Patent Publication Number: US-2022212813-A1

Title: Urban Drone Corridor

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the field of constructing a safe, reliable, and efficient aerial transportation infrastructure for unmanned aerial vehicles (UAV), commonly referred to as drones. 
     BACKGROUND OF THE INVENTION 
     Many time-critical first-mile and last-mile logistics originate and end in the urban areas, calling for the application of unmanned aerial vehicles (UAV). Despite many advantages foreseen, regular UAV flights or delivery services have not been achieved in the urban areas that are clouded by restricted or controlled airspaces. 
     Even in the urban areas where the regulation allows the use of the UAV, the UAV faces challenges such as unpredictable near-ground wind, attenuated weak GNSS signal, deliberated drone jamming, unexpected EMI interference, bad weather conditions, as well as public concerns about noise, privacy, and safety associated with the UAV. 
     Prior art reference U.S. Pat. No. 10,351,239, “Unmanned aerial vehicle delivery system”, discloses a UAV delivery system capable of virtual route planning in the sky. In the multi-corridor sections of the suggested virtual route, if two UAVs fly side by side, one UAV can take advantage of the wind created by another UAV. When two UAVs fly too close to each other, the avoidance system on the UAVs will ensure that a collision does not occur. It suggests enclosures be built individually in the first or second zone for security reasons. It does not discuss any UAV passage with enclosure connecting the two zones. 
     Prior art reference U.S. Pat. No. 10,580,310, “UAV routing in utility rights of way”, disclose a method using power line right of way as virtual tunnel-like UAV routing. It does not discuss any UAV passage physically built. 
     Prior art reference U.S. Pat. No. 10,835,070, “Safe mail delivery by unmanned autonomous vehicles”, disclose a method and a system for delivering mails by UAV into a specially designed mail receptacle. It discusses enforcing a virtual track path with Inverse-Geofencing, but it does not discuss any UAV passage physically built. 
     The global navigation satellite system (GNSS), including the global positioning system (GPS), becomes unreliable in interior spaces because there is no visual contact with the satellites. A large variety of indoor positioning systems (IPS) based on lights, radio waves, magnetic fields, acoustic signals have been developed and deployed in an indoor environment where GNSS or GPS lose their signal strength or experience a lack of accuracy. 
     Electromagnetic interference (EMI) can be found in many places, and can adversely affect the UAV operation. Furthermore, drone jammers are being developed against UAV. They will jam the frequency that a UAV uses to communicate with its ground station, forces the drone to activate its return to home function. Shielded enclosures, referred to as Faraday cages or metal structures connected to the ground are capable of preventing external radiofrequency energy from entering into the enclosure and preventing the strong internal signal from leaking out. 
     The performance of widely used multi-rotor drones, for example, the quadcopters, depends on air density that varies at different altitudes. The greater the density of the air, the greater the rotor efficiency, engine power output, and aerodynamic lift. Fixed-wing types of drones, being able to fly due to the lift force acting on the fixed wings, benefit also from dense air since the amount of lift produced is proportional to the density of the air. Air density changes with pressure, temperature, and humidity. In general, the greater the altitude, the less dense the air becomes, the less atmospheric pressure a given volume of air has. 
     Modern drones, especially the multi-copter type such as quadcopters are easy to fly in any direction and hover in place smoothly. Their propeller&#39;s direction along with the drone&#39;s motor rotation and speed, make such a level of maneuverability possible. Beyond the basic command-and-control flow as following: Remote Control Stick Movement/Central Flight Controller/Electronic Speed Control Circuits/Motors and Propellers/Quadcopter Movement or Hover, the flight controllers also make additional computation using programmed flight parameters and algorithms based on inputs from the encompassed inertial measurement unit, GPS, Gyroscope and other sensors, to achieve the high stability and maneuverability. Nowadays, the UAV system is capable of making exact movement necessary within centimeters of a structure. 
     Nevertheless, wind remains one of the biggest concerns in UAV flight missions and a major determinant of whether or not a UAV is capable of carrying out its mission. 
