Road surface type detection device
Provided is a road surface type detection device capable of distinguishing an asphalt reference road surface type from other road surface types in real time from comparison of magnitudes and frequencies of strain sensor signal waveforms that are excellent for information detection in a low-speed range. A road surface type detection device 10 that estimates a plurality of road surface types (asphalt, a gravel road, a grass road) includes at least one sensor element 1, 2, 3 that detects a physical amount of a vehicle, a road surface type estimation unit 4 , and a storage unit 411 that stores output values of the sensor element 1, 2, 3 corresponding to the plurality of road surface types. Any one road surface type asphalt, a gravel road, a grass road) is estimated out of the plurality of road surface types on the basis of a magnitude of a waveform of a sensor signal output by the sensor element 1, 2, 3 . It is thus possible to distinguish asphalt from other road surface types in real time.
1 . A road surface type detection device that estimates a plurality of road surface types, the road surface type detection device comprising:
at least one sensor element that detects a physical amount of a vehicle;
a road surface type estimation unit;
a storage unit that stores output values of the sensor element corresponding to the plurality of road surface types, wherein the storage unit further stores, as a magnitude of a reference waveform, a magnitude of a waveform of asphalt that is one road surface type out of the plurality of road surface types; and
a determination unit that determines any one road surface type out of the plurality of road surface types based on a magnitude of a waveform of a sensor signal output by the sensor element, wherein the determination unit is configured to:
compare the magnitude of the waveform of the sensor signal output by the sensor element with the magnitude of the reference waveform,
in response to a determination that the magnitude of the waveform of the sensor signal output is equivalent to the magnitude of the reference waveform in a plurality of times in succession, determine that a first road surface type is asphalt,
in response to a determination that the magnitude of the waveform of the sensor signal output is greater than the magnitude of the reference waveform by a specific amount at least once or is smaller than the magnitude of the reference waveform by a specific amount at least once, determine that a second road surface type is gravel, and
in response to a determination that the magnitude of the waveform of the sensor signal output is smaller than the magnitude of the reference waveform by a specific amount in a plurality of times in succession, determine a third road surface type is grass.
2 . The road surface type detection device according to claim 1 , wherein the determination unit makes a determination of another road surface type out of the plurality of road surface types when a case in which the magnitude of the waveform of the sensor signal output is greater than the magnitude of the reference waveform by a specific amount or is smaller than the magnitude of the reference waveform by a specific amount is confirmed at least once.
3 . The road surface type detection device according to claim 1 , wherein the determination unit makes a determination of another road surface type out of the plurality of road surface types when cases in which the magnitude of the waveform of the sensor signal output is smaller than the magnitude of the reference waveform by a specific amount are confirmed a plurality of times in succession.
4 . The road surface type detection device according to claim 1 , wherein the sensor element is a strain sensor element.
5 . A brake control system comprising:
a road surface type detection device including:
at least one sensor element that detects a physical amount of a vehicle, a road surface type estimation unit,
a storage unit that stores output values of the sensor element corresponding to a plurality of road surface types, wherein the storage unit further stores, as a magnitude of a reference waveform, a magnitude of a waveform of asphalt that is one road surface type out of the plurality of road surface types; and
a determination unit that determines any one road surface type out of the plurality of road surface types based on a magnitude of a waveform of a sensor signal output by the sensor element, wherein the determination unit is configured to:
compare the magnitude of the waveform of the sensor signal output by the sensor element with the magnitude of the reference waveform,
in response to a determination that the magnitude of the waveform of the sensor signal output is equivalent to the magnitude of the reference waveform in a plurality of times in succession, determine that a first road surface type is asphalt,
in response to a determination that the magnitude of the waveform of the sensor signal output is greater than the magnitude of the reference waveform by a specific amount at least once or is smaller than the magnitude of the reference waveform by a specific amount at least once, determine that a second road surface type is gravel, and
in response to a determination that the magnitude of the waveform of the sensor signal output is smaller than the magnitude of the reference waveform by a specific amount in a plurality of times in succession, determine a third road surface type is grass, and
a brake control device that includes a braking condition determination unit that determines a braking condition of the vehicle based on a road surface type determined by the road surface type detection device, the brake control device controlling a braking force of the vehicle.
6 . The brake control system according to claim 5 ,
wherein the brake control device includes a wheel locking condition table that stores relationships between friction coefficients of the road surface types and a braking force that does not allow wheels of the vehicle to be locked, the brake control device controlling a braking force of the vehicle to be the braking force that does not allow the wheels to be locked in accordance with the road surface types.