WO2020035715A1

WO2020035715A1 - Aircrafts with controllers and tiltable rotors for attitude-controlled flight

Info

Publication number: WO2020035715A1
Application number: PCT/IB2018/056136
Authority: WO
Inventors: Gary Anthony Daprato
Original assignee: Gary Anthony Daprato
Priority date: 2018-08-15
Filing date: 2018-08-15
Publication date: 2020-02-20

Abstract

An aircraft having controllers and tiltable rotors for attitude-controlled flight is provided. The aircraft includes a frame and a plurality of propulsion devices mounted to the frame to propel the aircraft. Each propulsion device includes a rotor, a motor to rotate the rotor, and an actuator to tilt the rotor. The aircraft further includes an energy source carried by the frame to power the plurality of propulsion devices. The aircraft further includes a rotor tilt controller to control the actuators of the propulsion devices to tilt a rotor of a first propulsion device of the plurality of propulsion devices, thereby controllably providing a horizontal thrust component to the aircraft, simultaneously with providing vertical thrust to the aircraft. The aircraft further includes a thrust controller to control thrust of the propulsion devices to control attitude of the aircraft during flight.

Description

Aircrafts with Controllers and Tiltable Rotors for Attitude-Controlled Flight

Field

[0001] The present disclosure relates generally to aircraft, and in particular to rotary aircraft.

Background

[0002] Conventional multi-rotor helicopters or similar rotary aircraft require extensive training to operate. The pilot or operator needs to be aware of basic aircraft position and movement, as well as other critical factors such as pitch, yaw, and roll.

[0003] The concepts of pitch, yaw, and roll contribute greatly to the complexity of flying an aircraft. This complexity is amplified when the pilot is onboard the aircraft and subject to the unintuitive character and dynamic forces of pitch, yaw, and roll. This problem may be one of the main reasons, if not the single most important reason, why personal aircraft have not yet become mainstream.

[0004] These and other problems exist in known aircraft.

Summary

[0005] According to an aspect of the disclosure, an aircraft with controllers and tiltable rotors is provided. The aircraft includes a frame and a plurality of propulsion devices mounted to the frame to propel the aircraft. Each propulsion device includes a rotor, a motor to rotate the rotor, and an actuator to tilt the rotor. The aircraft further includes an energy source carried by the frame to power the plurality of propulsion devices. The aircraft further includes a rotor tilt controller to control the actuators of the propulsion devices to tilt a rotor of a first propulsion device of the plurality of propulsion devices, thereby controllably providing a horizontal thrust component to the aircraft, simultaneously with providing vertical thrust to the aircraft. The aircraft further includes a thrust controller to control thrust of the propulsion devices to control attitude of the aircraft during flight. Brief Description of the Drawings

[0006] FIG. 1 is a schematic diagram of an example aircraft having controllers and tiltable rotors for attitude-controlled flight.

[0007] FIG. 2A is a perspective view of the aircraft of FIG. 1 having rotors tilted to provide a horizontal thrust component to the aircraft in a longitudinal axis.

[0008] FIG. 2B is a perspective view of the aircraft of FIG. 1 having rotors tilted to provide another horizontal thrust component to the aircraft in a lateral axis.

[0009] FIG. 3 is a top plan view of the aircraft of FIG. 1.

[0010] FIG. 4 is a perspective view of an example propulsion device of the aircraft of

FIG. 1.

[0011] FIG. 5 is a front view of the propulsion device of FIG. 4.

[0012] FIG. 6 is a side view of the propulsion device of FIG. 4.

[0013] FIG. 7 is a top view of the propulsion device of FIG. 4.

[0014] FIG. 8 is a perspective view of another example aircraft having controllers and tiltable rotors for attitude-controlled flight, the aircraft including wings.

[0015] FIG. 9 is a perspective view of another example aircraft having controllers and tiltable rotors for attitude-controlled flight.

[0016] FIG. 10 is a block diagram of a plurality of example aircraft having controllers and tiltable rotors for attitude-controlled flight, the aircraft joined together to form a modular aircraft.

