100 can generate output signals based on the portion of the difference attributable to the wind. For example, the data processing system 100 can generate control signals based on the portion of the difference is attributable to the thrust generated by aircraft propellers or rotors alone, or discount the portion of the difference attributable to the wind (e.g., where 1000 pounds of the difference is attributable by the wind, the data processing system can generate control signals to reduce the difference by 500 pounds).

The sensors 102 described herein are not intended to be limiting. The sensors 102 can include further sensors 102 such as inertial sensors 102 (e.g., accelerometers) configured to detect an attitude of an aerial vehicle, such as a disposition of the vehicle over a gradient or slope. The data processing system 100 can employ such sensors 102 to offset the difference in force applied to the wheels, such as where the aerial vehicle is navigating a sloped ground surface of a taxiway.

The data processing system 100 can include at least one user interface 104 designed, constructed, or operational to receive control inputs. The user interface 104 can include a communicative connection with an autonomous flight controller 108 to receive control inputs therefrom. For example, the control input can correspond to one or more rotors or propellers of an aerial vehicle, such as to generate thrust to propel the aerial vehicle along a taxiway. The user interface 104 can include one or more inputs such as buttons (e.g., a keypad), touchscreens, levers, pedals, or hands on throttle-and-stick (HOTAS) controls, to receive input from a human pilot. Portions of the user interface 104 are sometimes referred as human-machine interfaces (HMI).

The user interface 104 can include controls corresponding to one or more rotational airfoils of the vehicle. For example, the user interface 104 can include one or more control inputs corresponding to a rotor or a propeller. For example, the control inputs can correspond to a control output for an effector to cause an adjustment to a speed, blade pitch, or other control. The control inputs can include fine grain control such as anti-torque pedals, a cyclic stick, or a collective lever which can be continually adjusted by a pilot. The control inputs can include a velocity or acceleration reference. For example, the control inputs can include a keypad (sometimes referred to as a beeper) or other device to enter a discrete indication of a vehicle velocity, a rotational airfoil velocity, or an acceleration reference of the vehicle or rotational airfoil. The received velocity reference or acceleration reference can correspond to the propeller or rotor. For example, the reference can be a reference for the propeller, wherein the rotor can be controlled via other control inputs. Some aerial vehicles (e.g., quadcopters) can include several instances of rotors or propellers. The user interface 104 can include collective or separate controls for the various instances of the rotational airfoils.

The user interface 104 can include controls corresponding to various control surfaces or other vehicle controls. For example, control inputs can correspond to a rotational airfoil (e.g., a rotor or propeller) or to a wheel-brake of a wheel of any of the ground contact points. The control inputs can include a wheel-brake engagement command to brake the wheel. The wheel-brake engagement can adjust forces between the various ground contact points (e.g., increasing weight on front ground contact points based on forward pitch from braking). Such indications of braking can be received by the user interface 104.

The data processing system 100 can include at least one vehicle interface 106 designed, constructed, or operational to determine and generate control outputs to navigate the aerial vehicle based on received control inputs and sensor data 122. A control output can include control signals to actuate various effectors for control surfaces such as aerodynamic control surfaces, brakes, or propulsive elements such as rotational airfoils. The vehicle interface 106 can determine a difference between forces applied to various ground contact points, receive a control input, and determine a control output based on the control input and the difference. For example, the control output can cause a rotational airfoil (e.g., a rotor or propeller) to adjust a thrust generated to reduce a difference between forces detected at the various ground contact points of the aerial vehicle. Differences between the forces applied can include a commanded difference, such as to maintain a lower loading on a front landing gear assembly, relative to rear landing gear assembly.

The vehicle interface 106 can determine an adjustment to a horizontal or vertical component of a thrust produced by a rotational airfoil to reduce the difference between the forces applied to the ground contact points of the aerial vehicle. The vehicle interface 106 can generate control outputs based on the control inputs (e.g., responsive to the receipt thereof). Such control inputs can include any of the inputs received by the user interface 104, such as inputs from a human pilot or autonomous flight controller 108, including, for example, inputs associated with any number of rotational airfoils, or a wheel-brake engagement command.

