Method and system for measuring local ultraviolet exposure
View Patent ↗One variation of a method for measuring ambient ultraviolet light radiation including: calculating a target direct orientation of a light exposure device based on a location, a current date and time, and a direct solar position model; calculating a target diffuse orientation of the light exposure device based on the location, the current date and time, and a diffuse solar position model; in response to detecting alignment between orientation of the light exposure device and the target direct orientation, recording a direct ultraviolet value; in response to detecting alignment between orientation of the light exposure device and the target diffuse orientation, recording a diffuse ultraviolet value; in response to detecting alignment between orientation of the light exposure device and a target global orientation, recording a global ultraviolet value; and calculating an ultraviolet index based on the global ultraviolet value, the direct ultraviolet value, and the diffuse ultraviolet value.
1. A method comprising, during a first sampling interval:
accessing a first location of a mobile device comprising an ultraviolet sensor configured to detect intensity of incident ultraviolet radiation;
based on the first location and a time and a date of the first sampling interval, calculating a target direct orientation of the mobile device for which a primary axis of the ultraviolet sensor is normal to the Sun during the first sampling interval;
defining a target direct orientation window along the target direct orientation;
tracking an orientation of the mobile device;
in response to the orientation of the mobile device falling within the target direct orientation window at a first time, storing a first value read from the ultraviolet sensor at the first time as a first direct ultraviolet value; and
calculating a first ultraviolet index proximal a first location of the mobile device at the first time based on the first direct ultraviolet value.
2. The method of claim 1 , further comprising:
accessing a generic ultraviolet index curve defining a series of ultraviolet indices as a function of time;
adjusting the generic ultraviolet index curve to approximate the first ultraviolet index for the first time; and
estimating a first ultraviolet exposure at the mobile device by integrating the generic ultraviolet index exposure curve, adjusted according to the first ultraviolet index, from the first time to a second time succeeding the first time.
3. The method of claim 2 , further comprising:
in response to recording the first direct ultraviolet value, transitioning into a low-power mode for a preset duration of time at the mobile device;
in response to conclusion of the preset duration of time:
entering a high-power mode at the mobile device;
tracking the orientation of the mobile device;
in response to the orientation of the mobile device falling within the target direct orientation window at a second time, storing a second value read from the ultraviolet sensor at the second time as a second direct ultraviolet value; and
calculating a second ultraviolet index proximal a second location of the mobile device at the second time based on the second direct ultraviolet value; and
adjusting the generic ultraviolet index curve to approximate the second ultraviolet index for the second time; and
estimating a second ultraviolet exposure at the mobile device by integrating the generic ultraviolet index exposure curve, adjusted according to the second ultraviolet index, from the second time to a third time succeeding the second time;
calculating a total ultraviolet exposure based on a sum of the first ultraviolet exposure and the second ultraviolet exposure; and
in response to the total ultraviolet exposure exceeding a threshold ultraviolet exposure, serving a prompt to a user associated with the mobile device to reduce sun exposure.
4. The method of claim 1 , wherein defining the target direct orientation window comprises:
calculating a target direct orientation normal to the Sun during the first sampling interval; and
calculating the target direct orientation window defining a 15° cone axially aligned with the target direct orientation.
5. The method of claim 1 , wherein defining the target direct orientation window comprises:
calculating a target direct orientation normal to the Sun during the first sampling interval; and
calculating the target direct orientation window defining a 10° cone axially aligned with the target direct orientation.
6. The method of claim 1 , wherein defining the target direct orientation window comprises:
calculating a target direct orientation normal to the Sun during the first sampling interval; and
calculating the target direct orientation window defining a 5° cone axially aligned with the target direct orientation.