     Although manned aircraft accidents due to strong wind are rare nowadays, the low altitude flying UAVs, with their smaller size, lighter weight, lower speed are involved in many accidents and are more susceptible to wind disturbance than manned aircraft. Among all the wind effects such as constant wind, turbulent flow, wind shear, and propeller vortex, wind shear is the most dangerous wind field which can make the UAV out of control temporarily. When the UAVs fly in close formation one after another, the propeller vortices of the leading UAV can affect the following UAV. Fortunately, the speed of the UAV is generally low, so the following UAV could stabilize itself and avoid dropping off, however at a cost of wasting limited battery power. 
     Wind shear, sometimes called wind gradient, is a significant difference in speed and/or direction at a short distance. A wind gust, however, is an increase in wind speed at the surface, generally in the same direction as the prevailing wind. 
     SUMMARY OF THE INVENTION 
     The purpose of the present invention is to provide a physically real passage with closed housing for aerial transportation using an unmanned aerial vehicle (UAV). The UAV passage is equipped with wired and wireless communication links, accurate network-based indoor positioning, appropriate lighting, EMI shielding, air density regulation, anemometers, and other climate weather sensors. The UAV passage of the present invention is further divided into multiple corridors superposed vertically, enabling simultaneous UAV flights at different altitudes, reducing the construction cost of the passage associated with acquiring the right of way in the urban area. With additional lining, the UAV passage is configured to provide preferentially airflow resistance, noise dampening, impact attenuation, or thermal insulation. Such a UAV passage creates a safe, efficient, almost foolproof flying route for a UAV in autonomous waypoint flight mode, improving the safety of UAV travels, boosting the performances of the UAV, and making the regular UAV flight mission and UAV delivery possible in urban areas and under all weather conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other uses and advantages of the present invention will become apparent to those skilled in the art upon reference to the specification and the drawings, in which: 
         FIG. 1  is a schematic partial cutaway view of the UAV passage with corridors, according to an embodiment of the present invention; 
         FIG. 1A  is a partial cutaway side view of the UAV passage with corridors, having one side of the housing/enclosures partially removed, showing the internal arrangement of the passage. 
         FIG. 1B  is a partial closeup view of the cross-section of the corridor shown in  FIG. 1A . Also included are schematic views of airflows, represented by arrow icons, originated from a moving UAV and their interaction with the corrugated lining next to the enclosure; 
         FIG. 1C  is a cross-sectional view of the corridor  12 C shown in  FIG. 1A . 
         FIG. 2B  is a partial closeup view of the cross-section of a corridor according to an alternative embodiment of the present invention. Also included are schematic views of airflows, represented by arrow icons, originated from a moving UAV and their interaction with the corrugated lining next to the enclosure. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  depicts one embodiment of the present invention, a multi-corridor section  12  of an unmanned aerial vehicle (UAV) passage  10  connecting two UAV terminals  11 A and  11 B, wherein a plurality of UAV  11 C,  11 D,  11 E,  11 F,  11 G, and  11 H are traveling. 
     The UAV passage  10  is physically constructed with a housing  10 H at the exterior to protect the interior, a path space confined by the housing  10 H, from undesirable weather conditions such as strong wind, heavy rain, or snow. The UAV passage  10  has at least one gate  10 G at each end in connection with the terminal  11 A and  11 B. The gate  10 G is generally kept closed and only opens when the UAV enters or exits passage  10 . 
     Section  12  has its portion of passage  10  physically divided vertically into corridors  12 A,  12 B,  12 C, and  12 D, by enclosures  12 E. The multi-corridor structure allows multiple UAV travel simultaneously in their dedicated corridors at the same longitude and latitude, but at different altitudes without any chance of collision. An advantage of superposing the multiple corridors vertically lies in the low construction cost associated with gaining right-of-way in the urban areas. It should be noted that certain parts of the enclosures  12 E can take advantage of the existing housing  10 H without redundancy. 
