and Magneto resistive RAM.
In still another embodiment of the present disclosure values of the distance travelled and the endurance counter when the vehicle is switched OFF are added with the corresponding distance travelled and the endurance value of the current ignition cycle of the vehicle when switch ON.
Another embodiment of the present disclosure is a method of logging distance travelled by a vehicle during malfunction of emission system, said method comprising acts detecting malfunctioning of the emission system; and logging of the distance travelled by the vehicle into Engine control unit (ECU) upon detecting the malfunction of the emission system.
In yet another embodiment the malfunctioning of the emission system is detected by the ECU using sensors and actuators.
In still another embodiment the ECU comprises non-volatile memory for logging the distance travelled by the vehicle.
In still another embodiment the memory is selected from a group comprising of EPROM (Erasable Programmable Read Only Memory), EEPROM (Electronically Erasable Programmable Read Only Memory), flash memory and Magneto resistive RAM.

In still another embodiment endurance counter of each memory cell of the non-volatile memory is maintained.
In still another embodiment logging location in the memory is shifted based on the endurance counter value to increase endurance of the memory compared to logging of data without shifting the logging location.
In still another embodiment the distance travelled is calculated using vehicle speed, said vehicle speed is sensed using Instrument cluster vehicle speed fan-out.
In still another embodiment the distance travelled is calculated by sensing the vehicle speed using vehicle speed sensor.
Figure 1 shows the system for logging distance travelled by a vehicle in case of emission system malfunction.
The distance travelled by the vehicle is calculated inside the ECU (9) using the vehicle speed input from instrument cluster vehicle speed FAN out (2). The vehicle speed input to the instrument cluster comes from vehicle speed sensor (1) mounded on Speedo gear of the vehicle. The ECU (9) senses the vehicle speed input pulses on edge triggered interrupt and hence the number of incoming pulses are counted.
For the given vehicle,
460 pulses = 100m distance travelled
The ECU (9) detects any malfunction in emission system (10) through its interface with sensors and actuators of emission system in vehicle (3). Once the malfunction is confirmed by the ECY (9) the malfunction indicator lamp (4) is lit by the ECU (9) thus notifying the driver that malfunction has occurred. The driver is expected to drive the vehicle to the nearest service station.
Once this malfunction indicator (4) is on the CPU (7) start logging the distance travelled by vehicle in EEPROM (11). The algorithm to log data in memory (12) reliably logs this distance in the EEPROM (11). This data in EEPROM (11) is accessible to the external

world through Laptop using a standard on-board diagnostic (OBD) connector (5) using K-Line to serial (6) communication.
Figure 2 indicates the flow chart of control strategy to read the log distance travelled by vehicle in previous ignition cycle in case of emission system malfunction in EEPROM of ECU. The following block reads the previous values from EEPROM one time on ignition:
Block 13 reads the previous logged distance in km from EEPROM.
Block 14 reads the endurance count of the EEPROM which contains value corresponding to the total endurance encountered by the whole EEPROM.
Block 15 reads the current offset of the location where the 100m value is to be stored. From the offset the address of the low order byte is calculated (as the 100m value is 1 byte wide and the page address remains the same while the offset changes when endurance of a particular location is reached) and updated necessarily.
Block 16 checks if the endurance of the current address location where the 100m count (cnt) is stored is reached. If it is reached the offset 100m address is incremented and flag 100m_offset_addrlow_changed is made to 0. The offset 100m_addr is stored in EEPROM memory to be used in the next Ignition cycle.
Figure 3 shows the flowchart for calculating the distance travelled by the vehicle and writing the same into the non-volatile memory i.e. EEPROM. The following blocks of fig. 3 explain the method of calculating the distance travelled:
Block 17 checks whether the malfunction is detected and 100m is covered (i.e. number of input pulses for vehicle speed received equal to 460). If the 100m distance is covered and first condition is met i.e. malfunction detecting then it reads 100m_cnt from EEPROM. After reading it sets the flag that 100m_cnt (logged in previous Ignition cycle) is read from EEPROM. Distance 100m_cnt is incremented by 1 and flag is set to write to EEPROM.
Block 18 checks the parameter dist_100m_cnt whether equal to 10 or not, if

