Method for estimating the mass of a vehicle

1. A method for estimating a weight of a motor vehicle including a front wheel assembly and a rear wheel assembly, using a smart communication device, after loading of the vehicle, the method comprising:

(i) identifying the vehicle in the smart communication device;

(ii) using a camera of the smart communication device to capture and process a photograph of at least one wheel with at least one point of the vehicle brought to sink down jointly upon the loading of the vehicle with a suspension of the wheel of the vehicle, after loading, in order to determine a clearance of the wheel assembly of the photographed wheel as a function of the identified vehicle, the taking of the photograph of the wheel is subordinate to keeping the smart communication device in a plane at right angles to a plane of the photographed wheel except in a vertical position of the smart communication device;

(iii) measuring an angle of inclination of the vehicle after loading, using at least one accelerometer or inclinometer of the smart communication device that captured and processed the photograph, the angle of inclination being an angle between a longitudinal axis of a terrestrial reference frame and a longitudinal axis of a vehicle reference frame, and determining a clearance of the wheel assembly opposite the wheel photographed in step (ii) based on the angle of inclination of the vehicle;

(iv) using a calculation unit of the smart communication device to calculate a load value on the wheel assembly of the photographed wheel and a load value on the opposite wheel assembly as a function of the respective clearances of these wheel assemblies, to determine a total load value of the vehicle; and

(v) using the smart communication device to inform a user of a load state of the vehicle.

2. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein the processing of the photograph includes at least one step of calculating an invariant.

3. The method for estimating the weight of the motor vehicle as claimed in claim 2 , wherein the calculating the invariant is a crossratio performed on at least one point of the wheel and at least one point of the vehicle brought to sink down jointly upon the loading of the vehicle with the suspension of the wheel of the vehicle.

4. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein step (i) includes:

(i.1) determining, before loading, a distance between a wheel center and a center of a wheel housing of the wheel to be photographed in step (ii);

(i.2) determining the angle of inclination of the vehicle before loading; and

(i.3) determining a total permissible load of the identified vehicle.

5. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein step (ii) includes:

(ii.0) taking the photograph of the wheel of the vehicle;

(ii.1) converting the captured photograph of the wheel to a grayscale image;

(ii.2) using a first filter of a fuzzy Gaussian type to improve a sharpness of the image;

(ii.3) using a second filter of a Sobel type to obtain contours of the image;

(ii.4) breaking down the image into two parts, including a first part relating to the wheel and a second part relating to a wheel housing;

(ii.5) calculating a center and a radius of the wheel housing by a least squares method;

(ii.6) calculating values of minimum and maximum radii of the wheel as a function of the radius of the wheel housing and of the identified vehicle;

(ii.7) using a third filter of a Mexican hat wavelet type to improve a concentration of points near a center of the wheel;

(ii.8) calculating the center of the wheel on the basis of an accumulation of points in the wheel center, calculating a distance after loading between the wheel center and the center of the wheel housing, calculating a crossratio of said at least point of the wheel and of at least one point of the vehicle brought to sink down jointly upon the loading of the vehicle with the suspension of the wheel of the vehicle; and

(ii.9) calculating the clearance of the wheel assembly of the photographed wheel, using a difference in distance between the wheel center and the center of the wheel housing after and before loading.

6. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein step (iii) is based on a measurement of a difference in the angle of inclination before and after loading.

7. The method for estimating the weight of the motor vehicle as claimed in claim 6 , wherein, during the measuring the angle of inclination in step (iii), any detection of an acceleration beyond a certain predetermined threshold is considered to indicate that the smart communication device has been dropped and that step (iii) must be repeated.

8. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein step (iv) is executed by interpolation in a load/clearance map.

9. The method for estimating the weight of the motor vehicle as claimed in claim 1 , wherein step (i) includes identifying the vehicle selected from a list of models previously recorded in a non-volatile memory, the previously recorded list of models includes:

at least a distance information between a wheel center and a center of a wheel housing of the wheel to be photographed in step (ii); and

a total permissible load information of the identified vehicle.

10. A smart communication device, comprising:

a programmed application to activate a method for estimating the weight of a vehicle;

a human-machine interface to start the application for estimating the weight of a vehicle;

a camera to take a photograph of at least one wheel with at least one point of the vehicle brought to sink down jointly upon the loading of the vehicle with a suspension of the wheel of the vehicle;

at least one accelerometer and/or inclinometer to measure an angle of inclination between a terrestrial reference frame and a vehicle reference frame;

a processor configured to process the image and calculate clearance values and load values including calculating at least one invariant; and

at least one graphic and/or audio interface to alert a user to a load state of the vehicle.