Method for estimating and adjusting the speed and acceleration of a vehicle

Abstract

A method for estimating the speed of a motor vehicle includes defining a first speed threshold that corresponds to a minimum speed value supplied by a vehicle wheel angular speed sensor, defining a second speed threshold that is greater than the first, estimating low speed values when the vehicle is running below the first speed threshold by using an estimation method of adaptive filtered type, measuring high speed values when the vehicle is running above the second speed threshold by using vehicle speed values supplied by the wheel angular speed sensor, and in the intermediate zone between the first and second speed thresholds, mixing high speed with low speed.

1 - 6 . (canceled) 
     
     
         7 . A method for estimating the speed of a motor vehicle comprising:
 defining a first speed threshold that corresponds to a minimum speed value supplied by a vehicle wheel angular speed sensor;   defining a second speed threshold that is greater than the first speed threshold;   estimating low speed values when the vehicle is running below the first speed threshold using an estimation method of adaptive filtered type;   measuring high speed values when the vehicle is running above the second speed threshold by using vehicle speed values supplied by the wheel angular speed sensor; and   mixing, in the intermediate zone between the first speed threshold and the second speed threshold, high speed with low speed.   
     
     
         8 . The method according to  claim 7 , wherein the adaptive filter is a Kalman filter. 
     
     
         9 . The method according to  claim 8 , wherein, in the intermediate zone between the first speed threshold and the second speed threshold, the mixing is done periodically at successive instants by using a linear mixing method according to the formula: 
       
         
           
             
               Speed 
               = 
               
                 
                   Speed 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     low 
                     kalman 
                   
                   × 
                   
                     
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         2 
                       
                       - 
                       
                         Speed 
                         
                           t 
                           - 
                           1 
                         
                       
                     
                     
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         2 
                       
                       - 
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         1 
                       
                     
                   
                 
                 + 
                 
                   Speed 
                   ⁢ 
                   
                       
                   
                   ⁢ 
                   
                     high 
                     vehicule 
                   
                   × 
                   
                     
                       
                         Speed 
                         
                           t 
                           - 
                           1 
                         
                       
                       - 
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         1 
                       
                     
                     
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         2 
                       
                       - 
                       
                         SV 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         1 
                       
                     
                   
                 
               
             
           
         
         in which speed is the mixed speed at the current instant t, speed t−1  is the mixed speed at the instant t−1 at the preceding mixing instant t−1 (Speed Kalman   Low ) is the speed value calculated by the Kalman method at the current instant t, (Speed vehicle   high ) is the speed value measured by the angular sensor at the current instant t, SV 1  is first speed threshold, and SV 2  is the second speed threshold. 
       
     
     
         10 . The method according to  claim 7 , wherein the first threshold is 1 km/h. 
     
     
         11 . The method according to  claim 7 , wherein the second speed threshold is 1.5 km/h. 
     
     
         12 . The method according to  claim 8 , wherein the estimating includes estimating a value of acceleration using the Kalman filter and the mixing includes a mixing of the acceleration values between the first speed threshold and the second speed threshold.