Patent EP-3637078-A1 (EP)
Inventor: CIMPONERIU ANDREI-STEFAN
IPC: G01M1/22
Filed: 2018-10-11
Abstract: The invention relates to a method for localizing unbalance of a wheel (n = 1÷4 or n = FL, FR, RL, RR) of a vehicle during operation of said vehicle carried out in an Electronic Control Unit ECU (100) using a vibration signal (G(ti)) as provided by at least one vibration sensor (200) and wheels rotation angles (ϕn(tj), as provided by corresponding wheel rotation angle sensors (401÷404). The said method comprises the following steps: 
S1 measuring the vibration signal at first sampling times, as a sum of the vibration signals corresponding to perceived wheel unbalances and noise at the location of the Electronic Control Unit ECU based on an amplitude and a phase of said vibration signal for each wheel, and simultaneously measuring the wheel rotation angles, for each wheel at a second sampling times; 
S2 linearly interpolating the wheel rotation angles at times so that the interpolated wheel rotation angles correspond to the samples of said vibration signal; 
S3 determining wheel rotation full periods, for each of the wheels, by comparing the running wheel rotation angles with multiples of 360○ or 2□ radians; 
S4 calculating the sine and the cosine for the each of the interpolated wheel rotation angles for each wheel; 
S5 multiplying the vibration signal by the sine and cosine of the interpolated wheel rotation angles for each wheel; 
and then integrating vibration signal starting with first sampling time over a number of full periods resulting the sine projection and respectively cosine projection of the interpolated wheel rotation angles, 
and simultaneously calculating minimum and maximum speed of the vehicle and average vehicle speed for the same period of time corresponding to the integration; 
S6 calculating vibration amplitude at the location of the Electronic Control Unit ECU, said calculation being repeated over predetermined times for a total number of predetermined number of iterations or a predetermined duration; 
S7 calculating mean value and standard deviation of the vibration amplitude; 
S8 comparing the value of each standard deviation calculated for said predetermined number of iterations or said predetermined duration with a predetermined threshold value; 
if each standard deviation is smaller than or equal to said predetermined threshold value a first condition for localization of unbalance is met, and 
if any of the standard deviations is greater than said predetermined threshold value then steps 1-7 are repeated; 
 
S9 for the wheel for which the first localization of unbalance is met, 
comparing the value of the mean value of the vibration amplitude calculated for said predetermined number of iterations or said predetermined duration with a predetermined threshold mean value; 
if the calculated mean value is greater than said predetermined threshold value, the second condition for localization of unbalance is also met and the corresponding wheel is localized as unbalanced; 
 
S10 for the wheel for which both localization conditions are met, sending a warning signal via the CAN bus to the instrument panel to issue an alert to the driver or to a third party, according to the localization of the unbalanced wheel. 
     The invention further relates to a system for localizing said unbalanced wheel, Electronic Control Unit and storage medium.