[0017] FIG. 1 1 is a schematic diagram illustrating an example attitude-control feedback loop.

[0018] FIG. 12 is a schematic diagram illustrating an example system of predefined fixed flight levels for aircraft. Detailed Description

[0019] In conventional rotary aircraft (e.g. helicopters and drones), a rotor provides vertical lift to the aircraft. A pilot may pitch and/or roll the aircraft to provide a horizontal thrust component to maneuver the aircraft from one horizontal position to another.

[0020] As a result of pitching and/or rolling, conventional rotary aircraft do not maintain a normal attitude while moving horizontally. For example, conventional rotary aircraft are tilted forward while moving forward, and are tilted to a side while turning to a side. Aircraft which pitch and/or roll to move horizontally may be unsuitable for applications in which it is desirable to maintain the aircraft at a predetermined attitude, such as for transporting a sensitive payload that is to be maintained horizontal, or for maintaining a steady orientation of an instrument or passenger onboard the aircraft. In addition, pilots and passengers of such aircraft may be subjected to forces due to accelerations in three dimensions, which is a barrier to increased adoption of such aircraft. In particular, many people find it difficult to become accustomed to vertical G forces (up or down), which are typically small or non-existent in terrestrial modes of transport.

[0021] Further, aircraft that are pitched and/or rolled to move horizontally may rise or drop in altitude if the pilot does not properly compensate for the pitching or rolling. Such aircraft may be unsuitable for applications in which predictability of movement is important, such as for use as personal transport vehicles where several aircraft are to be flown independently by different pilots in close proximity within predetermined altitude ranges and/or lanes.

[0022] These problems associated with pitching and rolling aircraft may be an important reason why personal aircraft have not yet become mainstream.

[0023] In the present specification, an aircraft is provided which includes controllers and tiltable rotors to provide attitude-controlled flight. The aircraft further may be operated to provide altitude-controlled flight. The aircraft includes a frame and a plurality of propulsion devices mounted to the frame to propel the aircraft. Each propulsion device includes a rotor, a motor to rotate the rotor, and an actuator to tilt the rotor. The aircraft further includes an energy source carried by the frame to power the plurality of propulsion devices. The aircraft further includes a rotor tilt controller to control the actuators of the propulsion devices to tilt a rotor of a first propulsion device of the plurality of propulsion devices, thereby controllably providing a horizontal thrust component to the aircraft, simultaneously with providing vertical thrust to the aircraft.

The aircraft further includes a thrust controller to control thrust of the propulsion devices to control attitude of the aircraft during flight.

[0024] FIG. 1 is a schematic diagram of an example aircraft 100 having controllers and tiltable rotors for attitude-controlled flight. The aircraft 100 includes a frame 102 and a plurality of propulsion devices 120 mounted to the frame 102 to propel the aircraft 100, indicated as propulsion devices 120A, 120B, 120C, 120D, which may be referred to generally as propulsion devices 120. The aircraft 100 further includes a body 1 10 which houses an aircraft controller 140. The aircraft 100 further includes an energy source 104 carried by the frame 102 to power the plurality of propulsion devices 120, and which may power the aircraft controller 140 and any other systems onboard the aircraft 100.

[0025] A pitch axis 130, roll axis 132, and yaw axis 134 anchored to the aircraft 100 are depicted. A longitudinal axis 136, lateral axis 137, and vertical axis 138 anchored to a reference plane, such as the horizontal, are depicted. When the aircraft 100 is in horizontal attitude, the yaw axis 134 and vertical axis 138 are substantially parallel, and the pitch axis 130 and roll axis 132 lie in substantially the same plane as the longitudinal axis 136 and the lateral axis 137. Distinction is made between these two sets of axis because it is contemplated, as explained further below, that the aircraft 100 may travel horizontally with respect to a reference plane, such as the horizontal, without

necessarily needing to be fixed in a horizontal attitude.

