JPWO2020022263A1 - Flying body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a flying body capable of reducing vibration of the fuselage by devising a disposition position of a fuselage equipped with a control unit required as a flying body. SOLUTION: A plurality of propeller drive motors 102-1a to 102-4b that individually rotationally drive a plurality of propellers 101-1a to 101-4b, and a plurality of support arms 10 and 11 that support the plurality of propeller drive motors. And a frame formed by combining 12, 20, 21 and 22. The plurality of support arms support the propeller drive motor at their tip portions, and have an upper support arm and a lower support arm. Inside a space surrounded by a plurality of propellers, a three-dimensional space is defined by an upper support arm and a lower support arm, and a body 50 having a control unit is attached to the three-dimensional space. [Selection diagram] Figure 1

Description

The present invention relates to an aircraft represented by what is generally called a drone.

Aircraft with multiple propellers called drones, especially unmanned air vehicles, are being applied in the industrial field. Agricultural drones, which spray chemicals such as pesticides and liquid fertilizers on fields, are one of the application fields. In the following description, a "drone" is an air vehicle.

Aircraft such as industrial drones, such as agricultural drones, are equipped with various sensors to perform various controls such as automatic driving control, attitude control, speed control, and flight height control to make the aircraft fly along a defined route. It is installed. An industrial drone is a large drone that has a propeller with a relatively large diameter so that it can generate thrust that can withstand the load of a load for loading a load such as a drug, as seen in, for example, an agricultural drone. Is used. A drone having a large-diameter propeller has a large vibration of the airframe caused by the rotation of the propeller.

When the airframe of the drone vibrates due to the rotation of the propeller, the sensor also vibrates together with the airframe, and the accuracy of the detection data of each sensor decreases, and the accuracy of the various controls decreases.

As one of the sensors, there is a GPS sensor for detecting the position of the drone itself. In industrial drones, in order to detect the position with higher accuracy, a GPS sensor such as an RTK antenna and an RTK-GPS (Real Time Kinematic-Global Positioning System) module is often configured. Since the RTK-GPS uses radio waves in a short wavelength band in order to improve the resolution, when the RTK antenna vibrates together with the body, the position detection accuracy significantly deteriorates. RTK-GPS is one of high precision position detectors. In this specification, the RTK-GPS is used as an example of the high-accuracy position detector.

A 6-axis gyro sensor is used for attitude control and flight direction control of the drone. A 6-axis gyro sensor is used to measure the drone's acceleration in three mutually orthogonal directions, and further to calculate the velocity by integrating the acceleration. The 6-axis gyro sensor is also used for measuring the angular velocity centered on the 3 axes. When the 6-axis gyro sensor vibrates together with the airframe, the accuracy of measurement of acceleration and angular velocity decreases, and the accuracy of attitude control and flight direction control also decreases.

Some drones have a devised airframe structure so that the airframe does not easily vibrate (see, for example, Patent Document 1). Further, in a drone equipped with a measuring device such as a surveying device, the structure of the device is devised so that the vibration of the device does not affect the measuring device (for example, see Patent Document 2).

The invention described in Patent Document 1 includes a roof frame that covers the drone from above, a wall frame that is connected to the roof frame and laterally surrounds the entire drone, and a wall frame that is close to the tip end of the arm protruding in the radial direction of the airframe. It is equipped with a plurality of cross beams that are connected to each other in the form of a bridge. It is said that each of these members is made of a fiber reinforced plastic pipe material, so that a lightweight and strong drone flight safety frame can be obtained.

The invention described in Patent Document 2 has a pair of support frames that support a laser scanner of a surveying unit as a measuring device, and a pair of connection frames that connect the pair of support frames to each other and are detachably attached to the machine body. .. A first plate made of fiber reinforced resin is interposed between the laser scanner and the support frame, and a second plate made of fiber reinforced resin having a rigidity different from that of the first plate is provided between the support frame and the connection frame. Intervenes. With such a configuration, it is said that it is possible to reduce the vibration from the airframe in flight toward the measuring device.

Japanese Patent No. 6245566 JP, 2017-193251, A

Patent Document 1 describes that a high-strength frame can be obtained by devising a drone frame structure. However, the frame structure described in Patent Document 1 is complicated, and in industrial applications such as agricultural drones, ease of use such as ease of loading luggage is not considered.

A drone constitutes a system consisting of a propeller, its drive motor, its drive power supply, various sensors for flight control, and a control unit. However, the invention described in Patent Document 1 does not have the idea of stabilizing the posture by devising the layout of the system.

Patent Document 2 describes that it is possible to reduce vibration of the airframe during flight toward the measuring device mounted on the drone. However, the invention described in Patent Document 2 does not have the idea of stabilizing the posture by devising the system layout.

It is an object of the present invention to obtain an air vehicle whose posture can be stabilized by devising a necessary system layout.

The present invention is
An aircraft comprising a plurality of propellers, a plurality of propeller drive motors for individually rotating and driving the plurality of propellers, and a frame including a plurality of support arms coupled to support the plurality of propeller drive motors. ,
It has a sensor for attitude control of the aircraft,
In the area surrounded by the plurality of propellers, there is a center of rotation of the fuselage during attitude control at a position farthest from each of the propeller drive motors,
The most main feature is that the sensor is arranged at the center of rotation.

An area inside the space surrounded by a plurality of propellers is an area that is not easily affected by the vibration generated by the rotation of the propellers, and a three-dimensional space defined by the upper and lower support arms that form the frame is formed in this area. .. A fuselage equipped with a control unit is attached to the three-dimensional space, and the fuselage is in a layout in which the fuselage is less likely to be affected by vibration generated by rotation of the propeller. Therefore, when various sensors are arranged in the body, the sensor is less likely to be affected by the vibration due to the rotation of the propeller, and the accuracy of the detection signal of the sensor can be improved.

