| 摘要 |
Position ( x ref ) and heading ( H ) of a vehicle are tracked using wheel tick numbers coming from wheel tick units (5a, 5b) at the front wheels (3a; 3b) only from which a velocity (½) and a heading rate ( h ) are calculated. The calculations are based on an intermediate wheel angle (´). An exact solution ´ ex for the same depends on the velocities of the left front wheel ½ l and of the right front wheel ½ r according to ´ ex = arctan 2 �¢ p a 1 + p 2 + 1 - p 2 2 - 2 �¢ p a 2 where p = v l - v r v l + v r . . An approximate solution ´ app is calculated according to the simpler formula ´ app = ½ arcsin �¢ 2 �¢ p a and used wherever its deviation from the exact solution ´ ex is not significant, i.e., where the latter is not larger than a threshold wheel angle ´ thr . Only for ´ app >´ thr where the deviation is larger than, e.g., 2° or, preferably, 1°, the wheel angle according to the exact solution ´ ex is used. The latter is determined in that the approximate solution ´ app is first established and the corresponding exact solution ´ ex read from a look-up table, interpolation being used if necessary. |
