Patent attributes
A rotation angle sensing device calculates an average value of calculation values of time necessary for rotation of each one of sections provided by equally dividing one rotation of a crankshaft. The device calculates an average value of the average values of the entire sections to calculate an entire section average value. The device calculates ratios of the average values of the respective sections to the entire section average value. The device eliminates an influence of rotation fluctuation of the crankshaft from the ratios by using reference ratios, which are calculated as ratios of the average values of the respective sections to the entire section average value in the case where there is no structural error. Thus, the device calculates learning values for compensating for the structural error.
