Patent ID: 7707876

Claim:
A method for estimating the magnitude of a tire force acting on a rolling tire comprising: using seven sensors mounted on the tire at circumferentially different mounting positions; measuring a strain at seven different measuring positions (i) at a certain point of time during tire rolling by the use of said seven sensors, wherein each of the measuring positions (i) is such a position that the magnitude t(i) of the strain to be measured has a substantially linear correlation with each of seven force components which are a longitudinal force Fx, a side force Fy, a vertical load Fz, an overturning moment Mx, a rolling resistance moment My, a self-aligning torque Mz and an air pressure P acting on the tire, whereby the following conditional equation is satisfied: t ⁡ ( i ) = a ⁡ ( i ) · Fx + b ⁡ ( i ) · Fy + c ⁡ ( i ) · Fz + d ⁡ ( i ) · Mx + e ⁡ ( i ) · My + g ⁡ ( i ) · Mz + h ⁡ ( i ) · P wherein a(i), b(i), c(i), d(i), e(i), g(i) and h(i) are coefficients specific to the measuring position (i); obtaining the magnitude t(i) of the measured strain with respect to each of the seven different measuring positions (i), wherein (i) is from 1 to 7, whereby t 1= a 1· Fx+b 1· Fy+c 1· Fz+d 1· Mx+e 1· My+g 1· Mz+h 1· P t 2= a 2· Fx+b 2· Fy+c 2· Fz+d 2· Mx+e 2· My+g 2· Mz+h 2· P t 3= a 3· Fx+b 3· Fy+c 3· Fz+d 3· Mx+e 3· My+g 3· Mz+h 3· P t 4= a 4· Fx+b 4· Fy+c 4· Fz+d 4· Mx+e 4· My+g 4· Mz+h 4· P t 5= a 5· Fx+b 5· Fy+c 5· Fz+d 5· Mx+e 5· My+g 5· Mz+h 5· P t 6= a 6· Fx+b 6· Fy+c 6· Fz+d 6· Mx+e 6· My+g 6· Mz+h 6· P t 7= a 7· Fx+b 7· Fy+c 7· Fz+d 7· Mx+e 7· My+g 7· Mz+h 7· P; forming the following 7×7 matrix of said coefficients  a ⁢ ⁢ 1 b ⁢ ⁢ 1 c ⁢ ⁢ 1 d ⁢ ⁢ 1 e ⁢ ⁢ 1 g ⁢ ⁢ 1 h ⁢ ⁢ 1 a ⁢ ⁢ 2 b ⁢ ⁢ 2 c ⁢ ⁢ 2 d ⁢ ⁢ 2 e ⁢ ⁢ 2 g ⁢ ⁢ 2 h ⁢ ⁢ 2 a ⁢ ⁢ 3 b ⁢ ⁢ 3 c ⁢ ⁢ 3 d ⁢ ⁢ 3 e ⁢ ⁢ 3 g ⁢ ⁢ 3 h ⁢ ⁢ 3 a ⁢ ⁢ 4 b ⁢ ⁢ 4 c ⁢ ⁢ 4 d ⁢ ⁢ 4 e ⁢ ⁢ 4 g ⁢ ⁢ 4 h ⁢ ⁢ 4 a ⁢ ⁢ 5 b ⁢ ⁢ 5 c ⁢ ⁢ 5 d ⁢ ⁢ 5 e ⁢ ⁢ 5 g ⁢ ⁢ 5 h ⁢ ⁢ 5 a ⁢ ⁢ 6 b ⁢ ⁢ 6 c ⁢ ⁢ 6 d ⁢ ⁢ 6 e ⁢ ⁢ 6 g ⁢ ⁢ 6 h ⁢ ⁢ 6 a ⁢ ⁢ 7 b ⁢ ⁢ 7 c ⁢ ⁢ 7 d ⁢ ⁢ 7 e ⁢ ⁢ 7 g ⁢ ⁢ 7 h ⁢ ⁢ 7  about a combination of said seven different measuring positions (i); and computing the following equation including said matrix  Fx Fy Fz M ⁢ ⁢ x My Mz P  =  7 × 7 ⁢ ⁢ Matrix of Coefficients  - 1 ⁢ ⁢  t ⁢ ⁢ 1 t ⁢ ⁢ 2 t ⁢ ⁢ 3 t ⁢ ⁢ 4 t ⁢ ⁢ 5 t ⁢ ⁢ 6 t ⁢ ⁢ 7  to find at least one of the seven force components.