Laser drone communications

Abstract

Systems and methods providing dynamic alignment (both rapid and precise) of transmitting lasers and laser data receiver apparatus installed on drone platforms for data communications. Drone-to-drone data communications as well as drone-to-ground communications are supported, particularly for implementing drone-based data networks. Embodiments provide a data-transmitting laser and a data receiver positionally-coupled to a variable-angle swivelling gimbal mount installed on a drone. Laser pointing direction is adjusted by a dedicated directional controller which acquires and maintains a precise Line-Of-Sight bearing to the laser data communications apparatus of another drone. Control of the pointing angle is achieved by means of gimbal control in combination with control of the drone's attitude and local position.

Description

LASER DRONE COMMUNICATIONSCROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority of U.S. Provisional Patent Application Serial Number 63 / 652,679, entitled “Methods and systems for intersatellite communication”, filed May 29, 2024.FIELD

[0002] The present invention relates to data communications via laser beam, involving one or more drones in flight, including the configuration and operation of data networks among groups of drones in flight, where data is intercommunicated over the networks via laser beams.BACKGROUND

[0003] The evolution of drone technology has led to an increased need for high bandwidth communication that is secure and not adversely affected by RF environments. Traditional radio communication systems often face challenges such as spectrum congestion and bandwidth limitations. Laser communications offer solutions to these problems, enabling secure, high bandwidth, low RF interference communication. A practical benefit of employing laser data communication in drones is the ability to establish a high-speed data network among a group of drones distributed over an area of interest. For example, data gathered over the area of interest by many drones working together over the network can be efficiently analyzed and correlated in real-time to obtain far more relevant information about the area of interest than could be obtained by independent drones working on their own.

[0004] The use of laser-based data communications involving a drone in flight, however, introduces new challenges in implementation, particularly in the case of rotary- wing drones. Because laser beam communication is Line-Of-Sight (LOS) with a very narrow beam, precise directional alignment of the transmitting laser and the receiving sensor is necessary for successful communications. When the transmitting laser and the receiving sensor are located on independently-flying drones, the required precise alignment can be difficult to achieve, especially in the case of rotary-wing drones, whose high maneuverability can complicate the connection process. It would therefore be highly beneficial to have a system and method for rapidly and accurately positioning the direction of laser transmission aboard a drone in flight. This goal is attained by the present invention.SUMMARY

[0005] Embodiments of the present invention provide systems, apparatus, and methods for rapidly and accurately positioning the direction of laser data transmission aboard a drone, and for dynamically maintaining the directional alignment during flight. Systems, apparatus, and methods of the present invention provide reliable laser data communications between drones in flight, as well as between drones and ground stations, and also facilitate drone-based data networks set up for groups of independently- controllable drones in flight. Supported network topologies include mesh networks, where data can be relayed through multiple nodes; and dynamic open networks, where drones can enter and exit the networks via real-time re-configurable links, in order to be responsive to changes in local conditions and communication needs.

[0006] The present invention provides the versatility and other well-known advantages of laser-based data communications to airborne platforms, while efficiently and automatically handling all of the LOS requirements imposed by laser communications.Embodiments of the invention are usable in all types of aircraft, but are particularly well- suited for use in small rotary-wing drones. The system is easily adapted and integrated into existing drone platforms without significant modification, and features light-weight, small-footprint and energy-efficient components.

[0007] According to one embodiment of the invention, dynamic laser alignment is provided by directional adjustments of a variable gimbal-equipped laser mounting device. In another embodiment, laser directional alignment is provided by manipulating the drone’s angular attitude parameters. In a further embodiment, laser directional alignment is provided by controlling a variable angle gimbal-equipped laser mounting device in combination with a controlling of the drone’s angular attitude parameters and local positioning, both vertically (altitude) as well as horizontally.