     Each corridor has at least one aperture  12 G at each end, in connection with a preparation section  17  which is substantially larger than the corridor, allowing multiple UAVs to simultaneously park, recharge or replace their batteries, launch, land, and hover waiting for instructions within the preparation section  17 . As shown in  FIG. 1 , the UAV  11 F is landing and UAV  11 E is taking off in the preparation section  17 . 
       FIG. 1  shows that the UAV  11 C and  11 D are traveling inside the corridor  12 A and  12 B designated in the travel direction from the UAV terminal  11 B to the UAV terminal  11 A. The UAV  11 G and  11 H are traveling inside the corridor  12 C and  12 D designated in the travel direction from the UAV terminal  11 A to the UAV terminal  11 B. 
     The UAV passage  10  is supported by an elevated viaduct  13 , a bridge that consists of a series of piers, to avoid interruption of busy urban ground transportation. It should be noted that the UAV passage can also be built underground as a tunnel. Other alternative UAV passage construction arrangements taking advantage of the existing infrastructure with rights of the way on the ground, or inside the restricted/controlled airspaces are also envisioned, for example, attaching the UAV passage to the existing elevated highway, motorway, power line networks, or bridges, converting the underused railway tunnel or rail transit corridor into UAV passage, building the UAV passage along with the waterways, constructing UAV three-dimensional passage networks connecting the existing high-rise buildings with hospitals or direct delivery parcel distribution centers, as well as transportation hubs such as airports, heliports, seaports, railway yards/stations, or bus stations, etc. 
     It should be emphasized that although the illustrated UAV passage is in general oriented horizontally, the vertical passage with multi-corridors can also be built, either outside or inside a high-rise building. 
     The housing  10 H and enclosure  12 E, as well as the viaduct  13 , are made of any suitable construction material including but not limited to steel bar reinforced concrete, glass fiber reinforced concrete (FRC), fiber-reinforced plastic using glass fiber (fiberglass), other suitable polymers, plastic, suitable metals such as steel, steel alloy or aluminum alloy, architectural strengthened or laminated glass, treated or untreated wood, corrugated sheet in Fiberglass Reinforced Plastic (FRP)/metal/acrylic/polycarbonate, or composites combining the above-mentioned material, etc. 
     The gates  10 G are configured in a way that once closed, create an airtight path space in the UAV passage. The gate  10 G can be an automatic type and equipped with sensors and detectors, being capable of UAV identity recognition and performing other safety/security checks. 
       FIG. 1  and  FIG. 1A  also show that the UAV passage  10  is provided with integrated communication and indoor positioning module  14  that is composed of a plurality of communication nodes  14 B, a plurality of indoor positioning units  14 C, and a plurality of anemometers  14 W, being deployed along with the UAV passage  10 , as well as a ground computer  14 D outside the path space. Each node  14 B is in a wired connection with the ground computer  14 D using a cable  14 A, either a type of Ethernet cable or a type of fiber optic cable. 
     The indoor positioning unit  14 C and the anemometer  14 W are in wired or wireless connection with  14 B. 
     It should be noted that the wired connection achieved by cable  14 A can also be realized wirelessly with the suitable type of radio signal booster, extender, or repeater. 
     Each node  14 B contains a ground module of telemetry radio, a radio platform that covers a section of corridor  12  of approximately 500 meters. Node  14 B is capable of setting up telemetry connection, as well as command and control link with air module of telemetry radio integrated into the autopilots on board of traveling UAV at a certain frequency, for example, 915 MHz or 2.4 GHz. Upon receiving the data or instruction, the node  14 B automatically store them, and then
         relay wirelessly the instructions from the ground computer  14 D located outside the path space to the autopilots of the UAV traveling inside the path space;   relay the flight data from the UAV to the ground computer  14 D for UAV monitoring and flight control, through the high-speed wired connection using cable  14 A.       

     There are substantial overlaps between the coverage of one node  14 B and another node, so once connected in a network, they create full coverage of the path space accessible by the UAV. 