[0026] Each propulsion device 120 includes a rotor 122, a motor 124 to rotate the rotor 122, and an actuator 126 to tilt the rotor 122. The rotors 122 are oriented along the vertical axis 138 to provide direct upward thrust, and may be tilted by actuators 126 to provide a horizontal thrust component in any direction along the longitudinal axis 136 and/or lateral axis 137. Actuators 126 may include servo motors and servo arms, or other actuating mechanisms.

[0027] In the present example, each propulsion device 120 includes a rotor and a motor 124 coupled to the rotor 122 in a fixed orientation, and thus, when a rotor 122 is tilted, the propulsion device 120 may be said to be tilted as well. The actuators 126, although termed to be part of the propulsion devices 120, are understood to move relative to the frame 102 and the rotors 122 and/or motors 124 to cause the rotors 122 and/or motors 124 to tilt, and so may not necessarily tilt in the same manner as the rotor 122 when the rotor 122 is tilted. Further, a motor 124 need not necessarily tilt in the same direction or to the same degree as its associated rotor 122, such as when the rotor 122 and motor 124 are connected through a series of gears or other mechanisms. Thus, in this specification, it is to be understood that statements indicating that a rotor 122 is tilted, or that a propulsion device 120 is tilted, may be used interchangeably, and should be understood to mean that at least the rotor 122 is tilted so that the direction of thrust provided by the rotor 122 is changed.

[0028] With respect to an example propulsion device 120A, a rotor 122A is coupled with a motor 124A to rotate the rotor 122A, and is coupled with an actuator 126A to tilt the rotor 122A about the pitch axis 130 and/or the roll axis 132. The rotor 122A may provide vertical lift to the aircraft 100, and may be tilted about one or more of the pitch axis 130 and the roll axis 132 to provide a horizontal thrust component to the aircraft 100.

[0029] In the present example, each of the rotors 122 is tiltable about the pitch axis 130 and roll axis 132. In other examples, some of the rotors 122 may tilt about only one of the pitch axis 130 and the roll axis 132. In still other examples, some of the rotors may provide vertical lift only, and may not tilt about either the pitch axis 130 or the roll axis 132.

[0030] The aircraft 100 includes an aircraft controller 140, which includes a thrust controller 144 and a rotor tilt controller 142. The rotor tilt controller 142 controls the actuators 126 of the propulsion devices 120 to tilt the rotors 122 to provide horizontal thrust components to the aircraft by tilting the propulsion devices 120. The rotors 122 simultaneously provide vertical thrust to the aircraft 100. The thrust controller 144 controls the thrust of the propulsion devices 120 to control attitude of the aircraft 100 during flight, and may also control altitude of the aircraft 100 during flight. For example, the thrust controller 144 is coupled to motor 124A to drive the motor 124A to turn the rotor 122A, and the rotor tilt controller 142 is coupled to the actuator 126A to tilt the propulsion device 120A. It is to be understood, however, that the thrust controller 144 is coupled to the motors 124 of each of the propulsion devices 120, and the rotor tilt controller 142 is coupled to each of the actuators 126.

[0031] In some examples, the rotor tilt controller 142 and thrust controller 144 may cooperate to maintain horizontal attitude of the aircraft 100 in the following manner. The rotor tilt controller 142 may control one or more actuators 126 to tilt one or more rotors 122 to provide horizontal thrust components to the aircraft 100, and the thrust controller 144 may compensate for loss in vertical thrust to maintain horizontal attitude and altitude. For example, the rotor tilt controller 142 may tilt the rotors 122 of propulsion devices 120A, 120B, which are disposed toward the forward side 106 of the aircraft 100, about the pitch axis 130, thereby adding a horizontal thrust component to the aircraft 100 in the longitudinal axis 136. As another example, the rotor tilt controller 142 may tilt the rotors 122 of propulsion devices 120A, 120D, which are disposed toward the left side 107 of the aircraft 100, about the longitudinal axis 136, thereby adding a horizontal thrust component to the aircraft 100 in the lateral axis 137. In other examples, some rotors 122 may be tilted simultaneously about both the pitch axis 130 and roll axis 132.

