Method for determining the road temperature from inside a motor vehicle

A sensor arrangement for a motor vehicle for determining a surface temperature of the road on which a motor vehicle is travelling, the sensor arrangement comprising:

• a first light sensor, arranged to face towards the sky, for capturing a brightness of ambient light around the motor vehicle, the first light sensor having an unobstructed optical pathway to the sky;
• a second light sensor for capturing radiated light reflected from the road on which a motor vehicle is traveling;
• a third light sensor;
• a temperature sensor installed at air intake for a radiator of the motor vehicle configured to capture an ambient temperature of the vehicle;
• a moisture sensor configured to detect moisture on the road,
• wherein the surface temperature of the road is calculated using measured values for the brightness of the ambient light, the radiated light reflected from the road, the ambient temperature of the vehicle and the moisture on the road,
• wherein the first light sensor, the second light sensor and the third light sensor are arranged on a side of a windscreen, which is in an interior of the motor vehicle,
• wherein first light sensor, the second light sensor and the third light sensor are arranged in an area of the windscreen, which is swept by at least one windscreen wiper,
• wherein the surface temperature of the road is calculated by:
• storing the measured values for ambient conditions of an environment around the motor vehicle in an input vector v;
• applying a generalized polynomial function f1 to the input vector and calculating a first approximation of the surface temperature of the road f1(v) from the generalized polynomial function;
• determining various classes of ambient conditions from the measured values for the ambient conditions;
• assigning a polynomial function f2 to f9 to each of the classes;
• applying at least one of these polynomial functions f2 to f9 to the input vector;
• and
• calculating a further approximation of the surface temperature of the road via one of the polynomial function f2 to f9, and
• wherein a determination of the road surface temperature is enabled without external sensor devices.

A method for determining a surface temperature of a road on which a motor vehicle is travelling, the method comprising:

• capturing a brightness of ambient light around the motor vehicle using a first light sensor toward the sky around the motor vehicle, the first light sensor having an unobstructed optical pathway to the sky;
• capturing radiated light reflected from the road using a second light sensor;
• calculating the surface temperature of the road using measured values for the brightness of the ambient light and the radiated light reflected from the road;
• storing the measured values for ambient conditions of an environment around the motor vehicle are in an input vector v;
• applying a generalized polynomial function f1 to the input vector and calculating a first approximation of the surface temperature of the road f1(v) from the generalized polynomial function;
• determining various classes of ambient conditions from the measured values for the ambient conditions;
• making a differentiation between bright and dark conditions on the basis of a threshold value in the ambient light;
• making a differentiation between cold and warm conditions on the basis of a threshold value in the ambient temperature;
• making a differentiation between dry and wet conditions;
• assigning one polynomial function f2 to f9 to each of these differentiated classes created from these three differentiations;
• applying at least one of the polynomial functions f2 to f9 to the input vector;
• and
• calculating a further approximation of the surface temperature of the road via one the polynomial function f2 to f9,
• wherein a determination of the road surface temperature is enabled without external sensor devices.