Attitude control device

Abstract

To provide an attitude control device that can stabilize an attitude of a fuselage quickly.SOLUTION: A rotor control device 50 that controls an attitude of a fuselage of an aircraft comprises a VTOL rotor control unit 76 that controls respective rotors, on the basis of a roll moment command value, a pitch moment command value and a yaw moment command value. When magnitude of the roll moment value or magnitude of the pitch moment command value is equal to or greater than a threshold, the VTOL rotor control unit 76 controls respective rotors without using the yaw moment command value.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an attitude control device. [Background technology]

[0002] Patent Document 1 below discloses a multicopter with multiple rotors that generate lift. In this multicopter, in order to maintain the attitude of the aircraft, a system of simultaneous equations consisting of multiple conditional expressions is solved to set the thrust of each rotor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-227155 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology disclosed in Patent Document 1, if the attitude of the aircraft is significantly affected, excessive thrust may be set for some rotors. If the set thrust exceeds the capacity of the rotor, the attitude of the aircraft cannot be stabilized.

[0005] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0006] One aspect of the present invention is an attitude control device that controls the attitude of an aircraft body having a plurality of rotors that generate thrust in a vertical direction, the attitude control device comprising: a roll moment command value calculation unit that calculates a command value of a roll moment to be applied to the aircraft body; a pitch moment command value calculation unit that calculates a command value of a pitch moment to be applied to the aircraft body; a yaw moment command value calculation unit that calculates a command value of a yaw moment to be applied to the aircraft body; a rotor control unit that controls each of the rotors based on the roll moment command value, the pitch moment command value, and the yaw moment command value; and a controller that determines whether the magnitude of the roll moment command value is equal to or greater than a first threshold value, determines whether the magnitude of the pitch moment command value is equal to or greater than a second threshold value, and calculates a combined moment calculated from the roll moment command value and the pitch moment command value. and a determination unit that performs at least one of the following determinations: whether the magnitude of the roll moment command value is equal to or greater than the first threshold; whether the magnitude of the pitch moment command value is equal to or greater than the third threshold; and when the determination unit determines that the magnitude of the roll moment command value is equal to or greater than the first threshold, when the determination unit determines that the magnitude of the pitch moment command value is equal to or greater than the second threshold, or when the determination unit determines that the magnitude of the resultant moment command value is equal to or greater than the third threshold, the rotor control unit controls each of the rotors based on the roll moment command value and the pitch moment command value without using the yaw moment command value, or the rotor control unit corrects the magnitude of the yaw moment command value to be smaller, and controls each of the rotors based on the roll moment command value, the pitch moment command value, and the corrected yaw moment command value. [Effects of the Invention]

[0007] According to the present invention, the attitude of the aircraft can be stabilized quickly. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 is a schematic diagram of an aircraft. [Figure 2]FIG. 2 is a diagram showing the configuration of the power supply system. [Figure 3] FIG. 3 is a diagram showing the configuration of the power supply system. [Figure 4] FIG. 4 is a control block diagram of the rotor control device. [Figure 5] FIG. 5 is a flowchart showing the flow of rotor control processing performed by the rotor control device. [Figure 6] FIG. 6 is a control block diagram of the rotor control device. [Figure 7] FIG. 7 is a flowchart showing the flow of rotor control processing performed by the rotor control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] [Aircraft configuration] FIG. 1 is a schematic diagram of an aircraft 10. The aircraft 10 of this embodiment is an electric vertical take-off and landing aircraft (eVTOL aircraft). In the aircraft 10 of this embodiment, a rotor is driven by an electric motor. In the aircraft 10 of this embodiment, the rotor generates vertical thrust and horizontal thrust. The aircraft 10 of this embodiment is also a hybrid aircraft. The aircraft 10 of this embodiment has a motor generator and a battery as power sources for the electric motor.

[0010] The aircraft 10 has a fuselage 12. The fuselage 12 is provided with a cockpit, a cabin, etc. A pilot sits in the cockpit and pilots the aircraft 10. The cabin houses passengers, etc. The aircraft 10 may be piloted automatically.

[0011] The aircraft 10 has a front wing 14 and a rear wing 16. The front wing 14 is attached forward of the center of gravity G of the fuselage 12. The rear wing 16 is attached aft of the center of gravity G of the fuselage 12. When the aircraft 10 moves forward, lift is generated on each of the front wing 14 and the rear wing 16.

[0012] The aircraft 10 has eight VTOL rotors 18. The eight VTOL rotors 18 are rotor 18FLa, rotor 18FLb, rotor 18RLa, rotor 18RLb, rotor 18FRa, rotor 18FRb, rotor 18RRa, and rotor 18RRb. Each of the VTOL rotors 18 corresponds to a rotor of the present invention.

[0013] The rotors 18FLa, 18FLb, 18RLa, and 18RLb are attached to a boom 20L. The boom 20L extends in the front-to-rear direction. The boom 20L is attached to the front wing 14 and the rear wing 16. The boom 20L is provided to the left of the center of gravity G. In other words, the rotors 18FLa, 18FLb, 18RLa, and 18RLb are disposed to the left of the center of gravity G.

[0014] The rotors 18FRa, 18FRb, 18RRa, and 18RRb are attached to a boom 20R. The boom 20R extends in the fore-and-aft direction. The boom 20R is attached to the front wing 14 and the rear wing 16. The boom 20R is provided to the right of the center of gravity G. In other words, the rotors 18FRa, 18FRb, 18RRa, and 18RRb are disposed to the right of the center of gravity G.

[0015] When viewed from above the aircraft 10, the rotors 18FLa, 18RLa, 18FRb, and 18RRb each rotate counterclockwise. When viewed from above the aircraft 10, the rotors 18FRa, 18RRa, 18FLb, and 18RLb each rotate clockwise.

[0016] The rotating shafts (not shown) of the VTOL rotors 18 extend in the vertical direction. The thrust of each of the VTOL rotors 18 is controlled by adjusting the rotor rotation speed and the blade pitch angle. Each of the VTOL rotors 18 is used during vertical takeoff, when transitioning from vertical takeoff to cruising, when transitioning from cruising to vertical landing, when vertical landing, when hovering in the air, etc. Each of the VTOL rotors 18 is also used during attitude control. The rotating shafts of each of the VTOL rotors 18 may be angled (canted) by several degrees relative to the vertical direction.

[0017] Lift thrust is generated by controlling the thrust of each of the eight VTOL rotors 18. Lift thrust refers to thrust in the vertical direction. The magnitude of the lift thrust is determined according to the sum of the thrust of each of the eight VTOL rotors 18.

[0018] Controlling the thrust of each of the eight VTOL rotors 18 causes a roll moment to act on the airframe 12. The magnitude of the roll moment is determined according to the difference between the sum of the thrusts of the four VTOL rotors 18 arranged to the left of the center of gravity G and the sum of the thrusts of the four VTOL rotors 18 arranged to the right of the center of gravity G.

[0019] The four VTOL rotors 18 arranged to the left of the center of gravity G refer to rotor 18FLa, rotor 18FLb, rotor 18RLa, and rotor 18RLb. The four VTOL rotors 18 arranged to the right of the center of gravity G refer to rotor 18FRa, rotor 18FRb, rotor 18RRa, and rotor 18RRb.

[0020] Controlling the thrust of each of the eight VTOL rotors 18 applies a pitch moment to the airframe 12. The magnitude of the pitch moment is determined according to the difference between the sum of the thrusts of the four VTOL rotors 18 arranged forward with respect to the center of gravity G and the sum of the thrusts of the four VTOL rotors 18 arranged aft with respect to the center of gravity G.

[0021] The four VTOL rotors 18 arranged forward with respect to the center of gravity G refer to rotor 18FLa, rotor 18FLb, rotor 18FRa, and rotor 18FRb. The four VTOL rotors 18 arranged rearward with respect to the center of gravity G refer to rotor 18RLa, rotor 18RLb, rotor 18RRa, and rotor 18RRb.

[0022] By controlling the counter torque of each of the eight VTOL rotors 18, a yaw moment is applied to the airframe 12. The magnitude of the yaw moment is determined according to the difference between the sum of the counter torques of the four VTOL rotors 18 rotating counterclockwise and the sum of the counter torques of the four VTOL rotors 18 rotating clockwise.

[0023] When each rotating shaft of the VTOL rotors 18 is angled (canted) by several degrees relative to the vertical direction, the VTOL rotors 18 generate thrust in the lateral direction of the airframe 12. In this case, the magnitude of the yaw moment is determined by the difference in the total of the aforementioned counter torques, as well as the difference between the moment generated by the thrust generated in the counterclockwise rotation direction of the airframe 12 and the moment generated by the thrust generated in the clockwise rotation direction of the airframe 12.

[0024] The four VTOL rotors 18 that rotate counterclockwise refer to rotor 18FLa, rotor 18RLa, rotor 18FRb, and rotor 18RRb. The four VTOL rotors 18 that rotate clockwise refer to rotor 18FRa, rotor 18RRa, rotor 18FLb, and rotor 18RLb.

[0025] The aircraft 10 has two cruise rotors 22. The two cruise rotors 22 are rotor 22L and rotor 22R.

[0026] The rotor 22L and the rotor 22R are attached to the rear of the airframe 12. The rotor 22L is disposed to the left of the center line A of the airframe 12. The rotor 22R is disposed to the right of the center line A of the airframe 12.

[0027] The rotating shafts (not shown) of the cruise rotors 22 extend in the fore-and-aft direction. The thrust of each cruise rotor 22 is controlled by adjusting the rotor rotation speed and blade pitch angle. Each cruise rotor 22 is used during transition from vertical takeoff to cruise, during cruise, and during transition from cruise to vertical landing, etc. The rotating shafts of each cruise rotor 22 may be angled (canted) by several degrees relative to the fore-and-aft direction.

[0028] Cruise thrust is generated by controlling the thrust of each of the two cruise rotors 22. Cruise thrust refers to thrust in the horizontal direction. The magnitude of the cruise thrust is determined by the sum of the thrust of each of the two cruise rotors 22.

[0029] [Power supply system configuration] Fig. 2 is a diagram showing the configuration of the power supply system 24. Fig. 2 mainly shows the connection relationship between the four batteries 30 and the twelve electric motors 32. Fig. 3 is a diagram showing the configuration of the power supply system 24.

[0030] A set of drive units 26 is provided for each VTOL rotor 18. A drive unit 26FLa is provided for rotor 18FLa. A drive unit 26FLb is provided for rotor 18FLb. A drive unit 26RLa is provided for rotor 18RLa. A drive unit 26RLb is provided for rotor 18RLb. A drive unit 26FRa is provided for rotor 18FRb. A drive unit 26RRa is provided for rotor 18RRa. A drive unit 26RRb is provided for rotor 18RRb.

[0031] Two sets of drive units 26 are provided for each cruise rotor 22. A drive unit 26La and a drive unit 26Lb are provided for the rotor 22L, and a drive unit 26Ra and a drive unit 26Rb are provided for the rotor 22R.

[0032] One battery 30 is connected to three sets of drive units 26. Battery 30a is connected to drive unit 26FRa, drive unit 26RLa, and drive unit 26Ra. Battery 30b is connected to drive unit 26FLa, drive unit 26RRa, and drive unit 26La. Battery 30c is connected to drive unit 26FRb, drive unit 26RLb, and drive unit 26Rb. Battery 30d is connected to drive unit 26FLb, drive unit 26RRb, and drive unit 26Lb.

[0033] Each drive unit 26 has an electric motor 32 and an inverter 34. The electric motor 32 is a three-phase motor. An output shaft (not shown) of the electric motor 32 is coupled to the rotating shaft of the respective VTOL rotor 18 or the rotating shaft of the cruise rotor 22. The inverter 34 converts input DC power into three-phase AC power and outputs it to the electric motor 32.

[0034] As shown in Fig. 3, a drive module 36 is made up of three drive units 26 and one battery 30. Drive unit 26FRa, drive unit 26RLa, drive unit 26Ra, and battery 30a make up drive module 36a. Drive unit 26FLa, drive unit 26RRa, drive unit 26La, and battery 30b make up drive module 36b. Drive unit 26FRb, drive unit 26RLb, drive unit 26Rb, and battery 30c make up drive module 36c. Drive unit 26FLb, drive unit 26RRb, drive unit 26Lb, and battery 30d make up drive module 36d.

[0035] Each drive module 36 is connected to a power generation module 38. The power generation module 38 includes an engine 40, a motor generator 42, and a power control unit (hereinafter, PCU) 44.

[0036] The engine 40 is a gas turbine engine. The engine 40 may be a reciprocating engine. The motor generator 42 functions as a three-phase motor and also as a three-phase generator. A rotating shaft (not shown) of the motor generator 42 is connected to an output shaft (not shown) of the engine 40.

[0037] The PCU 44 is an inverter and converter. The PCU 44 converts three-phase AC power input from the motor generator 42 into DC power and outputs it. The PCU 44 also converts DC power input from each battery 30 into three-phase AC power and outputs it to the motor generator 42.

[0038] 3 , each drive module 36 has a switch 48. Each switch 48 has a switching element such as an IGBT and a diode. Each switch 48 always allows power to be supplied from the power generation module 38 to the drive module 36. When each switch 48 is on, it allows power to be supplied from the drive module 36 to the power generation module 38.

[0039] When each switch 48 is on, power is supplied from each battery 30 to each motor generator 42. This causes the motor generator 42 to operate and start the engine 40. When the engine 40 is operating, power generated by the motor generator 42 is supplied to each battery 30 and each electric motor 32. This causes each battery 30 to be charged. Also, each electric motor 32 operates.

[0040] 2 and 3 show an outline of the power supply system 24. Some components are omitted from the power supply system 24 shown in Figures 2 and 3. The omitted components include, for example, electrical loads other than the electric motor 32, resistors, coils, capacitors, various sensors, fuses, relays, breakers, precharge circuits, DC-DC converters, etc.

[0041] [Configuration of rotor control device] 4 is a control block diagram of the rotor control device 50. The rotor control device 50 performs rotor control to adjust the thrust of each VTOL rotor 18. The rotor control device 50 corresponds to the attitude control device of the present invention. The rotor control device 50 has a calculation unit 52 and a memory unit 54.

[0042] The calculation unit 52 is a processor such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc. The calculation unit 52 has a roll moment command value calculation unit 56, a pitch moment command value calculation unit 58, a yaw moment command value calculation unit 60, a lift thrust command value calculation unit 62, a cruise thrust command value calculation unit 64, an attitude return mode determination unit 66, a four-axis control command value generation unit 68, a three-axis control command value generation unit 70, a switching unit 72, a cruise rotor thrust command value generation unit 74, a VTOL rotor control unit 76, and a cruise rotor control unit 78.

[0043] The roll moment command value calculation unit 56, pitch moment command value calculation unit 58, yaw moment command value calculation unit 60, lift thrust command value calculation unit 62, cruise thrust command value calculation unit 64, attitude return mode determination unit 66, 4-axis control command value generation unit 68, 3-axis control command value generation unit 70, switching unit 72, cruise rotor thrust command value generation unit 74, VTOL rotor control unit 76, and cruise rotor control unit 78 are realized by the calculation unit 52 executing programs stored in the memory unit 54.

[0044] At least a portion of the roll moment command value calculation unit 56, pitch moment command value calculation unit 58, yaw moment command value calculation unit 60, lift thrust command value calculation unit 62, cruise thrust command value calculation unit 64, attitude return mode determination unit 66, 4-axis control command value generation unit 68, 3-axis control command value generation unit 70, switching unit 72, cruise rotor thrust command value generation unit 74, VTOL rotor control unit 76, and cruise rotor control unit 78 may be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array).

[0045] At least a portion of the roll moment command value calculation unit 56, pitch moment command value calculation unit 58, yaw moment command value calculation unit 60, lift thrust command value calculation unit 62, cruise thrust command value calculation unit 64, attitude return mode determination unit 66, 4-axis control command value generation unit 68, 3-axis control command value generation unit 70, switching unit 72, cruise rotor thrust command value generation unit 74, VTOL rotor control unit 76, and cruise rotor control unit 78 may be realized by electronic circuits including discrete devices.

[0046] The storage unit 54 is configured by a volatile memory (not shown) and a nonvolatile memory (not shown), which are computer-readable storage media. The volatile memory is, for example, a random access memory (RAM). The nonvolatile memory is, for example, a read-only memory (ROM), a flash memory, etc. Data, etc., are stored in the volatile memory. Programs, tables, maps, etc., are stored in the nonvolatile memory. At least a part of the storage unit 54 may be provided in the processor, integrated circuit, etc. described above.

[0047] The roll moment command value calculation unit 56 calculates a roll moment command value. The roll moment command value is determined according to the amount of operation of the operation input unit by the pilot. The operation input unit is, for example, a control stick, pedals, levers, etc. The amount of operation of the operation input unit and the roll moment command value do not need to correspond one-to-one. The roll moment command value may be made variable with respect to the amount of operation of the operation input unit, depending on the operation range of the operation input unit, the operation speed of the operation input unit, the angular velocity of the aircraft 12, etc. The angular velocity of the aircraft 12 is detected, for example, by a gyro sensor (not shown).

[0048] If the pilot does not input an operation to the operation input unit, the roll moment command value may be automatically determined and the aircraft may hover, regardless of the amount of operation of the operation input unit. Also, if the aircraft 10 is automatically controlled, the roll moment command value may be automatically determined according to a preset flight path, regardless of the amount of operation of the operation input unit.

[0049] The pitch moment command value calculation unit 58 calculates a pitch moment command value. The pitch moment command value is determined, for example, according to the amount of operation of the operation input unit by the pilot. The amount of operation of the operation input unit and the pitch moment command value do not need to correspond one-to-one. The pitch moment command value may be made variable relative to the amount of operation of the operation input unit, according to the operation range of the operation input unit, the operation speed of the operation input unit, the angular velocity of the aircraft 12, etc.

[0050] If the pilot does not input an operation to the operation input unit, the pitch moment command value may be automatically determined and the aircraft may hover, regardless of the amount of operation of the operation input unit. Also, if the aircraft 10 is automatically controlled, the pitch moment command value may be automatically determined according to a preset flight path, regardless of the amount of operation of the operation input unit.

[0051] The yaw moment command value calculation unit 60 calculates a yaw moment command value. The yaw moment command value is determined, for example, according to the amount of operation of the operation input unit by the pilot. The amount of operation of the operation input unit and the yaw moment command value do not necessarily have a one-to-one correspondence. The yaw moment command value may be made variable relative to the amount of operation of the operation input unit, according to the operation range of the operation input unit, the operation speed of the operation input unit, the angular velocity of the aircraft 12, etc.

[0052] If the pilot does not input an operation to the operation input unit, the yaw moment command value may be determined automatically, regardless of the amount of operation of the operation input unit, and the aircraft 10 may hover. Also, if the aircraft 10 is automatically controlled, the yaw moment command value may be determined automatically in accordance with a preset flight path, regardless of the amount of operation of the operation input unit.

[0053] The lift thrust command value calculation unit 62 calculates a lift thrust command value. The lift thrust command value is determined, for example, according to the amount of operation of the operation input unit by the pilot. The amount of operation of the operation input unit and the lift thrust command value do not need to correspond one-to-one. The lift thrust command value may be made variable relative to the amount of operation of the operation input unit, depending on the operation range of the operation input unit, the operation speed of the operation input unit, the altitude of the aircraft 12, etc. The altitude of the aircraft 12 is estimated, for example, based on the distance between the ground and the aircraft 12 detected by a ground range finder (not shown). The altitude of the aircraft 12 is estimated, for example, based on a signal received from a GNSS (Global Navigation Satellite System).

[0054] If the pilot does not input an operation to the operation input unit, the lift and thrust command values ​​may be automatically determined and the aircraft may hover, regardless of the amount of operation of the operation input unit. Also, if the aircraft 10 is automatically controlled, the lift and thrust command values ​​may be automatically determined according to a preset flight path, regardless of the amount of operation of the operation input unit.

[0055] The cruise thrust command value calculation unit 64 calculates a cruise thrust command value. The cruise thrust command value is determined, for example, according to the amount of operation of the operation input unit by the pilot. The amount of operation of the operation input unit and the cruise thrust command value do not need to correspond one-to-one. The cruise thrust command value may be made variable relative to the amount of operation of the operation input unit, depending on the operation range of the operation input unit, the operation speed of the operation input unit, the airspeed of the aircraft 12, etc. The airspeed of the aircraft 12 is detected, for example, by an airspeed sensor (not shown).

[0056] If the pilot does not input an operation to the operation input unit, the cruise thrust command value may be determined automatically, and the aircraft 10 may fly at a constant speed. Also, if the aircraft 10 is automatically controlled, the cruise thrust command value may be determined automatically according to a preset flight path, regardless of the amount of operation of the operation input unit.

[0057] The attitude return mode determination unit 66 determines whether or not to implement the attitude return mode. Whether or not to implement the attitude return mode is determined according to the magnitude of the roll moment command value, the magnitude of the pitch moment command value, or the magnitude of the resultant moment command value. The attitude return mode determination unit 66 corresponds to the determination unit of the present invention. The resultant moment command value is a moment obtained by combining a moment in the roll direction having the magnitude of the roll moment command value and a moment in the pitch direction having the magnitude of the pitch moment command value.

[0058] The attitude return mode determination unit 66 determines to implement the attitude return mode in the following cases: when it is determined that the magnitude of the roll moment command value is greater than the first threshold value, when it is determined that the magnitude of the pitch moment command value is greater than the second threshold value, or when it is determined that the magnitude of the total moment command value is greater than the third threshold value.

[0059] The first threshold, the second threshold, and the third threshold are each a predetermined value. The attitude recovery mode determination unit 66 may variably set each of the first threshold, the second threshold, and the third threshold depending on the state of each VTOL rotor 18. For example, if some of the eight VTOL rotors 18 fail, the attitude recovery mode determination unit 66 may reduce each of the first threshold, the second threshold, and the third threshold. For example, the first threshold, the second threshold, and the third threshold may be set depending on the number of failed VTOL rotors 18 out of the eight VTOL rotors 18. Furthermore, the attitude recovery mode determination unit 66 may variably set each of the first threshold, the second threshold, and the third threshold depending on the airspeed of the aircraft 12. For example, the higher the airspeed, the higher the first threshold, the second threshold, and the third threshold may be set.

[0060] The four-axis control command value generation unit 68 generates thrust command values ​​for each of the VTOL rotors 18. The four-axis control command value generation unit 68 generates the thrust command values ​​based on the roll moment command value, the pitch moment command value, the yaw moment command value, and the lift thrust command value.

[0061] The three-axis control command value generation unit 70 generates thrust command values ​​for each of the VTOL rotors 18. The three-axis control command value generation unit 70 generates the thrust command values ​​based on the roll moment command value, the pitch moment command value, and the lift thrust command value. In other words, the three-axis control command value generation unit 70 generates the thrust command values ​​without using the yaw moment command value.

[0062] When the attitude return mode is implemented, the switching unit 72 selects the thrust command value generated by the three-axis control command value generation unit 70 and outputs it to the VTOL rotor control unit 76. When the attitude return mode is not implemented, the switching unit 72 selects the thrust command value generated by the four-axis control command value generation unit 68 and outputs it to the VTOL rotor control unit 76.

[0063] The cruise rotor thrust command value generating unit 74 generates a thrust command value for each cruise rotor 22. The cruise rotor thrust command value generating unit 74 generates a thrust command value based on the cruise thrust command value.

[0064] The VTOL rotor control unit 76 controls the thrust of each VTOL rotor 18 based on the thrust command value for each VTOL rotor 18 generated in the four-axis control command value generation unit 68 or the three-axis control command value generation unit 70. The VTOL rotor control unit 76 corresponds to the rotor control unit of the present invention.

[0065] Cruise rotor control unit 78 controls the thrust of each cruise rotor 22 based on the thrust command value for each cruise rotor 22 generated by cruise rotor thrust command value generation unit 74.

[0066] As described above, when the attitude return mode is performed, the VTOL rotor control unit 76 controls the thrust in each VTOL rotor 18 based on a thrust command value generated without using a yaw moment command value. Therefore, as a result of controlling the roll moment and pitch moment, a yaw moment acts on the airframe 12 due to the counter torque generated in each VTOL rotor 18. However, the direction and magnitude of the yaw moment are not guaranteed.

[0067] As a result, when the attitude recovery mode is performed, thrust in each VTOL rotor 18 is not allocated to the control of the yaw moment. Therefore, a large thrust can be allocated to each VTOL rotor 18 to the control of the roll moment and pitch moment. As a result, it is possible to increase the difference in thrust between each VTOL rotor 18. Therefore, the attitude of the aircraft 12 can be stabilized quickly in the roll direction and pitch direction.

[0068] [Rotor Control] 5 is a flowchart showing the flow of rotor control processing performed by the rotor control device 50. The rotor control processing is repeatedly executed at a predetermined cycle while the aircraft 10 is in flight.

[0069] In step S1, the four-axis control command value generation unit 68 generates thrust command values ​​for each of the VTOL rotors 18 based on the four-axis control command values. Then, the process proceeds to step S2. The four-axis control command values ​​refer to four command values: a roll moment command value, a pitch moment command value, a yaw moment command value, and a lift thrust command value.

[0070] In step S2, the three-axis control command value generating unit 70 generates thrust command values ​​for each of the VTOL rotors 18 based on the three-axis control command values. Then, the process proceeds to step S3. The three-axis control command values ​​refer to three command values: a roll moment command value, a pitch moment command value, and a lift thrust command value.

[0071] In step S3, the cruise rotor thrust command value generating unit 74 generates thrust command values ​​for each cruise rotor 22 based on the cruise thrust command value. Then, the process proceeds to step S4.

[0072] In step S4, the posture return mode determination unit 66 determines whether or not to implement the posture return mode. If the posture return mode is to be implemented, the process proceeds to step S6. If the posture return mode is not to be implemented, the process proceeds to step S5.

[0073] If the attitude return mode is not performed, in step S5, the VTOL rotor control unit 76 controls the thrust of each VTOL rotor 18 using the thrust command values ​​corresponding to each VTOL rotor 18 generated based on the four-axis control command values. Then, the process proceeds to step S7.

[0074] When the attitude return mode is performed, in step S6, the VTOL rotor control unit 76 controls the thrust of each VTOL rotor 18 using thrust command values ​​corresponding to each VTOL rotor 18 generated based on the three-axis control command values. Then, the process proceeds to step S7.

[0075] In step S7, the cruise rotor control unit 78 controls the thrust of each cruise rotor 22 based on the thrust command value for each cruise rotor 22. Thereafter, the rotor control ends.

[0076] [Action and effect] In the aircraft 10 of this embodiment, the rotor control device 50 applies a roll moment, a pitch moment, and a yaw moment to the airframe 12 by generating differences in the thrust of the eight VTOL rotors 18. In this way, the rotor control device 50 performs attitude control to stabilize the attitude of the airframe 12. Even when attitude control of the airframe 12 is performed, it is necessary to ensure lift thrust by the eight VTOL rotors 18 to prevent the aircraft 10 from diving. The proportion of thrust generated by each VTOL rotor 18 to ensure lift thrust is large relative to the upper limit of the thrust of each VTOL rotor 18. Therefore, it may not be possible to generate a sufficient difference in the thrust of the multiple VTOL rotors 18 while ensuring lift thrust.

[0077] The rotor control device 50 of this embodiment prioritizes stabilizing the attitude of the airframe 12 in the roll and pitch directions over stabilizing the attitude of the airframe 12 in the yaw direction. This is primarily due to the following reason: if the attitude of the airframe 12 is disrupted in the roll or pitch direction, the angle of the lift thrust direction relative to the vertical direction increases. In this case, the airframe 12 cannot obtain sufficient lift from the VTOL rotor 18. On the other hand, if the attitude of the airframe 12 is disrupted in the yaw direction, the impact on the lift acting on the airframe 12 is small.

[0078] Therefore, in the rotor control device 50 of this embodiment, the thrust of each VTOL rotor 18 is controlled by each thrust command value generated based on the three-axis control command value in the following cases. These cases are when the magnitude of the roll moment command value is greater than a first threshold value, when the magnitude of the pitch moment command value is greater than a second threshold value, or when the magnitude of the total moment command value is greater than a third threshold value. The three-axis control command values ​​refer to three command values: a roll moment command value, a pitch moment command value, and a lift thrust command value. In other words, the rotor control device 50 performs attitude control without using a yaw moment command value.

[0079] This allows a larger thrust to be distributed to each VTOL rotor 18 for control of the roll moment and pitch moment. As a result, it becomes possible to increase the difference in thrust between each VTOL rotor 18. Therefore, the attitude of the airframe 12 can be stabilized quickly in the roll direction and pitch direction.

[0080] Furthermore, in the rotor control device 50 of this embodiment, when the attitude of the airframe 12 is stabilized to a certain extent in the roll direction and the pitch direction, the thrust of each VTOL rotor 18 is controlled by a thrust command value generated based on the four-axis control command value. The situation where the attitude of the airframe 12 is stabilized to a certain extent in the roll direction and the pitch direction is when the magnitude of the roll moment command value is equal to or less than a first threshold value and when the magnitude of the pitch moment command value is equal to or less than a second threshold value. Alternatively, the situation where the attitude of the airframe 12 is stabilized to a certain extent in the roll direction and the pitch direction is when the magnitude of the combined moment command value is equal to or less than a third threshold value. The four-axis control command value refers to four command values: the roll moment command value, the pitch moment command value, the lift thrust command value, and the yaw moment command position. In other words, the rotor control device 50 performs attitude control based on the yaw moment command value.

[0081] As a result, when the attitude of the airframe 12 in the roll direction and pitch direction is stabilized to a certain extent, the rotor control device 50 of this embodiment can also stabilize the attitude of the airframe 12 in the yaw direction.

[0082] Furthermore, in the rotor control device 50 of this embodiment, if some of the eight VTOL rotors 18 fail, the attitude recovery mode determination unit 66 reduces the first threshold, the second threshold, and the third threshold. This allows the rotor control device 50 to perform attitude control early on without using the yaw moment command value. Therefore, even if some of the VTOL rotors 18 fail, the rotor control device 50 of this embodiment can quickly stabilize the attitude of the airframe 12 in the roll direction and the pitch direction.

[0083] Furthermore, in the rotor control device 50 of this embodiment, the attitude recovery mode determination unit 66 sets higher the first threshold, the second threshold, and the third threshold, respectively, as the airspeed of the airframe 12 increases. The higher the airspeed of the airframe 12, the more efficient the VTOL rotor 18. Therefore, when the output power of the electric motor 32 that drives the VTOL rotor 18 is constant, the higher the airspeed of the airframe 12, the larger the roll moment and pitch moment acting on the airframe 12. As a result, the higher the airspeed of the airframe 12, the smaller the output power of the electric motor 32 used for attitude control in the roll direction and attitude control in the pitch direction, making it possible to allocate the output power of the electric motor 32 to attitude control in the yaw direction.

[0084] By the attitude recovery mode determination unit 66 increasing the first threshold, the second threshold, and the third threshold, attitude control in the yaw direction is performed for a longer period by the VTOL rotor 18. As a result, the rotor control device 50 of this embodiment can stabilize the attitude of the airframe 12 in the yaw direction by the VTOL rotor 18 while stabilizing the attitude of the airframe 12 in the roll direction and pitch direction by the VTOL rotor 18.

[0085] Second Embodiment When the attitude return mode is performed, the rotor control device 50 of the first embodiment generates thrust command values ​​for each of the VTOL rotors 18 based on the three-axis control command values. The three-axis control command values ​​do not include a yaw moment command value.

[0086] On the other hand, even when the attitude return mode is implemented, the rotor control device 50 of this embodiment generates thrust command values ​​for each VTOL rotor 18 based on the four-axis control command values. The four-axis control command values ​​include a yaw moment command value. However, when the attitude return mode is implemented, a corrected yaw moment command value is used.

[0087] [Configuration of rotor control device] 6 is a control block diagram of the rotor control device 50. The rotor control device 50 has a calculation unit 52 and a storage unit .

[0088] The calculation unit 52 has a roll moment command value calculation unit 56, a pitch moment command value calculation unit 58, a yaw moment command value calculation unit 60, a lift thrust command value calculation unit 62, a cruise thrust command value calculation unit 64, an attitude return mode determination unit 66, a yaw moment command value correction unit 80, a 4-axis control command value generation unit 68, a cruise rotor thrust command value generation unit 74, a VTOL rotor control unit 76, and a cruise rotor control unit 78.

[0089] The roll moment command value calculation unit 56, pitch moment command value calculation unit 58, yaw moment command value calculation unit 60, lift thrust command value calculation unit 62, cruise thrust command value calculation unit 64, attitude return mode determination unit 66, 4-axis control command value generation unit 68, cruise rotor thrust command value generation unit 74, and cruise rotor control unit 78 are the same as those in the first embodiment.

[0090] When the attitude return mode is implemented, the yaw moment command value corrector 80 corrects the magnitude of the yaw moment command value to a smaller value and outputs it to the 4-axis control command value generator 68. When the attitude return mode is implemented, the yaw moment command value corrector 80 may correct the magnitude of the yaw moment command value to 0. When the attitude return mode is not implemented, the yaw moment command value corrector 80 outputs the yaw moment command value to the 4-axis control command value generator 68 without correcting it.

[0091] The VTOL rotor control unit 76 controls the thrust of each VTOL rotor 18 based on the thrust command value for each VTOL rotor 18 generated by the four-axis control command value generation unit 68.

[0092] In the rotor control device 50 of the first embodiment, when the attitude return mode is implemented, the VTOL rotor control unit 76 controls the thrust in each VTOL rotor 18 using a thrust command value generated without being based on a yaw moment command value. Therefore, as a result of controlling the roll moment and pitch moment, a yaw moment acts on the airframe 12 due to the counter torque generated in each VTOL rotor 18. As a result, in the first embodiment, the attitude of the airframe 12 in the yaw direction may become more unstable while the attitude return mode is being implemented.

[0093] On the other hand, in the rotor control device 50 of this embodiment, when the attitude return mode is implemented, although the magnitude of the yaw moment command value is corrected to be smaller, the VTOL rotor control unit 76 uses a thrust command value generated based on the yaw moment command value to control the thrust of each VTOL rotor 18. Therefore, in this embodiment, while the attitude return mode is implemented, it is not possible to apply a yaw moment to the airframe 12 that is strong enough to resist an external force that attempts to change the attitude of the airframe 12 in the yaw direction, but it is possible to suppress an unintended increase in the rate of change of attitude in the yaw direction.

[0094] [Rotor Control] 7 is a flowchart showing the flow of rotor control processing performed by the rotor control device 50. The rotor control processing is repeatedly executed at a predetermined cycle while the aircraft 10 is in flight.

[0095] In step S11, the posture return mode determination unit 66 determines whether or not to implement the posture return mode. If the posture return mode is to be implemented, the process proceeds to step S12. If the posture return mode is not to be implemented, the process proceeds to step S13.

[0096] When the attitude recovery mode is performed, the yaw moment command value corrector 80 corrects the yaw moment command value to a smaller value in step S12, and then the process proceeds to step S13.

[0097] In step S13, the four-axis control command value generation unit 68 generates thrust command values ​​for each of the VTOL rotors 18 based on the four-axis control command values. Then, the process proceeds to step S14. The four-axis control command values ​​refer to four command values: a roll moment command value, a pitch moment command value, a yaw moment command value, and a lift thrust command value. If the yaw moment command value was corrected in step S12, the corrected yaw moment command value is used.

[0098] In step S14, the cruise rotor thrust command value generator 74 generates a thrust command value for each cruise rotor 22. The cruise rotor thrust command value generator 74 generates a thrust command value based on the cruise thrust command value. Then, the process proceeds to step S15.

[0099] In step S15, the VTOL rotor control unit 76 controls the thrust in each VTOL rotor 18 based on the thrust command value for each VTOL rotor 18. Then, the process proceeds to step S16.

[0100] In step S16, the cruise rotor control unit 78 controls the thrust of each cruise rotor 22 based on the thrust command value for each cruise rotor 22. Thereafter, the rotor control ends.

[0101] [Action and effect] The rotor control device 50 of this embodiment controls the thrust of each VTOL rotor 18 based on each thrust command value generated based on the four-axis control command value. The four-axis control command values ​​refer to four command values: a roll moment command value, a pitch moment command value, a yaw moment command value, and a lift thrust command value. However, the rotor control device 50 corrects the magnitude of the yaw moment command value to a smaller value in the following cases. These cases include when the magnitude of the roll moment command value is greater than a first threshold value, when the magnitude of the pitch moment command value is greater than a second threshold value, or when the magnitude of the resultant moment command value is greater than a third threshold value.

[0102] This reduces the amount of control required for attitude control in the yaw direction, allowing the rotor control device 50 of this embodiment to quickly stabilize the attitude of the airframe 12 in the roll and pitch directions.

[0103] [Inventions Obtained from the Embodiments] The invention that can be understood from the above embodiment will be described below.

[0104] An attitude control device (50) for controlling the attitude of an airframe (12) of an aircraft (10) having a plurality of rotors (18) for generating thrust in a vertical direction, the attitude control device (50) comprising: a roll moment command value calculation unit (56) for calculating a command value of a roll moment to be applied to the airframe; a pitch moment command value calculation unit (58) for calculating a command value of a pitch moment to be applied to the airframe; a yaw moment command value calculation unit (60) for calculating a command value of a yaw moment to be applied to the airframe; a rotor control unit (76) for controlling each of the rotors based on the roll moment command value, the pitch moment command value, and the yaw moment command value; and a controller (77) for determining whether the magnitude of the roll moment command value is equal to or greater than a first threshold value, determining whether the magnitude of the pitch moment command value is equal to or greater than a second threshold value, and calculating a yaw moment command value calculated from the roll moment command value and the pitch moment command value. and a determination unit (66) that performs at least one of the following determinations: whether the magnitude of the command value of the roll moment is equal to or greater than the first threshold; whether the magnitude of the command value of the pitch moment is equal to or greater than the second threshold; and whether the magnitude of the command value of the resultant moment is equal to or greater than the third threshold. When the determination unit determines that the magnitude of the command value of the roll moment is equal to or greater than the first threshold, when the determination unit determines that the magnitude of the command value of the pitch moment is equal to or greater than the second threshold, or when the determination unit determines that the magnitude of the command value of the resultant moment is equal to or greater than the third threshold, the rotor control unit controls each of the rotors based on the command value of the roll moment and the command value of the pitch moment without using the command value of the yaw moment, or when the rotor control unit corrects the magnitude of the command value of the yaw moment to be smaller, and controls each of the rotors based on the command value of the roll moment, the command value of the pitch moment, and the corrected command value of the yaw moment. This makes it possible to quickly stabilize the attitude of the airframe in the roll direction and the pitch direction.

[0105] In the attitude control device, when correcting the magnitude of the yaw moment command value to a smaller value, the rotor control unit may set the magnitude of the yaw moment command value to 0. This allows the attitude of the aircraft to be stabilized quickly in the roll direction and the pitch direction.

[0106] In the attitude control device, the determination unit may vary at least one of the first threshold, the second threshold, and the third threshold, thereby enabling the attitude of the aircraft to be stabilized quickly in the roll direction and the pitch direction.

[0107] In the attitude control device, the determination unit may vary at least one of the first threshold, the second threshold, and the third threshold depending on the number of failed rotors, thereby enabling the attitude of the aircraft to be stabilized quickly in the roll direction and the pitch direction. [Explanation of symbols]

[0108] 10...Aircraft 12...Aircraft 18...VTOL rotor (rotor) 50...Rotor control device (attitude control device) 56... Roll moment command value calculation unit 58... Pitch moment command value calculation unit 60... Yaw moment command value calculation unit 66... ​​Attitude recovery mode determination unit (determination unit) 76...VTOL rotor control unit (rotor control unit)

Claims

1. An attitude control device for controlling the attitude of an aircraft having a plurality of rotors that generate thrust in a vertical direction, a roll moment command value calculation unit that calculates a command value of a roll moment to be applied to the airframe; a pitch moment command value calculation unit that calculates a pitch moment command value to be applied to the airframe; a yaw moment command value calculation unit that calculates a yaw moment command value to be applied to the aircraft; a rotor control unit that controls each of the rotors based on the roll moment command value, the pitch moment command value, and the yaw moment command value; a determination unit that performs at least one of determining whether the magnitude of the command value for the roll moment is equal to or greater than a first threshold value, determining whether the magnitude of the command value for the pitch moment is equal to or greater than a second threshold value, and determining whether the magnitude of a command value for a resultant moment calculated from the command value for the roll moment and the command value for the pitch moment is equal to or greater than a third threshold value; Equipped with When the determination unit determines that the magnitude of the command value of the roll moment is equal to or greater than the first threshold value, when the determination unit determines that the magnitude of the command value of the pitch moment is equal to or greater than the second threshold value, or when the determination unit determines that the magnitude of the command value of the resultant moment is equal to or greater than the third threshold value, the rotor control unit controls each of the rotors based on the command value of the roll moment and the command value of the pitch moment without using the command value of the yaw moment. or the rotor control unit corrects the magnitude of the yaw moment command value to be smaller, and controls each of the rotors based on the roll moment command value, the pitch moment command value, and the corrected yaw moment command value.

2. 2. The attitude control device according to claim 1, When correcting the magnitude of the yaw moment command value to be smaller, the rotor control unit sets the magnitude of the yaw moment command value to zero.

3. 3. The attitude control device according to claim 1, The attitude control device, wherein the determination unit makes at least one of the first threshold value, the second threshold value, and the third threshold value variable.

4. 4. The attitude control device according to claim 3, The attitude control device wherein the determination unit varies at least one of the first threshold value, the second threshold value, and the third threshold value depending on the number of failed rotors.

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