The control outputs can effect adjustments of various rotational airfoils. For example, the control outputs can include or generate control signals to cause a rotor or propeller to adjust a vertical or horizontal component of the thrust. The adjustment can include a directional adjustment (e.g., of a swashplate) to adjust an orientation of a rotor, or can adjust a blade pitch, speed, or other aspect of vehicle operation. The vehicle interface 106 can effect the adjustment based on a comparison to one or more thresholds 124. For example, the threshold 124 can include a lift-off threshold 124 (e.g., a zero-force condition, or an offset therefrom, such as 1000 pounds, 500 pounds, or so forth). The control output can include an adjustment to a velocity reference or an acceleration reference. For example, the control output can include a wheel brake engagement command (e.g., to reduce the velocity or acceleration to a zero or non-zero value, based on an adjusted velocity reference or acceleration reference). The control output can include an adjustment to a horizontal component of the thrust produced by a rotational airfoil. For example, the adjustment can reduce a difference between the velocity of the aerial vehicle and a velocity reference, or the acceleration of the aerial vehicle and an acceleration reference. The adjustment can include an acceleration of the aerial vehicle. For example, a thrust generated by a propeller can be adjusted by adjusting a speed, blade pitch, or other parameter of the blades thereof; a thrust generated by a rotor can be adjusted by adjusting a speed, blade pitch, or other parameter of the blades thereof; or a thrust generated by a rotor can be adjusted by adjusting an aircraft attitude or a longitudinal axis thereof (e.g., fore-ward to increase a velocity of the aircraft or aft-ward to reduce the velocity). Such an attitude can maintain the contact points on a ground surface, such as by adjusting an extension of an adaptive landing gear.

The data processing system 100 can include at least one autonomous flight controller 108 designed, constructed, or operational to execute a navigational action to adjust a position of the aerial vehicle. The autonomous flight controller 108 can include a trajectory follower having aircraft flight controls (e.g., throttle, anti-torque controls or a cyclic control). For example, the trajectory follower of the autonomous flight controller 108 can directly control the flight of the aerial vehicle (e.g., in an autonomous aerial vehicle) to navigate a route determined or received by the data processing system 100, according to a path determined by a local motion planner. According to some implementations, the autonomous flight controller 108 can provide control inputs corresponding to other control inputs received from the user interface 104. In some implementations, the autonomous flight controller 108 can cause an actuation of such controls. In some implementations, the autonomous flight controller 108 can provide a message to the vehicle interface 106 including an indication of a command corresponding to such controls. Like other components of the present disclosure, some vehicles can omit an autonomous flight controller 108, wherein navigational actions referred to with regard to the autonomous flight controller 108 can be received from a pilot.

The data processing system 100 can include at least one command filter 110 designed, constructed, or operational to distinguish between lift-off commands and other control signal inputs. For example, the command filter 110 can receive control inputs from a human or non-human pilot (e.g., the autonomous flight controller 108). The command filter 110 can determine that an unadjusted control output can cause the aircraft to lift-off, or reduce a force to a within a predetermined threshold 124 or range (e.g., a net force at a ground contact point which is not less than 500 pounds). The command filter 110 can determine that a command which can cause the vehicle to lift-off or otherwise reduce the force at a ground contact point to less than the predetermined threshold 124 is or is not a lift-off command. In some implementation, the threshold 124 can be dynamic such as to adjust based on environmental conditions. For example, the command filter 110 can determine that a command input corresponding to an unadjusted command output which would cause the aerial vehicle to lift-off, but which would not have caused the aircraft to lift-off based on a windspeed condition within a preceding time window can be determined to be unintentional. The command filter 110 can determine that a command input corresponding to an unadjusted command output which would cause the aerial vehicle to lift-off with excess thrust less than a predefined threshold 124 is not intentional command (e.g., a throttle input that maps to a control output to generate 30,100 pounds of thrust for a 30,000 pound vehicle indicates a pilot intent to remain taxiing on the ground; whereas another throttle input corresponding to 40,000 pounds of thrust can indicate an instruction or command to lift-off).

