AIRFIELD LUMINAIRE OBSTRUCTION DETECTION

Methods, devices, and systems for airfield luminaire obstruction detection are described herein. In some examples, one or more embodiments include a controller for airfield luminaire obstruction detection, comprising a memory, and a processor configured to execute instructions stored in the memory to receive a signal from a light sensor of an airfield luminaire, determine, based on the signal, whether a lens of the airfield luminaire is obstructed by debris, and activate, based on whether the lens is obstructed, at least one of a vibration mechanism of the airfield luminaire and a heating mechanism of the airfield luminaire based on a temperature of the airfield luminaire to aid in clearing the debris.

TECHNICAL FIELD

The present disclosure relates to methods, devices, and systems for airfield luminaire obstruction detection.

BACKGROUND

Airfield infrastructure can include terminals, hangars, maintenance facilities, etc. Airfields can further include runways, approach ways, taxiways, and/or intersections therebetween to direct aircraft traffic and/or other vehicles in and/or around the airfield.

Airfields can include lighting systems to provide visual cues and/or signals for an airfield. For example, airfield lighting systems can include luminaires in order to direct aircraft and/or other vehicles in and/or around the airfield. The airfield lighting systems may, in some instances, be mandated by regulatory bodies such as the International Civil Aviation Organization (ICAO) and/or Federal Aviation Administration (FAA), among other examples. Airfield lighting systems can provide a safe and efficient way to regulate airfield traffic.

DETAILED DESCRIPTION

Methods, devices, and systems for airfield luminaire obstruction detection are described herein. In some examples, one or more embodiments include a controller for airfield luminaire obstruction detection, comprising a memory, and a processor configured to execute instructions stored in the memory to receive a signal from a light sensor of an airfield luminaire, determine, based on the signal, whether a lens of the airfield luminaire is obstructed by debris, and activate, based on whether the lens is obstructed, at least one of a vibration mechanism of the airfield luminaire and a heating mechanism of the airfield luminaire based on a temperature of the airfield luminaire to aid in clearing the debris.

Airfield luminaires can be located in, above, and/or around an airport surface. As used herein, the term “airfield luminaire” refers to a lighting unit including a light source and associated wiring. For example, airfield luminaires can include halogen and/or light emitting diode (LED) lamps and can be located around approach ways, mounted in the airport surface on runways, taxiways, intersections, etc.

The airfield luminaire can be, for instance, an inset luminaire. For example, the airfield luminaire can be installed within the pavement surface of the surface of the airfield. The inset airfield luminaires can provide guidance for aircraft during takeoff, landing, and ground movement (e.g., taxiing). The airfield luminaires can define the edges and/or a centerline of runways and/or taxiways, help pilots identify locations on the airfield, and/or give pilots directional information. Accordingly, airfield luminaires can help pilots safely navigate the airfield, especially during nighttime and/or during low visibility conditions.

Airfield luminaires can include a housing and can be mounted, via the housing, to a mounting location around the airfield. For example, an airfield luminaire can include a housing that can be connected to a base recessed into the runway, taxiway, intersections, etc. The housing can be connected to the base by bolts.

As airfield luminaires are located around airfields, they may be exposed to debris which can, in some instances, block the lens of the airfield luminaire such that light emitted by a light source of the airfield luminaire may be blocked, reducing or eliminating the light emitted from the airfield luminaire. Such debris can include dirt, sand, ice, snow, and/or rubber from tires of aircraft landing, taking off, taxiing, etc., among other types of debris.

When debris partially or fully blocks the light emitted from an airfield luminaire, a pilot may not be able to see the airfield luminaire. Accordingly, this blockage can prevent a pilot from safely navigating the airfield, as the pilot may not be able to easily determine directional information, identify locations on the airfield, and/or not be able to easily identify the edges and/or centerlines of runways/taxiways.

