Crosswind vertical take-off and landing drone and crosswind method thereof

Abstract

The application discloses an anti-crosswind vertical take-off and landing unmanned aerial vehicle and an anti-crosswind method thereof, and relates to the technical field of unmanned aerial vehicles. The anti-crosswind vertical take-off and landing unmanned aerial vehicle comprises an unmanned aerial vehicle body and a wind speed and direction instrument which is arranged separately from the unmanned aerial vehicle body. The unmanned aerial vehicle body comprises a fuselage, a flight control machine arranged in the fuselage, wings arranged on both sides of the fuselage, a propeller arranged in front of the wings, a motor in transmission connection with the propeller, a rudder surface arranged behind the wings, and a rudder in transmission connection with the rudder surface. The wind speed and direction instrument is in communication connection with the flight control machine, and the flight control machine is in cable connection with the motor and the rudder. The wind speed and direction information is measured by the wind speed and direction instrument, and the rudder is controlled to deflect and the motor is controlled to rotate according to the wind speed and direction information, attitude information and height information, so as to control the heading, height and yaw of the aircraft, make the wing span length direction consistent with the crosswind direction, and avoid landing of the aircraft in the case that the attitude is inclined without the need of a pilot to control and without the need of relying on the experience of the pilot.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) technology, and more specifically to a crosswind-resistant vertical take-off and landing UAV and its crosswind-resistant method. Background Technology

[0002] Crosswinds have a significant impact on flight safety during the takeoff and landing phases of drones, especially for tail-mounted vertical takeoff and landing drones, where the crosswind frontal area is large and the lateral force caused by the crosswind can cause the aircraft to deviate.

[0003] Existing wind resistance control schemes generally include the following:

[0004] The tilting method involves tilting the aircraft to balance the effects of lateral forces. Essentially, the tilting method is a common position control technique used in crosswind conditions. However, excessive frontal area can lead to two problems: 1. The aircraft tilts excessively during landing, potentially damaging the landing gear and causing landing failure; 2. Excessive frontal area results in excessive lateral overload, which increases with the strength of the crosswind and may cause structural damage.

[0005] Remote control: The pilot uses a remote controller for visual flight, judging the wind direction based on applied controls and the drone's response, and then maneuvers the aircraft to yaw it in line with the wingspan and crosswind direction. This method relies on the pilot and their experience, and has the following problems: 1. A pilot is required for control, increasing system costs; 2. Insufficient pilot experience makes it impossible to align the wingspan and crosswind direction, leading to problems inherent in the tilting method. Summary of the Invention

[0006] Therefore, the present invention provides a crosswind-resistant vertical take-off and landing (VTOL) drone and a method for resisting crosswinds, in order to solve the problem of crosswinds affecting the take-off and landing phases of VTOL drones.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, an anti-crosswind vertical takeoff and landing unmanned aerial vehicle (UAV) includes a UAV body and a wind speed and direction sensor separately disposed from the UAV body. The UAV body includes a fuselage, a flight controller disposed within the fuselage, wings disposed on both sides of the fuselage, a propeller disposed in front of the wings, a motor drivenly connected to the propeller, a control surface disposed behind the wings, and a servo motor drivenly connected to the control surface. The wind speed and direction sensor is communicatively connected to the flight controller, and the flight controller is connected to the motor and the servo motor via cables.

[0009] Furthermore, the rear end of the motor is fixed to the wing, and the propeller is fixed to the drive shaft at the front end of the motor.

[0010] Furthermore, the control surface is connected to the tail of the wing via a hinge shaft, the servo is disposed inside the wing, and the control surface can rotate around the hinge shaft under the drive of the servo.

[0011] Furthermore, the anemometer is connected to the ground station via cable, and the ground station is wirelessly connected to the flight controller.

[0012] Furthermore, an airborne terminal is provided at the head of the fuselage, which is connected to the flight controller cable and wirelessly communicates with the ground station.

[0013] A second aspect of the present invention provides a method for crosswind resistance in a crosswind-resistant vertical takeoff and landing unmanned aerial vehicle (UAV), comprising the following steps:

[0014] Receive wind speed and direction information measured by an anemometer;

[0015] Obtain attitude information;

[0016] Obtain high-altitude information;

[0017] Based on wind speed and direction information and attitude information, aileron channel control information is calculated and generated. Based on the aileron channel control information, wingspan direction control and tilt control are performed to control the aircraft's orientation.

[0018] Throttle control channel information is calculated and generated based on attitude and altitude information. Altitude and yaw control are then performed based on the throttle control channel information to control the aircraft's altitude and yaw.

[0019] Furthermore, receiving the wind speed and direction information measured by the anemometer includes the following steps:

[0020] The anemometer measures wind speed and direction, generates wind speed and direction information, and transmits this information to the ground station via cable.

[0021] The ground station transmits wind speed and direction information to the airborne terminal via wireless communication;

[0022] The airborne unit receives wind speed and direction information and transmits it to the flight controller via cable.

[0023] The flight controller receives wind speed and direction information.

[0024] Furthermore, the step of controlling altitude and yaw based on throttle control channel information to control aircraft altitude and yaw includes the following steps:

[0025] Drive the servo motor to deflect;

[0026] This causes the rudder surface to deflect;

[0027] Control the aircraft's heading.

[0028] Furthermore, the step of controlling altitude and yaw based on throttle control channel information to control aircraft altitude and yaw includes the following steps:

[0029] Drive motor to rotate;

[0030] Change the propeller speed;

[0031] Control the aircraft's altitude and yaw.

[0032] The present invention has the following advantages:

[0033] The flight controller obtains wind speed and direction information using an anemometer, and then controls the servo motors to deflect and the motors to rotate based on this information, along with the aircraft's attitude and altitude. This controls the aircraft's orientation, altitude, and yaw, ensuring that the wingspan direction aligns with the crosswind direction. This eliminates the need for pilot control, reducing system costs. Furthermore, it eliminates reliance on pilot experience, preventing improper operation that could cause the aircraft to tilt during landing and thus avoid landing failure. Attached Figure Description

[0034] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0035] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0036] Figure 1 This is a structural schematic diagram of a crosswind-resistant vertical takeoff and landing UAV provided in Embodiment 1 of the present invention (wind speed and wind direction instrument omitted).

[0037] Figure 2 This is a schematic diagram of the overall connection of the crosswind resistant vertical take-off and landing UAV provided in Embodiment 1 of the present invention (the wingspan direction and the crosswind direction are not the same).

[0038] Figure 3This is a schematic diagram of the overall connection of the crosswind resistant vertical take-off and landing UAV provided in Embodiment 1 of the present invention (the wingspan direction is consistent with the crosswind direction).

[0039] Figure 4 This is a flowchart of a method for resisting crosswinds in a vertical take-off and landing unmanned aerial vehicle (UAV) according to Embodiment 2 of the present invention.

[0040] Figure 5 This is a coordinate system diagram of the control algorithm for a crosswind-resistant vertical takeoff and landing UAV provided in Embodiment 2 of the present invention.

[0041] Figure 6 This is a schematic diagram of the tilt control method for an anti-crosswind vertical take-off and landing UAV provided in Embodiment 2 of the present invention.

[0042] Figure 7 This is a schematic diagram of yaw under the influence of crosswind in the control algorithm of the crosswind-resistant vertical take-off and landing UAV provided in Embodiment 2 of the present invention.

[0043] Figure 8 The diagram below shows the height control logic of a crosswind-resistant vertical take-off and landing UAV provided in Embodiment 2 of the present invention.

[0044] In the diagram: 1-fuselage, 2-flight controller, 3-wing, 4-propeller, 5-motor, 6-control surfaces, 7-servo motor, 8-airborne terminal, 9-wind speed and direction indicator, 10-ground station. Detailed Implementation

[0045] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] The terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Any changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0047] Example 1

[0048] like Figure 1-3As shown, Embodiment 1 provides a crosswind-resistant vertical takeoff and landing unmanned aerial vehicle (UAV), including the UAV body and a wind speed and direction instrument 9 separately installed from the UAV body. The UAV body includes a fuselage 1, a flight controller 2 installed inside the fuselage 1, wings 3 installed on both sides of the fuselage 1, a propeller 4 installed in front of the wings 3, a motor 5 connected to the propeller 4, a control surface 6 installed behind the wings 3, and a servo motor 7 connected to the control surface 6. The wind speed and direction instrument 9 is communicatively connected to the flight controller 2, and the flight controller 2 is connected to the motor 5 and the servo motor 7 by cables.

[0049] The rear end of motor 5 is fixed to wing 3, and propeller 4 is fixed to the drive shaft at the front end of motor 5. Control surfaces 6 are connected to the tail of wing 3 via hinge shafts, and servo motors 7 are located inside wing 3. Control surfaces 6 can rotate around the hinge shaft under the drive of servo motors 7. Anemometer 9 is cable-connected to ground station 10, and ground station 10 is wirelessly connected to flight controller 2. An airborne terminal 8, cable-connected to flight controller 2, is located at the nose of fuselage 1 and is wirelessly connected to ground station 10.

[0050] like Figure 2 and 3 As shown, Figure 2 This is the initial state of the crosswind-resistant vertical take-off and landing UAV in this embodiment. The wingspan direction is inconsistent with the crosswind direction, and automatic crosswind adjustment has not yet been performed at this time. Figure 3 This is a final state of the crosswind-resistant vertical takeoff and landing UAV in this embodiment after automatic crosswind adjustment, where the wingspan direction is aligned with the crosswind direction. When the UAV takes off or lands, an anemometer measures the wind speed and direction, generating wind speed and direction information, which is then transmitted to the ground station via cable. The ground station transmits the wind speed and direction information wirelessly to the airborne terminal. The airborne terminal receives the wind speed and direction information and transmits it to the flight controller via cable. The flight controller receives the wind speed and direction information and obtains the attitude and altitude information obtained from the UAV's self-measurement. Based on the wind speed and direction information and attitude information, the flight controller calculates and generates aileron channel control information, and performs wingspan direction control and tilt control based on the aileron channel control information, driving the servo motors to deflect and thus controlling the control surfaces, thereby controlling the aircraft's orientation. Based on the attitude and altitude information, the flight controller calculates and generates throttle control channel information, and performs altitude control and yaw control based on the throttle control channel information, driving the motors to rotate and changing the propeller speed, thereby controlling the aircraft's altitude and yaw. By aligning the wingspan direction with the crosswind direction, no pilot control is required, reducing system costs. Furthermore, it eliminates reliance on pilot experience, preventing improper operation that could cause the aircraft to tilt during landing and thus avoid landing failure.

[0051] This scheme applies to the takeoff and landing phases of an aircraft, where the entry and completion of these phases are typically determined by altitude. For example, in this embodiment, during landing, the aircraft begins the landing phase at an altitude of 15 meters above the ground and completes the landing phase when it reaches 0 meters above the ground. During takeoff, the aircraft begins the takeoff phase at 0 meters above the ground after the ground station sends the takeoff command, and completes the takeoff phase when it reaches an altitude of 15 meters above the ground.

[0052] Example 2

[0053] like Figure 4 As shown in Example 2, a method for resisting crosswinds in a crosswind-resistant vertical takeoff and landing (VTOL) UAV is provided, including the following steps:

[0054] The anemometer measures wind speed and direction, generates wind speed and direction information, and transmits this information to the ground station via cable.

[0055] The ground station transmits wind speed and direction information to the airborne terminal via wireless communication;

[0056] The airborne unit receives wind speed and direction information and transmits it to the flight controller via cable.

[0057] The flight controller receives wind speed and direction information.

[0058] The flight controller obtains attitude information;

[0059] The flight controller obtains altitude information;

[0060] The flight controller calculates and generates aileron channel control information based on wind speed, wind direction and attitude information. Based on the aileron channel control information, it performs wingspan direction control and tilt control, drives the servo motors to deflect, and drives the control surfaces to deflect, thereby controlling the aircraft's orientation.

[0061] Throttle control channel information is calculated and generated based on attitude and altitude information. Altitude and yaw control are then performed based on the throttle control channel information, driving the motor to rotate and changing the propeller speed, thereby controlling the aircraft's altitude and yaw.

[0062] The flight controller obtains wind speed and direction information using an anemometer, and then controls the servo motors to deflect and the motors to rotate based on this information, along with the aircraft's attitude and altitude. This controls the aircraft's orientation, altitude, and yaw, ensuring that the wingspan direction aligns with the crosswind direction. This eliminates the need for pilot control, reducing system costs. Furthermore, it eliminates reliance on pilot experience, preventing improper operation that could cause the aircraft to tilt during landing and thus avoid landing failure.

[0063] The main purpose of this invention is to resist crosswinds. This purpose is mainly achieved by the flight controller calculating the control surface deflection according to the current wind direction and a pre-set control algorithm. This method is consistent during takeoff and landing. However, the algorithm used for altitude control in the crosswind resistance phase is different from the conventional control algorithm only during the landing phase. Therefore, the control algorithm in the flight controller is illustrated here using the landing phase as an example.

[0064] A coordinate system is established under the Earth's axis, with true north representing the X-axis (i.e., Figure 5 The Xe axis in the diagram represents the Y axis, which is due east. Figure 5 The Ye axis in the aircraft wingspan coordinate system), the X axis in the aircraft wingspan coordinate system (i.e. Figure 5 The Xb axis (in the diagram) is positive to the right along the wing span direction, and the Y axis (i.e., ...) is positive to the right. Figure 5 In the diagram, the Yb axis is perpendicular to the direction pointing towards the back of the aircraft, with positive as the direction. Both wind direction and aircraft heading are represented using an angle of north-east. Figure 5 As shown.

[0065] A. Aileron Channel Control

[0066] a) Wingspan Direction Control

[0067] like As shown, the angle in the aircraft's span direction is This can be obtained through the magnetic heading sensor integrated inside the flight control computer; wind direction is... This can be measured using an anemometer and wind direction meter. Both have a range of... deg, then the aileron channel yaw control can use a PID control algorithm, and the control law expression is:

[0068] (1)

[0069] in, The aircraft's roll rate can be measured by inertial navigation sensors within the flight control computer. , and The parameters of the PID control law can be adjusted according to the specific aerodynamic characteristics of the aircraft.

[0070] (2)

[0071] Equation (2) represents the deviation between the wingspan direction and the wind direction, and converts it to... Within the deg range, to ensure that the aircraft does not rotate more than 180 deg when adjusting the wingspan direction.

[0072] The deflection of the left and right ailerons is:

[0073] (3)

[0074] The positive direction of the left and right ailerons is defined as the aileron trailing edge deflecting towards the positive direction of Yb.

[0075] In addition to serving as span control during vertical takeoff and landing (roll control during level flight), ailerons can also be used for pitch control during vertical takeoff and landing. This is because the aircraft will have a certain angle of tilt during the adjustment process, and the ailerons also need to be used for tilt control for landing safety.

[0076] b) Tilt control

[0077] Because crosswinds can affect the adjustment process, the aircraft needs to tilt to achieve balance. The tilt angle is expressed as follows: Figure 6 As shown.

[0078] The tilt angle is the angle between the aircraft's Z-axis (i.e., the Zb-axis) and the Earth's axial axis (Ze-axis) on the aircraft's plane of symmetry. To achieve a safe landing, this angle needs to be corrected to a relatively small value before landing. Another purpose of aileron channel control is to perform tilt control, correcting the tilt angle to a smaller value (ideally, it can be corrected to 0).

[0079] The tilt control algorithm is as follows:

[0080] (4)

[0081] In equation (4), The tilt angle, i.e., the pitch angle. For pitch rate, , and These are the proportional, integral, and derivative coefficients for tilt control, respectively.

[0082] When tilt control is performed, the left and right ailerons deflect in the same direction, acting as elevators, therefore:

[0083] (5)

[0084] c) Total control quantity

[0085] The total control quantity for the aileron passage is:

[0086] (6)

[0087] The control algorithm for the aileron channel can be obtained by combining equations (1) to (6).

[0088] B. Throttle Channel Control

[0089] Throttle channel control also has two control objectives: first, to reasonably control the aircraft's altitude so that it can land safely; second, because there are two motors, it can also differentially control the heading, so that the aircraft has a relatively small heading angle before landing to ensure landing safety.

[0090] a) Yaw control

[0091] In crosswinds, aircraft will not only tilt but also yaw, such as Figure 7 As shown.

[0092] In crosswinds, the aircraft's nose will deviate from the Z-axis of the Earth's axis. The component of this deviation in the wing span plane is the yaw angle. To ensure a safe landing, the yaw angle also needs to be kept relatively small.

[0093] Yaw angle correction can be achieved by differential control of the left and right motor throttles, resulting in different rotational speeds for the left and right propellers, thus providing yaw correction torque. The control law for yaw angle correction is as follows:

[0094] (7)

[0095] in, The yaw rate is measured by sensors integrated into the flight control system. , and These are the proportional, integral, and derivative coefficients for yaw control, respectively.

[0096] Let the left and right throttle be denoted as , and Then the throttle control value used for yaw control is:

[0097] (8)

[0098] b) Height control

[0099] When the aircraft is 0 meters above the ground, it completes the landing. For vertical take-off and landing drones, excessive speed or attitude during landing can affect landing safety. Therefore, it is necessary to control the aircraft's attitude angles (yaw and tilt angles) to a small range when approaching the ground, and then reduce the throttle to land safely.

[0100] Altitude control is divided into two stages: the first stage involves reducing the attitude angle, and the second stage involves decreasing altitude at a constant descent speed with a small throttle. In this embodiment, these two stages are separated by a height of 0.2 meters. The altitude control law flow logic is as follows: Figure 8 .

[0101] Depend on Figure 8The process logic can obtain the altitude change rate command, and then adjust the throttle through the altitude control law based on the altitude change rate command and the current altitude change rate to achieve altitude control.

[0102] The control law is as follows:

[0103] (9)

[0104] in, The altitude change rate command can be measured by sensors integrated into the flight control computer.

[0105] c) Total control quantity

[0106] (10)

[0107] In formula (10) and These represent the left and right throttle openings, respectively.

[0108] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A crosswind-resistant vertical takeoff and landing unmanned aerial vehicle (UAV), characterized in that, The device includes a drone body and a wind speed and direction sensor separately mounted on the drone body. The drone body includes a fuselage, a flight controller housed within the fuselage, wings on both sides of the fuselage, a propeller mounted in front of the wings, a motor connected to the propeller, control surfaces mounted behind the wings, and servo motors connected to the control surfaces. The wind speed and direction sensor is communicatively connected to the flight controller, and the flight controller is connected to the motor and the servo motor via cables. The anemometer measures wind speed and direction to generate wind speed and direction information, and the flight controller receives the wind speed and direction information; the flight controller obtains the attitude and altitude information obtained by the UAV itself through self-testing. The flight controller calculates and generates aileron channel control information based on wind speed, wind direction, and attitude information. Based on the aileron channel control information, it performs wingspan direction control and tilt control, drives the servo motors to deflect, and drives the control surfaces to deflect, thereby controlling the aircraft's orientation. The flight controller also calculates and generates throttle channel control information based on attitude and altitude information. Based on the throttle channel control information, it performs altitude control and yaw control, drives the motors to rotate, and changes the propeller speed, thereby controlling the aircraft's altitude and yaw. When performing wingspan directional control, the deflection of the left and right ailerons is: ； ； ； In the formula, For the aircraft's span direction angle, For wind direction, The aircraft's roll rate. , and These are the proportional, integral, and derivative coefficients for wingspan direction control, respectively. When performing tilt control, the left and right ailerons deflect in the same direction, with the deflection angle being: ， ； In the formula, The tilt angle, i.e., the pitch angle. For pitch rate, , and These are the proportional, integral, and derivative coefficients for tilt control, respectively. The total control quantity for the aileron passage is: ； When performing yaw control, the left and right throttle control values ​​are as follows: ； ； In the formula, The yaw rate is... , and These are the proportional, integral, and derivative coefficients for yaw control, respectively. The yaw angle refers to the component of the deviation between the aircraft's nose direction and the Z-axis of the ground axis system in the wing span plane under crosswind conditions.

2. The crosswind-resistant vertical takeoff and landing UAV according to claim 1, characterized in that, The rear end of the motor is fixed to the wing, and the propeller is fixed to the drive shaft at the front end of the motor.

3. The crosswind-resistant vertical takeoff and landing UAV according to claim 1, characterized in that, The control surface is connected to the tail of the wing via a hinge shaft. The servo motor is located inside the wing, and the control surface can rotate around the hinge shaft under the drive of the servo motor.

4. The crosswind-resistant vertical takeoff and landing UAV according to claim 1, characterized in that, The anemometer and wind direction instrument are connected to the ground station via cable, and the ground station is wirelessly connected to the flight controller.

5. The crosswind-resistant vertical takeoff and landing UAV according to claim 4, characterized in that, An airborne terminal is provided at the head of the fuselage, which is connected to the flight controller cable and wirelessly communicates with the ground station.

6. A method for resisting crosswinds in a crosswind-resistant vertical takeoff and landing unmanned aerial vehicle (UAV), characterized in that, Includes the following steps: Receive wind speed and direction information measured by an anemometer; Obtain attitude information; Obtain high-altitude information; Based on wind speed and direction information and attitude information, aileron channel control information is calculated and generated. Based on the aileron channel control information, wingspan direction control and tilt control are performed to control the aircraft's orientation. Throttle channel control information is calculated and generated based on attitude and altitude information. Altitude and yaw control are then performed based on the throttle channel control information to control the aircraft's altitude and yaw. When performing wingspan directional control, the deflection of the left and right ailerons is: ； ； ； In the formula, For the aircraft's span direction angle, For wind direction, The aircraft's roll rate. , and These are the proportional, integral, and derivative coefficients for wingspan direction control, respectively. When performing tilt control, the left and right ailerons deflect in the same direction, with the deflection angle being: ； In the formula, The tilt angle, i.e., the pitch angle. For pitch rate, , and These are the proportional, integral, and derivative coefficients for tilt control, respectively. The total control quantity for the aileron passage is: ， ； When performing yaw control, the left and right throttle control values ​​are as follows: ； ； In the formula, The yaw rate is... , and These are the proportional, integral, and derivative coefficients for yaw control, respectively. The yaw angle refers to the component of the deviation between the aircraft's nose direction and the Z-axis of the ground axis system in the wing span plane under crosswind conditions.

7. The method for resisting crosswinds in a crosswind-resistant vertical takeoff and landing UAV according to claim 6, characterized in that, Receiving wind speed and direction information measured by an anemometer includes the following steps: The anemometer measures wind speed and direction, generates wind speed and direction information, and transmits this information to the ground station via cable. The ground station transmits wind speed and direction information to the airborne terminal via wireless communication; The airborne unit receives wind speed and direction information and transmits it to the flight controller via cable. The flight controller receives wind speed and direction information.

8. The method for resisting crosswinds in a crosswind-resistant vertical takeoff and landing UAV according to claim 6, characterized in that, The process of controlling altitude and yaw based on throttle channel control information includes the following steps: Drive the servo motor to deflect; This causes the rudder surface to deflect; Control the aircraft's heading.

9. The method for resisting crosswinds in a crosswind-resistant vertical takeoff and landing UAV according to claim 6, characterized in that, The process of controlling altitude and yaw based on throttle channel control information includes the following steps: Drive motor to rotate; Change the propeller speed; Control the aircraft's altitude and yaw.

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