In some implementations, the command filter 110 can receive a discrete indication to lift-off or not to lift-off (e.g., a toggle switch, button press, or predefined message from an autonomous flight controller 108). The command filter 110 can discriminate between lift-off commands and other commands based on the discrete input. For example, the command filter 110 can map a command input to the status of the discrete input, or can adjust a threshold 124 based on the discrete indication. The command filter 110 can convey the determination of the instruction or command to lift-off (or remain taxiing) to the vehicle interface 106. Upon a receipt of such an indication, the vehicle interface 106 can generate control outputs to cause the aerial vehicle to lift-off or remain taxiing.

| FIG. 2 illustrates an example of an aerial vehicle 200 traversing a ground surface 201 of a taxiway, in accordance with one or more implementations. The aerial vehicle 200 can exert a downward force 220 based on a mass thereof, and interactions with the environment (e.g., wind forces transferred through the airframe of the aerial vehicle 200). The aerial vehicle 200 can include various propulsive elements such as the depicted rotational airfoils. For example, the aerial vehicle 200 can include a rear propeller 202. The propeller 202 can propel the aerial vehicle 200 with a horizontal (e.g., fore-ward) portion of a thrust 204 thereof. The propeller 202 can generate a vertical (e.g., upward or downward) portion of a thrust 206 thereof, such as based on an inclination or declination of the aerial vehicle 200 with respect to an environment, or the propeller with respect to the aerial vehicle 200. The aerial vehicle 200 can include a rotor, such as a substantially vertical rotor. For example, the aerial vehicle 200 can include a first rotor 208 and a second rotor 214 in a tandem rotor configuration. The first rotor 208 and second rotor 214 can generate respective first horizontal thrust 210 and second horizontal thrust 216 (e.g., fore-ward or rearward thrust), which is adjustable via one or more swashplates. The first rotor 208 and second rotor 214 can generate respective first vertical thrust 212 and second vertical thrust 218 (e.g., upward or downward). The total thrust of any of the rotational airfoils can be adjusted, such as according to a blade pitch or rotational speed. A proportion of the total thrust directed in a horizontal or vertical direction can be adjusted by adjusting a relative position of the rotational airfoil with respect to the chassis of the aircraft (e.g., via a swashplate adjustment), or a relative position of the aircraft with respect to the environment (e.g., an aerial vehicle attitude). References to adjusting a vertical or horizontal thrust can include changing a total thrust, or changing a proportion thereof directed in such a direction. References to adjusting an aircraft attitude can refer to maintaining at least a portion of the ground contact points in contact with the ground. For example, the aircraft attitude can change the attitude by absorbing a portion of suspension travel of a ground contact point.

A net of the vertical force imparted downward by the mass of the aerial vehicle 200 or environmental conditions and the thrust generated from the various propulsive elements thereof can be applied to a ground surface 201 via any number of contact points. For example, the ground contact points can include a first ground contact point 222 at the rear of the vehicle, transmitting a first force 224 to the ground surface 201, a second ground contact point 226 and third ground contact point 230, transmitting respective second force 228 and third force 232 to the ground surface 201. Sensors 102 of or coupled with the data processing system 100 can include sensors 102 mechanically coupled with the ground contact points to determine a force transmitted therethrough (e.g., an optical or electronic strain gauge sensor 102). Upon receipt of the various forces for the ground contact points, the data processing system 100 can determine a difference therebetween. The depicted forces are not intended to be limiting. For example, the ground contact points can exert horizontal forces, such as associated forces with a rolling resistance of a wheel or a lateral force applied to a braked wheel, a drag of a pontoon through an aqueous ground surface 201, or friction between a skid an a ground surface 201.