Accordingly, maintenance periods can be scheduled to ensure such airfield luminaires do not have debris causing a blockage of the light emission from the airfield luminaire. However, airfields may include many airfield luminaires. Clearing debris on these luminaires can be time consuming, costly, and expose maintenance personnel to injury. Additionally, flight activities may be temporarily suspended during debris clearance of airfield luminaires on the airfield, creating delays and/or increasing costs for airfields and/or airlines.

Airfield luminaire obstruction detection, in accordance with the present disclosure, can allow for remote monitoring of airfield luminaires for obstructions that may cause blockages of the light emitted from the airfield luminaires. Additionally, various mechanisms may be remotely and/or automatically activated to aid in clearing the debris from the airfield luminaires. Further, an alarm may be generated to notify a user of an obstruction from debris and the particular airfield luminaire having the obstruction, allowing for precise determination of obstructions and locations of luminaires having such obstructions. Accordingly, airfield luminaires can be individually determined for obstruction clearance, allowing for reduced maintenance time and increased safety for maintenance personnel, as well as an increase in efficiency of airport operations and reduction in costs as compared with previous approaches.

The figures herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits identify an element or component in the drawing. Similar elements or components between different figures may be identified by the use of similar digits. For example,102may reference element “02” inFIG.1, and a similar element may be referenced as202inFIG.2.

As used herein, “a”, “an”, or “a number of” something can refer to one or more such things, while “a plurality of” something can refer to more than one such things. For example, “a number of components” can refer to one or more components, while “a plurality of components” can refer to more than one component. Additionally, the designator “N”, as used herein particularly with respect to reference numerals in the drawings, indicates that a number of the particular feature so designated can be included with a number of embodiments of the present disclosure. This number may be the same or different between designations.

FIG.1is a block diagram of an example of an airfield luminaire100for airfield luminaire obstruction detection, in accordance with one or more embodiments of the present disclosure. The airfield luminaire100can include a controller102, a vibration mechanism104, a temperature sensor106, a heating mechanism108, a switch110, a light sensor112, a lens118, and a light source120.

As previously described above, the airfield luminaire100can be an inset luminaire which can provide guidance for aircraft. Such guidance can assist a pilot of the aircraft during takeoff, landing, and/or ground movement (e.g., taxiing). The airfield luminaire100can provide guidance by utilizing a light source120to emit light from the airfield luminaire100through the lens118. As used herein, the term “light source” refers to a device which generates light. The light source120can be, for example, a halogen lamp and/or a light emitting diode (LED), among other types of light sources120. As used herein, the term “lens” refers to a transparent material through which light travels. For example, the lens118can be a transparent material through which light emitted by the light source120can travel. Accordingly, the light emitted by the light source120may travel through the lens118to exit the airfield luminaire100in order to be seen by a pilot or other person navigating the airfield.

As previously mentioned above, in some instances, debris can block the lens118. For example, dirt, sand, ice, snow, and/or rubber from tires of aircraft landing, taking off, taxiing, etc. may be deposited in front of the lens118, which can cause a partial or full blockage of the lens118. In such a case, light emitted by the light source120may only partially visible or not visible at all by a person transiting the airfield. Accordingly, the airfield luminaire100can determine whether the lens118has an obstruction (e.g., debris) and utilize various mechanisms to aid in clearing the obstruction, as is further described herein.

In order to determine whether the lens118is obstructed by debris, a light sensor112can be utilized. As used herein, the term “sensor” refers to a device to detect events in its surrounding environment. For example, the light sensor112can be utilized to detect reflectance of a beam on any debris that might be located in front of the lens118. To do this, the light sensor112can include a photosensor114. As used herein, the term “photosensor” refers to a device that detects light and transmits an electrical signal in response to the detection of the light. Additionally, the light sensor112can include an infrared (IR) LED116.

