Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE OF INVENTION
System and Method for Determining Driving Condition of a Tractor

APPLICANT
MAHINDRA & MAHINDRA LIMITED, an Indian company, having its address at Mahindra Research Valley, Mahindra World City, Plot No:41/1, Anjur P.O., Chengalpattu, Tamil Nadu – 603004, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.
FIELD OF THE INVENTION
The present invention relates to a system and method for determining driving condition of a tractor, especially while travelling along an inclined surface.

BACKGROUND OF THE INVENTION
Tractors are used to perform tasks such as ploughing, tilling, harrowing, planting, etc. in fields which have rough or uneven terrain. Accordingly, tractors have a higher ground clearance and a higher centre of gravity compared to regular automobiles. Tractors thus are prone to rolling over causing fatal injuries to the tractor operator and even death in some cases. Most tractors are provided without a cabin, exposing operators of such tractors to a higher risk in cases of tractor overturn or rollover.
Abnormal uphill or downhill driving and/or overloading of a bucket of the tractor also leads to rollover of the tractor. This is either because the driver is driving a heavily loaded tractor at a very high speed or the driver fails to estimate the factors like the road condition, load of the bucket and speed of the tractor. While rollover protection system or structure (ROPS) are provided on tractors to protect the driver from injuries/fatalities caused due to tractor overturn or rollover, there is a need for determining stability of the tractor so as to avoid rollover of the tractor.

SUMMARY OF THE INVENTION
In one aspect, the present invention is directed to a system for determining driving condition of a tractor. The system comprises of a speed sensor configured to monitoring speed of the tractor. The system further comprises of a position sensor configured to monitoring orientation of the tractor with respect to the surface being travelled. The system also comprises of a control unit which is configured to receive physical parameters of the tractor. The physical parameters include height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass which is stored in a memory unit of the tractor. Further, the control unit is configured to receive speed data and orientation related data from the speed sensor and the position sensor. The control unit is configured to determine a stability index from the speed data, the orientation related data and physical parameters of the tractor. Further, the control unit is configured to determine a critical speed and for the determined stability index. The control unit is configured to compare the speed of the tractor with the critical speed and/or the determined stability index with a threshold value to estimate a tractor roll-over risk. The control unit is configured to generate an alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value, thereby alerting a driver of the tractor roll-over risk.
In an embodiment of the invention, the alert signal is a visual indication on the instrument cluster or an audio signal.
In an embodiment of the invention, the control unit is configured to generate a control signal for a motor controller to reduce speed of a motor driving the tractor. The speed of the motor is reduced to or below a safe speed in case the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value.
In an embodiment of the invention, the control unit is configured to reduce speed of the motor by adjusting an input voltage to the motor.
In an embodiment of the invention, the system includes an angle sensor configured to monitor orientation of a bucket of the tractor and a pressure sensor configured to monitor load of the bucket of the tractor.
In an embodiment of the invention, the control unit is configured to determine stability index of the tractor based on data from the angle sensor and the pressure sensor of the bucket.
In another aspect, the present invention is directed to a method for determining driving condition of a tractor. The method comprising the step of monitoring, by a speed sensor, speed of the tractor. The method comprising the step of monitoring, by a position sensor, orientation of the tractor with respect to the surface being travelled. The method comprising the step of receiving, by a control unit, physical parameters of the tractor. The physical parameters include height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass stored in a memory unit of the tractor. The method comprising the step of receiving, by the control unit, speed data and orientation related data from the speed sensor and the position sensor. The method comprising the step of determining, by the control unit, a stability Index from the speed data, the orientation related data and physical parameters of the tractor. The method comprising the step of determining, a critical speed for the determined stability index. The method comprising the step of comparing, by the control unit, the speed of the tractor with the critical speed and/or the determined stability index with a threshold value to estimate a tractor roll-over risk. The method comprising the step of generating, by the control unit, an alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value, thereby alerting a driver of the tractor roll-over risk.
In an embodiment of the invention, the method includes the step of generating, by the control unit, a control signal for a motor controller to reduce speed of a motor driving the tractor. the speed is reduced to or below a safe speed in case the speed of the tractor is greater than the critical speed or/and the determined stability index is less than the threshold value.
In an embodiment of the invention, the method includes the step of reducing, by the control unit, speed of the motor by adjusting an input voltage to the motor.
In an embodiment of the invention, the method includes the step of monitoring, by an angle sensor, orientation of a bucket of the tractor. The method further includes the step of monitoring, by a pressure sensor, load of the bucket of the tractor.
In an embodiment of the invention, the method includes the step of determining, by the control unit, the stability index of the tractor based on data from the angle sensor and the pressure sensor of the bucket.

BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 illustrates a system for determining driving condition of a tractor in accordance with an embodiment of the present invention.
Figure 2 illustrates a method for determining driving condition of a tractor in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed towards a system and method for determining driving condition of a tractor, whereby the system alerts a driver of the roll-over risk of the tractor. The system is also configured to control speed of the tractor to avoid roll-over and maintain stability of the tractor.
Figure 1 illustrates a system 100 for determining driving condition of a tractor (not shown). The tractor is an electric tractor comprising of a battery, and a motor 122 to control the speed of the tractor. The system 100 includes plurality of sensors to monitor various parameters of tractor. The plurality of sensors is powered by a microcontroller (not shown). As shown, the system 100 comprises of a speed sensor 106 to monitor the speed of the tractor. In a non-limiting example, the speed sensor 106 is a Hall effect sensor mounted on a front wheel of the tractor. The system 100 further comprises of a position sensor 108 to monitor orientation of the tractor with respect to the surface being travelled. In an embodiment, the position sensor 108 monitors the tilt or angle of the tractor with respect to the surface being travelled i.e., road surface. In a non-limiting example, the position sensor 108 is a Gyro sensor or an inclinometer or a tilt sensor which monitors centre of gravity of the tractor and the slope angle of the tractor from the road surface.
The system 100 further comprises of a control unit 102. The control unit 102 is configured to receive speed data and orientation related data from the speed sensor 106 and the position sensor 108. The control unit 102 is also configured to receive physical parameters of the tractor. The physical parameters of the tractor are height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass are stored on a memory unit (not shown) of the tractor. In an embodiment, parameters such as height of tractor, centre of gravity, tractor wheel track width, tractor mass, wheelbase are the tractor parameters which are measured from tractor. These parameters are fixed and known for specific tractor variant and will vary as per tractor variation. The parameters depending upon tractor variant are provided as an inbuilt feed value in the memory unit for the control unit 102 to access. In another embodiment, an interface is provided in the tractor to manually update the parameters. In a non-limiting example, the interface is an instrument cluster 116 or the interface can be any other means.
In an embodiment, the system 100 also includes an angle sensor 110 for monitoring orientation of a bucket 114 of the tractor and a pressure sensor 112 for monitoring load of the bucket 114 of the tractor. The data from the angle sensor 110 and the pressure sensor 112 of the bucket 114 are considered for determining stability index of the tractor.
As discussed hereinbefore, the control unit 102 receives the speed data, the orientation related data and physical parameters of the tractor. The control unit 102 is configured to determine a stability index from the speed data, the orientation related data and physical parameters of the tractor. In an embodiment, the stability index is determined by the control unit 102 by using a dedicated application which takes tractor parameters.
In an embodiment, the parameters for calculation of Tractor Stability Index (TSI) includes H- Height of tractor centre of gravity; W- Tractor wheel track width; mt- tractor mass; and wheel base which are pre-fed, Further, ? - Slope angle; Vf- tractor forward speed are dynamic parameters which are measured using sensors. TSI can be determined by calculating final height of center of gravity (h_f) and using h_fvalue in the below mentioned formula:
?TSI?_rollover=(h_critical - h_f)/(h_critical- H)
where,
h_critical is a preset value.
h_f is final height of center of gravity and can be determined by

and,
V_C is velocity of center of gravity of the tractor

d_r: distance between the center of gravity of the tractor and its rolling axis.
d_p: distance between the center of gravity of the tractor and its pitching axis.
g: acceleration due to gravity.
F=arctan(2H/W)
?_p and ?_r are the differentials of ß and ? with respect to time respectively. Where ß is the pitching angle and ? is the slope angle which are measurable.


; I_(xx )– Mass moment of inertia about x axis; I_(yy )– Mass moment of inertia about y axis,
, where is the moment of inertia of the tractor about the roll axis. , where, is the moment of inertia of the tractor about the pitch axis.
If the above determined stability index is less than the threshold value, the control unit 102 will generate an alert signal and send it to driver. Thereby alerting the driver of the tractor roll-over risk.
Further, in an embodiment, the control unit 102 is configured to determine a critical speed. The speed of the tractor corresponding to the tractor stability index threshold is the critical speed. In an embodiment, alternatively, it can also be calculated using below mentioned formula which is derived from the abovementioned formula of final height of center of gravity h_f.
V_fc=(V_c^2-2/m_t [h_critical-v(W^2/4+H^2 sin?(?+Ø) )-1/2 ¯(I_xx ) ?_r^2+¯(I_yy ) ?_p^2 ])^(1/2)

The critical speed is the speed above which the tractor roll over takes place, and the speed below the critical speed is safe speed.
Once the control unit 102 determines the critical speed, the control unit 102 is then configured to compare the speed of the tractor with the critical speed to estimate a tractor roll-over risk. As mentioned above, the control unit 102 is configured to compare the determined stability index with the threshold value and/or compare the speed of the tractor with the critical speed to estimate a tractor roll-over risk. In an embodiment, the threshold value is a predetermined stability index value stored in the memory unit of tractor which is accessed by the control unit 102. Further, the control unit 102 is configured to generate an alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index being less than the threshold value. Thereby alerting the driver of the tractor roll-over risk.
In an embodiment, the alert signal is a visual indication on the instrument cluster 116 or an audio signal. The visual indication may be a warning symbol displayed or blinked over a display screen of instrument cluster 116 or it is a text message. In another embodiment, the alert signal is an alarm buzzer which gives an audio alert through an audio unit 118 of the tractor. In an embodiment, the control unit 102 sends the alert signal to instrument cluster 116 over a Controller Area Network (CAN).
In another embodiment, if the speed of the tractor is above the critical speed and/or the determined stability index is less than the threshold value, the control unit 102 is configured to generate a control signal for a motor controller 120 to reduce speed of the motor 122 driving the tractor, whereby the speed is reduced to or below the safe speed. The motor 120 is a traction motor. In an embodiment, the control unit 102 sends the control signal to the motor controller 120 over CAN to reduce speed of a motor 122 to or below the safe speed. Once the motor controller 120 receives the control signal, accordingly the motor controller 120 reduces speed of the motor. The control unit 102 regulates the motor controller 120 to reduce speed of the motor 122, and thereby the electric tractor to the safe speed by adjusting an input voltage to the motor 122 of the electric tractor.
Figure 2 illustrates the method steps involved in a method 200 for determining driving condition of the tractor. The method is carried out on a system discussed hereinbefore. At step 202, speed of the tractor is monitored by the speed sensor 106. In an embodiment, the speed sensor 106 is a Hall effect sensor mounted on the front wheel of the tractor. At step 204, orientation of the tractor with respect to the surface being travelled is monitored by the position sensor 108. In an embodiment, the position sensor 108 is a Gyro sensor or an inclinometer or a tilt sensor which monitors centre of gravity of the tractor and the slope angle of the tractor from the road surface.
At step 206, physical parameters of the tractor such as height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass are received by the control unit 102. The physical parameters are stored in the memory unit of the tractor. In an embodiment, parameters such as height of tractor, centre of gravity, tractor wheel track width, tractor mass, wheelbase are the tractor parameters which are measured from tractor. These parameters are fixed and known for specific tractor variant and can be provided as an inbuilt feed value for the control unit 102 to access. In another embodiment, an interface is provided in the tractor to manually update the parameters. In a non-limiting example, the interface is the instrument cluster 116 or the interface can be any other means.
At step 208, the speed data and the orientation related data is received by the control unit 102 from the speed sensor 106 and the position sensor 108. At step 210, the stability index is determined by the control unit 102 from the speed data, the orientation related data and physical parameters of the tractor.
In an embodiment, the method 200 includes the steps of monitoring, orientation of the bucket 114 of the tractor by the angle sensor 110 and load of the bucket 114 of the tractor by the pressure sensor 112. The data from the angle sensor 110 and the pressure sensor 112 of the bucket 114 are considered for determining stability index of the tractor. In another embodiment, the stability index is determined by the control unit 102 by using a dedicated application which takes tractor parameters such as the physical parameters of the tractor. the speed data, and the orientation related data as discussed hereinbefore.
At step 212, the critical speed is calculated by the control unit 102 for the determined stability index.
At step 214, the control unit 102 compares the speed of the tractor with the critical speed and/or the determined stability index with the threshold value to estimate a tractor roll-over risk. In an embodiment, the threshold value is stored in a memory unit of tractor which is accessed by the control unit 102.
At step 216, the control unit 102 generates the alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value, thereby alerting the risk of roll-over to the driver of the tractor. In an embodiment, the alert signal is a visual indication on the instrument cluster 116 or an audio signal. The visual indication may be a warning symbol displayed or blinked over the display screen of instrument cluster 116 or it is the text message. In another embodiment, the alert signal is the alarm buzzer which gives the audio alert through an audio unit 118 of the tractor. In an embodiment, the control unit sends the alert signal to instrument cluster 116 over CAN.
In another embodiment, the control unit 102 generates a control signal for the motor controller 120 to reduce speed of the motor 122 driving the tractor, the speed is reduced to or below the safe speed in case the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value. The motor 122 is a traction motor. The control unit 102 sends the control signal to the motor controller 120 over CAN to reduce speed of the motor to or below the safe speed. Once the motor controller 120 receives the control signal, accordingly the motor controller 120 reduces speed of the motor 122. The control unit 102 regulates the motor controller 120 to reduce speed of the motor 122, and thereby the electric tractor to the safe speed by adjusting an input voltage to the motor 122 of the electric tractor.
Advantageously, the present invention provides determining stability of the tractor under different driving and load conditions. The present invention also alerts the driver and ensures that corrective action is taken during abnormal driving conditions. The invention also automatically takes corrective action even if the there is no manual corrective action taken by the driver. The present invention will thus obviate rollover of tractor and thus reduce number of accidents due to abnormal driving and loading conditions.
While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.
, Claims:WE CLAIM:

1. A system (100) for determining driving condition of a tractor, the system (100) comprising:
a speed sensor (106) configured to monitor speed of the tractor;
a position sensor (108) configured to monitor orientation of the tractor with respect to the surface being travelled;
a control unit (102) configured to:
receive physical parameters of the tractor, the physical parameters include height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass stored in a memory unit of the tractor;
receive speed data and orientation related data from the speed sensor (106) and the position sensor (108);
determine a stability index from the speed data, the orientation related data and physical parameters of the tractor;
determine a critical speed for the determined stability index;
compare the speed of the tractor with the critical speed and/or the determined stability index with a threshold value to estimate a tractor roll-over risk; and
generate an alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index being less than the threshold value, thereby alerting a driver of the tractor roll-over risk.

2. The system as claimed in claim 1, wherein the alert signal is a visual indication on an instrument cluster (116) or an audio signal.

3. The system as claimed in claim 1, wherein the control unit (102) is configured to generate a control signal for a motor controller (120) to reduce speed of a motor driving the tractor, the speed is reduced to or below a safe speed in case the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value.

4. The system as claimed in claim 3, wherein the control unit (102) is configured to reduce speed of the motor (122) by adjusting an input voltage applied to the motor (122).

5. The system (100) as claimed in claim 1, comprising:
an angle sensor (110) configured to monitor orientation of a bucket (114) of the tractor; and
a pressure sensor (112) configured to monitor load of the bucket (114) of the tractor.

6. The system (100) as claimed in claim 5, wherein the control unit (102) is configured to determine stability index of the tractor based on data from the angle sensor (110) and the pressure sensor (112) of the bucket (114).

7. A method (200) for determining driving condition of a tractor, the method (200) comprising the steps of:
monitoring, by a speed sensor (106), speed of the tractor;
monitoring, by a position sensor (108), orientation of the tractor with respect to the surface being travelled;
receiving, by a control unit (102), physical parameters of the tractor, wherein the physical parameters include height of tractor, centre of gravity of tractor, tractor wheel track width, wheelbase, and tractor mass stored in a memory unit of the tractor;
receiving, by the control unit (102), speed data and orientation related data from the speed sensor (106) and the position sensor (108);
determining, by the control unit, a stability index from the speed data, the orientation related data and physical parameters of the tractor;
determining, by the control unit, a critical speed for the determined stability index;
comparing, by the control unit, the speed of the tractor with the critical speed and/or the determined stability index with a threshold value to estimate a tractor roll-over risk; and
generating, by the control unit, an alert signal if the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value, thereby alerting a driver of the tractor roll-over risk.

8. The method (200) as claimed in claim 7, wherein the alert signal is a visual indication on the instrument cluster (116) or an audio signal.

9. The method (200) as claimed in claim 7 comprising the step of generating, by the control unit (102), a control signal for a motor controller (120) to reduce speed of the motor (122) driving the tractor, wherein the speed is reduced to or below the safe speed in case the speed of the tractor is greater than the critical speed and/or the determined stability index is less than the threshold value.

10. The method as claimed in claim 9, comprising the step of reducing, by the control unit (102), speed of the motor (122) by adjusting an input voltage to the motor (122).

11. The method as claimed in claim 7 comprising the step of:
monitoring, by an angle sensor (110), orientation of a bucket (114) of the tractor; and
monitoring, by a pressure sensor (112), load of the bucket (114) of the tractor.

12. The method as claimed in claim 11, comprising determining, by the control unit (102), stability index of the tractor based on data from the angle sensor (110) and the pressure sensor (112) of the bucket (114).

Dated this 25th day of January 2024

MAHINDRA & MAHINDRA LIMITED
By their Agent & Attorney

(Janaksinh Jhala)
of Khaitan & Co
Reg No IN/PA-2193