Various implementations of an aerial vehicle 200 can include various rotors or propellers. For example, some aerial vehicles 200 can include two or more rotors laterally spaced from one another (e.g., a first rotor 208 and second rotor 214 of a quadcopter), or a rotational airfoil which is rotatable about a transverse plane (e.g., to selectively operate in a substantially vertical or substantially horizontal configuration). In some implementations, the data processing system 100 can determine a difference in forces applied to contact points based on differing vertical forces, such as in the case of laterally spaced rotational airfoils exerting different vertical thrusts to generate a moment about the aerial vehicle 200 (e.g., a roll moment).

FIG. 3 illustrates an example data flow diagram of aerial vehicle 200 operation, in accordance with one or more implementations. Various control inputs 302 received from components of the user interface 104 can be conveyed to the data processing system 100 as control input signals 304. Sensor data 122 can be received from various sensors 102 of, or operatively coupled with, the aerial vehicle 200. The data processing system 100 can generate control outputs 308 based on the control inputs 302 (e.g., the control input signals 304) and the sensor data 122. For example, the control outputs 308 can include adjusted or unadjusted outputs corresponding to the inputs. The unadjusted outputs can be mapped outputs corresponding to a position of the control inputs 302 (e.g., a rotor tilt mapped to the position of the cyclic stick 312). The adjusted outputs can vary from mapped outputs. For example, the adjusted outputs can differ from an unadjusted output to prevent the aerial vehicle 200 from lifting off the ground surface 201, or to cause the aerial vehicle 200 to lift-off the ground surface 201, based on a condition detected by the command filter 110. The control outputs 308 from the data processing system 100 can include control output signals to actuate effectors for control surfaces 310 such as a propeller 202, a rotor 328, or a brake 330 (e.g., a wheel-brake 330).

The various control inputs 302 can include inputs from a cyclic stick 312, collective lever 314, throttle 316, beeper 318, or other input, such as an input from an autonomous flight controller 108. The cyclic stick 312 can receive control inputs 302 from the pilot to control the pitch and roll by tilting the stick in the corresponding direction. A control output 308 associated with the input can alter the angle of the rotor blades for maneuvering the aerial vehicle 200. The collective lever 314 can receive control inputs 302 from the pilot to control the lift of the aerial vehicle 200 by actuating the lever. A control output 308 associated with the control input 302 can alter the angle of the rotor blades for increasing or decreasing lift. The throttle 316 can receive control inputs 302 from the pilot to control the power output of the aerial vehicle 200 according to a position thereof. A control output 308 associated with the input can alter the power generated by an engine or output to one or more rotational airfoils (e.g., the rotor 328). The beeper 318 can receive discrete control inputs 302 from the pilot to control the power output of the aerial vehicle 200. For example, the beeper 318 can receive an entry via a keypad or other selection of a reference speed or acceleration of a propeller of the aerial vehicle 200. The entry can correspond to a selected acceleration reference or velocity reference. A control output 308 associated with the input can alter the power output to one or more rotational airfoils (e.g., the propeller 202). Such an adjustment can, for example, adjust a reference based on an application of a brake 330, which may aid a pilot in responding to a condition whereas generating a new entry for the beeper 318 may otherwise require additional time or attention. The disclosed control inputs are not intended to be limiting. For example, a throttle pedal can receive a control inputs 302 from a pilot including a yaw-command. Various control inputs 302 can be combined, disaggregated, or otherwise distributed to various control outputs 308. For example, a propeller 326 can include a lateral control to provide yaw power which can combine (e.g., additive or subtractive combinations) with yaw power corresponding to a differential torque between two or more rotor shafts.

The sensors 102 can include, for example, a windspeed sensor 320, attitude sensors 322 (e.g., an inertial measurement unit (IMU) or other data source for an electronic display indicator (EDI)), or contact point force sensors 324 (e.g., strain gauges). The data processing system 100 can receive sensor data 122 from the various sensors 102. The data processing system 100 can receive or store the sensor data 122 whereupon the data processing system 100 can generate control outputs 308 based on current or historical sensor data 122.