To determine whether the lens118is obstructed by debris, the IR LED116can generate and emit a beam. In some examples, the beam can be a pulsating beam. The beam generated by the IR LED116can be of a different wavelength than the light generated by the light source120such that the beam is not detectable in the spectrum band generated by the light source120. The beam generated by the IR LED116can be directed at the lens118. Accordingly, if debris is located in front of the lens118, the beam is reflected back towards the photosensor114. Upon detection of the beam by the photosensor114, the photosensor114can transmit an electrical signal (e.g., a light signal) to the controller102. In response to the amount of light of the beam that is reflected back to the photosensor114being greater than a threshold amount, the controller102can determine the lens118is obstructed by debris (e.g., indicating that a large portion of the beam contacted the debris and reflected instead of traveling out of the lens118). Additionally, in response to the amount of light of the beam that is reflected back to the photosensor114being less than the threshold amount, the controller102can determine the lens118is not obstructed by debris (e.g., indicating that a large portion of the beam did not contact any objects located proximate to the lens118and instead of traveled out of the lens118).

As mentioned above, the lens118may be partially or fully blocked by debris. In some examples, the controller102may utilize different thresholds to determine whether the lens118is partially or fully blocked. For example, the controller102can determine that in response to the amount of light of the beam that is reflected back to the photosensor114being greater than a first threshold amount but not greater than a second threshold amount (e.g., where the second threshold amount is greater than the first threshold amount), the lens118is partially obstructed by debris. Further, the controller102can determine that in response to the amount of light of the beam that is reflected back to the photosensor114being greater than a first threshold amount and greater than a second threshold amount (e.g., where the second threshold amount is greater than the first threshold amount), the lens118is fully obstructed by debris.

In order to aid in the clearing of such debris, the airfield luminaire100may utilize various mechanisms. For example, the airfield luminaire100may utilize the vibration mechanism104and/or the heating mechanism108, as is further described herein.

As illustrated inFIG.1, the airfield luminaire100can include a vibration mechanism104. As used herein, the term “vibration mechanism” refers to a device that causes a mechanical oscillation. For example, the vibration mechanism104can be a solid-state piezo-based actuator. The vibration mechanism104can oscillate over a wide range of frequencies which can aid in breaking a bond between an outer housing of the airfield luminaire100and ice/snow/rubber. As a result, the vibration mechanism104can cause ice to crack and melt faster (e.g., along with heat generated by a heating mechanism108, as is further described herein), and/or cause weak molecular bonded tire rubber particles to shake loose from the outer housing of the airfield luminaire100. The airfield luminaire100may utilize the vibration mechanism104to vibrate loose debris that may be obstructing lens118under certain conditions, as is further described in connection withFIG.2.

Additionally, the airfield luminaire100can include a temperature sensor106and a heating mechanism108. As used herein, the term “temperature sensor” refers to a device that detects temperature and transmits an electrical signal in response to detection of the temperature. As used herein, the term “heating mechanism” refers to a device that generates heat. For example, the heating mechanism108can be a solid-state thick-film type resistor that can act as a resistive heater. The airfield luminaire100can utilize the heating mechanism108to generate heat in order to aid in melting debris such as ice and/or snow that may be obstructing lens118under certain conditions, as is further described in connection withFIG.2.

The heating mechanism108can be switched on or off utilizing the switch110. As used herein, the term “switch” refers to an electrical device that can disconnect or connect a conducting path in an electrical circuit. The switch110can be a solid-state alternating-current (AC) switch comprised of metal-oxide-semiconductor field-effect transistor(s) (MOSFET). The switch110can cause the heating mechanism108to turn on to generate heat when a temperature of the airfield luminaire100(e.g., determined by the temperature sensor106) is below a certain threshold, and can shunt the heating mechanism108to turn the heating mechanism108off when the temperature of the airfield luminaire100is above a certain threshold, as is further described in connection withFIG.2.