     In addition to the flight data received from the UAV, the measuring results from the climate weather sensors, for example, anemometer  14 W for the wind speeds and the wind directions are also transferred to the ground computer  14 D to verify the fitness of each location for UAV travel. The anemometers can be any suitable type including but not limited to cup type, vane type, hot-wire type, Laser-Doppler type, ultrasonic type, pressure type, or digitally instrumented type, etc. 
     Each unit  14 C contains at least three radio signal readers or three ultrasonic signal readers with fixed known positions, being paired with a time-distance reporter integrated into the node  14 B of communication module  14 . When a small mobile transmitter tag (not shown in the figures) carried by the traveling UAV enters the section of the corridor covered by the unit  14 C, the time-distance reporter is capable of measuring the distance between the mobile transmitter tag and each signal reader, determining accurately the position of the UAV from the three or more distances measured, and reporting in real-time the position of the UAV to the ground computer  14 D through the communication module. 
     The UAV may carry a mobile transmitter tag all the time as a permanent permit to access the UAV passage or it may pick up a temporary one at the entrance gate  10 G and drop off the tag at the exit. 
     It should be noted that other suitable indoor positioning technology can be applied to the UAV passage, for example, a proximity-based system, laser-based system, WIFI based system, and Infrared (IR) system. The measurement principle can be based on distance only or angle and distance. 
     The ground computer  14 D, with ground version software about the communication network, the telemetry, the indoor positioning, the logistics management, provides an interface for human control of UAV from outside the path space, either directly at the computer  14 D or indirectly by remote control in wired or wireless connection with computer  14 D. The interface can take any suitable form, for example, it may resemble a virtual cockpit which includes but is not limited to multiple monitoring screens, the control joystick, and throttle. The screens show maps, views of the surveillance camera, data of UAVs in the UAV passage  10  versus the planned waypoints, as well as information about the articles to be delivered. 
     The ground computer  14 D, with ground version software about the flight mission planning and operation, traffic control, as well as safety and security surveillance, is also capable of directing autonomous UAV flights or UAV deliveries, through the UAV passage  10 , with activated waypoint flight mode on UAV. For example, the set of waypoints are set up according to the exact longitude, latitude, and altitude of the points along the centerlines of the corridor  12 A,  12 B,  12 C, and  12 D. The possible routings can be identified by considering the available openings  12 P along each corridor. The possible flight plans can be determined by identifying available empty flying blocks, a slot of moving path space reserved for only one UAV, respecting the safety standard in terms of minimum separation, taking into account the UAV flights already in execution or scheduled represented by the occupied flying blocks. Therefore scheduling a new UAV travel request resembles filling the empty flying blocks available. Detailed guidance can also be given to each UAV to either follow the planned UAV block or switch to an alternative block for rerouting in case of accidents or undesirable flying conditions such as strong wind picked up by the anemometer  14 W. 
     The ground computer  14 D is also capable of pre-checking the fitness of the particular UAV before issuing a permit and loading the flight plan including the chosen set of waypoints corresponding to the coordinates of the points inside the UAV passage  10 . 
     It should be noted that the computer  14 D can be any suitable type of machine that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. 
     The UAV passage is provided with a power line  15 A and an internal lighting unit  15  that is capable of meeting the minimum illumination requirement for the UAV operation, for example at a level greater than 50 lux. The lighting unit contains a plurality of lamps  15 B based on light-emitting diode (LED), halogen lamps, fluorescents, or the incandescent light bulb. 
     The battery charging stations deployed along with the passage are also envisioned by the present invention, for example, the deployment of wired or wireless charging pads, etc. 
     As shown in  FIG. 1  and  FIG. 1A , the UAV passage  10  is also equipped with an air density regulation unit  16  comprising
         a plurality of local self-regulated valves  16 AA with the capacity of measuring the air density of the path space at the planned sites, each in connection with an auxiliary compressed air reservoir  16 RA, In operation, the self-regulated valve  16 AA lets the auxiliary reservoir  16 RA feed the path space with stored the compressed air when the measured air density is below the predetermined level and exhaust the air from the path space when the measured air density is higher than the predetermined level;   a separate pipeline  16 C connects the auxiliary reservoirs with the main reservoir  16 RM, a main self-regulated valve  16 AM, and an air compressor  16 B. In operation, sensing the air pressure drop in the pipeline  16 C by the self-regulated valve  16 AM, the main compressed air reservoir  16 RM starts to replenish the air in the auxiliary reservoir  16 RA to quickly restore the target tank pressure level and meanwhile, the air compressor  16 B starts to draw air from outside, pump and store them in the main reservoir  16 RM until the target tank pressure level is reached.       

     Such a pressurized path space with air density stabilized at a predetermined level greater than 1.2 kg/m 3 , enables the production of a consistent UAV lift and improved its power efficiency regardless of the actual altitude the UAV is flying. It should be noted that other suitable air pressure increasing techniques may be applied instead of using mechanical compressors. 
     It should also be noted that instead of measuring air density directly, other techniques of indirect determination of the air density level are envisioned. For example, by measuring temperature, humidity, and air pressure, a firmware integrated into the local self-regulated valve can calculate the air density level according to the known relationships. 
       FIG. 1A  depicts the same embodiment of the present invention as in  FIG. 1  with additional details of
         openings  12 P in the corridor enclosure  12 E and their roles of allowing the traveling UAV to switch from one corridor to another, enabling surpassing one slow-moving UAV by another fast-moving UAV;   a layer of electromagnetic interference (EMI) shielding  18  being disposed of next to the enclosure;   a layer of resilient lining  19  with corrugation being disposed of next to the enclosure.       

     Two examples of the traveling UAV switching from one corridor to another corridor are shown in  FIG. 1A . The UAV  11 F switches from position  11 FB in corridor  12 D to position  11 FA in the corridor  12 C. The UAV  11 D switches from position  11 DB in corridor  12 A to position  11 DA in corridor  12 B. In general, any two UAVs in the same corridor fly one after another respecting a safe separation distance.  FIG. 1A  demonstrates that the presence of the openings  12 P in the corridor make surpassing between UAVs possible without compromising safety. It is also envisioned by the present invention to set up a general UAV travel speed range for each corridor. 
     Section  12  of passage  10  is furnished with EMI shielding  18  next to the housing  10 H and enclosure  12 E. Although shielding  18  is presented here as a separate layer in this embodiment, it should be understood that it can well be integrated with housing  10 H, enclosure  12 E, or resilient lining  19 . For example, a conductive coating may be applied to the surfaces of the housing, the enclosure, or the lining. The shielding can be made of any suitable material with a certain texture capable of offering shielding effectiveness greater than 30 dB, including but not limited to copper or aluminum sheet, foil or mesh, as well as conductive fabric, conductive textile, conductive foil or mesh made of nylon or polyester metalized with nickel and copper, ferrite absorber tile, pyramidal absorber foam, or conductive rubber/conductive elastomer. 
       FIG. 1A ,  FIG. 1B  and  FIG. 1C  shows the arrangement of a resilient lining  19  that offers noise dampening in the populated urban zone and impact attenuation in case of crash accidents, protecting the UAV, the articles that the UAV carries, as well as the structure of the UAV passage. Lining  19  is made of any suitable material including but not limited to
         rigid foams with polyurethane, polyethylene, polyisocyanurate, polystyrene, fiberglass, polyester fiber, or metal;   composite foams for absorption, or sandwich composite foam,   corrugated sheet in Fiberglass Reinforced Plastic (FRP), metal, acrylic, or polycarbonate.       

     The internal surface of lining  19  has corrugation, with grooves extended generally in directions perpendicular to the longitudinal direction of the corridor, increasing the airflow resistance and pressure drag through the UAV passage and the corridors. 
     As shown in  FIG. 1B , the UAV  11 F flies from right to left, leaving behind the propeller vortices moving from left to right. Since the UAV flies at relatively low speeds, usually laminar boundary layer flow condition develops near a smooth housing or enclosure surface. However, in the case shown in  FIG. 1B , when the vortices hit the corrugated surface of lining  19 , the boundary layer separation occurs and turbulences form in proximity to the corrugation behind the UAV. The occurrence of boundary layer separation and turbulences increases pressure drag and dissipates rapidly the kinetic energy of the airflow into frictional heat. It helps restore the still air environment behind the traveling UAV  11 F faster than the case of smooth surface, shortening the required minimum separation distance between any two UAVs and increasing the flow capacity of the UAV passage. 
       FIG. 2B  depicts an alternative embodiment of the present invention to the one presented in  FIG. 1B . A UAV passage  20 , identical to the UAV passage  10  except for the configuration of shielding  28  and the resilient lining  29  that are both shaped in a corrugation. Both the shielding  28  and the lining  29  are disposed of next to the enclosure  22 E defining a generally column-shaped zone  22 DL around the centerline of the corridor  22 D, and a generally ring-column-shaped zone  22 DT between the internal surface of the enclosure  22 E and the external surface of the shielding  28 . 
     Each corrugation groove has two flanks, each flank defining a surface normal vector  29 NA or  29 NB. The positive normal vector  29 NA pointing to the zone  22 DL takes an acute angle  29 A with the designated travel direction of the corridor, while the other positive normal vector  29 NB pointing to the zone  22 DL takes an obtuse angle  29 B with the designated travel direction of the corridor. Instead of making general perforation evenly across the corrugated surface, a plurality of perforation is made only on the flank of the groove with the normal vector  29 NA, making lining  29  and shielding  28  permeable to achieve a preferential flow resistance. 
     In operation, as shown in  FIG. 2B , the UAV  21 F flies from right to left, leaving behind the propeller vortices moving from left to right. When the vortices hit the corrugation, boundary layer separation occurs and turbulences form in proximity to the corrugation behind the UAV. Meanwhile, a portion of the air passes through perforated holes  29 P created only on the group of the flanks with surface vector  29 NA, from zone  22 DL to zone  22 DT. As shown in  FIG. 2 , a new relatively strong airflow passes through the holes  29 P at the point  22 DT 1  where the propeller vortices just hit. The increase of air pressure in zone  22 DT 1  helps develop reverse airflows in the zone  22 DT 2  and  22 DT 3  against the incoming airflows through the nearby perforated holes, resulting in a preferential resistance, an additional pressure drag, to airflow from left to right. It is acknowledgeable that the above configuration will not develop reverse airflow if the UAV  21 F flies from left to right. 
     It should be noted that the same increase of air pressure in zone  22 DT 1  results in airflow from zone  22 DT 4  to part of the zone  22 DL ahead of the UAV that remains still-aired. This airflow helps propel and float the moving UAV  21 F. 
     It should be noted that it is the intent of the present invention to diminish the airflows left behind a traveling UAV by quickly converting the kinetic energy of the airflow to frictional heat and to restore the still-air environment as quickly as possible for the next UAV passing the same section of the path space. To achieve this purpose,
         the corrugation is shaped either on the internal surface of the enclosure or the housing when no lining is present or the corrugation is shaped on the internal surface of the lining when it is furnished or in other words, corrugation being formed on the immediate boundary of the path space accessible by the UAV;   the mesh-like perforation  29 P is structured, making the lining permeable;   the reversing airflow in zone  22 DT is created, resulting in additional turbulences in the preferential direction.       

     All the above help dissipate the kinetic energy quickly into frictional heat in the air. 
     Other alternative arrangements using one-way active check valves or passive check valves, for example, Tesla valvular conduit are envisioned to achieve a preferential airflow resistance. 
     It should be noted that lining  19  can act as thermal insulation being disposed of next to the enclosure and the housing. With further temperature sensors, heating and/or cooling equipment in place, the UAV passage may acquire the capacity of temperature regulation. 
     The present invention has been described in connection with the preferred embodiments of the various figures. It is to be understood that other similar embodiments may be used, or modifications and additions may be made to the described embodiment for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.