In the example where the rotors 122 of propulsion devices 120A, 120B are tilted forward, the tilting may result in a loss of vertical thrust, tending to drop the forward side 106 of the aircraft 100. However, the thrust controller 144 may compensate for this loss in vertical thrust by increasing thrust provided by the motors 124 to the rotors 122 until the vertical thrust provided by rotors 122 of propulsion devices 120A, 120B, balances against the vertical thrust provided by the rotors 122 of propulsion devices 120C, 120D, to maintain horizontal attitude of the aircraft 100. The thrust controller 144 may alternatively decrease thrust to the rotors of propulsion devices 120C, 120D. The thrust controller 144 may similarly compensate for tilting of rotors 122 in other directions. [0032] The thrust controller 144 may further control rotors 122 to increase or decrease vertical lift to move the aircraft 100 in the vertical axis 138. Thus, the aircraft 100 may to remain substantially horizontal, or maintain a substantially constant attitude with respect to another plane, and move along any of the longitudinal axis 136, lateral axis 137, and vertical axis 138, without experiencing substantial pitching or rolling.

[0033] Further, it is to be understood that the thrust controller 144 may further control thrust of the propulsion devices 120 to maintain altitude of the aircraft 100, or to selectively alter the altitude of aircraft 100 while maintaining horizontal attitude. Further, it is to be understood that the thrust controller 144 may maintain attitude of the aircraft 100 at an attitude other than a horizontal attitude. For example, the aircraft 100 may be maintained pitched or rolled at about 30, about 45, or about 60 degrees from the horizontal, or at other angles. The aircraft 100 may be maintained at such an attitude where, for example, the aircraft 100 carries an instrument which is to be aimed in a particular direction for a period of time, or where the aircraft 100 carries a display surface which is to be displayed in a particular direction for a period of time.

[0034] Allowing the aircraft 100 to maintain a horizontal attitude while travelling in a horizontal direction may improve aerodynamics of the aircraft 100 since maintaining a horizontal attitude may entail minimizing the area of the aircraft 100 facing the direction of travel.

[0035] Further, in some examples, the thrust controller 144 may permit the aircraft 100 to tilt to a pre-determined degree to boost the horizontal thrust component provided to the aircraft 100 by tilting of a propulsion device 120. For example, when the aircraft 100 is instructed to make a hard stop, or to accelerate quickly in a horizontal direction, a greater horizontal thrust component may be achieved from the propulsion devices 120 by allowing the aircraft 100 to tilt by, for example, about 10% of the amount of tilting that a conventional rotary aircraft would experience. The thrust controller 144 may be configurable to eliminate tilt to the aircraft 100, to allow a degree of tilting such as about 10%, about 50%, or about 90%, or to allow all tilting. In other words, the thrust controller 144 may be switched between fully“on”, fully“off” or“mixed” tilting configurations. The degree to which tilting of the aircraft 100 may be selectable via the input device 50. In mixed configuration, the degree to which tilt is compensated for may be determined by factors such as the current speed of the aircraft 100, strength of an input command from the input device 50, or another factor, according to a linear, geometric, binary, or other relationship.

[0036] Further, in some examples, the rotor tilt controller 142 may meter the actuators 126 to tilt the rotors 122 at a predetermined rate. For example, the rotors 122 may be configured to tilt at a rate of 45 angular degrees per second. Thus, the rotors 122 may be configured to rotate smoothly. Smooth rotation of the rotors 122 may reduce abrupt jerking forces against the aircraft 100, which may contribute to smooth flight.

[0037] The aircraft controller 140 may include sensors 146 such as an inertial measurement unit including gyroscopes and accelerometers, and the like, to determine velocities, accelerations, and orientations of the aircraft 100, and the like, for the thrust controller 144 to determine the required thrusts to control attitude of the aircraft 100.

The sensors 146 may provide a feedback loop to the thrust controller 144 to continually maintain pitch and roll to compensate for tilting of the propulsion devices 120. As illustrated in FIG. 1 1 , a target attitude (e.g. set by the thrust controller 144) and sensed attitude (e.g. as determined by sensors 146) are input into an attitude control system (e.g. thrust controller 144). The attitude control system outputs thrust signals to the aircraft (e.g. to propulsion devices 120). Further, a command is issued to a horizontal movement control system (e.g. rotor tilt controller 142), which outputs tilt signals to the aircraft (e.g. propulsion devices 120). The aircraft responds (e.g. by tilting slightly), which provides sensory feedback (e.g. from the sensors 146) to the attitude control system (e.g. thrust controller 144).

