Abstract: An estimation apparatus for a water film thickness on a road surface includes a data acquisition unit and an estimation unit. The data acquisition unit sequentially acquires a data set including driving force data representing a driving force output from a driving source of a vehicle and acceleration data representing a longitudinal acceleration of the vehicle, while the vehicle is traveling. The estimation unit estimates a thickness of a water film on a road surface on which the vehicle travels, based on a relationship between a speed of the vehicle and a fluid resistance that the vehicle receives from the water film, the flow resistance being calculated based on the data set.

Abstract: A wheel load estimation device includes a wheel speed acquisition unit, a frequency characteristic ratio calculation unit, a load ratio calculation unit, and a wheel load calculation unit. The wheel speed acquisition unit acquires wheel speed information of each wheel included in the vehicle. The frequency characteristic ratio calculation unit calculates a front-to-rear frequency characteristic ratio and a left-to-right frequency characteristic ratio. The load ratio calculation unit calculates the front-to-rear load ratio and the left-to-right load ratio. The wheel load calculation unit calculates, a wheel load ratio representing a relative wheel load among the wheels included in the vehicle, for at least one of the wheels of the vehicle. The load ratio calculation unit calculates the front-to-rear load ratio by taking a linear combination of the calculated two or more front-to-rear gain ratios using weights that are different from one another.

Abstract: An abnormality detecting apparatus includes a signal obtaining unit, a first index calculation unit, a spectrum calculation unit, a standardization unit, and a second index calculation unit. The signal obtaining unit obtain signals indicating a rotation speed of the wheel assembly, as pulses having a rise. The first index calculation unit calculates a first index indicating a temporal variation of the rise of each of the pulses. The spectrum calculation unit calculates a frequency spectrum of rotational orders from a first order to an mth order of the first index calculated for each of the pulses. The standardization unit standardizes a gain for each rotational order of the frequency spectrum using a mean value and a standard deviation of the gain for each rotational order when there is no abnormality. The second index calculation unit calculates a second index for determining whether there is an abnormality.