The present invention relates to the field of remote sensing, and in particular to a system and technique for airborne remote sensing using camera arrays.
A need to reduce methane and other greenhouse gas (GHG) emissions have driven the development of innovative solutions for remote sensing of GHG emissions. Significant efforts have been put into attempts to find cost-effective technologies that could help companies find and manage emissions in a faster, more efficient way. To date, however, leak detection technology has remained slower and more expensive than would be desirable, limiting the ability to find and manage those undesirable emissions.
In one general aspect, a remote sensing system for mounting on an aircraft may include a plurality of remote imaging sensors combined as an array of remote imaging sensors for a combined larger field of view than provided by any one of the plurality of remote imaging sensors. A remote sensing system for mounting on an aircraft may also include a housing, configured for mounting on the aircraft, where the array of remote imaging sensors is disposed within the housing. A remote sensing system for mounting on an aircraft may furthermore include a mounting bracket, configured for attaching the housing to the aircraft.
In a second general aspect, a method of remote sensing may include combining a plurality of remote imaging sensors into an array of remote imaging sensors having a combined field of view larger than any one of the plurality of remote imaging sensors. A method of remote sensing may also include mounting the array of remote imaging sensors in a housing. A method of remote sensing may furthermore include mounting the housing and the array of remote imaging sensors on an aircraft. A method of remote sensing may in addition include flying the aircraft over a predetermined target area. A method of remote sensing may moreover include capturing remote sensing imagery in flight.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings,
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. References to numbers without subscripts are understood to reference all instances of subscripts corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.
Although some of the following description is written in terms that relate to software or firmware, embodiments can implement the features and functionality described herein in software, firmware, or hardware as desired, including any combination of software, firmware, and hardware. References to daemons, drivers, engines, modules, or routines should not be considered as suggesting a limitation of the embodiment to any type of implementation. The actual specialized control hardware or software code used to implement these systems or methods does not limit the implementations. Thus, the operation and behavior of the systems and methods are described herein without reference to specific software code with the understanding that software and hardware can be used to implement the systems and methods based on the description herein
As used herein, satisfying a threshold may, depending on the context, refer to a value being greater than the threshold, greater than or equal to the threshold, less than the threshold, less than or equal to the threshold, equal to the threshold, or the like, depending on the context.
Although particular combinations of features are recited in the claims and disclosed in the specification, these combinations are not intended to limit the disclosure of various implementations. Features may be combined in ways not specifically recited in the claims or disclosed in the specification.
Although each dependent claim listed below may directly depend on only one claim, the disclosure of various implementations includes each dependent claim in combination with every other claim in the claim set. No element, act, or instruction used herein should be construed as critical or essential unless explicitly described as such.
Various types of remote sensing techniques have been used to date. Various parties have used piloted drones, trucks, satellites, airplanes, and combinations of those systems. Drones require a skilled drone pilot to travel from place to place, launch the drone and pilot it in the air, then recover the drone. The data collected by the drone must then be downloaded and analyzed. Because the types of drones used in such a system have significantly limited flight time limitations, the area that can be examined by a drone in a single flight is necessarily also significantly limited. In addition, the cost of hiring a drone pilot and transporting the drone pilot from place to place is significant.
Truck-mounted sensing systems are simpler, typically requiring only a truck driver with sufficient training to operate the truck-mounted sensing equipment. However, the range of truck-mounted sensing equipment is low, the truck is typically limited to areas with good roads, and the time required to drive the truck from site to site can be extensive.
Satellite-based remote sensing systems are highly expensive, with significant infrastructure required to manage the satellite while in orbit. Although satellite remote sensing systems have increased their capabilities since the earliest Landsat satellites were launched in the 1970s, the resolution of remote sensing satellites with a high revisit rate is still larger than desired, while remote sensing satellites with a better resolution rate typically have a prohibitively low revisit rate.
Aircraft flying at low altitudes providing aerial surveillance have been in use for decades and can provide high-resolution sensing capability. However, a single aircraft equipped with a single remote sensing camera can cover a limited area at any time, because of field of view (FOV) limitations. In addition, the cost of the aircraft and skilled pilot are high.
The desired approach is to get high resolution sensing of large areas at the lowest possible cost. In one embodiment, a remote sensing system uses a single plane on which is mounted at least one array of remote imaging sensors, expanding the coverage area at a lower cost than multiple planes, while reducing the time that a single plane with a single remote imaging sensor would need to cover the same area.
The remote sensing aircraft is preferably an aircraft capable of flying low and slow over a predetermined target area. Thus, aircraft of the type used for crop dusting or aerial advertising are a good match for a remote sensing aircraft. The most common agricultural aircraft are fixed-wing aircraft such as the Air Tractor®, the Cessna® Ag-wagon, and the Thrush, but other types of aircraft, such as helicopters, blimps, or other types of airships can also be used. (AIR TRACTOR is a registered trademark of Air Tractor, Inc.; CESSNA is a registered trademark of Textron Aviation, Inc.; THRUSH is a registered trademark of Thrush Aircraft, Inc.) Most such aircraft have piston or turboprop engines, although jet engines could be used. The same or similar type of aircraft is used for aerial advertising and an aerial advertising aircraft could be used for remote sensing operations. Another category of aircraft that can be used for the purpose because of their above-average glide ratio and fuel efficiency is the category of light sport aircraft, such as from Pipistrel d.o.o Ajdo{hacek over (v)}čina.
The remote sensing aircraft is configured by mounting one or more remote imaging sensors, typically mounted in an array on one or both wings of the aircraft. However, in some embodiments, the remote imaging sensors are mounted on the fuselage of the aircraft, on the undercarriage, or in the fuselage aimed through an aperture in the cockpit or other desired portion of the fuselage. The remote imaging sensors are mounted so that multiple sensors can gather data simultaneously over the same location.
Preferably, multiple remote imaging sensors are located vertically or on a gyroscope so that they always capture nadir imagery directly below the aircraft at a given overlap from the previous image, to allow properly stitching the data together into a continuous remote sensing record.
Any orientation and type of remote imaging sensor can be used. For example, each remote imaging sensor of the array of remote imaging sensors can be a forward-looking thermal imaging system that includes a mid-wave infrared camera or a multispectral or hyperspectral camera in a nadir orientation. Because the remote imaging sensor is mounted on the remote sensing aircraft, the sensor preferably includes image stabilization capabilities. One source of such cameras is FLIR Systems, Inc., which provides several models of thermal imaging camera systems.
The remote imaging sensors that comprise the array of remote imaging sensors 120 include a plurality of sensor elements, including any power source required by the sensor elements and other supporting equipment such as high precision Global Positioning System (GPS), Global Navigation Satellite Systems (GNSS), or Real-Time Kinematics (RTK) units and associated antennas.
In this example, each of the eight infrared cameras 210A-H are connected via an IEEE 1394 connector to one of a pair of IEEE 1394 hubs 220A-B. The hubs 220A-B are then connected to an IEEE 1394 interface card 230 that provides a connection to a data collection computer 240. Although illustrated as an external card in
In this example, one of the groups of four cameras 210A-D may be mounted in an array unit on wing 115 of the aircraft 110, while the other group of cameras 210E-H may be mounted in an array unit on wing 117, the opposite wing of the aircraft 110. The number of cameras 210A-H and hubs 220A-B is illustrative and by way of example only, and any number of cameras or hubs may be used as desired, such as to fit into a desired form factor for the camera array. Although the cameras 210A-H are illustrated as connected via IEEE 1394 connectors, other types of digital or analog connectors and communication protocols can be used as desired. The computer 240 may be any type of device capable of connecting to the cameras 210A-H for collecting and processing the data. In some embodiments, the data is simply collected by the computer 240, then made available for later analysis by other computers or other devices. In other embodiments, the data collected by the computer 240 may be analyzed in real-time during flight, and the analysis used by the aircraft pilot to guide the path of aircraft 110 or to provide any other useful guidance to an operator of the sensing system 200, which may be a different person than the pilot. In some embodiments, the data collected by the computer 240 is continuously processed in situ and stored on the computer 240 or another device in the aircraft from which the data may be downloaded after the flight. In some embodiments, the data may be transmitted while in flight to a ground station via a wireless network, a satellite data network, or a mobile telephone data network such as a 4G or 5G data network. Although illustrated in
In one embodiment, the housing 300 is mounted to a wing 115 or 117 of the aircraft 110 in a removable manner, using a mounting bracket 310 of the housing 300. In some embodiments, the housing 300 mounting bracket 310 is configured to allow rotation of the housing 300 relative to the aircraft 110, either to a predetermined orientation, configured pre-flight, or to a variable orientation that can rotate or otherwise reorient the camera array during flight as desired by an operator. This configurability of the mounting bracket 310 allows a given housing 300 and an array of cameras 210 to be configured based upon the needs of the operator. For example, an operator may choose to orient the array to aim the field of view of the cameras parallel to the flight path of the aircraft 110 (forward-looking), perpendicular to the flight path (sideways-looking), or at any other angle relative to the flight path of the aircraft 110. Openings 330 in an exterior surface 320 of the housing 300 may allow a portion of at least some of the cameras 210 to protrude through the openings 330 external to the housing 300. In some embodiments, at least some of the cameras 210 do not protrude through the openings 330 but are configured to at least approximate the exterior surface 320 of the housing 300 to reduce aerodynamic drag caused by the cameras 120. The position of the openings 330 in the housing 300 as illustrated in
Although some embodiments may provide real-time communication of sensor data from the members of the array of remote imaging sensors to either an aircraft receiver system or a ground-based receiver, some embodiments provide onboard data storage that can be downloaded using wired or wireless connectivity once the towed array is landed.
Data generated by the cameras 210 may be stored in an onboard data storage contained in the housing 300, making the housing 300 and included electronics a relatively self-contained unit. In such an embodiment, the computer 240 may be disposed within the housing 300 and may be a special-purpose device for collecting and storing data from the cameras 210. Alternately, data generated in the housing 300 may be transmitted back to a system elsewhere in the plane, such as a system mounted inside the fuselage of the aircraft 110, using either a wired connection to the housing 300 or a wireless transmission technique. In such an embodiment, the computer 240 may be responsible for the collection and data transmission inside the housing 300, and another computer 240 may be mounted in the fuselage or a ground station for receiving the transmissions from the computer 240 in the housing 300. If a system mounted inside the fuselage of the aircraft 110 is provided, it may perform any or all of: (a) storing the received data; (b) analyzing the received data; or (c) transmitting the received data, any analysis results, or both to a ground receiver. The system mounted inside the fuselage of the aircraft 110 may be battery-powered or powered by an electrical system of the aircraft 110, as desired.
The data collected from the cameras 210 and any analysis data created by the computer 240 may be encrypted by the computer 240 for the security of transmission of the data from the aircraft 110 to a ground station if desired.
The aircraft 110 may be flown at various altitudes. In an embodiment in which the aircraft is flown at a low altitude between approximately 300 meters (approximately 1,000 feet) above ground level and approximately 1,800 meters (approximately 6,000 feet) the highest resolution data may be captured, but at a cost of a smaller coverage area. In other embodiments in which the aircraft 110 is flown at medium altitudes between approximately 1,800 meters (approximately 6,000 feet) to approximately 3,650 meters (approximately 12,000 feet) above ground level, the system can capture an increased cross-track area with the remote sensing cameras 210. The greater cross-track area allows for imaging multiple target areas per trip. In addition, the increased flight altitude of a medium altitude allows for a higher airspeed and more efficient aircraft operation due to reduced aerodynamic drag at medium altitudes compared to low altitudes. Furthermore, medium-altitude embodiments provide a higher margin of safety since the pilot has more time to land in the event of an aircraft malfunction. Typically, the remote sensing system onboard the aircraft will only collect data while the aircraft 110 cruises at the desired altitude range, rather than during takeoff or landing.
In some embodiments, the data may be captured by the remote sensing equipment at variable altitudes. When the aircraft 110 encounters obstacles to ideal image capture, such as a cloud layer or other aircraft, the aircraft 110 may decrease or increase altitude as needed to continue continuously capturing images of the target area. The resulting imagery may then be downsampled or upsampled as appropriate to maintain a consistent resolution and scale for the target area. compensating for the altitude variations.
By using a low- or medium altitude, relatively slow aircraft on which are mounted one or more arrays of remote imaging sensors, a larger coverage area can be covered in a single pass than in conventional techniques that mount a single remote imaging sensor with a limited field of view. Because remote imaging sensors may be small and can be mounted in the housing 300 that generates only a small amount of aerodynamic drag, a far more efficient airborne remote sensing system can be provided, reducing the cost and time required for coverage of a desired area substantially over an aircraft with a single wing- or fuselage-mounted remote imaging sensor. The coverage area can be significantly larger than any ground-based sensing technique, and requires fewer skilled operators, providing a major improvement in the field of remote sensing. The data collected by the remote sensing system can be analyzed for the detection of emissions such as hydrocarbon leaks or other types of surveillance activity.
As shown in
Although
While certain example embodiments have been described in detail and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not devised without departing from the basic scope thereof, which is determined by the claims that follow.
This patent application claims priority to U.S. Provisional Patent Application No. 63/202,700, filed on Jun. 21, 2021, and entitled “AIRBORNE REMOTE SENSING WITH SENSOR ARRAYS.” The disclosure of the prior application is considered part of and is incorporated by reference into this patent application.
Number | Date | Country | |
---|---|---|---|
63202700 | Jun 2021 | US |