[0008] Therefore, an embodiment of the present invention provides a communication system for a drone, which includes: a directionally-variable optical signal transmission unit with a variable pointing direction and a laser transmitter configured to transmit an outgoing laser beam optical signal in the pointing direction; a receiver configured to receive an incoming laser beam optical signal, where the receiver determines an incoming beacon direction of the incoming laser beam; and a controller including at least one actuator for adjusting the pointing direction of the outgoing laser beam optical signal according to the incoming beacon direction, in order to achieve a dynamic alignment of the outgoing laser beam optical signal with the incoming laser beam optical signal. A related embodiment provides a controller that is configured to send a dynamic alignment control signal to a controller of the drone and thereby control a parameter related to altitude, horizontal position, roll, pitch, and / or yaw.

[0009] In addition, other embodiments of the present invention provide a method for drone communications having the steps of: receiving an incoming laser beam opticalsignal; measuring a direction of the incoming laser beam optical signal; measuring a pointing direction of an outgoing laser beam optical signal; computing a pointing error as the difference between the incoming laser beam optical signal direction and the outgoing laser beam optical signal direction; and adjusting the pointing direction to cancel the pointing error via an actuator in a directionally-variable optical signal transmission unit, in order to adjust the pointing direction. In a related embodiment, adjusting the pointing direction includes controlling a drone controller to adjust a drone parameter related to altitude, horizontal position, roll, pitch, and yaw.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The subject matter disclosed may best be understood by reference to the following detailed description when read with the accompanying drawings in which:

[0011] Fig. 1 illustrates features of laser beam alignment between two independent drones in flight, according to an embodiment of the present invention.

[0012] Fig. 2 illustrates a. directionally-variable gimbal mount for a transmitting laser on a drone, according to an embodiment of the present invention.

[0013] Fig. 3 is a conceptual block diagram showing the interconnections of the controller modules of a drone laser communication system in the context of a drone-based data network in communication with a command center, according to an embodiment of the present invention.

[0014] Fig. 4 is a flowchart of a method for dynamic laser beam directional alignment in a drone-based laser communication system, according to an embodiment of the present invention.

[0015] The drawings are conceptual in nature, in order to convey the basic principles of the present invention and its embodiments. For simplicity and clarity of illustration, elements shown in the figures are not necessarily drawn to scale, and the dimensions ofsome elements may be exaggerated relative to other elements. In addition, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.DETAILED DESCRIPTION

[0016] Fig. 1 illustrates certain features of the laser beam alignment between two independent drones in flight, according to an embodiment of the present invention. A reference coordinate system 100 is used to describe the degrees of freedom of the drones. A vertical x-axis 101 provides a measure of the up-and-down position of the drone (altitude), while a first horizontal z-axis 105 provides a measure of the forward position of the drone, and a second horizontal y-axis 103 provides a measure of the sideways position of the drone. Yaw of the drone is measured according to an angular rotation 102 about x-axis 101, while pitch of the drone is measured according to an angular rotation 104 about y-axis 103, and roll of the drone is measured according to an angular rotation 106 about z-axis 105.

[0017] Drones 110 and 120 are shown as rotary-wing drones, for which there is not necessarily any functional distinction between “forward” motion and “sideways” motion; likewise for such drones, there is not necessarily any functional distinction between “pitch” and “roll”. Nevertheless, for purposes of clarity in descriptions, a drone is considered to have a specified “fore”, a specified “aft”, a specified “starboard” (right) side, and a specified “port” (left) side - acknowledging that the drone can just as easily fly e.g., in the “port” direction as it can in the “fore” direction. The vertical x axis 101, however, is fixed as the up-down position (altitude); and likewise the yaw rotation 102 is fixed as the rotation of the drone in the horizontal plane.

[0018] Fig. 1 conceptually illustrates first drone 110 receiving an incoming beacon optical signal 124 from second drone 120, which originates from a laser beamtransmit / receive unit 122 of drone 120. The term "beacon ” herein denotes a laser beam optical signal emitted from a laser transmitter of a drone to signal its position relative to other drones (or, alternatively, to a ground station). A beacon may be modulated with data (such as drone identification data, data packet headers, and so forth), but its primary function is to indicate its position relative to other drones for purposes of directional alignment and for establishing a data link. The illustrated width of beacon optical signal 124 is greatly exaggerated for purposes of visual presentation. In reality, the beam diameter of beacon 124 from drone 120 is very small. According to embodiments of the invention, however, beacon optical signal 124 may be swept or scanned over a fairly large area to facilitate detection, as suggested in Fig. 1.

[0019] After having acquired incoming beacon optical signal 124 from drone 120, drone 110 computes a relative “pointing direction” for a laser beam transmit / receive unit 112 mounted on drone 110 to laser beam transmit / receive unit 122 mounted on drone 120, and uses the computed relative pointing direction to establish a data communications link from drone 110 to drone 120 via a modulated laser beam optical signal 114. In a manner similar to that of beacon optical signal 124, the illustrated width of laser beam optical signal 114 is greatly exaggerated for purposes of visual presentation; and in reality the beam diameter of laser beam 114 is very small. According to embodiments of the invention, however, the direction of laser beam optical signal 114 may be adjusted over a fairly large area before being precisely locked in to its correct pointing direction for establishing the desired data connection. The correct pointing direction is the Line-Of- Sight (LOS) direction from laser beam transmit / receive unit 112 of drone 110 to laser beam transmit / receive unit 122 of drone 120. The systems, apparatus, and methods of the present invention for achieving the desired LOS data communication link between drone 110 and drone 120 are disclosed in detail herein below.

[0020] Continuing with Fig. 1, a control module 130 is embedded in drone 110, containing sensors and actuators for controlling the yaw, pitch, and roll of drone 110. The sensors and actuators include: a yaw actuator 131 and a yaw sensor 134; a pitch actuator 132 and a pitch sensor 135; and a roll actuator 133 and a roll sensor 136. Similarly, drone 120 includes an embedded control module 140 containing a yaw actuator 141 and a yaw sensor 144; a pitch actuator 142 and a pitch sensor 145; and a roll actuator 143 and a roll sensor 146. The actuators all have inputs from control circuitry, and the sensors all have outputs to reading and detection circuitry. Both actuator and sensor facilities related to yaw, pitch, and roll are necessary for the drone to function properly in flight, and they are typically included as standard features in a stock rotary-wing drone as supplied by the manufacturer. The individual units illustrated in Fig. 1 (elements 131 - 136 in controller 130, and elements 141 - 146 in controller 140) are logical units, however, and are not necessarily manifest in separately-identifiable physical components. For example, it is usually less expensive, more efficient, and more reliable to implement these functionalities via firmware code embedded in a programmable integrated controller within the drone.

[0021] Fig. 2 conceptually illustrates a. gimbal-mounted directionally-variable optical signal transmission unit 200 including a transmitting laser for a drone, according to an embodiment of the present invention. (The following description of unit 200 is applicable to units 112 and 122 in Fig. 1; unit 200 also appears in Fig. 3 and Fig. 4.) A directionally- variable housing 211 contains a laser transmitter 212 for transmitting a laser beam optical signal. In certain embodiments of the present invention, housing 211 also contains a receiver sensor 213 (described below).

[0022] Housing 211 provides a variable pointing direction as follows:

[0023] First, housing unit 211 is rotatably mounted on studs 217a and 217b of a supporting bracket 214 so that the angular position of housing 211 is adjustable to a 9 (theta) angle 216 by a 0 actuator 241. A 0 sensor 244 senses the 0 position of housing 211 and outputs a reading corresponding to the current actual value of 0. In an embodiment of the invention, actuator 241 includes an electromechanical angular stepping device.

[0024] Second, supporting bracket 214 is rotatably mounted on a first drone via a swivel mount 215 so that the angular position of bracket 214 is adjustable to a <p (phi) angle 216 by a <p actuator 242. A cp sensor 244 senses the cp position of bracket 214 and outputs a reading corresponding to the current actual value of cp. In an embodiment of the invention, actuator 242 includes an electromechanical angular stepping device.

[0025] Also according to embodiments of the present invention, a laser transmission / beacon signal actuator 243 controls the operation of laser 212, including the modulation of laser 212 for data transmission.