The data processing system 100 can generate control outputs 308 for the control of various control surfaces 310 of the vehicle. For example, the control outputs 308 can include control signals for effectors of the various control surfaces 310. The control surfaces 310 can include aerodynamic control surfaces 310, or other control surfaces 310, such as wheel-brakes 330. The control outputs 308 can be determined based on the control inputs 302 and the sensor data 122. For example, the control inputs 302 can map to unadjusted control outputs 308. The data processing system can determine that the unadjusted control outputs 308 can be adjusted. For example, the determination can be based on a difference in forces between ground contact points, or an absolute value of one or more such forces (e.g., indicative of lift-off of at least one ground contact point) The data processing system 100 can generate the determination based on the receipt of the sensor data 122. The data processing system 100 (e.g., the vehicle interface 106) can adjust the corresponding control output 308 to prevent or cause a lift-off of the aerial vehicle 200, or to reduce a difference between ground contact points of the aerial vehicle 200.

FIG. 4 illustrates an example flow diagram of a method 400 of aircraft taxiing, in accordance with one or more implementations. The flow diagram depicts ACTs associated with the method 400. The method 400 can be executed, performed, or otherwise carried out by a data processing system 100, which can include one or more processors or other elements of the computer system 500 described herein in conjunction with FIG. 5, or any other computing devices.

At ACT 405 the method 400 can include a detection, by the data processing system 100, of a difference between forces applied to ground contact points. The detection can be at a data processing system 100 responsive to sensor data 122 from one or more force sensors 102, such as strain gauges mechanically coupled to the ground contact points. The difference can be determined between any ground contact points, such as to determine a maximum difference between contact points or a difference between various ground contact points. The differences can be an absolute difference, or a difference from an offset. For example, the data processing system 100 can include vehicle attributes 126 associating ground contact points with non-equal forces (e.g., a rear wheel can be configured to support lesser weight than a front wheel). In some implementations, the difference between the forces is a time-average (e.g., over a trailing widow, such as three or five seconds). In some implementations, the difference between the forces is an instantaneous difference (e.g., a ‘snapshot’). In some implementations, a first time-averaged difference is comparted to a first threshold 124, and a second snapshot difference is comparted to a second threshold 124.

At ACT 410 the method 400 can include a determination, by the data processing system 100, of an adjustment to a vertical thrust. The adjustment can be an adjustment to a rotor 328 or propeller 326 configured to reduce the difference. For example, the data processing system 100 can adjust the speed or blade pitch of the rotor 328 to adjust the force at one or more ground contact points upward or downward. The data processing system 100 can effect the adjustment to the vertical thrust by adjusting a total thrust having a vertical component, or by adjusting (e.g., via a swashplate effector) a proportion of vertical thrust and horizontal thrust. Thus, the adjustment to the vertical thrust can adjust horizontal thrust. The adjustment can reduce a difference between forces, such as to equalize the forces between a right and left skid or pontoon, or otherwise reduce an absolute or offset difference between forces corresponding to the various ground contact points.

At ACT 415 the method 400 can include a generation, by the data processing system 100, of a control output 308 to reduce the differential between the contact points. The control output 308 can include various aerodynamic or other control surfaces 310. For example, the control output 308 can include control signals configured to actuate effectors for control surfaces 310 for aerodynamic control surfaces 310 (e.g., rotational airfoils such as rotors 328 or propellers 326), or other control surfaces 310, such as frictional surfaces of braking elements configured to couple with wheels of the aerial vehicle 200 (e.g., wheel-brakes 330).