As described above, the vibration mechanism104, the heating mechanism108, and the switch110are described as solid-state devices. As used herein, the term “solid-state device” refers to a device that is semiconductor based. As previously mentioned above, the airfield luminaire100may be located on an area of the airfield which can expose the airfield luminaire100to forces from shocks and/or vibrations by aircraft landing, taking off, taxiing, etc. For instance, jet blasts from aircraft landing, taking off, and/or taxiing, and/or the weight of aircraft and/or other vehicles can generate vibrations that airfield luminaires may be exposed to. Such vibrations may cause damage to traditional devices utilized in previous approaches. For example, a heating element controlled by a mechanical bi-metal strip type thermostat utilized in previous approaches can have a limited operational life due to mechanical contacts utilized turning on and/or off, and can malfunction and/or break sooner because of vibrations caused by aircraft and/or other vehicles as described above. Accordingly, utilizing a solid-state vibration mechanism104, solid-state heating mechanism108, and solid-state switch110can prolong the life of such devices even under the vibrations caused by aircraft and/or other vehicles, as compared with previous approaches.

As illustrated inFIG.1, the controller102can be included in the airfield luminaire100. As mentioned above, the controller102can receive a signal (e.g., the light signal) from the light sensor112, and determine based on the light signal from the light sensor112whether the lens118is obstructed by debris. Accordingly, the controller102can activate, based on whether the lens118is obstructed, the vibration mechanism104and/or the heating mechanism108to aid in clearing the debris, as is further described in connection withFIG.2.

FIG.2is an example of an airfield luminaire200inset in a surface224of an airfield for airfield luminaire obstruction detection, the airfield luminaire200having debris222causing an obstruction, in accordance with one or more embodiments of the present disclosure. As previously described in connection withFIG.1, the airfield luminaire200can include a controller202, a vibration mechanism204, a temperature sensor206, a heating mechanism208, a light sensor212, a lens218, and a light source220.

As previously described in connection withFIG.1, the airfield luminaire200can be an inset luminaire. As illustrated inFIG.2, the airfield luminaire200can be partially located under a surface224of the airfield. For example, the airfield luminaire200can include a housing which can include a casing and support for the light source220, as well as associated wiring. As shown inFIG.2, the airfield luminaire200can be connected to a power cable226.

Although not illustrated inFIG.2for clarity and so as not to obscure embodiments of the present disclosure, the airfield luminaire200can be connected to an AC source regulator. As used herein, the term “AC source regulator” refers to a device that varies voltage across a load to maintain a constant electric current. For example, the AC source regulator can maintain a constant current in a range of 2.8 amperes (A) to 6.6 A to regulate luminaire light intensity. Additionally although not illustrated inFIG.2for clarity and so as not to obscure embodiments of the present disclosure, the airfield luminaire200can be connected to the AC source regulator via a series isolation transformer to prevent any breakage of electrical continuity between the airfield luminaire and the AC source regulator due to an open lamp condition in the airfield luminaire, as well as provide for galvanic isolation for safety, as is further described in connection withFIG.4.

While the airfield luminaire200is partially located under the surface224, a portion of the housing can be located above the surface224of the airfield. For example, the portion of the housing having the light source220and the lens218can be located above the surface224of the airfield such that light emitted by the light source220is visible to pilots and/or others navigating the airfield (e.g., when not obstructed by debris222).

In order to aid in clearing the debris222, the controller202can utilize a signal from the light sensor212. As previously described in connection withFIG.1, the light sensor212can utilize an IR LED to generate and emit a beam at the lens218. As the debris222is located proximate to the lens218obstructing the lens218, the beam can be reflected back towards a photosensor. As a result of the photosensor detecting the reflected beam, the light sensor212can transmit the signal to the controller202.

The controller202can determine, based on the signal, whether the lens218is obstructed by the debris222. For example, in response to the signal indicating that the amount of light of the beam reflected back to the photosensor is greater than a threshold amount, the controller202can determine the lens218is obstructed by debris.