dist_100m_cnt is equal to 100, then dist_100m_cnt is made 0 and dist_km_cnt is incremented by 1.
Block 19 calculates dist_km_cnt final by adding dist_km_cnt i.e. distance travelled in terms of km in current Ignition cycle and last_km_cnt distance travelled in km in the previous Ignition cycle. A flag is set to write dist_km_cnt_final i.e. the total distance travelled in kilometres into EEPROM and the current endurance counter is incremented by 1.
Block 20 checks whether flag to write 100m_cnt i.e. write 100 meters count is set so that the corresponding data i.e. 100m_cnt is written into EEPROM. After writing the data into the EEPROM 100_cnt is reset. Also, dist_km_cnt_final i.e. final distance travelled in terms of kilometres count is set or not is checked so that the corresponding data dist_km_cnt_final is written into EEPROM. After writing the data into the EEPROM dist_km_cnt_final is reset.
At Block 21, if the malfunction is not detected in the system then it reads the previous endurance counter from EEPROM and compares it with the current endurance counter, if both the values are not equal then the current endurance counter is written into the EEPROM.
If the malfunction not detected on the first scan, the dist_km_cnt_final and 100m_cnt are reset to 0 and stored in EEPROM.
Figure 4 indicates the location in EEPROM for writing the data of all the parameters involved in calculating the distance travelled by the vehicle. The memory locations and the corresponding values are as follows:
AA – this is the storage location of 100m distance
BB – this is the storage location of Kilometre distance
CC – this is the storage location for the offset for 100m storage
DD – this is the storage location for the endurance counter value
EE – if malfunction is their in vehicle then any location is 1

A method for extending the endurance of non-volatile memory using data encoding is made possible by encoding one bit in one word. This requires more space of EEPROM memory and is complex.
Finally, while the present disclosure has been described with reference to a few specific embodiments, the description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Various modifications may occur to those skilled in the art without departing from the true spirit and scope of the disclosure as defined by the appended claims.

We claim:
1. A system to log distance travelled by a vehicle during emission system malfunction
comprises:
sensors and actuators of emission system (3) connected to an Engine Control Unit (ECU) (9) to detect malfunctioning of emission system;
vehicle speed sensor (1) connected to the ECU (9) via instrument cluster (2) to detect vehicle speed; and
Engine Control Unit (ECU) (9) comprising central processing unit (CPU) (7) to calculate the distance travelled by the vehicle using the vehicle speed and log the distance travelled into non-volatile memory (11) upon detecting malfunction of the emission system, logging location in the non-volatile memory is shifted based on endurance counter value of each memory cell.
2. The system as claimed in claim 1, wherein the ECU is connected with an indicator lamp (4), said lamp glows to indicate the malfunctioning of the emission system.
3. The system as claimed in claim 1, wherein the ECU is connected with on-board diagnostic (OBD) (5) connector to communicate data logged in the memory to external devices.
4. The system as claimed in claim 1, wherein the non-volatile memory is selected from a group comprising of EPROM (Erasable Programmable Read Only Memory), EEPROM (Electronically Erasable Programmable Read Only Memory), flash memory and Magneto resistive RAM.
5. The system as claimed in claim 1, wherein values of the distance travelled and the endurance counter when the vehicle is switched OFF are added with the corresponding distance travelled and the endurance value of the current ignition cycle of the vehicle when switch ON.
6. A method of logging distance travelled by a vehicle during malfunction of emission system, said method comprising acts of:
detecting malfunctioning of the emission system; and

logging of the distance travelled by the vehicle into Engine control unit (ECU) upon detecting the malfunction of the emission system.
7. The method as claimed in claim 6, wherein the malfunctioning of the emission system is detected by the ECU using sensors and actuators.
8. The method as claimed in claim 6, wherein the ECU comprises non-volatile memory for logging the distance travelled by the vehicle.
9. The method as claimed in claim 8, wherein the memory is selected from a group comprising of EPROM (Erasable Programmable Read Only Memory), EEPROM (Electronically Erasable Programmable Read Only Memory), flash memory and Magneto resistive RAM.
10. The method as claimed in claim 8, wherein endurance counter of each memory cell of the non-volatile memory is maintained.
11. The method as claimed in claim 10, wherein logging location in the memory is shifted based on the endurance counter value to increase endurance of the memory compared to logging of data without shifting the logging location.
12. The method as claimed in claim 6, wherein the distance travelled is calculated by sensing the vehicle speed using vehicle speed sensor.
13. A system to log distance travelled by a vehicle during emission system malfunction and a method thereof as herein substantiated in the description along with accompanied drawings.