[0038] The aircraft controller 140 may be in communication with an input device 50 which issues flight commands to aircraft controller 140. The input device 50 may include a pilot’s control column or other flight instruments onboard the aircraft 100, a portable radio communication device to control flight of the aircraft 100 remotely, an autopilot system, a control tower, a satellite communication link, or another suitable input device to issue flight commands to aircraft controller 140.

[0039] The thrust controller 144 may include a flight controller configurable to maintain one or more of pitch, yaw, roll, altitude, and horizontal position of the aircraft 100. The flight controller may include inputs to receive pitch, yaw, roll, altitude, and horizontal position commands. To maintain attitude of the aircraft 100, the inputs to receive pitch and roll commands may be disabled or omitted. Further, the input to receive yaw commands may be disabled or omitted. The flight controller may include a Global Positioning System (GPS) to receive altitude and/or horizontal position commands. In some examples, the flight controller may receive and control propulsion devices 120 to satisfy a yaw input, an altitude input, and/or a GPS input.

[0040] In some examples, the rotor tilt controller 142 and thrust controller 144 may be implemented in a single controller device, i.e. , the aircraft controller 140. A controller device may include a processor, memory, and communication interface; the term “processor” may refer to any quantity and combination of a processor, a central processing unit (CPU), a microprocessor, a microcontroller, a field-programmable gate array (FPGA), and similar. The rotor tilt controller 142 and thrust controller 144 may be implemented as separate processor-executable programs or within the same processor- executable program. In other examples, the rotor tilt controller 142 and thrust controller 144 may be implemented in separate controller devices.

[0041] FIG. 2A is a perspective view of the aircraft 100 having the rotors 122 of propulsion devices 120A, 120B, tilted to the forward side 106 to provide horizontal thrust components 202 to move the aircraft 100 in the longitudinal axis 136 in addition to a vertical thrust components 204 to provide vertical lift to the aircraft 100. The thrust controller 144 (FIG. 1 ) compensates for the lost vertical thrust by controlling the rotors 122 to control attitude of the aircraft 100.

[0042] FIG. 2B is a perspective view of the aircraft 100 having rotors 122 of propulsion devices 120A, 120D, tilted to the left side 107 provide horizontal thrust components 212 to the aircraft in the lateral axis 137 in addition to vertical thrust components 214 to provide vertical lift to the aircraft 100. The thrust controller 144 (FIG. 1 ) compensates for the lost vertical thrust by controlling the rotors 122 to control attitude of the aircraft 100.

[0043] FIG. 3 is a top plan view of the aircraft 100. In the present example, the propulsion devices 120, devices care arranged in a plane defined by the pitch axis 130 and roll axis 132. In the present example, the frame 102 of the aircraft 100 is

rectangular, and each of the propulsion devices 120 is situated in a corner of the frame 102. This arrangement allows for a pair of two propulsion devices 120, namely the propulsion devices 120A and 120B, or 120C and 12B, to be tilted about the pitch axis 130 to stably move the aircraft 100 along the longitudinal axis 136. Similarly, this arrangement allows for a pair of two propulsion devices 120, namely propulsion devices 120A and 120C, or 120B and 120D, to be tilted about the roll axis 132 to stably move the aircraft 100 along the lateral axis 137.

[0044] In other examples, however, it is contemplated that the propulsion devices 120 may be arranged differently in the frame 102. The propulsion devices 120 need not all lie in the same plane, and need not be at the corners of the frame 102. However, it is to be understood that the propulsion devices 120 are to be arranged to balance the aircraft 100 appropriately to move horizontally while maintaining a fixed attitude.