It is a perspective view showing an example of a flying body concerning the invention in this application. It is a top view of the said Example. It is a front view of the said Example. It is a right view of the said Example. It is a bottom view of the said Example. It is a top view which shows the said Example in the state which removed the propeller. It is a front view which shows the said Example in the state which removed the propeller. It is a right view which shows the said Example in the state which removed the propeller. It is a perspective view which expands and shows the principal part of the said Example. It is a schematic diagram which shows roughly the example at the time of using the flying body which concerns on this invention for agriculture. It is a block diagram which shows the example of the control system of the flying body which concerns on this invention.

Hereinafter, an embodiment of an aircraft (hereinafter referred to as “drone”) according to the present invention will be described with reference to the drawings. The drawings are all examples, and the configuration of the aircraft according to the present invention is not limited to the configuration of the embodiment. In this specification, a drone refers to any flying body having a plurality of rotary wings or flight means regardless of the power system or the control system. Power systems include those using electric power and those using prime movers such as internal combustion engines. The control method includes a wireless or wired method, an autonomous flight type or a manual control type.

[Overall drone configuration]
1 to 5, the drone includes propellers 101-1a, 101-1b, 101-2a, 101-2b, 101-3a, 101-3b, 101-4a, 101-, which are also called rotors at four positions. 4b. These propellers are parts for flying a drone, and in consideration of the stability of flight, the size of the aircraft, and the balance of battery consumption, there are four sets of two-stage propellers, for a total of eight aircraft. .. The rotation centers of the four sets of propellers are located at the corners of the rectangle in plan view. The propeller 101-2a, 101-2b, 101-4a, 101-4b side is the front side in the traveling direction of the drone.

Each of the above propellers is a propeller drive motor (hereinafter sometimes simply referred to as "motor") 102-1a, 102-1b, 102-2a, 102-2b, 102-3a, 102-3b, 102-4a, 102-4b. Are individually driven to rotate. A pair of upper and lower propellers, such as 101-1a and 101-1b, have their axes collinear for the stability of the flight of the drone, etc. Is driven to rotate. The upper and lower propellers of each set are rotationally driven in opposite directions, so that the upper and lower propellers together generate a downward flow, and generate thrust for raising the drone. The upper and lower propellers of the other sets are similarly constructed and similarly generate thrust.

The illustrated embodiment is an agricultural drone, which is provided with four drug nozzles 103-1, 103-2, 103-3, 103-4 for spraying drugs downward. As used herein, drug generally refers to liquids or powders applied to the field, such as pesticides, herbicides, liquid fertilizers, pesticides, seeds and water.

The drone has a drug tank 104 for containing the drug to be sprayed. The medicine tank 104 is provided at a position close to the center of gravity of the drone and lower than the center of gravity from the viewpoint of weight balance. A pump 106 is attached to the lower side of the medicine tank 104, and the pump 106 is connected to a medicine hose 105. The drug hose 105 extends linearly in the lower part of the front side in the traveling direction of the drone and over substantially the entire width direction of the drone. In the medicine hose 105, four medicine nozzles 103-1, 103-2, 103-3, 103-4 are arranged at regular intervals in the length direction. When the pump 106 operates, the medicine in the medicine tank 104 is discharged from each medicine nozzle and is sprayed on the field.

[Frame configuration]
Next, the frame structure of the drone according to the present embodiment and the structure of the body 50 will be described in detail with reference to FIGS. 6 to 9 as well. In the present specification, the “fuselage” is a part on which a control component for controlling the operation of the drone, a battery serving as a driving power source, sensors, and the like are mounted, and corresponds to a fuselage of a helicopter or an airplane. The entire drone, including the fuselage, frame, propeller, and propeller drive motor, is referred to herein as the "body." The drone has a frame serving as its skeleton, and the frame is composed of a plurality of support arms that are integrally coupled to each other and that support the plurality of propeller drive motors. The frames composed of a plurality of support arms form a pair in the upper and lower sides, and the upper and lower frames are integrally coupled at a predetermined interval.

The plurality of support arms that form the upper frame include one first support arm 10 that supports the propeller drive motor at both ends, and two second support arms 11 and 12 that extend from the first support arm 10. To have. The second support arms 11 and 12 extend obliquely symmetrically from the middle of the first support arm 10 in the lengthwise direction, and the tip ends, that is, the ends located on the rear side of the drone extend in a direction in which they spread out from each other.

The second support arms 11 and 12 are joined by a reinforcing beam 13 in the middle of the length direction. The reinforcing beam 13 is parallel to the first supporting arm 10, and is formed in a trapezoidal shape in plan view by the first supporting arm 10, the second supporting arms 11 and 12, and the reinforcing beam 13, and is close to a so-called truss structure. It is structured. Since the frame has a structure close to the truss structure, the mechanical strength of the frame can be increased while the structure is relatively simple. The first support arm 10, the second support arms 11 and 12, and the reinforcing beam 13 are coupled to each other via an appropriate coupling member so as to be located in the same plane.

Motors 102-2a and 102-4a are supported at both ends of the first support arm 10, respectively. Propellers 101-2a and 101-4a are attached to the rotary output shafts of the motors 102-2a and 102-4a, respectively, and the propellers are individually rotatably driven by the motors. Motors 102-1a and 102-3a, which are different from the above motors, are supported by the respective tip portions of the second support arms 11 and 12. Propellers 101-1a and 101-3a are attached to rotation output shafts of the motors 102-1a and 103-3a, respectively, and the propellers are individually rotatably driven by the motors.