The temperature sensor206can additionally take readings of the temperature of the airfield luminaire200and transmit the signal to the controller202. Accordingly, the controller202can receive a temperature signal from the temperature sensor206and determine a temperature of the airfield luminaire200based on the temperature signal. For example, the controller202can determine the temperature of the airfield luminaire200to be 4 degrees Celsius (° C.). As another example, the controller202can determine the temperature of the airfield luminaire200to be 9° C. The controller202can activate both the vibration mechanism204and the heating mechanism208, or only the vibration mechanism204, based on the lens218being obstructed and based on the temperature of the airfield luminaire200, as is further described herein.

As a first example, the controller202can determine the temperature of the airfield luminaire200to be 4° C. The controller202can compare the temperature of the airfield luminaire200(e.g., 4° C.) to a first threshold temperature (e.g., 5° C.), and determine that the temperature of the airfield luminaire200is less than the first threshold temperature. Accordingly, the controller202can activate, in response to the temperature of the airfield luminaire200being less than the first threshold temperature, the vibration mechanism204and the heating mechanism208to aid in clearing the debris222. For example, the debris222may be ice, and the vibration mechanism204, when activated, can cause cracks in the ice to form, allowing for heat generated by the heating mechanism208to melt the ice faster than non-cracked ice.

Additionally, the controller202can determine whether the lens218is obstructed by the debris222based on a further signal from the light sensor212. For example, after a predetermined amount of time has passed, the light sensor212can again determine whether the lens218is obstructed by the debris222. The controller202can accordingly deactivate the vibration mechanism204and the heating mechanism208in response to the further signal from the light sensor212indicating the lens218is not obstructed by the debris222. For example, the vibration mechanism204may have cracked the ice sufficiently and the heating mechanism208melted the ice sufficiently such that the ice has dissipated and is no longer obstructing the lens218. Accordingly, light from the light source220can again be emitted through the lens218as the debris222obstructing the lens218has been cleared.

As a second example, the controller202can determine the temperature of the airfield luminaire200to be 9° C. The controller202can compare the temperature of the airfield luminaire200(e.g., 9° C.) to a first threshold temperature (e.g., 5° C.), and determine that the temperature of the airfield luminaire200is greater than the first threshold temperature. Additionally, the controller202can compare the temperature of the airfield luminaire200(e.g., 9° C.) to a second threshold temperature (e.g., 8° C.), and determine that the temperature of the airfield luminaire200is greater than the second threshold temperature. Accordingly, the controller202can activate, in response to the temperature of the airfield luminaire200being greater than the first threshold temperature and the second threshold temperature, only the vibration mechanism204to aid in clearing the debris222. For example, the debris222may be rubber, and the vibration mechanism204, when activated, can assist in breaking the bond between the luminaire housing and the rubber. In this second example in which the temperature of the airfield luminaire200exceeds the first and the second threshold, the heating mechanism208may not be necessary to activate, since the ambient/outdoor temperature at the airfield may be high enough such that ice and/or snow formation does not occur.

Additionally, the controller202can determine whether the lens218is obstructed by the debris222based on a further signal from the light sensor212. For example, after a predetermined amount of time has passed, the light sensor212can again determine whether the lens218is obstructed by the debris222. The controller202can accordingly deactivate the vibration mechanism204in response to the further signal from the light sensor212indicating the lens218is not obstructed by the debris222. For example, the vibration mechanism204may have weakened the bond between the rubber and the housing of the airfield luminaire200such that the rubber is able to be blown away from the lens218(e.g., via wind, brushing by a user, airflow caused by aircraft and/or other vehicles passing by, by other aircraft tires contacting the debris222and sweeping it away, etc.) and is no longer obstructing the lens218. Accordingly, light from the light source220can again be emitted through the lens218as the debris222obstructing the lens218has been cleared.

In both of the two examples above, debris222was partially or fully obstructing the lens218. If debris222is obstructing the lens218(e.g., either partially or fully, and no matter the temperature of the airfield luminaire200), the controller202can generate and transmit an alert in response to the lens218being obstructed by the debris222. The alert can be information indicating a fault with the airfield luminaire200and can include a unique address of the airfield luminaire200. Such information can alert a user to the debris222and to which airfield luminaire200has the debris222obstructing the lens218. This can allow for the user to determine the location of the airfield luminaire200on the airfield and, if necessary, dispatch a maintenance technician to clear the debris.

The controller202can transmit the alert on the power cable226. For example, the power cable226can be a preexisting power cable226connected to the airfield luminaire200that, while providing power to the airfield luminaire200(e.g., via AC Mains), can also serve to transmit the alert to a remote computing device (e.g., not illustrated inFIG.2). The remote computing device can be a central monitoring device, and can also transmit the alert to a mobile device (e.g., not illustrated inFIG.2) of a user.

FIG.3is an example flow chart350of a method for airfield luminaire obstruction detection, in accordance with one or more embodiments of the present disclosure. The method can be performed by, for example, a controller included in an airfield luminaire.

At352, the controller can determine a lens of an airfield luminaire is obstructed. For example, a light sensor can be utilized to determine debris is obstructing the lens.

At354, the controller can determine whether a temperature of the airfield luminaire is less than a first threshold temperature. The airfield luminaire can include a temperature sensor that can transmit a temperature signal to the controller. Based on the temperature signal, the controller can compare the temperature of the airfield luminaire to the first threshold temperature.

In response to the temperature of the airfield luminaire being less than the first threshold temperature, at356, the controller can activate a vibration mechanism of the airfield luminaire and a heating mechanism of the airfield luminaire. Additionally, the controller can generate an alert and transmit the alert to notify a user of the obstruction in front of the lens. The vibration mechanism can break bonds with the debris in front of the lens, and if the debris is ice and/or snow, the heating mechanism can melt the ice and/or snow.

In response to the temperature of the airfield luminaire being greater than a first threshold temperature, at360, the controller can determine whether a temperature of the airfield luminaire is greater than a second threshold temperature. Based on the temperature signal, the controller can compare the temperature of the airfield luminaire to the second threshold temperature. In response to the temperature of the airfield luminaire being greater than the first threshold temperature and greater than the second threshold temperature, at358, the controller can activate only a vibration mechanism of the airfield luminaire (e.g., but not the heating mechanism of the airfield luminaire). Additionally, the controller can generate an alert and transmit the alert to notify a user of the obstruction in front of the lens. The vibration mechanism can break bonds with the debris in front of the lens. Since the temperature of the airfield luminaire is greater than the first and second threshold temperatures, it is unlikely the debris is ice and/or snow, and as such, it is not necessary to activate the heating mechanism.

At362, the controller can determine the lens is not obstructed. For instance, in the first example, the vibration mechanism and the heating mechanism may have cleared the debris from the lens. In the second example, the vibration mechanism may have cleared the debris from the lens. Accordingly, at364, the controller can deactivate the heating mechanism and the vibration mechanism, or deactivate the vibration mechanism.

Airfield luminaire obstruction detection, in accordance with the present disclosure, can allow for remote monitoring of airfield luminaires for obstructions that may cause blockages of the light emitted from the airfield luminaires, and remote activation of various mechanisms to aid in clearing the obstructions. Solid-state mechanisms can be utilized to improve performance and life-cycles of such mechanisms as compared to previous approaches. Accordingly, airfield luminaires can be individually determined for obstruction clearance, allowing for reduced maintenance time (e.g., and reduced airfield downtime) and increased safety for maintenance personnel, as well as an increase in efficiency of airport operations and reduction in costs as compared with previous approaches.