Further, in other examples, an aircraft may include more than four propulsion devices, at least three propulsion devices, or at least two propulsion devices. In some examples, a single vertically-fixed propulsion device may provide vertical lift to the aircraft, and a propulsion device having a tiltable rotor may provide horizontal components to the move aircraft horizontally, while a thrust controller controls thrust to each of the two propulsion devices to control attitude of the aircraft.

[0045] Further, it is contemplated that in some examples, a single propulsion device 120 may include a plurality of rotors 122. Thus, a rotor 122 may be pivotably locked together with another propulsion device 120. Pivotably locking together propulsion devices may simplify actuation of the rotors 122 by reducing the number of actuators 126 used, and/or to reduce burden on the number of propulsion devices 120 to be controlled by the aircraft controller 140.

[0046] FIGs. 4-7 are perspective, front, side, and top views, respectively, of an example propulsion device of the aircraft 100. The propulsion device 120 includes a rotor 122, a motor 124, and an actuator 126. The motor 124 is coupled to the rotor 122 by an input shaft (not shown) to drive the rotor 122, which serves as a mast for the rotor 122. In a neutral position, the mast is oriented parallel with the yaw axis 134 of the aircraft 100. The actuator 126 includes a first servo motor 420 which is coupled to a first servo arm 422 and second servo motor 430 which is coupled to a second servo arm 432.

[0047] In the present example, the propulsion device 120 further includes a rigid support structure 400, including a first platform 402 to support the motor 124, a second platform 404 below the first platform 402 to support the first servo motor 420, and a third platform 406 below the second platform 404 to support the second servo motor 430.

[0048] The first platform 402 is connected to the third platform 406 by rigid support columns 408. The rigid support columns 408 pass through slots 410 in the second platform 404 to allow the rigid support columns 408 tilt, about the roll axis 132, through the slots 410. The third platform 406 is connected to the second platform 404 by roll hinges 412. The second platform 404 is connected to the frame 102 of the aircraft 100 by pitch hinges 414. In this arrangement, the second platform 404 may pivot about the pitch axis 130 on pitch hinges 414, which causes the rotor 122 to pivot about the pitch axis 130 in the same direction. Further, the third platform 406 may pivot about the roll axis 132 on roll hinges 412, which causes the rotor 122 to pivot about the roll axis 132 in the same direction. Thus, the rotor 122, and the propulsion device 120, may pivot about one or more of the pitch axis 130 and the roll axis 132 of the aircraft 100.

[0049] The rigid support structure 400 further includes a rigid arch 416 extending around a side of the second platform 404. The first servo motor 420 is fixed to the second platform 404, and is connected to the rigid arch 416 by a first servo arm 422.

The first servo motor 420 may thereby rotate the first servo arm 422 to tilt the second platform 404, and thus the rotor 122, about the pitch axis 130 on pitch hinges 414. The second servo motor 430 is fixed to the third platform 406, and is connected to the second platform by a second servo arm 432. The second servo motor 430 may thereby rotate the second servo arm 432 to tilt the third platform 406, and thus the rotor 122, about the roll axis 132 on roll hinges 412. Thus, the rotor 122, and the propulsion device 120, may be actuated to pivot about one or more of the pitch axis 130 and the roll axis 132 of the aircraft 100. It is to be understood that the actuator 126 may include other actuation devices other than servo motors.

[0050] Thus, in the present example, the propulsion device 120 may be described as being mounted to the frame 102 by a motorized dual-axis gimbal. In other examples, the propulsion device 120 may be mounted to the frame 102 by a ball joint, and include other actuators to tilt the propulsion device 120 about the pitch axis 130 and roll axis 132. In some examples, each of the four propulsion devices 120 of the aircraft 100 are mounted via ball joints to an h-frame which is underslung to the frame 102, with the h- frame being attached by a dual-axis rail assembly connected to the frame 102. The h- frame may be actuated by a central actuator, thereby impart tilting forces to each of the propulsion devices 120. The central actuator may include a cable actuator, a hydraulic actuator, and electromechanical actuator, a magnetic rail, or another actuator.

[0051] In the present example, the rotor 122 includes a dual counter-rotating rotor.