The lower frame has almost the same structure as the upper frame. The lower frame has one first support arm 20 for supporting the propeller drive motors 102-2b, 102-4b at both ends, and two second support arms 21, 22 extending from the first support arm 20. And. The second support arms 21 and 22 extend obliquely symmetrically from the middle of the length direction of the first support arm 20, and in the directions in which the tip ends, that is, the ends located on the rear side of the drone, expand. The first supporting arm 20 and the second supporting arms 21 and 22 are coupled to each other via an appropriate coupling member so as to be located in the same plane. The propeller drive motors 102-1b and 102-3b are supported at the respective tip portions of the second support arms 21 and 22.

The upper and lower frames are joined under the interposition of an appropriate number of columns so as to be parallel to each other. The upper and lower paired second support arms 11 and 21 and the other paired second support arms 12 and 22 are coupled by columns 30 and 30 at intermediate portions in the longitudinal direction. In addition, the pair of upper and lower first support arms 10 and 20 are respectively provided with pillars 31 in the vicinity of the connecting portion with the upper second supporting arms 11 and 21 and in the vicinity of the connecting portion with the lower second supporting arms 12 and 22. , 31 are connected. The respective support arms and the respective columns are joined by interposing an appropriate joining member.

The pair of pillars 30 and 30 are coupled to each other via a reinforcing beam 23 at a position lower in the vertical direction. The reinforcing beam 23 is also a reinforcing beam for the lower frame composed of the first supporting arm 20 and the second supporting arms 21, 22 and also functions as a reinforcing beam for the entire upper and lower frames. The reinforcing beam 13 is parallel to the first supporting arm 10, and is formed in a trapezoidal shape in plan view by the first supporting arm 10, the second supporting arms 11 and 12, and the reinforcing beam 13, and is close to a so-called truss structure. It is structured.

The first supporting arms 10 and 20, the second supporting arms 11, 12, 21 and 22, the reinforcing beams 13 and 23, and the columns 30 and 31 connecting the upper and lower frames, which form the upper and lower frames, are pipe-shaped members. is there. Further, the above-mentioned members constituting the frame, at least the materials of the first support arm, the second support arm and the reinforcing beam are made of a heat conductive material such as an aluminum alloy or a carbon fiber composite material. Examples of the carbon fiber composite material include carbon fiber reinforced plastic (CFRP) and carbon fiber reinforced carbon composite material. Since the material of the member forming the frame is made of an aluminum alloy or a carbon fiber composite material and is a pipe-shaped member, it is possible to reduce the weight of the frame while giving the frame necessary strength. Further, as will be described later in detail, the heat dissipation effect can be enhanced.

[Propeller guard]
The propellers 101-1a and 101-1b supported by the tip ends of the pair of upper and lower second support arms 11 and 21 are surrounded by the propeller guard 41 and rotate within the propeller guard 41. The propeller guard 41 includes a pair of upper and lower annular frames, a columnar intervening member that connects these frames in parallel at regular intervals, a hub at the center of the upper and lower frames, and upper and lower frames. A plurality of spokes connecting with the hub. The upper and lower hubs are connected to the tips of the second support arms 11 and 21 with their centers aligned with the rotation centers of the propellers 101-1a and 101-1b.

The propellers 101-2a and 101-2b supported at the right end portions of the pair of upper and lower first support arms 10 and 20 when viewed from the front are surrounded by the propeller guard 42 and rotate in the propeller guard 42.

The propellers 101-3a and 101-3b supported by the tip ends of the pair of upper and lower second support arms 12 and 22 are surrounded by the propeller guard 43 and rotate within the propeller guard 43.

The propellers 101-4a and 101-4b supported by the left end portions of the pair of upper and lower first support arms 10 and 20 when viewed from the front are surrounded by the propeller guard 44 and rotate within the propeller guard 44.

Each of the propeller guards 42, 43, 44 is configured similarly to the propeller guard 41. That is, each of the propeller guards 42, 43, and 44 includes a pair of upper and lower annular frames, a plurality of columnar intervening members that connect these frames in parallel, a hub at the center of the upper and lower frames, and a top and bottom respectively. And a plurality of spokes that connect the frame and the hub. The upper and lower hubs of the propeller guard 42 are connected to the right end portions of the first support arms 10 and 20 when viewed from the front. The upper and lower hubs of the propeller guard 43 are connected to the tips of the second support arms 12 and 22. The upper and lower hubs of the propeller guard 44 are joined to the left end portions of the first support arms 10 and 20 when viewed from the front.

The spacing between the propellers 101-1a and 101-1b located on the right rear of the drone and the propellers 101-2a and 101-2b located on the front right is narrow, and the annular frames that form these propeller guards 41 and 42 are Are in contact. The space between the propellers 101-3a and 101-3b located on the left rear of the drone and the propellers 101-4a and 101-4b located on the left front is also narrow, and the annular frames that form these propeller guards 43 and 44 are Are in contact.

The material of the frame, the hub and the spokes forming each propeller guard 41, 42, 43, 44 is preferably a heat conductive material. At least the spokes arranged in a grid pattern on the upper and lower surfaces of the propeller guards 41, 42, 43, 44 are preferably made of a heat conductive material.

The spacing between propellers located on the left and right is wider than the spacing between propellers located before and after the drone. That is, the intervals between the propellers 101-4a, 101-4b and the propellers 101-2a, 101-2b located on the left and right of the drone and the intervals between the propellers 101-3a, 101-3b and the propellers 101-1a, 101-1b are It is getting wider. These propeller guards 44 and 42 and 43, 41 are separated from each other.

[body]
In plan view, the line connecting the rotation centers of the four sets of propellers 101-1a, 101-1b, 101-2a, 101-2b, 101-3a, 101-3b and 101-4a, 101-4b is horizontally long. It has a rectangular shape. There is a space between the left and right propeller guards 43 and 44 arranged side by side and the right side propeller guards 41 and 42 arranged front and rear. That is, the space is a space surrounded by the plurality of propellers 101-1a to 101-4b. Inside the space, a three-dimensional space is defined by the upper support arms 10, 11, 12 and the lower support arms 20, 21, 22.

The upper frame having the upper support arms 10, 11, 12 and the lower frame having the lower support arms 20, 21, 22 are trapezoidal in plan view as described above. There is. Therefore, the three-dimensional space is a trapezoidal three-dimensional space formed by a pair of upper and lower frames that are integrally coupled with each other at a predetermined interval. This three-dimensional space is a vibration damping area which is separated from the rotation area of each propeller and in which vibration due to rotation of each propeller is difficult to be transmitted. In the trapezoidal three-dimensional space which is a vibration damping area, a body 50 having a power battery, a control unit, a motor drive circuit, a flight control sensor, and the like is arranged.

The body 50 has a flat dish-shaped bottom plate 51 and a cover 52 placed on the bottom plate 51. The bottom plate 51 and the cover 52 are made of a heat conductor such as an aluminum alloy or a carbon fiber composite material. An internal space surrounded by the bottom plate 51 and the cover 52 serves as a component mounting portion for incorporating built-in components such as a power battery, a motor drive circuit, a control circuit, and a flight control sensor. The body 50 is long in the front-rear direction and has a semicircular plan shape at the front end in the traveling direction.

The body 50 is arranged in a space formed between the left and right propellers and the left and right propeller guards 41, 42 and 43, 44, and between the upper and lower reinforcing beams 13, 23. The bottom plate 51 of the body 50 has a bottom surface connected to the lower reinforcing beam 23 via a connecting member. The coupling member is a plate-shaped member made of a material having good heat conductivity, and holds the reinforcing beam 23 for almost half the circumference, and is fastened in a state where both side edges are in surface contact with the bottom surface of the bottom plate 51.

The cover 52 forming the body 50 is joined to the upper reinforcing beam 13 via a joining member 59. The coupling member 59 is also a plate-shaped member made of a material having good heat conductivity, and is wound around the reinforcing beam 13 over approximately half the circumference, and is fastened in a state where both side edges are in surface contact with the upper surface of the cover 52.

FIG. 9 shows an outline of component arrangement in the component mounting portion in the body 50. About half the space 56 on the rear side (obliquely lower right side in FIG. 9) in the body 50 is close to the upper and lower reinforcing beams 13 and 23, and has a high cooling effect. The space 56 is vertically divided into layers, and a battery mounting space 153 is provided in the upper layer portion. The battery mounting space 153 is provided with a battery receiving member 152 and two battery fasteners 154 so that two secondary batteries, that is, rechargeable batteries 55 can be arranged in parallel.

Two batteries 55 are loaded in the battery mounting space 153 during operation of the aircraft. One battery is the main battery and is used during normal operation, the other battery is the spare battery. If the storage capacity of the main battery becomes low while using the main battery, or if there is a problem with the main battery, the spare battery is switched to continue flight, and evacuation behavior described later. To take In this way, by installing two batteries 55, the power supply system has so-called redundancy, and when a power supply trouble occurs, appropriate processing is performed to prevent the development of a fatal trouble. To do.

FIG. 9 shows a state where only one battery 55 is loaded. The battery 55 is also one of the heat-generating components, and the battery 55 is loaded in the space 56 having a high cooling effect so as to suppress the temperature rise of the battery 55.

The battery 55 itself is a component having high mechanical strength and rigidity, and the battery 55 is firmly tightened and mounted by the battery fastener 154 so as to function as a reinforcing component that enhances the strength and rigidity of the body 50. Further, since the battery 55 is a heavy component and has a vibration damping property, the battery 55 is mounted on the body 50 so that the battery 55 functions as a vibration damping component.

In order to cause the battery 55 to function as a reinforcing component and a vibration damping component of the body 50, the mechanical strength and rigidity of the components constituting the battery receiving member 152, the battery fastener 154 and the battery mounting space 153 are also enhanced. Therefore, not only the battery 55, but also the components of the battery receiving member 152, the battery fastener 154, and the battery mounting space 153 function as a reinforcing component and a vibration damping component of the body 50.

The body 50 is attached to the above-described vibration damping area, and is originally arranged at a position where it is hardly affected by the vibration due to the rotation of each propeller. In addition to this, by making the components of the battery receiving member 152, the battery fastener 154, and the battery mounting space 153 function as the vibration damping parts of the body 50, the vibration damping effect of the body 50 can be further enhanced.

About half of the rear side of the cover 52 is a lid that can be opened and closed so that the battery 55 can be attached to and detached from the battery mounting space 153. The reinforcing beam 13 of the upper frame is provided at a position offset from the reinforcing beam 23 of the lower frame so as to open and close the lid.

In the space 56, a mounting substrate for a heat-generating component is disposed in a layer below the battery mounting space 153 so as to make surface contact with the bottom plate 51. A rotation speed control component (ESC: Electronic Speed Control) of the motor and a step-down electric machine are mounted on the mounting board. The step-down voltage electric machine steps down the DC power supplied from the battery 55 to a voltage suitable for the drive voltage of the motor or the drive voltage of the control circuit and distributes the voltage. The ESC and the step-down electric machine generate high heat.

An appropriate number of circuit boards 58 are arranged on the bottom plate 51 of the body 50 in front of the space 56. On these circuit boards 58, a drone control unit including a control circuit such as a flight controller, a processing circuit for signals from various sensors, and a communication circuit is mounted.

A 6-axis gyro sensor, which is a means for measuring the acceleration of the drone and further calculating the speed by integrating the acceleration, is arranged on the back surface, that is, the lower surface side of the battery receiving member 152 constituting the battery mounting space 153. The 6-axis gyro sensor has an acceleration sensor that detects accelerations in three mutually orthogonal axis directions, and an angular velocity sensor that detects rotations about the three axes, for example, angular velocity of pitching, rolling, and yawing. ing.

The 6-axis gyro sensor detects the attitude of the drone body and controls the attitude of the drone body by this detection signal, and is one of flight control sensors.

The fuselage 50 is arranged in the vibration damping area as described above, and the battery receiving member 152, the battery fastener 154 and the like function as vibration damping components, so that the fuselage 50 is less susceptible to the vibration due to the rotation of the propeller. It has become. Therefore, the flight control sensor such as the 6-axis gyro sensor arranged on the body 50 is not easily affected by the vibration due to the rotation of the propeller, and the detection accuracy of the sensor can be kept high. Since the detection accuracy of the sensor is high, the accuracy of flight control can be kept high.

The position of the center of gravity of the drone when the two batteries 55 are loaded in the battery mounting space 153 is between the two batteries 55 when viewed from the plane direction, that is, when the drone is viewed from above. Further, the center of gravity of the drone in the vertical direction is relatively lower by mounting the heavy battery 55. On the other hand, as shown in FIG. 2, the rotation center P of the drone attitude control by the rotation control of the four sets of motors is seen in the plane direction, as shown in FIG. As shown in FIG. 3, it is at the center position of the separation distance between the upper and lower motors.

The horizontal line of the lift force generated by the rotation of the four motors, that is, the horizontal line including the rotation center P of the attitude control is above the center of gravity of the drone or at the same height as the center of gravity. In other words, by disposing the battery 55 which is a fixed heavy object, the center of gravity of the drone is located below the rotation center P or at the same height as the rotation center P.

By setting the positional relationship between the center of gravity of the drone and the horizontal line of lift generation as described above, it is possible to stabilize the attitude of the drone and save energy required for attitude control.

Below the body 50, a medicine tank 104 is arranged with a space 70 between the lower surface of the body 50 and the body 50. The drug tank 104 contains the drug to be sprayed, and since the drug is sprayed while flying over the field, the drug tank 104 is a variable weight object. The drug tank 104, which is a variable heavy object, is arranged further below the center of gravity of the drone, and is designed so that the influence of the fluctuation of the weight on the attitude control of the drone is reduced.

[GPS sensor]
GPS sensors 60, 60 are attached upward to the two second support arms 11, 12 that form the upper frame. The GPS sensors 60, 60 are composed of, for example, a high precision position detector antenna and a high precision position detector module. The GPS sensors 60, 60 measure the absolute position of the drone, determine whether the measured position is, for example, a position according to a program, and if the position is deviated, rotate the drive motors so that the drive motors are in correct positions. To control.

The GPS sensors 60, 60 including a high-accuracy position detector module that detects the position of the aircraft with high accuracy are one of the flight control sensors along with the 6-axis gyro sensor for attitude control.

When the GPS sensors 60, 60 vibrate, the accuracy of the drone's absolute position measurement deteriorates, and the position control accuracy also deteriorates. Therefore, in the illustrated embodiment, the GPS sensors 60, 60 are separated from the drive motors, which are vibration sources, by the vibrations of the drive motors. , 12 are installed at approximately the center in the length direction.

The installation positions of the GPS sensors 60, 60 are between the front and rear propeller guards 41, 42 and between the propeller guards 43, 44, respectively, when viewed from the plane direction. Further, the GPS sensors 60, 60 are near the columns 30, 30 that connect the upper and lower frames, and are in positions where the second support arms 11, 12 are less likely to vibrate. Therefore, the GPS sensors 60, 60 are hardly affected by the vibrations of the drive motors, and the position of the drone can be measured with high accuracy.

[Cooling effect of frame]
According to the configurations of the flying body and its frame described above, the following cooling effects can be obtained.

On the body 50, components including heat generation components such as a motor rotation control component and a distribution electric machine are mounted. The bottom plate 51 and the cover 52 that form the body 50 are made of a heat conductive material, and the heat generated from the heat generating component is transferred to the body 50 and dissipated. Therefore, the body 50 is a main part that dissipates the heat generated in the heat-generating component.

Further, the bottom plate 51 of the body 50 is connected to the reinforcing beam 23 of the lower frame made of a heat conductive material, and the reinforcing beam 23 is further connected to the second supporting arms 21 and 22. The cover 52 of the body 50 is also connected to the reinforcing beam 13 of the upper frame made of a heat conductive material, and the reinforcing beam 13 is connected to the second support arms 11 and 12. In this way, the heat generated in the built-in components is easily transferred from the body 50 to the frame, and even if the heat dissipation by the body 50 is insufficient, the frame has a structure that compensates for the heat dissipation.

The body 50 is surrounded by a pair of front and rear propellers located on the left and right sides thereof. When each propeller is rotationally driven, a downward flow of air is generated along the left and right side surfaces of the body 50. The descending flow of air flows at a relatively high speed in a substantially triangular space viewed from a plane defined by the left and right side surfaces of the body 50 and the front and rear propeller guards. In the present embodiment, the propellers at four locations are respectively arranged in upper and lower two stages, and it is known that the downward flow is concentrated and a stronger downward flow is generated as compared with the propeller having the single stage structure.

As described above, in the present embodiment, both side surfaces of the body 50 and a part of the frame are located in the flow passage of the descending flow that is concentrated and is generated at a high speed by the two-stage propeller. More specifically, a downward flow flows along both side surfaces of the body 50, both ends of the first support arms 10 and 20, almost the entire second support arms 11, 12, 21, and 22, the reinforcing beams 13 and 23. Both ends of the cross section of the downward flow. Therefore, the heat transmitted to the frame from the body 50 itself and the body 50 is effectively dissipated, and the temperature rise of the mounted components is suppressed.

[Example of drone use]
FIG. 10 schematically shows an overall conceptual diagram of a system using an example of a drug spraying application of the drone 100 according to the present invention. The pilot 401 can transmit a command to the drone 100 by the operation of the user 402, and can display information received from the drone 100, for example, information such as position, drug amount, remaining battery level, and camera image. .. The pilot 401 may be realized by a portable information device such as a general tablet terminal that runs a computer program.

Although the drone 100 according to the present embodiment is controlled so as to perform autonomous flight, it is desirable that manual operation can be performed during basic operations such as takeoff and return, and in an emergency. In addition to the portable information device, an emergency operating device having a function dedicated to emergency stop may be used. It is desirable that the emergency operation device be a dedicated device equipped with a large emergency stop button or the like so that it can quickly respond in an emergency. It is desirable that the pilot 401 and the drone 100 perform wireless communication by Wi-Fi or the like.

The farm field 403 is a rice field, a field, or the like targeted for drug spraying by the drone 100. Actually, the topography of the farm field 403 is complicated, and there are cases where the topographic map cannot be obtained in advance, or the topographic map and the situation at the site are inconsistent. Normally, the farm field 403 is adjacent to a house, a hospital, a school, another crop farm field, a road, a railroad, and the like. In addition, there may be obstacles such as buildings and electric wires in the field 403.

The base station 404 is a device that provides a master device function of Wi-Fi communication and the like, and it is preferable that the base station 404 also functions as a base station of a high-accuracy position detector and can provide an accurate position of the drone 100. The master device function of Wi-Fi communication and the base station of the high-accuracy position detector may be independent devices. The farm cloud 405 is typically a group of computers operated on a cloud service and related software, and is preferably wirelessly connected to the controller 401 by a mobile phone line or the like.

The farm cloud 405 may analyze the image of the field 403 captured by the drone 100, grasp the growing condition of the crop, and perform a process for determining a flight route. The farm cloud 405 can provide the drone 100 with the stored topographical information of the farm field 403, etc. In addition, the history of the flight and the captured video of the drone 100 may be accumulated and various analysis processes may be performed. ..

Usually, the drone 100 takes off from a departure/arrival point 406 outside the field 403 and returns to the departure/arrival point 406 after spraying a drug on the field 403 or when it becomes necessary to replenish or charge the drug. The flight route (also referred to as an intrusion route) from the landing point 406 to the target field 403 may be stored in advance in the farm cloud 405 or the like, or may be input by the user 402 before the start of takeoff. ..

[Drone control system]
FIG. 11 is a block diagram showing the control function of the embodiment of the drug spraying drone according to the present invention. The flight controller 501 is a component that controls the entire drone, and specifically may be an embedded computer including a CPU, a memory, related software, and the like. The flight controller 501 uses the control information such as ESC (Electronic Speed Control) to control the motors 102-1a and 102-1b based on the input information received from the controller 401 and the input information obtained from various sensors described below. , 102-2a, 102-2b, 102-3a, 102-3b, 102-4a, 102-4b are controlled to control the flight of the drone 100.

The actual number of revolutions of each motor is fed back to the flight controller 501, and it is possible to monitor whether or not the motor is rotating normally. The propeller may be provided with an optical sensor or the like, and the rotation speed of the propeller may be fed back to the flight controller 501.

The software used by the flight controller 501 is preferably rewritable through a storage medium or the like for function expansion/change, problem correction, or the like, or through communication means such as Wi-Fi communication or USB. It is desirable to protect with encryption, checksum, electronic signature, virus check software, etc. so that rewriting by unauthorized software is not performed.

Further, a part of the calculation process used by the flight controller 501 for control may be executed by another computer existing on the operation unit 401, the farm cloud 405, or another place. The flight controller 501 is a highly important part that forms the core of the drone, and it is desirable that some or all of its components be duplicated.

Battery 55 is the source of power to flight controller 501 and other components of the drone and is preferably rechargeable. The battery 55 is connected to the flight controller 501 via a power supply unit including a fuse or a circuit breaker. The battery 55 is preferably a smart battery having a function of transmitting the internal state, that is, the amount of stored electricity, the cumulative usage time, etc. to the flight controller 501 in addition to the power supply function.

The flight controller 501 communicates with the controller 401 via the Wi-Fi slave device function 503 and further via the base station 404, receives a necessary command from the controller 401, and outputs necessary information to the controller 401. Can be sent to. It is advisable to encrypt communications to prevent illegal acts such as interception, spoofing, and hijacking of devices.

The base station 404 preferably has an RTK-GPS base station function in addition to the Wi-Fi communication function. By combining the signal from the RTK base station and the signal from the GPS positioning satellite, the GPS module 504 can measure the absolute position of the drone 100 with an accuracy of about several centimeters. Since the GPS module 504 is highly important, it is desirable to duplicate/multiplex it. Further, in order to cope with a failure of a specific GPS satellite, it is desirable that each redundant GPS module 504 be controlled to use another satellite.

The 6-axis gyro sensor 505 is a means for measuring the acceleration of the drone aircraft in the directions of the 3 axes orthogonal to each other, a means for calculating the velocity by integrating the acceleration, and a means for detecting the angular velocity of rotation about the 3 axes. .. The geomagnetic sensor 506 is a means for measuring the direction of the drone body by measuring the geomagnetism. The atmospheric pressure sensor 507 is a means for measuring the atmospheric pressure, and can indirectly measure the altitude of the drone. The laser sensor 508 is a means for measuring the distance between the drone body and the ground surface by utilizing the reflection of laser light, and it is preferable to use an infrared (IR) laser. The sonar 509 is means for measuring the distance between the drone body and the ground surface by utilizing the reflection of sound waves such as ultrasonic waves.

These sensors may be selected depending on the drone's cost goals and performance requirements. Further, a gyro sensor (angular velocity sensor) for measuring the tilt of the machine body, a wind force sensor for measuring wind force, and the like may be added. Moreover, it is desirable that these sensors be duplicated or multiplexed. When there are a plurality of sensors for the same purpose, the flight controller 501 may use only one of them, and when it fails, the flight controller 501 may switch to another sensor for use. Alternatively, a plurality of sensors may be used simultaneously, and if the measurement results do not match, it may be considered that a failure has occurred.

The flow rate sensor 510 is a means for measuring the flow rate of the medicine, and is preferably provided at a plurality of places on the path from the medicine tank 104 to the medicine nozzle 103. The liquid shortage sensor 511 is a sensor that detects that the amount of the medicine has become equal to or less than a predetermined amount. The multi-spectral camera 512 is a means for photographing the field 403 and acquiring data for image analysis. The obstacle detection camera 513 is a camera for detecting a drone obstacle, and since the image characteristics and the orientation of the lens are different from those of the multispectral camera 512, they are attached separately from the multispectral camera 512.

The switch 514 is a means for the user 402 of the drone 100 to make various settings. The obstacle contact sensor 515 is a sensor for detecting that the drone 100, in particular, its rotor or propeller guard portion has come into contact with an obstacle such as an electric wire, a building, a human body, a tree, a bird, or another drone. The cover sensor 516 is a sensor that detects that the operation panel of the drone 100 and the cover for internal maintenance are open. The drug injection port sensor 517 is a sensor that detects that the injection port of the drug tank 104 is open.

These sensors may be duplicated/multiplexed. In addition, a sensor may be provided in an external base station 404, a control device 401, or another place so that the read information can be transmitted to the drone. For example, a wind sensor may be provided in the base station 404, and information regarding wind force/wind direction may be transmitted to the drone 100 via Wi-Fi communication.

The flight controller 501 transmits a control signal to the pump 106 to adjust the medicine ejection amount and stop the medicine ejection. It is desirable that the current status of the pump 106, such as the number of revolutions, be fed back to the flight controller 501.

The LED 107 is a display unit for informing the drone operator of the state of the drone. Instead of or in addition to the LEDs, display means such as a liquid crystal display may be used. The buzzer 518 is an output means for notifying a drone state, particularly an error state, by an audio signal. The Wi-Fi cordless handset function 519 is an optional component for communicating with an external computer or the like in addition to the controller 401, for example, for software transfer.

In addition to or in addition to the Wi-Fi cordless handset function, other wireless communication means such as infrared communication, Bluetooth (registered trademark), ZigBee (registered trademark), NFC, or wired communication means such as USB connection is used. May be used. The speaker 520 is an output means for notifying a drone state, particularly an error state, by using a recorded human voice, synthesized voice, or the like. Depending on the weather conditions, it may be difficult to see the visual display of the drone 100 in flight, and in such a case, it is effective to communicate the situation by voice. The warning light 521 is a display means such as a strobe light for notifying the drone state, particularly an error state. These input/output means may be selected according to the cost target and performance requirements of the drone, and may be duplicated/multiplexed.

[Relaxation sensor]
As shown in FIG. 11, a relaxation sensor 530 is mounted in addition to the various sensors described above, and a detection signal of the relaxation sensor 530 is input to the flight controller 501. The relaxation sensor 530 is a sensor that detects looseness or rattling of structural parts of a machine body mainly composed of a frame including the first support arms 10 and 20 and the second support arms 11, 12, 21, and 22. is there.

As the relaxation sensor 530, for example, a microphone can be used. There is a difference in the sound or noise emitted when the propeller is rotationally driven, between the normal state where the structural parts of the aircraft have no looseness or rattling and the case where looseness or rattling occurs. Occurs. The difference in sound or noise between the normal state and the abnormal state is mainly the difference in frequency or the abnormal noise generated only in the abnormal state. Therefore, a microphone for detecting the noise of the drone is attached to the drone, and the detection signal electroacoustically converted by the microphone is processed to detect the abnormality.

When the output signal of the microphone is filtered for each frequency band and an abnormality is found in a specific frequency band, it can be determined that the airframe is loose or rattling. Alternatively, in contrast to the detection signal at the normal time, even when an abnormal signal that does not appear at the normal time is detected, it can be determined that the body is loose or rattling. The method of determining looseness or rattling of the machine body by the output signal of the microphone is not limited to these methods, and other methods may be used.

When the body of the drone is loosened, the output signal of the accelerometer attached to the drone becomes abnormal. Therefore, an acceleration sensor may be used as the relaxation sensor 530. The acceleration sensor may be attached only for detecting the relaxation of the machine body, or the 6-axis gyro sensor 505 may also be used as the relaxation sensor 530. When the 6-axis gyro sensor 505 is also used as the relaxation sensor 530, not only the acceleration sensor of the 6-axis gyro sensor 505 but also the angular velocity sensor can be used as the relaxation sensor 530.

Although the mounting position of the relaxation sensor 530 is arbitrary, it is preferably a position where the looseness or rattling of the machine body can be effectively detected. In the aircraft body of the drone according to the above-described embodiment, the frames having the first and second support arms form an upper and lower pair, and the upper and lower frames are connected by the pillars. The upper and lower frames each have a reinforcing beam to form a trapezoidal three-dimensional space. The relaxation sensor 530 is arranged inside the trapezoidal three-dimensional space. More specifically, the body 50 is arranged in the trapezoidal three-dimensional space, and the relaxation sensor 530 is mounted in the body 50.

When the 6-axis gyro sensor 505 also serves as the relaxation sensor 530, the 6-axis gyro sensor 505 is arranged in the body 50 as described above. Inside the body 50, a component mounting portion for mounting components including vibration suppressing components such as the battery 55, the battery receiving member 152, and the battery fastener 154 is arranged. The component mounting portion has layers in the vertical direction, and the 6-axis sensor is arranged in a layer below the layer on which the vibration suppressing component is mounted. Therefore, when the 6-axis gyro sensor 505 also functions as the relaxation sensor, the relaxation sensor is mounted inside the body 50 and below the mounting portion of the vibration suppressing component.

[Evacuation behavior]
When looseness or rattling occurs in a structural part of a drone body having the frame, the body makes an abnormal noise. The abnormal sound may be a sound in a frequency band different from that in a normal state, or may be a sound generated suddenly or irregularly. The abnormal sound is detected by the relaxation sensor 530 (see FIG. 11) including the microphone and the acceleration sensor, and an abnormal signal is output. When an abnormality detection signal is input from the relaxation sensor 530, the flight controller 501 controls the rotation of each of the propeller drive motors 102-1a to 102-4b via the ESC to cause the drone to perform a retracting action.

The evacuation action is either an emergency return, an emergency landing, or an emergency stop, and the flight controller 501 causes any of the above evacuation actions according to the degree of abnormal noise, that is, the abnormality detection signal strength of the relaxation sensor 530. If the abnormal noise is relatively minor, an emergency return is performed. If the abnormal noise is moderate, an emergency landing is performed. If the abnormal noise is strong, stop the emergency. An emergency return is, for example, returning to the original position where the aircraft took off and landing. Emergency landing is landing on the spot. An emergency stop is to stop all propeller drive motors and crash on the spot. It is safer to crash the drone than to lose control.

As one of the evacuation behaviors, hovering may be performed once, and when the abnormality detection signal from the relaxation sensor 530 disappears during hovering, the normal operating state may be restored. If an abnormality detection signal is output from the relaxation sensor 530 during hovering, either emergency return, emergency landing, or emergency stop is performed according to the abnormality detection signal strength.

When the evacuation action is taken, the flight controller 501 stops the pump 106 to stop the spraying of the medicine. Further, the flight controller 501 may operate the LED 517 and the warning light 521 to visually display the emergency, and may operate the buzzer 518 and the speaker 520 to acoustically display the emergency.

As described above, according to the embodiment of the flying body of the present invention, the vibration of the flying body 50 can be reduced by devising the arrangement position of the flying body 50 including the control unit required as the flying body. .. A flight control sensor is mounted on the body 50. By reducing the vibration of the body 50, it is possible to reduce the vibration of the flight control sensor and improve the accuracy of the sensor output. Therefore, the accuracy of flight control can be improved.

As described above, the agricultural chemical spray drone has been described as an example of the present description, but the technical idea of the present invention is not limited to this and is applicable to drones in general.

10 1st support arm 11 2nd support arm 12 2nd support arm 13 Reinforcement beam 20 1st support arm 21 2nd support arm 22 2nd support arm 23 Reinforcement beam 50 Body 51 Bottom plate 60 GPS sensor 152 Battery receiving member 153 Battery mounting Space 530 Relaxation sensor

Claims (16)

A propeller having a plurality of propeller drive motors for individually rotating and driving a plurality of propellers, and a frame including a plurality of support arms for supporting the plurality of propeller drive motors coupled to each other,
The plurality of support arms support the propeller drive motor at respective tip portions thereof, and include an upper support arm and a lower support arm,
Inside the space surrounded by the plurality of propellers, a three-dimensional space is defined by the upper support arm and the lower support arm,
A flying body in which a fuselage equipped with a control unit is attached to the three-dimensional space. Each of the upper support arm and the lower support arm has one first support arm that supports the propeller drive motor at both ends, and is diagonally symmetrical from the middle of the length of the first support arm. Two second support arms that extend at their tips to support a propeller drive motor different from the propeller drive motor that is supported by the first support arm, and the two second support arms at intermediate positions in the longitudinal direction. 2. The reinforcing beam connected to each other according to claim 1, wherein the two second support arms extend from the first support arm in a direction in which respective tip ends of the two second support arms form the trapezoidal frame. Flying body. The aircraft according to claim 2, wherein the trapezoidal frames are vertically paired, the upper and lower frames are integrally coupled at a predetermined interval, and the three-dimensional space is a trapezoidal three-dimensional space. The flight vehicle according to claim 1, 2 or 3, wherein a heavy component having high mechanical strength is mounted as a vibration damping component in the fuselage. The aircraft according to claim 4, wherein the vibration damping component is a battery. The flight vehicle according to claim 5, wherein a battery receiving member for loading the battery is provided in the body. The aircraft according to claim 6, wherein the battery receiving member is a vibration damping component of the fuselage together with the battery. The aircraft according to claim 6, wherein the battery receiving member is a reinforcing component of the fuselage together with the battery. The flight vehicle according to claim 1, wherein a flight control sensor is mounted in the fuselage. The aircraft according to claim 9, wherein the flight control sensor includes a 6-axis sensor for controlling the attitude of the aircraft. The aircraft according to claim 9 or 10, wherein the flight control sensor includes a high-accuracy position detector that detects the position of the aircraft with high accuracy. The flight according to any one of claims 5 to 11, wherein a mounting portion of the battery inside the body is vertically layered, and a battery is mounted on an upper layer and the flight control sensor is mounted on a lower layer. body. The aircraft according to claim 11, wherein the high-accuracy position detector is mounted near the reinforcing beams of the two second support arms that form the frame. The aircraft according to claim 12, wherein the battery is mounted below a center of lift generated by rotational driving of the plurality of propellers or at the same height as a center of the lift. The aircraft according to claim 14, wherein a container for accommodating variable weight objects is mounted below the battery as a fixed weight object. The aircraft according to claim 15, wherein the variable weight object is a medicine to be sprayed, and the container is a medicine tank.

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