FIG.4is an example of an airfield ground lighting circuit430for airfield luminaire obstruction detection, in accordance with one or more embodiments of the present disclosure. The airfield ground lighting circuit430can include an AC mains442, a constant current regulator432, airfield luminaires400-1,400-2,400-3,400-4,400-N, and series isolation transformers434-1,434-2,434-3,434-4,434-N. The constant current regulator432can include a power transformer436, an input filter438, and a feedback control440.

As illustrated inFIG.4, the airfield ground lighting circuit430can include airfield luminaires400-1,400-2,400-3,400-4,400-N. The airfield luminaires400-1,400-2,400-3,400-4,400-N can include a light source which can be utilized to direct aircraft and/or other vehicles in and/or around the airfield, as previously described in connection withFIGS.1-3.

The airfield luminaires400-1,400-2,400-3,400-4,400-N can be connected to the airfield ground lighting circuit430via series isolation transformers434-1,434-2,434-3,434-4,434-N, respectively. As used herein, the term “series isolation transformer” refers to a device to transfer electrical power from a power source to a load. For example, the series isolation transformers434-1,434-2,434-3,434-4,434-N can transfer electrical power from an AC mains442to each of the airfield luminaires400-1,400-2,400-3,400-4,400-N, respectively.

As illustrated inFIG.4, the airfield ground lighting circuit430can be connected to an AC mains442. As used herein, the term “AC mains” refers to a power source to provide power to the airfield ground lighting circuit430. The AC mains442can provide a 50 Hz/60 Hz AC power source in a range of 2.8 A to 6.6 A, although embodiments of the present disclosure are not limited to a 50 Hz/60 Hz AC power source and/or a range of 2.8 A to 6.6 A.

The AC mains442can provide power to the airfield ground lighting circuit430via the constant current regulator432. As used herein, the term “constant current regulator” refers to a device to regulate an AC power source. For example, the constant current regulator432can regulate current from the AC mains442by providing current to the airfield ground lighting circuit430in the range of 2.8 A to 6.6 A, as well as provide isolation between the AC mains442and the rest of the airfield ground lighting circuit430in the event of an electrical power surge.

The constant current regulator432can include a power transformer436. The power transformer436can isolate an AC signal (e.g., from the AC mains442) from the airfield ground lighting circuit430.

The power transformer436can be connected to an input filter438. The input filter438can attenuate rippling that may occur as a result of the operation of the constant current regulator432.

The constant current regulator432can include feedback control440. The feedback control440can include a controller (not illustrated inFIG.4for clarity and so as not to obscure embodiments of the present disclosure) that can monitor an input current from the AC mains442to keep the input voltage and current of the AC signal in phase.

FIG.5is an example of a controller502for airfield luminaire obstruction detection, in accordance with one or more embodiments of the present disclosure. The controller502can include a processor544and a memory546.

The memory546can be any type of storage medium that can be accessed by the processor544to perform various examples of the present disclosure. For example, the memory546can be a non-transitory computer readable medium having computer readable instructions (e.g., computer program instructions) stored thereon that are executable by the processor544for airfield luminaire obstruction detection in accordance with the present disclosure.

The memory546can be volatile or nonvolatile memory. The memory546can also be removable (e.g., portable) memory, or non-removable (e.g., internal) memory. For example, the memory546can be random access memory (RAM) (e.g., dynamic random access memory (DRAM) and/or phase change random access memory (PCRAM)), read-only memory (ROM) (e.g., electrically erasable programmable read-only memory (EEPROM) and/or compact-disc read-only memory (CD-ROM)), flash memory, a laser disc, a digital versatile disc (DVD) or other optical storage, and/or a magnetic medium such as magnetic cassettes, tapes, or disks, among other types of memory.

Further, although memory546is illustrated as being located within the controller502, embodiments of the present disclosure are not so limited. For example, memory546can also be located internal to another computing resource (e.g., enabling computer readable instructions to be downloaded over the Internet or another wired or wireless connection).