Irradiance-controlled fixture for horticultural applications

1. A horticultural lighting system, comprising:

a plurality of lighting fixtures that irradiate a plant bed, wherein the plurality of lighting fixtures supports a plurality of color channels and each of the plurality of lighting fixtures:

comprises a plurality of light emitting diodes (LEDs); and

stores calibration data that converts a user input to a pulse width modulation (PWM) setting; and

a controller coupled to the plurality of lighting fixtures and configured to:

receive, from each lighting fixture, a maximum light output for each color channel;

setting, for each color channel, a maximum allowable light output equal to a smallest maximum light output received from each of the plurality of lighting fixtures for that color channel;

receive a user input for a first color channel in the plurality of color channels, wherein the user input comprises a light parameter measured at a plant canopy of one or more plants grown in the plant bed;

determine, for each of the plurality of lighting fixtures, a pulse width modulation (PWM) setting of the first color channel such that the plurality of lighting fixtures irradiates the plant bed according to the user input based on the calibration data of each of the plurality of lighting fixtures; and

apply, to each of the plurality of lighting fixtures, the maximum allowable light output of the first color channel modulated by the determined PWM setting of the first color channel for that lighting fixture.

2. The system of claim 1 , further comprising a computing device communicatively coupled to the controller, wherein the user input is transmitted from the computing device.

3. The system of claim 1 , wherein the light parameter comprises a desired irradiance at the plant canopy.

4. The system of claim 1 , wherein the calibration data depends on one or more factors, including least one of a distance between the each of the plurality of lighting fixtures and the plant canopy, a layout of the plurality of LEDs on each of the plurality of lighting fixtures, a geometry of the plant bed, a structure of each of the plurality of lighting fixtures, and optical properties of one or more lenses on each of the plurality of lighting fixtures.

5. The system of claim 4 , wherein each of the plurality of lighting fixtures stores a plurality of sets of calibration data, each set of calibration data associated with a different set of the one or more factors.

6. The system of claim 5 , wherein when at least one of the one or more factors is changed for a first lighting fixture in the plurality of lighting fixtures, the controller is configured to:

select, for the first lighting fixture, another set of calibration data from the plurality of sets of calibration data that corresponds to the changed one or more factors; or

generate, for the first lighting fixture, a new set of calibration data corresponding to the changed one or more factors.

7. The system of claim 1 , wherein the calibration data comprises:

a total light output of the plurality of LEDs measured in an integrating sphere; and

an irradiance map of irradiance values of the plurality of color channels, including the first color channel, driven at a predetermined PWM setting at a predetermined distance from the plurality of lighting fixtures.

8. The system of claim 1 , wherein the determined PWM setting is expressed as a percentage of a maximum current for each of the plurality of lighting fixtures.

9. The system of claim 1 , wherein the determined PWM setting for each of the plurality of lighting fixtures is different.

10. The system of claim 1 , wherein each lighting fixture stores different calibration data, the differences caused by manufacturing differences between each lighting fixture.

11. A method for operating a plurality of lighting fixtures supporting a plurality of color channels, the method comprising:

receiving, from each lighting fixture, a maximum light output for each color channel;

setting, for each color channel, a maximum allowable light output equal to the smallest maximum light output received from each of the plurality of lighting fixtures for that color channel;

receiving a user input for a first color channel in the plurality of color channels, wherein the user input comprises a light parameter measured at a plant canopy of one or more plants grown in a plant bed irradiated by the plurality of lighting fixtures;

determining a pulse width modulation (PWM) setting of the first color channel such that the plurality of lighting fixtures irradiates the plant bed according to the user input based on calibration data stored in each of the plurality of lighting fixtures, wherein the calibration data converts the user input into PWM settings; and

apply, to each of the plurality of lighting fixtures, the maximum allowable light output of the first color channel modulated by the determined PWM setting of the first color channel for that lighting fixture.

12. The method of claim 11 , wherein the light parameter comprises a desired irradiance at the plant canopy.

13. The method of claim 11 , wherein the calibration data depends on one or more factors, including least one of a distance between the lighting fixture and the plant canopy, a layout of the plurality of LEDs on the lighting fixture, a geometry of the plant bed, a structure of the lighting fixture, and optical properties of one or more lenses on the lighting fixture.

14. The method of claim 13 , wherein each lighting fixture stores a plurality of sets of calibration data, each set of calibration data associated with a different set of the one or more factors.

15. The method of claim 14 , wherein when at least one of the one or more factors is changed, the method further comprises one of:

selecting another set of calibration data from the plurality of sets of calibration data that corresponds to the changed one or more factors; and

generating a new set of calibration data corresponding to the changed one or more factors.

16. The method of claim 11 , wherein the calibration data comprises:

a total light output of the plurality of LEDs measured in an integrating sphere; and

an irradiance map of irradiance values of the plurality of color channels, including the first color channel, driven at a predetermined PWM setting at a predetermined distance from the lighting fixture.

17. The method of claim 11 , wherein the determined PWM setting is expressed as a percentage of a maximum current for the lighting fixture.

18. The method of claim 11 , wherein the determined PWM setting for each of the plurality of lighting fixtures is different.

19. The method of claim 11 , wherein each lighting fixture stores different calibration data, the differences caused by manufacturing differences between each lighting fixture.

20. A non-transitory processor-readable storage medium having stored thereon processor executable instructions configured to cause a processor of a controller to perform operations comprising:

receiving, from each of a plurality of lighting fixtures supporting a plurality of color channels, a maximum light output for each color channel;

setting, for each color channel, a maximum allowable light output equal to the smallest maximum light output received from each of the plurality of lighting fixtures for that color channel;

receiving a user input for a first color channel in the plurality of color channels, wherein the user input comprises a light parameter measured at a plant canopy of one or more plants grown in a plant bed irradiated by the plurality of lighting fixtures;

determining a pulse width modulation (PWM) setting of the first color channel such that the plurality of lighting fixtures irradiates the plant bed according to the user input based on calibration data stored in each of the plurality of lighting fixtures, wherein the calibration data converts the user input into PWM settings; and

apply, to each of the plurality of lighting fixtures, the maximum allowable light output of the first color channel modulated by the determined PWM setting of the first color channel for that lighting fixture.