JP7577168B2 - Multicopter - Google Patents

Description

This disclosure relates to a multicopter, a rotorcraft equipped with multiple rotors (propellers).

Patent Document 1 discloses an electric aircraft (multicopter) having multiple rotors, motors that rotate each of the rotors, and a battery module that supplies power to the motors. In this electric aircraft, when the aircraft tilts, attitude control is performed to keep the aircraft horizontal by increasing the power supplied from the battery module to the motor on the side where the aircraft is lowered and reducing the power supplied from the battery module to the motor on the side where the aircraft is raised, thereby lowering the rotation speed of the rotors.

JP 2016-222031 A

In the multicopter disclosed in Patent Document 1, there are cases where the attitude of the multicopter cannot be controlled by supplying power from the battery module to the motor. For example, there is an upper limit to the power that can be supplied from the battery module to the motor, so if the required power supply to the motor exceeds the upper limit of the power that can be supplied from the battery module to the motor, the attitude of the multicopter cannot be controlled. As a result, there is a risk that the attitude of the multicopter cannot be maintained well.

Therefore, this disclosure has been made to solve the above problems, and aims to provide a multicopter that can maintain good posture.

One embodiment of the present disclosure made to solve the above problem is a multicopter having a plurality of rotors, a plurality of motors for driving the rotors, a power generation unit for generating power to be supplied to the motors, and a battery for charging the power generated by the power generation unit and supplying the charged power to the motors. The multicopter has a control unit for controlling an attitude of the multicopter, and defines a duty value of a voltage instructed to be applied to the motors as an instructed DUTY value. Under normal circumstances, the control unit controls the attitude of the multicopter by supplying power from the battery and the power generation unit to the motors, and a difference between the instructed DUTY values of the motors facing each other about a central axis of the multicopter is a predetermined When the command DUTY value of the opposing motor is equal to or greater than a predetermined upper threshold, the command DUTY value of the opposing motor is determined, and when the command DUTY value of either of the opposing motors is equal to or greater than a predetermined upper threshold, a supply power increase control is performed for the motor whose command DUTY value is equal to or greater than the predetermined upper threshold, or for all of the motors, to increase the output of the power generation unit to be higher than the normal state to increase the supply power, and when the command DUTY value of either of the opposing motors is equal to or less than a predetermined lower threshold, a supply power reduction control is performed for the motor whose command DUTY value is equal to or less than a predetermined lower threshold, or for all of the motors, to reduce the output of the power generation unit to be lower than the normal state to reduce the supply power .

This aspect allows the attitude of the multicopter to be quickly stabilized and maintained in a good position.

In the above aspect, it is preferable that the control unit adjusts the command DUTY value of the motor for which the supply power increase control has been performed to control the rotation speed of the rotor provided in the motor for which the supply power increase control has been performed, or adjusts the command DUTY value of the motor for which the supply power reduction control has been performed to control the rotation speed of the rotor provided in the motor for which the supply power reduction control has been performed .

This allows you to maintain good posture.

The multicopter disclosed herein can maintain good posture.

FIG. 1 is an external perspective view of a multicopter according to an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a multicopter according to an embodiment of the present invention. FIG. 1 is an explanatory diagram of attitude control during hovering. FIG. 1 is an explanatory diagram of attitude control during hovering. FIG. 4 is a control flowchart showing the content of control performed in the first embodiment. FIG. 13 is a diagram showing an example of an instruction DUTY value when the engine output is a rated output. FIG. 13 is a diagram showing an example of an instruction DUTY value when the engine output is an emergency output. FIG. 11 is a diagram showing a case where the maximum value of the voltage that can be applied to the motor is a normal voltage. FIG. 13 is a diagram showing a case where the maximum value of the voltage that can be applied to the motor is an emergency voltage. FIG. 11 is a diagram showing an example of a command DUTY value when the engine output is an emergency output in the modified example. FIG. 11 is a control flowchart showing the content of control performed in the second embodiment. FIG. 13 is a diagram showing an example of an instruction DUTY value when the engine output is a rated output. FIG. 13 is a diagram showing an example of an instruction DUTY value when the engine output is an emergency output. FIG. 11 is a control flowchart showing the content of control performed in the third embodiment. FIG. 13 is a control flowchart showing the content of control performed in the fourth embodiment. FIG. 13 is a control flowchart showing the content of control performed in the fifth embodiment.

The following describes an embodiment of the multicopter disclosed herein.

<Overview of Multicopter>
(Multicopter configuration)
As shown in FIG. 1 , the multicopter 1 of this embodiment has an airframe 11 and an engine-generator unit 12 .

The aircraft 11 includes a propeller 21, a motor 22, an aircraft main body 23, and a suspension member 24.

Multiple propellers 21 (e.g., eight) are provided. The multiple propellers 21 are rotated simultaneously to allow the multicopter 1 to fly. The propellers 21 are an example of a "rotor" in this disclosure. In the example shown in FIG. 1, eight propellers 21 are provided, and the eight propellers 21 are composed of a first propeller 21-1, a second propeller 21-2, a third propeller 21-3, a fourth propeller 21-4, a fifth propeller 21-5, a sixth propeller 21-6, a seventh propeller 21-7, and an eighth propeller 21-8.

The motors 22 are provided in a number of locations, each for each propeller 21, and rotate (drive) the propellers 21. As shown in FIG. 2, the motors 22 are electrically connected to the battery 31 and generator 42, which will be described later, via the ESC 36 (inverter (not shown)) and power control unit 35, which will be described later. As a result, the power generated by the generator 42 and the power discharged from the battery 31 are supplied to the motors 22 via the power control unit 35 and ESC 36. In the example shown in FIG. 1, eight motors 22 are provided, and the eight motors 22 are composed of the first motor 22-1, the second motor 22-2, the third motor 22-3, the fourth motor 22-4, the fifth motor 22-5, the sixth motor 22-6, the seventh motor 22-7, and the eighth motor 22-8.

As shown in FIG. 1, the aircraft body 23 is provided above the suspension member 24. As shown in FIG. 2, the aircraft body 23 is provided with a battery 31, a fuel tank 32, a control unit 33, a flight controller (FC) 34, a power control unit 35, an electric speed controller (ESC) 36, and the like.

The battery 31 is a charge/discharge unit (secondary battery, storage battery) capable of charging and discharging power. As shown in FIG. 2, the battery 31 is electrically connected to the generator 42 via the power control unit 35, and charges the power generated by the generator 42. The battery 31 is also electrically connected to the motor 22 via the power control unit 35 and the ESC 36, and discharges the power to be supplied to the motor 22. The battery 31 is also provided with sensors that detect the current and voltage of the battery 31, the temperature of the battery 31, and the SOC (State of Charge), and the sensors send signals related to this information to the control unit 33.

The fuel tank 32 stores fuel (e.g., gasoline) used to drive the engine 41, which will be described later. In addition, a level sensor (not shown) provided in the fuel tank 32 sends a signal to the control unit 33 regarding information on the remaining amount of fuel.

The control unit 33 is configured as a small computer and controls the entire multicopter 1. For example, the control unit 33 controls the drive of the engine 41 and controls the power generation by the generator 42. The control unit 33 also performs attitude control (balance control) of the multicopter 1, which will be described later.

The FC 34 is a device that controls the flight of the multicopter 1. The FC 34 sends thrust command signals to the control unit 33 and the ESC 36, while also receiving signals related to SOC information from the control unit 33. The FC 34 also receives user operation command signals from the controller 51, which will be described later, and receives signals related to detection result information from various sensors 52, which will be described later.

The power control unit 35 is a device that controls the power supplied to the motor 22. This power control unit 35 receives power generated by the generator 42, supplies and receives power to and from the battery 31, and supplies power to the ESC 36. The power control unit 35 also receives a signal from the control unit 33 instructing it to switch between charging and discharging.

The ESC 36 is a device that controls the rotation speed of the motor 22. The ESC 36 supplies the power supplied from the power control unit 35 to the motor 22 as drive power. The ESC 36 also receives a thrust command signal from the FC 34.

As shown in FIG. 1, the engine generator unit 12 is provided below the suspension member 24. This engine generator unit 12 is a power generating section that generates power to be supplied to the motor 22 and the battery 31, and includes an engine 41 and a generator (i.e., a generator) 42, as shown in FIGS. 1 and 2. The engine 41 is the power source of the generator 42, and is, for example, a small diesel engine or a reciprocating engine. That is, the engine 41 drives the generator 42 to generate power to be supplied to the motor 22 or the battery 31. The engine 41 also receives a signal instructing the generator 42 to generate power from the control section 33. The engine generator unit 12 is an example of a "power generating section" in this disclosure.

The multicopter 1 also has a controller 51 and various sensors 52, as shown in FIG. 2.

The controller 51 is an operation unit held by the user of the multicopter 1, such as a joystick. The various sensors 52 are sensors that detect altitude, attitude, latitude, longitude, acceleration, obstacles, etc.

In addition, in the multicopter 1 of this embodiment, a series hybrid system is configured with the motor 22, battery 31, and engine 41. That is, in the multicopter 1, the engine 41 is used only for generating electricity, the motor 22 is used to drive the propeller 21, and a system is configured with the battery 31 for recovering electricity. In this way, the multicopter 1 flies by generating electricity in the generator 42 driven by the engine 41, and using the generated electricity to drive the motor 22 and drive the propeller 21. In addition, the multicopter 1 temporarily stores surplus electricity generated by the generator 42 driven by the engine 41 in the battery 31, and uses it to drive the motor 22 as needed.

(Multicopter action)
The multicopter 1 having such a configuration flies by supplying power to the motor 22 and rotating the multiple propellers 21. By controlling the rotation speed of the propellers 21 and balancing the lift obtained by the rotation of the propellers 21 with the gravity of the multicopter 1 itself, the multicopter 1 can realize hovering flight, forward, backward, and left and right movement flight. In addition, the multicopter 1 can realize an upward flight by increasing the lift generated by the propellers 21, and can realize a downward flight of the multicopter 1 by decreasing the lift generated by the propellers 21. In addition, the multicopter 1 can realize forward, backward, and left and right movement flight by controlling the rotation speed of each propeller 21 and causing an imbalance in the lift generated by the rotation of the multiple propellers 21. In addition, a turning (rotational) flight can be realized by providing a difference in the rotation speed of the opposing propellers 21.

(Regarding attitude control)
Here, the attitude control of the multicopter 1 performed by the control unit 33 will be described. When the control is performed to maintain the tilt angle of the multicopter 1 at the target angle, for example, when the multicopter 1 is hovering (during hovering (flying)), as shown in FIG. 3, the attitude control is performed so that the lift forces LFA and LFB obtained by the rotation of the propeller 21 and the gravity G are balanced. Therefore, when the multicopter 1 is hovering in this way, as shown in FIG. 4, assuming that a strong crosswind blows from the outside, a force FA that tries to roll the multicopter 1 by the wind acts. Therefore, in order to obtain a force that tries to keep the multicopter 1 hovering in place by avoiding the rollover of the multicopter 1, the lift force LFA is increased and attitude control is performed. The tilt angle of the multicopter 1 is the angle between the central axis CA of the multicopter 1 (airframe 11) and the axis indicating the direction of action of gravity G (the up and down direction in Figures 3 and 4) (the angle θ between the central axis CA when the multicopter 1 is tilted, shown by the dashed line in Figure 4, and the axis indicating the direction of action of gravity G).

<Control to maintain good posture>
Next, in the multicopter 1 that performs the above-described attitude control, the control for maintaining the attitude of the multicopter 1 in a good state will be described.

First Embodiment
First, the first embodiment will be described.

The multicopter 1 has a battery 31 as its power source, and the lift generated by driving the propellers 21 provided on each motor 22 in controlling the attitude of the multicopter 1 (hereinafter referred to as "propeller 21 lift") is limited by the power that can be supplied from the battery 31 to the motor 22. If the attitude of the multicopter 1 can only be controlled within the range of power (voltage) that can be supplied from the battery 31 to the motor 22, there is a risk that the lift of the propellers 21 required for attitude control of the multicopter 1 will be insufficient if an unexpected state occurs (for example, when the multicopter 1 is exposed to a very strong wind).

For example, as shown in FIG. 4, when a strong crosswind blows from the outside, it is necessary to increase the lift of the fourth propeller 21-4 to control the attitude of the multicopter 1. However, at this time, if the power to be supplied to the fourth motor 22-4 that drives the fourth propeller 21-4 exceeds the upper limit of the power that can be supplied from the battery 31 to the motor 22, there is a risk that the lift of the fourth propeller 21-4 will be insufficient.

If the propellers 21 do not provide enough lift to control the attitude of the multicopter 1, it will be difficult to control the attitude of the multicopter 1, and the attitude of the multicopter 1 will not be maintained properly, which may result in the multicopter 1 being unable to fly stably.

Therefore, in this embodiment, in order to keep the attitude of the multicopter 1 good (horizontal) during hovering (i.e., to maintain the tilt angle of the multicopter 1 at the target angle during hovering (e.g., 0°)), the control unit 33 performs power supply increase control to increase the output of the engine generator unit 12 above normal to increase the power supplied to a specific motor 22 when there is a risk that the multicopter 1 will tilt relative to the horizontal direction during hovering (i.e., there is a risk that the tilt angle of the multicopter 1 will deviate from the target angle during hovering).

The output of the engine generator unit 12 is an example of the "output of the power generation unit" in this disclosure, and more specifically, the output of the engine 41. The supply power increase control is an example of the "supply power control" in this disclosure.

(Flowchart explanation)
Specifically, the control unit 33 performs control based on the control flowchart shown in Fig. 5. As shown in Fig. 5, the control unit 33 reads the command DUTY value of each motor 22 (step S1), and calculates the difference between the command DUTY values of the opposing motors 22 (step S2).

Here, the rotation speed of the propeller 21 is controlled by controlling the voltage (effective voltage) applied to the motor 22 through duty control. The commanded DUTY value is an example of the "applied voltage" in this disclosure, and is the duty value (duty ratio value) of the voltage (pulse voltage) commanded to be applied to the motor 22.

The "opposing motors 22" refer to the motors 22 that face each other around the central axis CA of the multicopter 1, as shown in FIG. 6, or in other words, a pair of motors 22 that face each other on a diagonal line of a polygon formed by connecting the positions at which all the motors 22 are arranged. In the example shown in FIG. 6, for example, the first motor 22-1 and the fifth motor 22-5, the second motor 22-2 and the sixth motor 22-6, the third motor 22-3 and the seventh motor 22-7, and the fourth motor 22-4 and the eighth motor 22-8 are each the opposing motors 22.

In addition, in Figure 6 (and also in Figures 7, 10, 12, and 13), the command duty value of each motor 22 is shown diagrammatically, with the command duty value = 0% at the position of the central axis CA of the multicopter 1, and the command duty value increasing from there toward the outer periphery, and the command duty value = 100% at the outermost position.

Returning to the explanation of FIG. 5, the control unit 33 determines whether the difference in the command DUTY values calculated in step S2 is equal to or greater than the threshold value THA (step S3). The threshold value THA is, for example, 60%. The threshold value THA is a predetermined threshold value and is an example of the "predetermined voltage difference" of the present disclosure.

Then, if the difference in the command DUTY values is not equal to or greater than the threshold value THA (step S3: NO), i.e., if the difference in the command DUTY values is less than the threshold value THA, the control unit 33 sets the engine output to the rated output RO (step S4).

Here, "engine output" refers to the output of the engine 41, i.e., corresponds to the power generated by the generator 42 when the engine 41 is driven. Also, "rated output RO" refers to the normal output when the multicopter 1 is hovering.

In this way, when the difference in the command DUTY values of the opposing motors 22 is small, the difference in lift generated by the opposing propellers 21 is small, so it is considered that the multicopter 1 is less likely to tilt (i.e., the tilt angle of the multicopter 1 is less likely to deviate from the target angle during hovering). Therefore, the control unit 33 controls the attitude of the multicopter 1 while keeping the engine output at the rated output RO.

On the other hand, if the difference in the command DUTY values is equal to or greater than the threshold value THA (step S3: YES), the control unit 33 determines whether the command DUTY value of one of the opposing motors 22 is equal to or greater than the threshold value THB (step S5). Note that the threshold value THB is, for example, 90%. The threshold value THB is a predetermined upper limit threshold, and is an example of the "predetermined upper limit voltage value" of the present disclosure.

In this way, when the difference in the command DUTY values is equal to or greater than the threshold value THA, the difference in lift generated by the opposing propellers 21 becomes large, and it is considered that there is a high possibility that the multicopter 1 will tilt (i.e., there is a high possibility that the tilt angle of the multicopter 1 will deviate from the target angle during hovering). Therefore, when the difference in the command DUTY values is equal to or greater than the threshold value THA, the control unit 33 determines that there is a possibility that the attitude of the multicopter 1 cannot be maintained well, and determines whether the command DUTY value of either of the opposing motors 22 (for example, either the fourth motor 22-4 or the eighth motor 22-8 shown in FIG. 6) is equal to or greater than the threshold value THB.

Then, if the command DUTY value of either of the opposing motors 22 is not equal to or greater than the threshold value THB (step S5: NO), i.e., if the command DUTY values of both opposing motors 22 are both less than the threshold value THB, the engine output is set to the rated output RO (step S4).

In this way, even if the difference in the command DUTY values is equal to or greater than the threshold value THA, if the command DUTY values of both opposing motors 22 are both less than the threshold value THB, it is considered possible to control the command DUTY values and maintain a good attitude of the multicopter 1. Therefore, the control unit 33 controls the attitude of the multicopter 1 while keeping the engine output at the rated output RO.

On the other hand, if the command DUTY value of either of the opposing motors 22 is equal to or greater than the threshold value THB (step S5: YES), the engine output is set to the emergency output EOH (step S6), and the power supplied to the motor 22 whose command DUTY value is equal to or greater than the threshold value THB is increased (step S7). Note that the "emergency output EOH" is an output higher than the rated output RO.

For example, as shown in FIG. 6, when the command DUTY value of the fourth motor 22-4 of the opposing fourth motor 22-4 and eighth motor 22-8 is equal to or greater than the threshold value THB, the engine output is set to the emergency output EOH, and the power supplied to the fourth motor 22-4 is increased.

In this manner, in this embodiment, the control unit 33 performs supply power increase control to increase the engine output above normal to increase the power supplied to a particular motor 22. In particular, when the command DUTY value of at least one motor 22 is equal to or greater than the threshold value THB, the control unit 33 performs supply power increase control to increase the engine output above normal to increase the power supplied to the motor 22 whose command DUTY value is equal to or greater than the threshold value THB.

Returning to the explanation of FIG. 5, the control unit 33 increases the power supplied to the motor 22 whose command duty value is equal to or greater than the threshold value THB until the command duty value of the motor 22 to which the supply power has been increased becomes less than the threshold value THB (steps S8: NO, S7).

For example, as shown in FIG. 7, the power supplied to the fourth motor 22-4 is increased until the command DUTY value of the fourth motor 22-4 becomes less than the threshold value THB. In this way, the power supplied to the fourth motor 22-4 is increased, and the command DUTY value of the fourth motor 22-4 becomes less than the threshold value THB. That is, by increasing the power supplied to the fourth motor 22-4 and increasing the maximum value of the voltage that can be applied to the fourth motor 22-4 from the normal voltage V0 to the emergency voltage V1, for example, as shown in FIG. 8 and FIG. 9, the command DUTY value of the fourth motor 22-4 (the duty value for applying the effective voltage Va to the fourth motor 22-4) is reduced from the normal duty value D0 to the emergency duty value D1 (<D0).

In this way, by lowering the command DUTY value of the fourth motor 22-4, the command DUTY value of the fourth motor 22-4 can have a margin with respect to its maximum value (100%). Therefore, by adjusting the command DUTY value of the fourth motor 22-4 to control the effective voltage Va applied to the fourth motor 22-4, the rotation speed of the fourth propeller 21-4 provided on the fourth motor 22-4 can be controlled to control the lift of the fourth propeller 21-4. For example, by increasing the command DUTY value of the fourth motor 22-4 within a range below the threshold value THB and increasing the effective voltage Va applied to the fourth motor 22-4, the rotation speed of the fourth propeller 21-4 is increased to increase the lift of the fourth propeller 21-4. In this way, the attitude of the multicopter 1 can be controlled to maintain a good attitude of the multicopter 1.

Returning to the explanation of FIG. 5, when the command DUTY value of the motor 22 to which the supply of power has been increased falls below the threshold value THB (step S8: YES), the control unit 33 switches the engine output from the emergency output EOH to the rated output RO (step S4).

(Modification)
As a modified example, in step S7, the control unit 33 may increase the power supply to all of the motors 22. As a result, as shown in Fig. 10, the command DUTY values of all of the motors 22 may be lowered, and for example, the command DUTY value of the fourth motor 22-4 may be set to less than the threshold value THB.

In the examples shown in Figures 6, 7, and 10, the power supply to the fourth motor 22-4 is increased, but if the command DUTY value of the other motors 22 is equal to or greater than the threshold value THB, the control unit 33 also increases the power supply to the other motors 22 whose command DUTY values are equal to or greater than the threshold value THB. In other words, when the command DUTY value of at least one motor 22 in the multicopter 1 is equal to or greater than the threshold value THB, the control unit 33 performs a power supply increase control to increase the power supply to the motors 22 whose command DUTY values are equal to or greater than the threshold value THB or to all motors 22.

Even with the above modified examples, it is possible to achieve the same effects as the above embodiment.

(Effects of this embodiment)
As described above, according to this embodiment, when there is a risk of the multicopter 1 tilting during hovering, the control unit 33 performs power supply increase control to increase the engine output above normal and increase the power supplied to a specific motor 22 or all of the motors 22.

In this way, when there is a risk that the multicopter 1 may tilt during hovering, the engine output is increased from normal to increase the power supplied to a specific motor 22 or all of the motors 22. As a result, even if the lift of the propeller 21 cannot be controlled to the desired magnitude by supplying power from the battery 31 to the motors 22, the lift of the propeller 21 provided on the specific motor 22 or all of the motors 22 can be controlled to the desired magnitude by supplying power from the generator 42 to the specific motor 22 or all of the motors 22, thereby suppressing tilt of the multicopter 1. Therefore, the attitude of the multicopter 1 can be controlled to maintain a good attitude.

In other words, when the attitude of the multicopter 1 is unstable, the power supplied to a specific motor 22 or all of the motors 22 can be temporarily increased to control the lift of the propellers 21 provided on the specific motor 22 or all of the motors 22, thereby quickly stabilizing the attitude of the multicopter 1. In this way, the attitude of the multicopter 1 can be maintained well with easy control.

In addition, in controlling the attitude of the multicopter 1 to be stable, performing control to temporarily increase the power supply to a specific motor 22 can reduce energy consumption compared to performing control to temporarily increase the power supply to all motors 22.

When the difference between the command DUTY values of the opposing motors 22 is equal to or greater than the threshold value THA and the command DUTY value of at least one motor 22 is equal to or greater than the threshold value THB, the control unit 33 performs supply power increase control as the supply power control. This supply power increase control is a control that increases the engine output higher than normal to increase the power supplied to the motor 22 whose command DUTY value is equal to or greater than the threshold value THB, or to all motors 22.

In this way, when the difference between the command DUTY values of the opposing motors 22 becomes large, and when the command DUTY value of at least one motor 22 is equal to or greater than the threshold value THB, the engine output is increased from normal to increase the power supplied to the motor 22 whose command DUTY value is equal to or greater than the threshold value THB or to all motors 22. This makes it possible to lower the command DUTY value of the motor 22 whose command DUTY value is equal to or greater than the threshold value THB to less than the threshold value THB. Therefore, the command DUTY value of the motor 22 whose command DUTY value has been lowered to less than the threshold value THB is adjusted to control the lift of the propeller 21 provided on that motor 22 to a desired magnitude, thereby controlling the attitude of the multicopter 1 and maintaining a good attitude of the multicopter 1.

Second Embodiment
Next, a second embodiment will be described. Explanation of the same contents as in the first embodiment will be omitted, and the differences will be mainly described.

In this embodiment, when there is a risk that the multicopter 1 may tilt during hovering, the control unit 33 performs power supply reduction control to reduce the output of the engine generator unit 12 from normal to reduce the power supply to a specific motor 22. Note that the power supply reduction control is an example of the "power supply control" of the present disclosure.

(Flowchart explanation)
Specifically, the control unit 33 performs control based on the control flowchart shown in Fig. 11. As shown in Fig. 11, when the difference between the command DUTY values calculated in step S102 is equal to or greater than the threshold value THA (step S103: YES), the control unit 33 determines whether the command DUTY value of either of the opposing motors 22 is equal to or less than the threshold value THC (step S105). Note that the threshold value THC is, for example, 30%. The threshold value THC is a predetermined lower limit threshold value, and is an example of the "predetermined lower limit voltage value" of the present disclosure.

In this way, if the difference in the command DUTY values is equal to or greater than the threshold value THA, it is considered that there is a high possibility that the multicopter 1 will tilt. Therefore, the control unit 33 determines that there is a possibility that the attitude of the multicopter 1 cannot be maintained well, and determines whether the command DUTY value of either of the opposing motors 22 (for example, either the second motor 22-2 or the sixth motor 22-6, or either the third motor 22-3 or the seventh motor 22-7 shown in FIG. 12) is equal to or less than the threshold value THC.

If the command DUTY value of either of the opposing motors 22 is not equal to or less than the threshold value THC (step S105: NO), i.e., if the command DUTY values of both of the opposing motors 22 are greater than the threshold value THC, the engine output is set to the rated output RO (step S104).

In this way, even if the difference in the command DUTY values is equal to or greater than the threshold value THA, if the command DUTY values of both opposing motors 22 are both greater than the threshold value THC, it is considered possible to control the command DUTY values and maintain a good attitude of the multicopter 1. Therefore, the control unit 33 controls the attitude of the multicopter 1 while keeping the engine output at the rated output RO.

On the other hand, if the command DUTY value of either of the opposing motors 22 is equal to or less than the threshold value THC (step S105: YES), the battery output is stopped (step S106), the engine output is set to the emergency output EOL (step S107), and the power supply to the motor 22 whose command DUTY value is equal to or less than the threshold value THC is reduced (step S108).

Note that "battery output" refers to the supply of power from the battery 31 to the motor 22. Also, "emergency output EOL" is an output lower than the rated output RO.

For example, as shown in FIG. 12, when the command DUTY value of the sixth motor 22-6 of the opposing second motor 22-2 and sixth motor 22-6 is equal to or less than the threshold value THC, the battery output is stopped and the engine output is set to the emergency output EOL, reducing the power supply to the sixth motor 22-6. Note that in the example shown in FIG. 12, the command DUTY value of the seventh motor 22-7 of the opposing third motor 22-3 and seventh motor 22-7 is also equal to or less than the threshold value THC, so the power supply to the seventh motor 22-7 is also reduced.

In this manner, in this embodiment, the control unit 33 performs supply power reduction control to reduce the engine output to a lower level than normal to reduce the power supplied to a specific motor 22. In particular, when the command DUTY value of at least one motor 22 is equal to or less than the threshold value THC, the control unit 33 performs supply power reduction control to reduce the engine output to a lower level than normal to reduce the power supplied to the motor 22 whose command DUTY value is equal to or less than the threshold value THC as supply power control. Furthermore, when performing supply power reduction control, the control unit 33 performs battery output stop control to stop the battery output.

Returning to the explanation of FIG. 11, the control unit 33 reduces the power supplied to the motor 22 whose command duty value is equal to or less than the threshold value THC until the command duty value of the motor 22 to which the supply power has been reduced becomes greater than the threshold value THC (steps S109: NO, S108).

For example, as shown in FIG. 13, the power supplied to the sixth motor 22-6 and the seventh motor 22-7 is reduced until the command DUTY value of the sixth motor 22-6 and the seventh motor 22-7 becomes greater than the threshold value THC. In this way, the power supplied to the sixth motor 22-6 and the seventh motor 22-7 is reduced, and the command DUTY value of the sixth motor 22-6 and the seventh motor 22-7 becomes greater than the threshold value THC.

In this way, by increasing the command duty values of the sixth motor 22-6 and the seventh motor 22-7, it is possible to provide a margin for the command duty values of the sixth motor 22-6 and the seventh motor 22-7 relative to their minimum value (0%). Therefore, by adjusting the command duty values of the sixth motor 22-6 and the seventh motor 22-7 to control the effective voltage Va applied to the sixth motor 22-6 and the seventh motor 22-7, it is possible to control the rotation speed of the sixth propeller 21-6 and the seventh propeller 21-7 provided on the sixth motor 22-6 and the seventh motor 22-7, thereby controlling the lift of the sixth propeller 21-6 and the seventh propeller 21-7. For example, by lowering the command DUTY value of the sixth motor 22-6 and the seventh motor 22-7 within a range greater than the threshold THC and lowering the effective voltage Va applied to the sixth motor 22-6 and the seventh motor 22-7, the rotation speed of the sixth propeller 21-6 and the seventh propeller 21-7 is reduced, and the lift of the sixth propeller 21-6 and the seventh propeller 21-7 is reduced. In this way, the attitude of the multicopter 1 can be controlled to maintain a good attitude of the multicopter 1.

Returning to the explanation of FIG. 11, when the command DUTY value of the motor 22 with reduced power supply becomes greater than the threshold value THC (step S109: YES), the control unit 33 resumes battery output (step S110) and switches the engine output from the emergency output EOL to the rated output RO (step S104).

(Modification)
As a modified example, in step S108, the control unit 33 may reduce the power supply to all of the motors 22. This may increase the command DUTY values of all of the motors 22, so that, for example, the command DUTY values of the sixth motor 22-6 and the seventh motor 22-7 are made larger than the threshold value THC.

In the example shown in Figures 12 and 13, the power supply to the sixth motor 22-6 and the seventh motor 22-7 is reduced, but if the command DUTY value of the other motors 22 is equal to or less than the threshold THC, the control unit 33 also reduces the power supply to the other motors 22 whose command DUTY values are equal to or less than the threshold THC. In other words, if the command DUTY value of at least one motor 22 in the multicopter 1 is equal to or less than the threshold THC, the control unit 33 performs power supply reduction control to reduce the power supply to the motors 22 whose command DUTY values are equal to or less than the threshold THC or to all motors 22.

Even with the above modified examples, it is possible to achieve the same effects as the above embodiment.

(Effects of this embodiment)
As described above, according to this embodiment, when there is a risk of the multicopter 1 tilting during hovering, the control unit 33 performs power supply reduction control to reduce the engine output below normal levels and reduce the power supplied to a specific motor 22 or all motors 22.

In this way, when there is a risk that the multicopter 1 may tilt during hovering, the engine output is lowered below normal to reduce the power supplied to a specific motor 22 or all of the motors 22. As a result, even if the lift of the propeller 21 cannot be controlled to the desired magnitude by supplying power from the battery 31 to the motors 22, the lift of the propeller 21 provided on the specific motor 22 or all of the motors 22 can be controlled to the desired magnitude by supplying power from the generator 42 to the specific motor 22 or all of the motors 22, thereby suppressing the tilt of the multicopter 1. Therefore, the attitude of the multicopter 1 can be controlled to maintain a good attitude.

In other words, when the attitude of the multicopter 1 is unstable, the lift of the propellers 21 provided on the specific motor 22 or all of the motors 22 can be controlled by temporarily reducing the power supplied to the specific motor 22 or all of the motors 22, thereby quickly stabilizing the attitude of the multicopter 1. In this way, the attitude of the multicopter 1 can be maintained in a good state with easy control.

When the difference between the command DUTY values of the opposing motors 22 is equal to or greater than the threshold value THA and the command DUTY value of at least one motor 22 is equal to or less than the threshold value THC, the control unit 33 performs supply power reduction control as the supply power control. This supply power reduction control is a control that reduces the engine output below normal and reduces the power supplied to the motors 22 whose command DUTY values are equal to or less than the threshold value THC, or to all motors 22.

In this way, when the difference between the command DUTY values of the opposing motors 22 becomes large, and when the command DUTY value of at least one motor 22 is equal to or less than the threshold value THC, the engine output is lowered from the normal state to reduce the power supplied to the motors 22 whose command DUTY values are equal to or less than the threshold value THC or to all motors 22. This makes it possible to increase the command DUTY value of the motors 22 whose command DUTY values are equal to or less than the threshold value THC to be greater than the threshold value THC. Therefore, the command DUTY value of the motor 22 whose command DUTY value is increased to be greater than the threshold value THC is adjusted to control the lift of the propeller 21 provided on that motor 22 to a desired magnitude, thereby controlling the attitude of the multicopter 1 and maintaining a good attitude of the multicopter 1.

In addition, by reducing the engine output, the consumption of fuel in the fuel tank 32 required to drive the engine 41 can be suppressed. This allows the multicopter 1 to maintain a good attitude with good fuel economy.

When performing supply power reduction control, the control unit 33 also performs battery output stop control to stop the supply of power from the battery 31 to the motor 22.

In this way, the supply of power from the battery 31 to the motor 22 is stopped, so the charge consumption of the battery 31 can be reduced. This reduces the engine output required to generate the power to charge the battery 31, so the consumption of fuel required to drive the engine 41 can be reduced. This allows the attitude of the multicopter 1 to be maintained in a good condition more efficiently and with better fuel economy.

Third Embodiment
Next, a third embodiment will be described. Explanation of the same contents as those of the first and second embodiments will be omitted, and the differences will be mainly described.

In this embodiment, the control unit 33 performs control to increase the power supply when the remaining fuel amount is large, and performs control to reduce the power supply when the remaining fuel amount is small.

(Flowchart explanation)
Specifically, the control unit 33 performs control based on the control flowchart shown in Fig. 14. As shown in Fig. 14, when the command DUTY value of either of the opposing motors 22 is equal to or greater than the threshold value THB (step S205: YES), it is determined whether or not the remaining fuel amount is equal to or greater than a predetermined amount PAM (step S206). Note that the "remaining fuel amount" refers to the amount of fuel remaining in the fuel tank 32.

If the remaining fuel amount is equal to or greater than the predetermined amount PAM (step S206: YES), the engine output is set to the emergency output EOH (step S207), and the power supplied to the motor 22 whose command DUTY value is equal to or greater than the threshold value THB is increased (step S208). Note that the predetermined amount PAM is, for example, an amount equivalent to 20% when the amount of fuel in the fuel tank 32 is 100% when it is full. The predetermined amount PAM is also an example of the "predetermined remaining amount of fuel" in this disclosure.

Then, the power supplied to the motor 22 is increased until the command DUTY value of the motor 22 to which the supply power has been increased becomes less than the threshold value THB (step S209: NO, S208). When the command DUTY value of the motor 22 to which the supply power has been increased becomes less than the threshold value THB (step S209: YES), the engine output is switched from the emergency output EOH to the rated output RO (step S204).

On the other hand, if the remaining fuel amount is less than the predetermined amount PAM (step S206: NO), it is determined whether the command DUTY value of one of the opposing motors 22 is equal to or less than the threshold value THC (step S210).

If the command DUTY value of either of the opposing motors 22 is equal to or less than the threshold THC (step S210: YES), the battery output is stopped (step S211), the engine output is set to the emergency output EOL (step S212), and the power supply to the motor 22 whose command DUTY value is equal to or less than the threshold THC is reduced (step S213).

Then, the control unit 33 reduces the power supplied to the motor 22 whose command duty value is equal to or less than the threshold value THC until the command duty value of the motor 22 to which the supply power has been reduced becomes greater than the threshold value THC (steps S214: NO, S213).

After that, when the command DUTY value of the motor 22 with the reduced supply power becomes greater than the threshold value THC (step S214: YES), the control unit 33 resumes battery output (step S215) and switches the engine output from the emergency output EOL to the rated output RO (step S204).

(Effects of this embodiment)
As described above, according to this embodiment, the control unit 33 performs supply power increase control when the remaining amount of fuel in the fuel tank 32 is equal to or greater than the predetermined amount PAM, and performs supply power reduction control when the remaining amount of fuel in the fuel tank 32 is less than the predetermined amount PAM.

In this way, when there is a large amount of fuel remaining in the fuel tank 32, the engine output is increased from normal to increase the power supplied to the motor 22. This makes it possible to prevent the fuel in the fuel tank 32 from running out, even if the amount of fuel consumed in the fuel tank 32 increases by increasing the engine output. Also, when there is a small amount of fuel remaining in the fuel tank 32, the engine output is reduced from normal to reduce the power supplied to the motor 22. This makes it possible to reduce the amount of fuel consumed in the fuel tank 32 and prevent the fuel in the fuel tank 32 from running out.

Fourth Embodiment
Next, a fourth embodiment will be described. Explanations of the same contents as those of the first to third embodiments will be omitted, and differences will be mainly described.

In this embodiment, when the attitude of the multicopter 1 cannot be maintained well (i.e., the tilt angle of the multicopter 1 deviates from the target angle during hovering), control is performed to return the attitude of the multicopter 1 to a good attitude (i.e., return the tilt angle of the multicopter 1 to the target angle during hovering). In detail, in this embodiment, although supply power increase control is performed as the supply power control when there is a risk of the multicopter 1 tilting during hovering in the first and third embodiments (see Figures 5 and 14), supply power reduction control is performed as the supply power control when the multicopter 1 tilts.

(Flowchart explanation)
Specifically, the control unit 33 performs control based on the control flowchart shown in Fig. 15. As shown in Fig. 15, the control unit 33 acquires the tilt angle of the multicopter 1 from the gyro sensor 61 (see Fig. 2), which is an angle sensor (step S301), and determines whether the tilt angle of the multicopter 1 is equal to or greater than a predetermined angle (step S302).

If the tilt angle of the multicopter 1 is equal to or greater than the predetermined angle (step S302: YES), the control unit 33 identifies a tall motor 22 based on information from the gyro sensor 61 (step S303), stops the battery output, sets the engine output to the emergency output EOL (step S304), and reduces the power supply to the identified motor 22 (step S305). Note that a tall motor 22 is a motor 22 that is located higher than the other motors 22, for example, a motor 22 that is located higher than the lowest motor 22 by a predetermined value or more.

In this way, the control unit 33 performs supply power reduction control when the multicopter 1 tilts during hovering (i.e., when the tilt angle of the multicopter 1 deviates from the target angle during hovering (e.g., 0°)).

Next, the control unit 33 determines whether the tilt angle of the multicopter 1 is less than the predetermined angle (step S306). If the tilt angle of the multicopter 1 is less than the predetermined angle (step S306: YES), the control unit 33 sets the engine output to the rated output RO (step S307). On the other hand, if the tilt angle of the multicopter 1 is equal to or greater than the predetermined angle (step S306: NO), the control unit 33 performs the process of step S303 again.

If the tilt angle is less than the predetermined angle in step S302 (step S302: NO), the control unit 33 sets the engine output to the rated output RO (step S307).

(Effects of this embodiment)
As described above, according to this embodiment, when the multicopter 1 tilts during hovering, supply power reduction control is performed to reduce the power supplied to a specific motor 22 (i.e., the motor 22 that is taller) as supply power control.

This allows the lift of the propeller 21 attached to a particular motor 22 to be controlled to a desired magnitude, and the attitude of the multicopter 1 to be returned to a good attitude (i.e., a hovering attitude). Therefore, even if the attitude of the multicopter 1 cannot be maintained good even after performing the control of the first to third embodiments, the attitude of the multicopter 1 can be returned to a good attitude by performing the control of this embodiment. Note that the control unit 33 may perform the control of this embodiment without performing the control of the first to third embodiments.

In this embodiment, when the control unit 33 performs supply power increase control as the supply power control when there is a risk that the multicopter 1 will tilt during hovering, if the multicopter 1 tilts, it performs supply power decrease control as the supply power control.

In this way, when the multicopter 1 tilts during hovering, a different power supply control is performed than the power supply control performed when there is a risk of the multicopter 1 tilting during hovering. This allows for attitude control that is more suited to the situation, and more reliably returns the attitude of the multicopter 1 to a good attitude.

(Another example of this embodiment)
In this embodiment, the power supply to the identified tall motor 22 is reduced, but the power supply to the adjacent motors 22 in addition to the identified motor 22 may also be reduced.

Fifth Embodiment
Next, the fifth embodiment will be described. Explanation of the same contents as those of the first to fourth embodiments will be omitted, and the differences will be mainly described.

In this embodiment, similar to the fourth embodiment, when the attitude of the multicopter 1 cannot be maintained in a good state, control is performed to return the attitude of the multicopter 1 to a good attitude. In detail, in this embodiment, although supply power reduction control is performed as the supply power control when there is a risk of the multicopter 1 tilting during hovering in the second and third embodiments (see Figures 11 and 14), when the multicopter 1 tilts, supply power increase control is performed as the supply power control.

(Flowchart explanation)
Specifically, the control unit 33 performs control based on the control flowchart shown in Fig. 16. As shown in Fig. 16, the difference from the fourth embodiment is that when the tilt angle of the multicopter 1 is equal to or greater than a predetermined angle (step S402: YES), the control unit 33 identifies a motor 22 with a low height based on information from the gyro sensor 61 (step S403), sets the engine output to the emergency output EOH (step S404), and increases the power supply to the identified motor 22 (step S405). The low motor 22 is a motor 22 that is located lower than the other motors 22, for example, a motor 22 that is located lower than the motor 22 located at the highest position by a predetermined value or more.

In this way, the control unit 33 controls the supply of increased power when the multicopter 1 tilts during hovering.

(Effects of this embodiment)
As described above, according to this embodiment, when the multicopter 1 tilts during hovering, supply power increase control is performed to increase the power supplied to a specific motor 22 (i.e., the motor 22 with a low height) as supply power control.

This allows the lift of the propeller 21 attached to a particular motor 22 to be controlled to a desired magnitude, and the attitude of the multicopter 1 to be returned to a good attitude (i.e., a hovering attitude). Therefore, even if the attitude of the multicopter 1 cannot be maintained good even after performing the control of the first to third embodiments, the attitude of the multicopter 1 can be returned to a good attitude by performing this embodiment. Note that the control unit 33 may perform the control of this embodiment without performing the control of the first to third embodiments.

In this embodiment, when the control unit 33 performs supply power reduction control as the supply power control when there is a risk that the multicopter 1 will tilt during hovering, if the multicopter 1 tilts, it performs supply power increase control as the supply power control.

In this way, when the multicopter 1 tilts during hovering, a different power supply control is performed than the power supply control performed when there is a risk of the multicopter 1 tilting during hovering. This allows for attitude control that is more suited to the situation, and more reliably returns the attitude of the multicopter 1 to a good attitude.

(Another example of this embodiment)
In this embodiment, the power supply to the identified motor 22 at the lower height is increased, but the power supply to the adjacent motors 22 in addition to the identified motor 22 may be increased.

The control unit 33 may perform control of both the fourth and fifth embodiments.

The above-described embodiments are merely examples and do not limit the present disclosure in any way. Needless to say, various improvements and modifications are possible without departing from the spirit of the present disclosure.

For example, the altitude of the multicopter 1 (hereinafter simply referred to as "altitude") may be included in the criteria for determining whether to use the supply power increase control or the supply power reduction control. Specifically, the control unit 33 may perform the supply power increase control when the altitude is less than a predetermined altitude, and perform the supply power reduction control when the altitude is equal to or greater than the predetermined altitude. Generally, the higher the altitude, the greater the disturbances such as wind. Therefore, by performing the supply power reduction control, the altitude of the multicopter 1 can be lowered while maintaining balance, and the multicopter 1 can be safely returned to an environment with less influence of disturbances. On the other hand, if the balance of the multicopter 1 is significantly lost even though the altitude is less than the predetermined altitude, it is necessary to focus on stabilizing the attitude of the multicopter 1 by performing the supply power increase control, even if the altitude of the multicopter 1 becomes slightly higher.

In the above explanation, a case where the tilt angle of the multicopter 1 may deviate (or has deviated) from the target angle is given as an example of a case where the multicopter 1 may tilt (or has tilted) during hovering. However, another example can also be a case where the tilt angle of the multicopter 1 may deviate (or has deviated) from the target angle while the multicopter 1 is moving.

The multicopters disclosed herein can also be used in multicopters (hybrid drones) equipped with engines fueled by ethanol fuel, LP gas, natural gas, etc., or diesel engines.

Furthermore, the multicopters disclosed herein are not limited to those configured with a series hybrid system, but can also be applied to multicopters configured with other hybrid systems and drones that operate with engine power.

The multicopter disclosed herein can also be applied to a multicopter (hybrid drone) equipped with a fuel cell system. In this case, the fuel cell system has a fuel cell that generates electricity using fuel and an oxidizer, a fuel supply unit (such as a fuel injection valve (injector)) that drives to supply fuel to the fuel cell, and a charge/discharge unit that charges and discharges the electricity generated by the fuel cell. The fuel cell corresponds to the "power generation unit," the fuel supply unit corresponds to the "drive unit," and the charge/discharge unit corresponds to the "battery."

The multicopter disclosed herein can also be applied to a multicopters that does not have a drive unit such as an engine. In this case, the power generation unit can be, for example, a solar power generation unit or a wind power generation unit.

1 Multicopter 11 Airframe 12 Engine generator unit 21 Propeller (rotor)
22 Motor 31 Battery 32 Fuel tank 33 Control unit 41 Engine 42 Generator
61 Gyro sensor CA (multicopter) central axis THA Threshold THB Threshold THC Threshold RO Rated output EOH Emergency output EOL Emergency output PAM Predetermined amount

Claims (2)

A plurality of rotors are provided;
a plurality of motors for driving the rotors;
A power generation unit that generates power to be supplied to the motor;
A battery that charges the power generated by the power generation unit and supplies the charged power to the motor.
A control unit that controls the attitude of the multicopter,
The duty value of the voltage instructed to be applied to the motor is defined as an instructed DUTY value,
The control unit is
During normal operation, power is supplied from the battery and the power generation unit to the motor to control the attitude of the multicopter,
When the difference between the command DUTY values of the motors facing each other around the central axis of the multicopter is equal to or greater than a predetermined threshold value,
Determining the command DUTY value of the opposing motor,
When the command DUTY value of either of the opposing motors is equal to or greater than a predetermined upper threshold, a supply power increase control is performed for the motor whose command DUTY value is equal to or greater than the predetermined upper threshold or for all of the motors, in which the output of the power generating unit is increased to a level higher than the normal state to increase the supply power;
when the command DUTY value of either of the opposing motors is equal to or less than a predetermined lower threshold value, performing a supply power reduction control for reducing the output of the power generation unit to a level lower than the normal state to reduce the supply power for the motor whose command DUTY value is equal to or less than the predetermined lower threshold value or for all of the motors;
A multicopter that features: The multicopter of claim 1,
The control unit is
adjusting the command DUTY value of the motor for which the supply power increase control has been performed, and controlling the rotation speed of the rotor provided in the motor for which the supply power increase control has been performed ;
or
adjusting the command DUTY value of the motor for which the supply power reduction control has been performed, to control the rotation speed of the rotor provided in the motor for which the supply power reduction control has been performed ;
A multicopter that features:

Images