[0026] Embodiments of the present invention also provide a receiver 213 configured to detect a laser beacon and to receive an incoming optical signal from a laser mounted on a second drone. Fig. 2 illustrates an embodiment wherein receiver 213 is included in housing 211 of the first drone. According to other embodiments, however, one or more instances of receiver 213 are mounted separately on the first drone outside of housing 211. According to certain embodiments of the present invention, receiver 213 is a direction-sensitive receiver for an incoming optical signal, a non-limiting example of which is a camera; and receiver 213 may include various optical components including, but not limited to: lenses, mirrors, prisms, wave-plates, and filters. A laser receiver sensor / beacon sensor 246 outputs an electrical signal that an incoming beacon or laser transmission has been received, and also determines and outputs a beacon direction as a data element which represents the relative direction of the incoming beacon or laser beam transmission. The term “beacon direction” herein denotes the direction of an incoming beacon signal that may be unmodulated, but may also be an incoming laser optical signal that is modulated to carry data. Laser receiver sensor / beacon sensor 246 also demodulates an incoming laser transmission to extract data, if present, in the incoming signal. According to another embodiment, the beacon / laser transmission direction is specified in angular coordinates, a non-limiting example of which includes the values of 0 and (p for the incoming beacon or laser transmission.

[0027] Fig. 2 also illustrates coordinate systems 220 for defining and measuring the relative beacon direction of an incoming beacon / reception 221 in terms of 0b and c t,; and for defining and measuring pointing direction 222 in terms of 0Pand <pp. It is noted that these 0 and <p values are directional magnitudes which are measured in the same manner regardless of whether the direction is incoming or outgoing. That is, for dynamic alignment according to embodiments of the present invention 0P= 0b and <pp= <pb, even though 0Pand <pprelate to outgoing transmissions whereas 0b and q>b relate to incoming receptions. It is noted that 0b and <pb are measured by direction-sensitive receiver 213, and 0Pand <ppare set equal to 0b and <pb, respectively, by actuators, as described below, to attain the dynamic alignment provided by the present invention.

[0028] An embodiment of the present invention provides 0 actuator 241, 0 sensor 244; <p actuator 242, <p sensor 245; laser transmission / beacon signal actuator 243; and laser receiver sensor / beacon sensor 246 as being logically included within a 0, cp, lasertransmission (Tx), reception (Rx) sensor - modem controller 240. (Controller 240 also appears in Fig. 3 and Fig. 4.)

[0029] Fig. 3 is a conceptual block diagram 300 showing the interconnections of the controller modules of a drone 301 laser communication system in the context of a dronebased data network in communication with a command center 320, according to an embodiment of the present invention.

[0030] A drone control unit 304 logically-incorporating an XYZ yaw, pitch, roll controller 305 is typically included as standard equipment on a drone, as delivered from the drone’s manufacturer. Such a unit communicates directly with command center 320 via a link 321.

[0031] In Fig. 3, directionally- variable gimbal-mounted transmit / receive / beacon unit 200 communicates with controller 240, which also communicates with an XYZ - yaw, pitch, roll controller 395 through a link 308a to an XYZ adapter 309, and thence to controller 305 via a link 308b. XYZ adapter 309 converts real-time x-y-z values into alternative closely-related variables. For example, time-related changing x-y-z values yield velocities (yx, vy, and vz) and accelerations (ax, ay, and az) when differentiated, and local position incremental values (Ax, Ay, and Az) when velocities and accelerations are integrated. According to coordinate system 100 (Fig. 1), the x-coordinate is the drone’s altitude, and the y-z plane determines the horizontal position of the drone, The vy, ay, and Ay values are aerodynamically-related to the roll; and the vza-, and Az values are aerodynamically-related to the pitch. Yaw control can be accomplished without varying any x-y-z values, by altering torques on the respective rotors without introducing any roll, pitch, or change in altitude. According to embodiments of the present invention, XYZ adapter 309 is a logical unit which may be realized by various means, such as via software or firmware code in a Central Processing Unit (CPU) aboard drone 301.

[0032] It is noted that dynamic alignment according to the present invention is usually accomplished by 0Pand <ppangular adjustment of the pointing direction. However, according to certain embodiments of the present invention, in some cases it may be advantageous to fine-adjust the drone’s local position via translational corrections in A (altitude), Ay and / or Az (horizontal position) corrections as provided by XYZ adapter 309. In related embodiments of the invention, the decision to use such translational adjustments instead of angular adjustments for dynamic alignment is made by controller 240 according to predetermined thresholds of the pointing error magnitude.

[0033] Thus, according to embodiments of the present invention, controller 240 is able to control the pointing direction of transmit / receive / beacon unit 200 by a combination of signals to 0 actuator 241 and <p actuator 242 (within unit 200) along with signals to XYZ yaw, pitch, roll controller 305 (within drone control unit 304), wherein the signals to controller 305 are converted as necessary by XYZ adapter 309. In particular, yaw control and tp-control are somewhat interchangeable, possibly within certain practical or operational limits.

[0034] With the dynamic alignment capabilities for transmitting lasers and laser data receiver apparatus as provided by the present invention, it is possible to configure a stable data network of intercommunicating drones. This is accomplished via a network interface 311 communicating via a link 310 with controller 240. Network interface 311 also communicates with command center 320 via a link 322.

[0035] Fig. 4 is a flowchart 410 of a method for dynamic laser beam directional alignment in a drone-based laser communication system, according to an embodiment of the present invention. In embodiments of the present invention, the steps of this method are logically performed, at least in part, by controller 240.

[0036] In a step 411 transmit / receive / beacon unit 200 of drone 301 receives a beacon signal from a second drone e.g., from a transmit / receive / beacon unit 122 of drone 120, in Fig. 1 ). At a loop starting point 412, a dynamic alignment sequence is initiated to begin a data connection between drone 301 and the second drone. In a step 413 the incoming beacon direction is measured, and the relative angles for the direction are stored in a data storage 414. Then, in a step 415 the pointing direction of the laser transmitter in unit 200 is measured and stored in a data storage 416. Following this, a step 417 computes the pointing error as the difference between incoming beacon direction 414 and pointing direction 416, and the pointing error is stored in a data storage 418.

[0037] In a step 419 the pointing direction is adjusted to cancel pointing error 418 by sending pointing error value 418 to controller 240 (Fig. 2) with an execute command.

[0038] At a decision point 420, if the connection is not to be continued, an abort step 421 is executed. Otherwise, the connection is maintained, and at a loop end 422 control is returned to the top of the loop 412.

Claims

CLAIMSWhat is claimed is:

1. A communication system for a drone, comprising: a directionally-variable optical signal transmission unit with a variable pointing direction, and having a laser transmitter configured to transmit an outgoing laser beam optical signal in the pointing direction; a receiver configured to receive an incoming laser beam optical signal, wherein the receiver is operative to determine an incoming beacon direction of the incoming laser beam; and a controller including at least one actuator for adjusting the pointing direction of the outgoing laser beam optical signal according to the incoming beacon direction, for a dynamic alignment of the outgoing laser beam optical signal with the incoming laser beam optical signal.

2. The communication system of claim 1 , wherein the receiver is included within the directionally-variable optical signal transmission unit.

3. The communication system of claim 1, wherein the controller is further operative to send a dynamic alignment control signal to a drone controller of the drone to control a drone parameter selected from a group consisting of: altitude; horizontal position, roll, pitch, and yaw.

4. The communication system of claim 3, wherein the drone is a rotary-wing drone.

5. A method for drone communications, the method comprising: receiving an incoming laser beam optical signal;measuring a direction of the incoming laser beam optical signal; measuring a pointing direction of an outgoing laser beam optical signal; computing a pointing error as a difference between the incoming laser beam optical signal direction and the outgoing laser beam optical signal pointing direction; and adjusting the pointing direction to cancel the pointing error, wherein the adjusting the pointing direction includes actuating an actuator in a directionally- variable optical signal transmission unit, wherein the actuator is operative to adjust the pointing direction.

6. The method of claim 5, wherein the adjusting the pointing direction also includes controlling a drone controller of the drone to adjust a drone parameter selected from a group consisting of: altitude; horizontal position, roll, pitch, and yaw.

7. The method of claim 6, wherein the drone is a rotay-wing drone.

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