In other examples, the rotor 122 may include a single rotor, where the aircraft includes other mechanisms to counter the torque of the single rotor.

[0052] In the present example, the propulsion device 120 further includes a landing gear 440. The landing gear 440 may comprise an elastic or rigid arch to support the aircraft 100 on a surface.

[0053] FIG. 8 is a perspective view of another example aircraft 800 having controllers and tiltable rotors for attitude-controlled flight. The aircraft 800 is substantially similar to the aircraft 100 with like components having like numbers, however in a“800” series rather than a“100” series. Thus, the aircraft 800 includes a frame 802, and propulsion devices 820 having rotors 822, motors 824, and actuators 826. Although not shown, it is to be understood that the aircraft 800 includes an aircraft controller similar to the aircraft controller 140 and an energy source similar to the energy source 104.

However, the aircraft 800 further includes wings 805 to provide vertical lift to the aircraft 800.

[0054] FIG. 9 is a perspective view another example aircraft 900 having controllers and tiltable rotors for attitude-controlled flight. The aircraft 900 is substantially similar to the aircraft 100 with like components having like numbers, however in a“900” series rather than a“100” series. Thus, the aircraft 900 includes a frame 902, and propulsion devices 920 having rotors 922, motors 924, and actuators 926. Although not shown, it is to be understood that the aircraft 900 includes an aircraft controller similar to the aircraft controller 140 and an energy source similar to the energy source 104. However, the aircraft 900 further includes a passenger cabin 905 to carry passengers. In some examples, the aircraft 900 may include an input device onboard the aircraft 900 to receive flight commands from a pilot. The aircraft 900 may be configured to maintain a particular altitude in addition to a stable attitude. The aircraft 900 may thereby serve as a personal aircraft in which the pilot is spared the complexities of yaw and roll movements, allowing the aircraft 900 to be piloted in a predictable manner similar to how conventional motor vehicles are driven. A pilot may accelerate the aircraft 900 forward, reverse the aircraft 900 backward, and turn (yaw) the aircraft 900 to move the aircraft 900 in a horizontal plane in a manner which approximates driving a car. As illustrated in FIG. 12, aircraft which is configured for attitude-controlled flight and altitude-controlled flight, as described herein, may fly at predefined fixed flight levels. In a predefined fixed flight level, such an aircraft may freely fly horizontal at the specified height, or may travel within designated horizontal lanes (not shown). Such an aircraft may controllingly change altitude between the predefined fixed flight levels, similar to how terrestrial vehicles merge on and off of highways and/or change lanes on a road. Thus, attitude-controlled flight, and further altitude-controlled flight, may facilitate a mode of safe and familiar personal aircraft transport similar which is similar to conventional terrestrial motor vehicle transport. [0055] FIG. 10 is a block diagram of a plurality of example aircraft 1000 joined together to form a modular aircraft. Each aircraft 1000 may be substantially similar to the aircraft 100 with like components having like numbers, however in a“1000” series rather than a“100” series. Thus, each aircraft 1000 includes a frame 1002, propulsion devices 1020, and aircraft controller 1040. Although not shown, it is to be understood that each aircraft 1000 includes an energy source 1004 similar to the energy source 104. However, each aircraft 1000 further includes coupling mechanisms 1060 to join the frame 1002 of one aircraft 1000 to another frame 1002 of another aircraft 1000 to form a modular aircraft. The coupling mechanisms 1060 may include combination of mechanical and/or magnetic mechanisms to fix one frame 1002 to another. The coupling mechanisms 1060 may include several contact points between frames 1002 to inhibit relative rotation of the frames 1002.

[0056] With a plurality of aircraft 1000 joined together in a modular aircraft, pitch, yaw and roll forces, and forces in the longitudinal, lateral, and vertical directions, may act on the modular aircraft as a whole. Further, vertical lift and horizontal thrust components provided by propulsion devices 1020 may act on the modular aircraft as a whole to provide attitude-controlled horizontal flight to the modular aircraft. The aircraft controllers 1040 may communicate to coordinate thrust and tilt of the propulsion devices 120 accordingly.

[0057] The aircraft controllers 1040 may include communication interfaces to communicate via any suitable telecommunications means to coordinate sensory information and flight commands. The aircraft controllers 1040 may communicate via a central server, or an aircraft controller 1040 designated to serve as a communication router, or may be configured to form peer-to-peer networks with nearby or coupled aircraft 1000.

[0058] Thus, it may be seen that an aircraft having controllers and tiltable rotors for attitude-controlled flight may be provided. The aircraft may maintain horizontal attitude during flight, thereby allowing stable movement in horizontal and vertical directions without the complexity of pitch and roll movements. Such aircraft may be beneficial in applications in which a predetermined attitude is to be maintained, or in applications in which predictability of movement is important, such as for use as personal transport vehicles. An aircraft which is configured for with attitude-controlled flight, and further with and altitude-controlled flight, may be piloted similar to how a terrestrial vehicle is driven over a road or other surface, making personal aircraft more widely accessible.

[0059] Persons skilled in the art will appreciate that there are yet more alternative examples and modifications possible, and that the above examples are only illustrations of one or more examples. The scope, therefore, is only to be limited by the claims appended hereto.

Claims

What is claimed is:

1. An aircraft, comprising:

a frame;

a plurality of propulsion devices mounted to the frame to propel the aircraft, each propulsion device including a rotor, a motor to rotate the rotor, and an actuator to tilt the rotor;

an energy source carried by the frame to power the plurality of propulsion devices;

a rotor tilt controller to control the actuators of the propulsion devices to tilt a rotor of a first propulsion device of the plurality of propulsion devices thereby controllably providing a horizontal thrust component to the aircraft simultaneously with providing vertical thrust to the aircraft; and

a thrust controller to control thrust of the propulsion devices to control attitude of the aircraft during flight.

2. The aircraft of claim 1 , wherein the thrust controller is further to maintain horizontal attitude of the aircraft by controlling thrust of the propulsion devices.

3. The aircraft of claim 2, wherein the thrust controller comprises a flight controller to maintain roll and pitch of the aircraft by controlling thrust of the propulsion devices.

4. The aircraft of claim 1 , wherein the rotor of the first propulsion device is pivotable about one or more of a pitch axis and a roll axis of the aircraft.

5. The aircraft of claim 1 , wherein the first propulsion device is mounted to the frame by a motorized dual-axis gimbal.

6. The aircraft of claim 1 , wherein the first propulsion device is mounted to the frame by a ball joint.

7. The aircraft of claim 1 , wherein the thrust controller comprises a flight controller to control the propulsion devices to satisfy one or more of: a yaw input, an altitude input, and a GPS input.

8. The aircraft of claim 1 , wherein the rotor tilt controller and the thrust controller are implemented by a single controller device.

9. The aircraft of claim 1 , wherein the rotor tilt controller and the thrust controller are implemented as a processor-executable program.

10. The aircraft of claim 1 , wherein the plurality of propulsion devices comprises four propulsion devices arranged rectangularly in a plane defined by a pitch axis and a roll axis of the aircraft.

1 1. The aircraft of claim 1 , wherein the first propulsion device further comprises a landing gear to support the aircraft on a surface.

12. The aircraft of claim 1 , wherein the first propulsion device comprises a dual counter- rotating rotor.

13. The aircraft of claim 1 , further comprising a wing to generate lift for the aircraft.

14. The aircraft of claim 1 , further comprising a passenger cabin supported by the frame.

15. The aircraft of claim 1 , further comprising a coupling mechanism to join the frame of the aircraft to another frame of another aircraft to form a modular aircraft.

16. The aircraft of claim 1 , wherein the thrust controller is further to control attitude of the aircraft to boost the horizontal thrust component provided to the aircraft by tilting of the rotor of the first propulsion device.

17. The aircraft of claim 1 , wherein the first propulsion device is pivotably locked together with another propulsion device of the plurality of propulsion devices.

18. The aircraft of claim 1 , wherein the rotor tilt controller meters the actuator of the first propulsion device to tilt the rotor of the first propulsion device at a predetermined rate.