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

TITLE OF INVENTION
A Method for estimating tire pressure for a saddle-type vehicle and a System thereof

APPLICANT
SEDEMAC Mechatronics Pvt Ltd, an Indian Company, of 211, 2nd Floor, Bldg No 1, Sona Udyog Ind. Estate, Parsi Panchayat Road, Andheri East, Mumbai 400069, Maharashtra, 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
[001] The present invention relates to a method and system for estimating tire pressure for a saddle-type vehicle.

BACKGROUND OF THE INVENTION
[002] The purpose of a tyre pressure monitoring system (TPMS) is to detect and alert riders about underinflated tyres. The rider can take proactive measures to readjust the tire pressure whenever the TPMS indicates under-inflation. One way of achieving above objective is by mounting pressure sensors on tires. This method is called direct TPMS. While this method is the simplest to implement, pressure sensors are typically expensive, and having such pressure sensors is generally not preferred in for two-wheeler applications, where cost of such sensors is substantial in comparison to vehicle price.
[003] An alternative solution for the above problem is to use indirect methods that leverages data from a set of relatively inexpensive sensors to evaluate parameters indicative of tire pressure. Such technologies are referred to as indirect TPMS. Indirect TPMS can be further classified into two types: wheel spectrum analysis and radius estimation method. Wheel spectrum analysis estimates tire resonance frequency of angular velocity signal from wheel speed sensor, where a low tire pressure is correlated to low resonance frequency. A disadvantage of implementing the wheel spectrum analysis in two-wheeler having an internal combustion engine is that there is a substantial interference of engine vibration noise with tire resonance frequency. And it is impractical to decouple engine vibration from the desired frequency.
[004] Thus, in the context of two-wheelers, the radius estimation approach is preferred. Under the radius estimation approach, a deviation from a pre-defined rolling radius corresponds to low tire pressure. A drawback of using rolling radius estimate in two-wheeler vehicles to conclude TPMS output is that a decrease in rolling radius could be either due to under-inflation or it could be attributed to a heavier payload present on the vehicle. The payload is determined by number of passengers and their respective weight, and for a two-wheeler the tire deflection is very sensitive to number of passengers, thereby affecting rolling radius. Hence, the indirect TPMS technology that leverages radius estimation requires the knowledge of payload before analyzing the radius estimate for tire pressure.
[005] Thus, there is a need in the art for a method and system for estimating tire pressure for a saddle-type vehicle which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[006] In one aspect of the invention, the present invention is directed at a method for estimating tire pressure for a saddle-type vehicle. The method has the steps of: receiving by a control unit, a set of dynamic vehicle parameters from an inertial measurement unit, a set of positional vehicle parameters from a navigation module, and a rotational speed of a wheel from a wheel speed sensor; estimating by the control unit, a rolling radius of the wheel based on the set of positional vehicle parameters and the rotational speed of the wheel, estimating by the control unit, a vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters; and estimating by the control unit, the tire pressure based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value.
[007] In an embodiment of the invention, the vehicle chassis pitch inclination value includes of a terrain component and a payload component.
[008] In an embodiment of the invention, the method has the step of estimating, by the control unit, the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters.
[009] In another embodiment of the invention, the method has the steps of: estimating by the control unit, the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters received from the inertial measurement unit; estimating by the control unit, the terrain component of the vehicle chassis pitch inclination value based on the set of positional vehicle parameters received from the navigation module; estimating by the control unit, the payload component of the chassis pitch inclination value by subtracting the terrain component of the vehicle chassis pitch inclination value from the vehicle chassis pitch inclination value; and estimating, by the control unit, the tire pressure based on the estimated rolling radius of the wheel and the estimated payload component of the vehicle chassis pitch inclination value.
[010] In a further embodiment of the invention, the set of dynamic vehicle parameters include accelerations and angular rates of the vehicle.
[011] In a further embodiment of the invention, the set of positional vehicle parameters include timing and location data of the vehicle.
[012] In another embodiment of the invention, the method has the step of: checking by the control unit, whether the estimated tire pressure is lower than a threshold tire pressure; and operating by the control unit, an indicator when estimated tire pressure is below the threshold tire pressure.
[013] In another aspect, the present invention relates to a system for estimating tire pressure for a saddle-type vehicle. The system has an inertial measurement unit to obtain a set of dynamic vehicle parameters; a navigation module to obtain a set of positional vehicle parameters and a wheel speed sensor to obtain a rotational speed of a wheel. The system further has a control unit to receive the set of dynamic vehicle parameters from the inertial measurement unit, the set of positional vehicle parameters from the navigation module and the rotational speed of the wheel from the wheel speed sensor; estimate a rolling radius of the wheel based on the set of positional vehicle parameters and the rotational speed of the wheel; estimate a vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters; and estimate the tire pressure based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value.
[014] In an embodiment of the invention, the vehicle chassis pitch inclination value includes of a terrain component and a payload component.
[015] In an embodiment of the invention, the control unit is configured to estimate the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters.
[016] In another embodiment of the invention, the control unit estimate the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters received from the inertial measurement unit; estimate the terrain component of the vehicle chassis pitch inclination value based on the set of positional vehicle parameters received from the navigation module; estimate the payload component of the chassis pitch inclination value by subtracting the terrain component of the vehicle chassis pitch inclination value from the vehicle chassis pitch inclination value; and estimate the tire pressure based on the estimated rolling radius of the wheel and the estimated payload component of the vehicle chassis pitch inclination value.
[017] In a further embodiment of the invention, the set of dynamic vehicle parameters includes accelerations and angular rates of the vehicle.
[018] In a further embodiment of the invention, the set of positional vehicle parameters includes timing and location data of the vehicle.
[019] In another embodiment, the control unit checks whether the estimated tire pressure is lower than a threshold tire pressure; and operate an indicator when estimated tire pressure is below the threshold tire pressure.

BRIEF DESCRIPTION OF THE DRAWINGS
[020] 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 estimating tire pressure for a saddle-type vehicle, in accordance with an embodiment of the invention.
Figure 2 illustrates method steps involved in a method for estimating tire pressure for a saddle-type vehicle, in accordance with an embodiment of the invention.
Figure 3 illustrates method steps involved in the method for estimating tire pressure for a saddle-type vehicle, in accordance with an embodiment of the invention.
Figure 4a illustrates a visual representation of vehicle chassis pitch inclination ( ) for a payload ( ), in accordance with an embodiment of the invention.
Figure 4b illustrates a visual representation of vehicle chassis pitch inclination ( ) for another payload ( ), in accordance with an embodiment of the invention.
Figure 4c illustrates graphical representation of the resultant pitch estimate convergence for two different load conditions corresponding to Fig 4a and Fig 4b, in accordance with an embodiment of the invention.
Figure 5 illustrates the graphical representation of averaged rolling radius convergence results for two different pressure conditions, in accordance with an embodiment of the invention.
Figure 6 illustrates a visual representation of instantaneous terrain elevation ( ), in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[021] The present invention relates to a method and system for estimating tire pressure for a saddle-type vehicle.
[022] Figure 1 illustrates a system 100 for estimation of tire pressure for a saddle-type vehicle. The system 100 comprises of an inertial measurement unit 110 which is configured to obtain a set of dynamic vehicle parameters. In an embodiment, the set of dynamic vehicle parameters comprise of accelerations and angular rates of the vehicle. In an embodiment, the inertial measurement unit 110 comprises of one or more gyroscopes and accelerometers for obtaining the accelerations and angular rates of the vehicle.
[023] Further, the system 100 comprises of a navigation module 106 which is configured obtain a set of positional vehicle parameters. In an embodiment, the set of positional vehicle parameters comprise of timing and location data of the vehicle. Furthermore, the system 100 comprises of a wheel speed sensor 112 which is configured to obtain a rotational speed of a wheel. The system 100 further comprises of a control unit 108 which receive the set of dynamic vehicle parameters from the inertial measurement unit 110, the set of positional vehicle parameters from the navigation module 106 and the rotational speed of the wheel from the wheel speed sensor 112.
[024] The control unit 108 is further configured to estimate a rolling radius of the wheel based on the set of positional vehicle parameters and the rotational speed of the wheel. The control unit 108 is further configured to estimate a vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters. Thereafter, the control unit 108 is further configured to estimate the tire pressure based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value. Herein, in an embodiment tire pressure includes tire pressure for a front wheel of the vehicle, and a rear wheel of the vehicle, which is estimated simultaneously.
[025] In an embodiment, the vehicle chassis pitch inclination value comprises of a terrain component and a payload component. Herein, the terrain component of the vehicle chassis pitch inclination value corresponds to the pitch inclination caused in the vehicle chassis due to change in terrain elevation over a certain period time. Similarly, the payload component of the vehicle chassis pitch inclination value corresponds to the pitch inclination caused in the vehicle chassis due to the payload on the vehicle such as weight of the passenger or any luggage that is kept on the saddle type vehicle. As illustrated in Figures 4a, 4b and 4c, the payload of the vehicle is in a directly proportional relationship with the vehicle chassis pitch inclination value.
[026] Figure 4a depicts the visual representation of the vehicle chassis pitch inclination ( ) for a payload ( ). Similarly, Figure 4b depicts the visual representation of the vehicle chassis pitch inclination ( ) for a different payload ( ), where payload ( ) is greater than payload ( ). As the payload increases ( ), the pitch angle of the vehicle chassis increases ( ). This change in the vehicle chassis pitch inclination is substantial because of suspension compression which increases as the payload increases. This change in the vehicle chassis pitch inclination value is utilized in distinguishing payload. Fig 4c illustrates graphical representation of the resultant vehicle chassis pitch inclination value convergence for two different load conditions corresponding to Figure 4a and Figure 4b.
[027] In an embodiment, the control unit 108 is configured to estimate the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters.In this embodiment, the control unit 108 estimates the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters received from the inertial measurement unit 110, the terrain component of the vehicle chassis pitch inclination value based on the set of positional vehicle parameters received from the navigation module 106.
[028] Thereafter, the control unit 108 estimates the payload component of the chassis pitch inclination value by subtracting the terrain component of the vehicle chassis pitch inclination value from the estimated vehicle chassis pitch inclination value. Thereafter, the control unit 108 estimates the tire pressure based on the estimated rolling radius of the wheel and the estimated payload component of the vehicle chassis pitch inclination value.
[029] In an embodiment, the control unit 108 checks whether the estimated tire pressure is lower than a threshold tire pressure and operates an indicator 116, 118 when estimated tire pressure is below the threshold tire pressure. In an embodiment, a battery 102 provide power to the inertial measurement unit 110, navigation module 106, the control unit 108 through a logic power supply 104. In an embodiment, the system 100 further comprises of indicators 116, 118 which receives output/commands from the control unit 108.
[030] In an embodiment, in operation, the system 100 for estimating the tire pressure is configured for estimating tire pressure in both the wheels of the saddle type vehicle simultaneously. In that, the control unit 108 is configured to operate one of the indicators 116 when the tire pressure in the front wheel is lower than the threshold tire pressure for the front wheel. Similarly, the control unit 108 is configured to operate the other indicator 118 when the tire pressure in the rear wheel is lower than the threshold tire pressure for the rear wheel
[031] Figure 2 illustrates the method steps involved in a method 200 for estimating tire pressure for a saddle-type vehicle. At step 2A, a set of dynamic vehicle parameters are received by a control unit 108 from an inertial measurement unit 110. In an embodiment, the set of dynamic vehicle parameters comprise of accelerations and angular rates of the vehicle. At step 2B, a set of positional vehicle parameters are received from a navigation module 106 by the control unit 108. In an embodiment, the set of positional vehicle parameters comprise of timing and location data of the vehicle. At step 2C, a rotational speed of a wheel from a wheel speed sensor 112 is obtained by the control unit 108. At step 2D, a rolling radius of the wheel is estimated by the control unit 108 based on the set of positional vehicle parameters and the rotational speed of the wheel. At step 2E, a vehicle chassis pitch inclination value is estimated by the control unit 108 based on the set of dynamic vehicle parameters. And at step 2F, the tire pressure is estimated by the control unit based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value.
[032] In the embodiment illustrated in Figure 3, at step 2A, the set of dynamic vehicle parameters are received by the control unit 108 from the inertial measurement unit 110. In an embodiment, the set of dynamic vehicle parameters comprise of accelerations and angular rates of the vehicle. At step 2B, the set of positional vehicle parameters are received from the navigation module 106 by the control unit 108. In an embodiment, the set of positional vehicle parameters comprise of timing and location data of the vehicle. At step 2C, the rotational speed of the wheel from the wheel speed sensor 112 is obtained by the control unit 108.
[033] At step 2D, a rolling radius of the wheel is estimated by the control unit 108 based on the set of positional vehicle parameters and the rotational speed of the wheel. The control unit 108 checks if radius estimation constraints are met for accurate rolling radius estimation. When the constraints are satisfied, the instantaneous rolling radius is estimated, and the average rolling radius is updated. Figure 5 illustrates the graphical representation of averaged rolling radius (R1 and R2) convergence results for two different tire pressure conditions (P1 and P2), where P1 > P2, wherein the rolling radius is a function of the tire pressure, in accordance with embodiment of the invention.
[034] In an embodiment, as illustrated as step 2E, the method 200 comprises the step of estimating, by the control unit 108, the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters. Reference is made to Figure 4a and 4b wherein, the visual representation of vehicle chassis pitching phenomenon for two different payloads are illustrated. As explained earlier, Figure 4a depicts the visual representation of vehicle chassis pitch inclination ( ) for a payload ( ). Similarly, Figure 4b depicts the visual representation of vehicle chassis pitch inclination ( ) for another payload ( ), where payload ( ) is greater than payload ( ). As the payload increases ( ), the pitch angle of the vehicle chassis increases ( ). This change in pitch angle is substantial because of suspension compression which increases as the payload increases. This change in the vehicle chassis pitch inclination value is utilized in distinguishing payload. Fig 4c illustrates graphical representation of the resultant pitch estimate convergence for two different load conditions corresponding to Figure 4a and Figure 4b.
[035] In an embodiment, the vehicle chassis pitch inclination value comprises of the terrain component and the payload component. In another embodiment, at step 2E’, a terrain component of the vehicle chassis pitch inclination value is estimated by the control unit 108 based on the set of positional vehicle parameters received from the navigation module 106.
[036] Figure 6 illustrates an instantaneous terrain elevation estimation ( ). For any location xi, caused due to change in geographical height or terrain change ?h is calculated, and the summation of it over the distance provides averaged pitch inclination of the vehicle chassis due to terrain change or elevation. The desired vehicle chassis pitch inclination value, that is the payload component of the vehicle chassis pitch inclination value is computed from the difference of averaged pitch inclination of the vehicle chassis from the inertial measurement unit 110 ( ) and averaged pitch inclination of vehicle chassis due to terrain elevation or change ( ). Based on the above obtained desired vehicle chassis pitch inclination value, vehicle payload is estimated from pre-defined data. The real time vehicle chassis pitch inclination value from the inertial measurement unit 110 ( ) and pitch inclination in vehicle chassis due to terrain elevation are averaged with respect to distance in real time using the formulas below.

[037] In further embodiment, at step 2E”, the payload component of the chassis pitch inclination value is estimated by the control unit 108 by subtracting the terrain component of the vehicle chassis pitch inclination value from the vehicle chassis pitch inclination value, as explained above.
[038] And then at step 2F, the tire pressure is estimated by the control unit based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value due to payload component. In another embodiment, at step 2G, the control unit 108 checks whether the estimated tire pressure is lower than a threshold tire pressure. The control unit 108 operates an indicator 116, 118 corresponding to front and rear tire when estimated tire pressure is below the threshold tire pressure.
[039] Advantageously, the present invention provides a more accurate method for estimation of tire pressure of the saddle type vehicle. As the present invention uses the concept of payload estimation along with rolling radius estimation for estimating accurate vehicle chassis pitch inclination value, it makes the tire pressure measurement more accurate.
[040] Further, the system and method of the present invention are capable of being integrated in any saddle-type vehicle, thereby providing a system for estimation of tire pressure, which is not only highly accurate, but is also less expensive. An accurate prediction of tire pressure indicates to the user as to when the vehicle is required to be inflated or deflated in case it is over-inflated. And due to the accurate prediction of tire pressure, lower mileage, accidents and sudden tire puncture can be avoided. The accurate estimation of tire pressure also increases performance and durability of the tires.
[041] 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 modification may be made without departing from the scope of the invention as defined in the following claims.
, C , Claims:WE CLAIM:
1. A method (200) for estimating tire pressure for a saddle-type vehicle, comprising the steps of:
receiving, by a control unit (108), a set of dynamic vehicle parameters from an inertial measurement unit (110), a set of positional vehicle parameters from a navigation module (106), and a rotational speed of a wheel from a wheel speed sensor (112);
estimating, by the control unit (108), a rolling radius of the wheel based on the set of positional vehicle parameters and the rotational speed of the wheel;
estimating, by the control unit (108), a vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters; and
estimating, by the control unit (108), the tire pressure based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value.

2. The method (200) as claimed in claim 1, wherein the vehicle chassis pitch inclination value comprises of a terrain component and a payload component.

3. The method (200) as claimed in claim 2, comprising the step of estimating, by the control unit (108), the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters.

4. The method (200) as claimed in claim 3, comprising the steps of: estimating, by the control unit (108), the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters received from the inertial measurement unit (110);
estimating, by the control unit (108), the terrain component of the vehicle chassis pitch inclination value based on the set of positional vehicle parameters received from the navigation module (106);
estimating, by the control unit (108), the payload component of the chassis pitch inclination value by subtracting the terrain component of the vehicle chassis pitch inclination value from the vehicle chassis pitch inclination value; and
estimating, by the control unit (108), the tire pressure based on the estimated rolling radius of the wheel and the estimated payload component of the vehicle chassis pitch inclination value.

5. The method (200) as claimed in claim 1, wherein the set of dynamic vehicle parameters comprise accelerations and angular rates of the vehicle.

6. The method (200) as claimed in claim 1, wherein the set of positional vehicle parameters comprise timing and location data of the vehicle.

7. The method (200) as claimed in claim 1, comprising the step of:
checking, by the control unit (108), whether the estimated tire pressure is lower than a threshold tire pressure; and
operating, by the control unit (108), an indicator (116, 118) when estimated tire pressure is below the threshold tire pressure.

8. A system (100) for estimating tire pressure for a saddle-type vehicle, comprising:
an inertial measurement unit (110) configured to obtain a set of dynamic vehicle parameters;
a navigation module (106) configured to obtain a set of positional vehicle parameters;
a wheel speed sensor (112) configured to obtain a rotational speed of a wheel;
a control unit (108) configured to:
receive the set of dynamic vehicle parameters from the inertial measurement unit (110), the set of positional vehicle parameters from the navigation module (106) and the rotational speed of the wheel from the wheel speed sensor (112);
estimate a rolling radius of the wheel based on the set of positional vehicle parameters and the rotational speed of the wheel;
estimate a vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters; and
estimate the tire pressure based on the estimated rolling radius of the wheel and the estimated vehicle chassis pitch inclination value.

9. The system (100) as claimed in claim 8, wherein the vehicle chassis pitch inclination value comprises of a terrain component and a payload component.

10. The system (100) as claimed in claim 9, wherein the control unit (108) is configured to estimate the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters and the set of positional vehicle parameters.

11. The system (100) as claimed in claim 10, wherein the control unit (108) is configured to:
estimate the vehicle chassis pitch inclination value based on the set of dynamic vehicle parameters received from the inertial measurement unit (110);
estimate the terrain component of the vehicle chassis pitch inclination value based on the set of positional vehicle parameters received from the navigation module (106);
estimate the payload component of the chassis pitch inclination value by subtracting the terrain component of the vehicle chassis pitch inclination value from the vehicle chassis pitch inclination value; and
estimate the tire pressure based on the estimated rolling radius of the wheel and the estimated payload component of the vehicle chassis pitch inclination value.

12. The system (100) as claimed in claim 8, wherein the set of dynamic vehicle parameters comprise accelerations and angular rates of the vehicle.

13. The system (100) as claimed in claim 8, wherein the set of positional vehicle parameters comprise timing and location data of the vehicle.

14. The system (100) as claimed in claim 8, wherein the control unit (108) is configured to:
check whether the estimated tire pressure is lower than a threshold tire pressure; and
operate an indicator (116, 118) when estimated tire pressure is below the threshold tire pressure.

Dated this 19th day of August 2022
SEDEMAC Mechatronics Pvt Ltd
By their Agent & Attorney

(Nikhil Ranjan)
of Khaitan & Co
Reg No IN/PA-1471