FIG. 5 illustrates a block diagram of an example computer system 500. The computer system or computing device 500 can include or be used to implement the data processing system 100, or its components. The computing system 500 includes at least one bus 505 or other communication component for communicating information and at least one processor 510 or processing circuit coupled to the bus 505 for processing information. The computing system 500 can also include one or more processors 510 or processing circuits coupled to the bus 505 for processing information. The computing system 500 also includes at least one main memory 515, such as a random-access memory (RAM) or other dynamic storage device, coupled to the bus 505 for storing information, and instructions to be executed by the processor 510. The computing system 500 can further include at least one read only memory (ROM) 520 or other static storage device coupled to the bus 505 for storing static information and instructions for the processor 510. A storage device 525, such as a solid-state device, magnetic disk, or optical disk, can be coupled to the bus 505 to persistently store information and instructions.

The computing system 500 can be coupled via the bus 505 to a display 535, such as a liquid crystal display, or active-matrix display, for displaying information to a user such as an administrator of the data processing system 100 (e.g., a pilot). An input device 530, such as a keyboard or voice interface can be coupled to the bus 505 for communicating information and commands to the processor 510. The input device 530 can include a touch screen display 535. The input device 530 can also include a cursor control, such as a mouse, a trackball, or cursor direction keys, for communicating direction information and command selections to the processor 510 and for controlling cursor movement on the display 535. The display 535 can be part of the display devices 535, or other components of FIG. 5.

The processes, systems, and methods described herein can be implemented by the computing system 500 in response to the processor 510 executing an arrangement of instructions contained in main memory 515. Such instructions can be read into main memory 515 from another computer-readable medium, such as the storage device 525. Execution of the arrangement of instructions contained in main memory 515 can cause the computing system 500 to perform the illustrative processes described herein. One or more processors in a multi-processing arrangement can also be employed to execute the instructions contained in main memory 515. Hard-wired circuitry can be used in place of or in combination with software instructions together with the systems and methods described herein. Systems and methods described herein are not limited to any specific combination of hardware circuitry and software.

Although an example computing system has been described in FIG. 5, the subject matter including the operations described in this specification can be implemented in other types of digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them.

Some of the description herein emphasizes the structural independence of the aspects of the system components and illustrates one grouping of operations and responsibilities of these system components. Other groupings that execute similar overall operations are understood to be within the scope of the present application. Modules can be implemented in hardware or as computer instructions on a non-transient computer readable storage medium, and modules can be distributed across various hardware- or computer-based components.

The systems described above can provide multiple ones of any or each of those components, and these components can be provided on either a standalone system or on multiple instantiations in a distributed system. In addition, the systems and methods described above can be provided as one or more computer-readable programs or executable instructions embodied on or in one or more articles of manufacture. The article of manufacture can be cloud storage, a hard disk, a CD-ROM, a flash memory card, a PROM, a RAM, a ROM, or a magnetic tape. In general, the computer-readable programs can be implemented in any programming language, such as LISP, PERL, C, C++, C#, PROLOG, or in any byte code language such as JAVA. The software programs or executable instructions can be stored on or in one or more articles of manufacture as object code.

Example and non-limiting module implementation elements include sensors 102 providing any value determined herein, sensors 102 providing any value that is a precursor to a value determined herein, datalink or network hardware including communication chips, oscillating crystals, communication links, cables, twisted pair wiring, coaxial wiring, shielded wiring, transmitters, receivers, or transceivers, logic circuits, hard-wired logic circuits, reconfigurable logic circuits in a particular non-transient state configured according to the module specification, any actuator including at least an electrical, hydraulic, or pneumatic actuator, a solenoid, an op-amp, analog control elements (springs, filters, integrators, adders, dividers, gain elements), or digital control elements.

The subject matter and the operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. The subject matter described in this specification can be implemented as one or more computer programs, e.g., one or more circuits of computer program instructions, encoded on one or more computer storage media for execution by, or to control the operation of, data processing apparatuses. Alternatively, or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to a suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. While a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate components or media (e.g., multiple CDs, disks, or other storage devices include cloud storage). The operations described in this specification can be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources.