JP6811976B2 - Aircraft - Google Patents

Description

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

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

Industrial drones, as seen in agricultural drones, for example, carry loads such as chemicals, so large drones with relatively large diameter propellers that can generate thrust that can withstand the load of the load. Is used. A drone with a large-diameter propeller has a large vibration of the airframe caused by the rotation of the propeller. Airframes 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 for flying according to a defined route.

When the drone's airframe vibrates due to the rotation of the propeller, the sensors also vibrate with the airframe, the accuracy of the respective detection data by each sensor decreases, and the accuracy of the various controls decreases.

As one of the sensors, there is a GPS sensor for the drone itself to detect its own position. In industrial drones, for example, a GPS sensor using an RTK antenna and an RTK-GPS (Real Time Kinematic-Global Positioning System) module is often configured in order to detect a position with higher accuracy. Since the RTK-GPS uses radio waves in a short wavelength band in order to improve the resolution, if the RTK antenna vibrates together with the airframe, the position detection accuracy is significantly reduced.

A 6-axis gyro sensor is used for attitude control and flight direction control of the drone. The 6-axis gyro sensor is used to measure the acceleration of a drone in three axes orthogonal to each other and to calculate the velocity by integrating the acceleration. The 6-axis gyro sensor is also used for measuring the angular velocity around the above 3 axes. When the 6-axis gyro sensor vibrates together with the aircraft, the accuracy of acceleration measurement decreases, and the accuracy of attitude control and flight direction control decreases.

The structure of industrial drones has been devised so that the aircraft does not vibrate easily, but as the number of operations increases, the aircraft becomes rattling, and the accuracy of various controls deteriorates accordingly. ..

Patent Document 1 describes an invention in which an abnormality of an unmanned aerial vehicle is detected and the aircraft is landed. The invention described in Patent Document 1 detects the rotation speeds of a plurality of motors for driving a plurality of rotors and the current flowing through each motor, and from the relationship between the rotation speed and the current, each motor or the corresponding motor is abnormal. It determines whether or not.

The invention described in Patent Document 1 detects an abnormality of each motor for driving a plurality of propellers and an abnormality of each propeller, and does not detect vibration of an airframe of an airframe. Therefore, the invention described in Patent Document 1 does not consider any decrease in detection accuracy and various control accuracy of various sensors due to vibration of the airframe.

JP-A-2007-210111

The present invention detects looseness and rattling of airframe structural parts, and when looseness and rattling are detected, it performs an evacuation action, and can avoid problems caused by various deteriorations in control accuracy in advance. The purpose is to obtain.

The present invention
It has an airframe and a plurality of propeller drive motors mounted on the airframe to individually rotate and drive a plurality of propellers, and the airframe is coupled with a plurality of support arms for supporting the plurality of propeller drive motors. An airframe with a frame
A relaxation sensor that detects looseness and rattling of structural parts of the airframe including the frame is attached to the airframe.
The most important feature is to perform an evacuation action when the relaxation sensor outputs an abnormal signal.

According to the present invention, when the relaxation sensor detects looseness or rattling of the airframe structural parts including the frame, an abnormal signal is output. Therefore, appropriate measures can be taken by outputting the abnormal signal, and the relaxation sensor can be detected. It is possible to avoid a decrease in various control accuracy due to a decrease in accuracy.

It is a perspective view which shows the Example of the flying object which concerns on this invention. It is a top view of the said Example. It is a front view of the said Example. It is a right side 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 the propeller is removed. It is a front view which shows the said Example in the state which the propeller is removed. It is a right side view which shows the said Example in the state which the propeller is removed. It is a perspective view which shows the main part of the said Example in an enlarged manner. It is a schematic diagram which shows typically the example of the case where the flying object which concerns on this invention is used for agriculture. It is a block diagram which shows the example of the control system of the flying object which concerns on this invention.

Hereinafter, embodiments of an air vehicle (hereinafter referred to as “drone”) according to the present invention will be described with reference to the drawings. The figures are all examples, and the configuration of the flying object according to the present invention is not limited to the configuration of the embodiment. In the present specification, the term "drone" refers to an overall vehicle having a plurality of rotor blades or flight means regardless of the power system or the flight system. As the power system, there are those using electric power and those using a prime mover such as an internal combustion engine. The maneuvering method includes wireless or wired, and autonomous flight type or manual maneuvering type.

[Overall drone configuration]
In FIGS. 1 to 5, the drone has four propellers 101-1a, 101-1b, 101-2a, 101-2b, 101-3a, 101-3b, 101-4a, 101-, which are also called rotors above and below. Has 4b. These propellers are a means for flying a drone, and are equipped with four sets of two-stage propellers, for a total of eight, in consideration of the balance between flight stability, aircraft size, and battery consumption. .. The centers of rotation of the four sets of propellers are located at the corners of the rectangle in plan view. The propellers 101-2a and 101-4a are on the front side in the direction of travel of the drone.

Each of the above propellers is a propeller drive motor (hereinafter, may be simply referred to as a "motor") 102-1a, 102-1b, 102-2a, 102-2b, 102-3a, 102-3b, 102-4a, 102-4b. It is driven to rotate individually. A set of upper and lower propellers, for example, 101-1a and 101-1b, have axes on the same straight line for the sake of drone flight stability, etc., and are in opposite directions by motors 102-1a and 102-1b. It is driven to rotate. The upper and lower propellers of each set are rotationally driven in opposite directions to generate a downward flow, and generate thrust in the direction of raising the drone. The upper and lower propellers of the other sets are similarly configured to generate thrust in the same way.

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

The drone has a drug tank 104 for accommodating the drug to be sprayed. The drug tank 104 is provided at a position close to the center of gravity of the drone and at a position 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 the medicine hose 105. The drug hose 105 extends linearly in the lower part of the front side in the traveling direction of the drone, straddling almost the entire width direction of the drone. Four drug nozzles 103-1, 103-2, 103-3, and 103-4 are arranged on the drug hose 105 at regular intervals in the length direction thereof. When the pump 106 is operated, the medicine in the medicine tank 104 is discharged from each medicine nozzle and sprayed to the field.

[Frame configuration]
Next, the structure of the drone frame and the structure of the body 50 according to the embodiment will be described in detail with reference to FIGS. 6 to 9. In the present specification, the "body" is a part on which control parts for controlling the operation of the drone, batteries and sensors for driving power are mounted, and corresponds to the body of a helicopter or an airplane. The entire drone, including the fuselage, frame, propeller, and propeller drive motor, is called the "airframe." The frame of the drone is integrally connected to each other and is composed of a plurality of support arms that support the plurality of propeller drive motors. A frame composed of a plurality of support arms is composed of a pair of frames that are integrally connected vertically at predetermined intervals.

The plurality of support arms constituting 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 extending from the first support arm 10. Must have. The second support arms 11 and 12 extend obliquely symmetrically from the middle of the length direction of the first support arm 10 and in a direction in which the tip portions spread out from each other.

The second support arms 11 and 12 are connected by a reinforcing beam 13 in the middle of the length direction. The reinforcing beam 13 is parallel to the first support arm 10, and the first support arm 10, the second support arms 11, 12 and the reinforcing beam 13 are formed in a trapezoidal shape in a plan view, which is close to a so-called truss structure. It has a structure. Since the frame has a structure similar to a truss structure, it is possible to increase the mechanical strength while having a relatively simple structure. The first support arm 10, the second support arms 11, 12 and the reinforcing beam 13 are connected via an appropriate connecting 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 each propeller is individually rotationally driven by the motors. Motors 102-1a and 102-3a different from the above motors are supported at the tips of the second support arms 11 and 12. Propellers 101-1a and 101-3a are attached to the rotary output shafts of the motors 102-1a and 103-3a, respectively, and each propeller is individually rotationally driven by the motors.

The lower frame has almost the same structure as the upper frame. The lower frame includes one first support arm 20 that supports the propeller drive motor at both ends, and two second support arms 21 and 22 extending from the first support arm 20. The second support arms 21 and 22 extend diagonally symmetrically from the middle of the length direction of the first support arm 20 and in a direction in which the tip portions spread out from each other. The first support arm 20 and the second support arms 21 and 22 are connected via appropriate coupling members so as to be located in the same plane.

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 pairs of the second support arms 11 and 21 and the other pair of the second support arms 12 and 22 are connected by columns 30 and 30, respectively, at the intermediate portion in the length direction. Further, the pair of upper and lower first support arms 10 and 20 have columns 31 in the vicinity of the joints with the upper second support arms 11 and 21 and in the vicinity of the joints with the lower second support arms 12 and 22, respectively. , 31 are combined. Each of the support arms and each pillar is connected by interposing an appropriate connecting member.

The pair of columns 30, 30 are connected by a reinforcing beam 23 at a position downward in the vertical direction. The reinforcing beam 23 is also a reinforcing beam of the lower frame including the first support arm 20 and the second support arms 21 and 22, and also functions as a reinforcing beam of the entire upper and lower frames. The reinforcing beam 13 is parallel to the first support arm 10, and the first support arm 10, the second support arms 11, 12 and the reinforcing beam 13 are formed in a trapezoidal shape in a plan view, which is close to a so-called truss structure. It has a structure.

The first support arms 10, 20, the second support arms 11, 12, 21, 22, and the reinforcing beams 13, 23 that form the upper and lower frames, and the columns 30, 31 that connect the upper and lower frames are pipe-shaped members. is there. Further, the above-mentioned members constituting the frame, at least the material of the first support arm, the second support arm and the reinforcing beam are made of a heat conductive material, for example, 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 constituting the frame is made of an aluminum alloy, a carbon fiber composite material, or the like, and is a pipe-shaped member, the weight of the frame can be reduced while giving the frame the strength required. Further, as will be described in detail later, the heat dissipation effect can be enhanced.

[Propeller guard]
The propellers 101-1a and 101-1b supported by the tips of the pair of upper and lower second support arms 11 and 21 are surrounded by the propeller guard 41 and rotate in 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. It has a plurality of spokes that connect to the hub. The upper and lower hubs are connected to the tips of the second support arms 11 and 21 so that their centers coincide with the rotation centers of the propellers 101-1a and 101-1b.

The propellers 101-2a and 101-2b supported by the right end 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 in the propeller guard 43.

The propellers 101-4a and 101-4b supported by the left end 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 in the propeller guard 44.

Each of the propeller guards 42, 43, 44 is configured in the same manner as the propeller guard 41. That is, each of the propeller guards 42, 43, 44 has 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 upper and lower frames, respectively. It consists of 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 ends on the right side when viewed from the front of the first support arms 10 and 20. The upper and lower hubs of the propeller guard 43 are coupled to the tips of the second support arms 12 and 22. The upper and lower hubs of the propeller guard 44 are connected to the left end of the first support arms 10 and 20 when viewed from the front.

The distance between the propellers 101-1a and 101-1b located on the right rear side of the drone and the propellers 101-2a and 101-2b located on the right front side is narrow, and the annular frame constituting these propeller guards 41 and 42 is formed. Are in contact. The distance between the propellers 101-3a and 101-3b located on the left rear side of the drone and the propellers 101-4a and 101-4b located on the left front side is also narrow, and the annular frame constituting these propeller guards 43 and 44 is formed. Are in contact.

It is desirable that the materials of the frames, hubs and spokes constituting the propeller guards 41, 42, 43 and 44 are heat conductive materials. It is desirable that at least the spokes arranged in a grid pattern on the upper and lower surfaces of the propeller guards 41, 42, 43, 44 are made of a heat conductive material.

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

[body]
In a plan view, the lines connecting the rotation centers of the four sets of propellers 101-1a, 101-1b, 101-2a, 101-2b, 101-3a, 101-3b, 101-4a, and 101-4b are horizontally long. It is a rectangle. There is a space between the front and rear left propeller guards 43 and 44 and the front and rear right propeller guards 41 and 42, and this space supports built-in parts such as the power battery, control circuit, and motor drive circuit. The body 50 to be used is arranged.

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

The fuselage 50 is arranged in the 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 surface of the bottom plate 51 constituting the body 50 is connected to the lower reinforcing beam 23 via a connecting member. The connecting member is a plate-shaped member made of a material having good thermal conductivity, holds the reinforcing beam 23 over almost half a circumference, and is fastened with both side edges in surface contact with the bottom surface of the bottom plate 51.

The cover 52 constituting the body 50 is connected to the upper reinforcing beam 13 via a connecting member 59. The connecting member 59 is also a plate-shaped member made of a material having good thermal conductivity, and the reinforcing beam 13 is wound around about half a circumference and is fastened with both side edges 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 fuselage 50. Approximately half of the space 56 on the rear side (diagonally lower right side in FIG. 9) in the fuselage 50 is close to the upper and lower reinforcing beams 13 and 23, and is a space having a high cooling effect. The space 56 is divided into upper and lower 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 side by side in parallel.

During operation of the aircraft, two batteries 55 are loaded in the battery mounting space 153. One battery is the main battery and is used during normal operation, the other battery is a spare battery. If the storage capacity of the main battery becomes low while the main battery is in use, or if the main battery malfunctions, continue the flight to switch to the spare battery and perform the evacuation action described later. Let me take it. By installing the two batteries 55 in this way, the power supply system is provided with so-called redundancy, and when a power supply trouble occurs, appropriate processing is performed to avoid developing a fatal trouble. can do.

FIG. 9 shows a state in which only one battery 55 is loaded. The battery 55 is also one of the heat generating parts, and is devised so as to suppress the temperature rise of the battery 55 by loading the battery 55 in the space 56 having a high cooling effect. The battery 55 itself is a component having high mechanical strength and rigidity, and the strength and rigidity of the fuselage 50 can be increased by firmly tightening and loading the battery 55 with the battery fastener 154. The battery 55, the battery mounting space 153, the battery receiving member 152, and the battery fastener 154 each also contribute as members for ensuring the strength of the frame.

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 so as to be displaced in front of the reinforcing beam 23 of the lower frame in order to enable opening and closing of the lid.

In the space 56, a mounting substrate for heat-generating components is arranged in the lower layer of the battery mounting space 153 so as to be in surface contact with the bottom plate 51. The rotation speed control component (ESC: Electronic Speed Control) of the motor and the step-down electric component are mounted on the mounting board. The step-down electric unit steps down the DC power supplied from the battery 55 to a voltage suitable for the drive voltage of the motor and the drive voltage of the control circuit and distributes the DC power supply. The above ESC and 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. A control circuit such as a flight controller, a signal processing circuit from various sensors, a communication circuit, and the like are mounted on these circuit boards 58.

A 6-axis gyro sensor, which is a means for measuring the acceleration of the drone and 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 axial directions that are orthogonal to each other, and an angular velocity sensor that detects angular velocities of rotation, for example, pitching, rolling, and yawing, respectively, around the above three axes. ing.

The position of the center of gravity of the drone with the two batteries 55 loaded in the battery mounting space 153 is in the plane direction, that is, between the two batteries 55 when the drone is viewed from above, and the heavy battery 55 is loaded. By doing so, it is in a relatively lower position in the vertical direction. On the other hand, the rotation center P of the attitude control of the drone by the rotation control of the four sets of motors is the intersection position of the lines connecting the centers of the motors at diagonal positions as shown in FIG. 2 in the vertical direction. , As shown in FIG. 3, is located at the center of the separation distance between the upper and lower motors.

The horizontal line of lift generated by the rotation of the four sets of motors, that is, the horizontal line including the rotation center P of attitude control, is above the position of the center of gravity of the drone. In other words, by arranging the battery 55, which is a fixed weight object, the center of gravity of the drone is located below the rotation center P.

By setting the positional relationship between the position of 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 the energy required for attitude control.

Below the body 50, a drug tank 104 is arranged with a space 70 between the body and the lower surface of the body 50. Since the medicine tank 104 contains the medicine to be sprayed and the medicine is sprayed while flying over the field, the medicine tank 104 is a variable weight object. The drug tank 104, which is a variable weight object, is arranged further below the position of the center of gravity of the drone, and is considered so that the influence of the weight fluctuation 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 and 12 constituting the upper frame. The GPS sensors 60, 60 are composed of, for example, an RTK antenna and an RTK-GPS (Real Time Kinematic-Global Positioning System) module. The GPS sensors 60, 60 measure the absolute position of the drone, determine whether the measured position is, for example, the position according to the program, and if the position is deviated, the rotation of each drive motor so as to be the correct position. To control.

When the GPS sensors 60, 60 vibrate, the absolute position measurement accuracy of the drone is lowered, and the position control system is also lowered. Therefore, in the illustrated embodiment, the second support arm 11 is located at a position as far as possible from each of the drive motors so that the GPS sensors 60 and 60 are not affected by the vibration of each of the drive motors which are vibration sources. , 12 is installed in the central part in the length direction.

The GPS sensors 60 and 60 are installed between the front and rear propeller guards 41 and 42 and between the propeller guards 43 and 44 when viewed from the plane. Further, the second support arms 11 and 12 are located in the vicinity of the pillars 30 and 30 connecting the upper and lower frames of the GPS sensors 60 and 60 so as not to vibrate easily. Therefore, the GPS sensors 60 and 60 are not easily affected by the vibration of each of the drive motors, and the position of the drone can be measured with high accuracy.

[Frame cooling effect]
According to the configuration of the flying object and its frame described above, the following cooling effects can be obtained.

Built-in parts including a rotation control part of a motor and a heat generating part such as a distribution electric machine are mounted on the body 50. The bottom plate 51 and the cover 52 constituting 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 for dissipating the heat generated by the heat generating parts.

Further, the bottom plate 51 of the body 50 is coupled to the reinforcing beam 23 of the lower frame made of the heat conductive material, and the reinforcing beam 23 is further coupled to the second support arms 21 and 22. The cover 52 of the fuselage 50 is also connected to the reinforcing beam 13 of the upper frame made of the heat conductive material, and the reinforcing beam 13 is connected to the second support arms 11 and 12. As described above, the structure is such that the heat generated by the built-in parts 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 supplements the heat dissipation.

The fuselage 50 is surrounded by a pair of front and rear propellers located on the left and right sides of the fuselage 50. When each propeller is rotationally driven, a downward flow of air is generated along the left and right side surfaces of the fuselage 50. The downward flow of air flows at a relatively high speed in a substantially triangular space viewed from the plane direction defined by the left and right side surfaces of the fuselage 50 and the front and rear propeller guards. In this embodiment, each of the four propellers has an upper and lower two-stage configuration, and it is known that the downward flow is more concentrated and stronger than the one-stage propeller.

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

[Example of using drone]
FIG. 10 schematically shows an overall conceptual diagram of a system using an embodiment of the drone 100 for chemical spraying according to the present invention. The controller 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 a position, a drug amount, a remaining battery level, and a camera image. .. The controller 401 may be realized by a portable information device such as a general tablet terminal that runs a computer program.

The drone 100 according to this embodiment is controlled to perform autonomous flight, but it is desirable that the drone 100 can be manually operated 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 is a dedicated device equipped with a large emergency stop button or the like so that an emergency response can be taken quickly. It is desirable that the controller 401 and the drone 100 perform wireless communication by Wi-Fi or the like.

The field 403 is a rice field, a field, or the like that is the target of chemical spraying by the drone 100. In reality, the topography of the field 403 is complicated, and the topographic map may not be available in advance, or the topographic map and the situation at the site may be inconsistent. Normally, the field 403 is adjacent to a house, a hospital, a school, another crop field, a road, a railroad, or the like. In addition, obstacles such as buildings and electric wires may exist in the field 403.

The base station 404 is a device that provides a master unit function for Wi-Fi communication, and it is desirable that the base station 404 also functions as an RTK-GPS base station so that the accurate position of the drone 100 can be provided. The base unit function of Wi-Fi communication and the RTK-GPS base station may be independent devices. The farming cloud 405 is typically a group of computers operated on a cloud service and related software, and it is desirable that the farming cloud 405 is wirelessly connected to the controller 401 by a mobile phone line or the like.

The farming cloud 405 may analyze the image of the field 403 taken by the drone 100, grasp the growing condition of the crop, and perform a process for determining the flight route. The farming cloud 405 can provide the drone 100 with the topographical information of the field 403 that has been saved, and in addition, may accumulate the history of the flight and captured images of the drone 100 and perform various analysis processes. ..

Normally, the drone 100 takes off from the departure / arrival point 406 outside the field 403 and returns to the departure / arrival point 406 after spraying the chemicals on the field 403 or when the chemicals need to be replenished or charged. The flight route (which can be said to be an intrusion route) from the departure / arrival point 406 to the target field 403 may be stored in advance in the farming 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 a control function of an embodiment of the drug spraying drone according to the present invention. The flight controller 501 is a component that controls the entire drone, and may be an embedded computer including a CPU, memory, related software, and the like. The flight controller 501 is based on the input information received from the controller 401 and the input information obtained from various sensors described later, and the motors 102-1a and 102-1b via a control means such as ESC (Electronic Speed Control). , 102-2a, 102-2b, 102-3a, 102-3b, 102-4a, 102-4b to control the flight of the drone 100.

The actual rotation speed of each of the above motors is fed back to the flight controller 501 so that it can be monitored whether normal rotation is performed. An optical sensor or the like may be provided on the propeller so that the rotation speed of the propeller is fed back to the flight controller 501.

It is desirable that the software used by the flight controller 501 be rewritable through a storage medium or the like for function expansion / change, problem correction, etc., or through communication means such as Wi-Fi communication or USB. It is desirable to protect with encryption, checksum, digital signature, virus check software, etc. so that it will not be rewritten by malicious software.

In addition, a part of the calculation process used by the flight controller 501 for control may be executed by another computer located on the pilot 401, the farming cloud 405, or somewhere else. The flight controller 501 is a core and important part of the drone, and it is desirable that some or all of its components are duplicated.

The battery 55 is a means of supplying power to the 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 fuse, a power supply unit including a circuit breaker, or the like. It is desirable that the battery 55 is a smart battery having a function of transmitting the internal state, that is, the amount of electricity stored, the total usage time, and the like to the flight controller 501 in addition to the power supply function.

The flight controller 501 communicates with the pilot 401 via the Wi-Fi slave unit function 503 and further via the base station 404, receives necessary commands from the pilot 401, and receives necessary information from the pilot 401. Can be sent to. It is advisable to encrypt the communication so that fraudulent activities such as interception, spoofing, and device hijacking can be prevented.

It is desirable that the base station 404 also has a function of an RTK-GPS base station in addition to a communication function by Wi-Fi. 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 very important, it is desirable to duplicate and multiplex it. In addition, it is desirable to control each redundant GPS module 504 to use a different satellite in order to cope with the failure of a specific GPS satellite.

The 6-axis gyro sensor 505 is a means for measuring the acceleration of the drone body in the three axes orthogonal to each other, a means for calculating the speed by integrating the acceleration, and a means for detecting the angular velocity of rotation about the above three axes. .. The geomagnetic sensor 506 is a means for measuring the direction of the drone body by measuring the geomagnetism. The barometric pressure sensor 507 is a means for measuring barometric pressure, and can also 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 the laser beam, and it is desirable to use an infrared (IR) laser. The sonar 509 is a 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 according to the cost target and performance requirements of the drone. In addition, a gyro sensor (angular velocity sensor) for measuring the inclination of the aircraft, a wind power sensor for measuring wind power, and the like may be added. Further, it is desirable that these sensors are duplicated or multiplexed. If there are multiple sensors for the same purpose, the flight controller 501 may use only one of them, and if it fails, it may switch to an alternative sensor for use. Alternatively, a plurality of sensors may be used at the same time, 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 drug, and it is desirable that the flow rate sensor 510 is provided at a plurality of locations on the path from the drug tank 104 to the drug nozzle 103. The liquid drain sensor 511 is a sensor that detects that the amount of the drug has fallen below a predetermined amount. The multispectral camera 512 is a means of photographing the field 403 and acquiring data for image analysis. The obstacle detection camera 513 is a camera for detecting a drone obstacle, and is mounted separately from the multispectral camera 512 because the image characteristics and the orientation of the lens are different from those of 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, particularly its rotor or propeller guard portion, has come into contact with an obstacle such as an electric wire, a building, a human body, a standing 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 in an open state. The drug injection port sensor 517 is a sensor that detects that the injection port of the drug tank 104 is in an open state.

These sensors may be selected according to the cost target and performance requirements of the drone, and may be duplicated or multiplexed. Alternatively, sensors may be provided at an external base station 404, pilot 401, or other location to transmit the read information to the drone. For example, a wind power sensor may be provided in the base station 404 to transmit information on the wind power and the wind direction to the drone 100 via Wi-Fi communication.

The flight controller 501 transmits a control signal to the pump 106 to adjust the drug discharge amount and stop the drug discharge. It is desirable that the current state of the pump 106, for example, the number of revolutions, is fed back to the flight controller 501.

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

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

[Relaxation sensor]
Next, a characteristic component of the present invention will be described. As shown in FIG. 11, in addition to the various sensors described above, a relaxation sensor 530 is provided so that the detection signal of the relaxation sensor 530 is input to the flight controller 501. The relaxation sensor 530 is a sensor that detects looseness and rattling of structural parts of the airframe mainly composed of a frame having the first support arms 10, 20, and second support arms 11, 12, 21, 22,. is there. Further, as will be described later, the relaxation sensor 530 may be arranged inside the accommodation space of the substrate of the drone body.

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 there is no looseness or rattling in the structural parts of the aircraft and the case where there is looseness or rattling. Occurs. The difference in sound or noise between normal and abnormal is mainly the difference in frequency or abnormal noise that occurs only in abnormal. Therefore, a microphone for detecting the noise of the drone is attached to the drone, and the detection signal converted into electroacoustic is processed by the microphone to detect an abnormality.

The output signal of the microphone is filtered for each frequency band, and if an abnormality is found in a specific frequency band, it can be determined that the aircraft is loose or rattling. Alternatively, when an abnormal signal that does not appear in the normal state is detected in comparison with the detection signal in the normal state, it can be determined that the aircraft is loose or rattling. The method for determining looseness or rattling of the airframe based on the output signal of the microphone is not limited to these methods, and other methods may be used.

In particular, the relaxation sensor 530 using a microphone also serves as a sensor used for flight control of a drone (hereinafter, also referred to as an "existing sensor" for convenience) such as an acceleration sensor, a 6-axis gyro sensor 505, and an angular velocity sensor, which will be described later. It has a higher sampling frequency than the case where the relaxation sensor is configured.

The sampling frequency of the existing sensor depends on the control cycle of the drone aircraft, and is, for example, about 100 Hz. On the other hand, the frequency band of the vibration that increases due to the aged deterioration of the drone is a high frequency band of 1 kHz to 2 kHz. Vibration in this frequency band is caused by loosening of gel washers such as silicon washers, or bushes between frames or for fixing a substrate. Further, the vibration in this frequency band is a vibration that affects the elements on the substrate, and is a vibration that is likely to lead to a failure such as breaking a defective solder.

The sensor generally uses a frequency that is sufficiently lower than the Nyquist frequency, about one-third of the sampling frequency, as a detectable range. Therefore, it is difficult to detect the vibration in the above frequency band by the existing sensor. Further, if the sampling frequency of the existing sensor is set to be high, the control cycle of the drone aircraft will be changed, which will have a great influence on other configurations. Therefore, by separately providing a microphone that is driven at a sampling frequency higher than that of the existing sensor, it is possible to measure the vibration in the high frequency band independently of the control cycle of the drone aircraft.

The sampling frequency of the microphone may be a frequency capable of sufficiently measuring a frequency of at least 1 kHz to 2 kHz, for example, 6 kHz or more, and may be a microphone capable of collecting sound in the audible region.

The relaxation sensor 530 may be configured by combining a plurality of sensors that detect vibrations in different frequency bands.

The microphone is located inside the drone body, especially inside the accommodation space of the substrate. Further, the microphone is connected to a recording medium different from the recording area in which the data of the existing sensor is recorded, and the sound collection data by the microphone is stored in the recording medium. According to the configuration in which the microphone is arranged inside the accommodation space of the substrate, it is possible to prevent the microphone from being contaminated by dust or water as compared with the configuration in which the microphone is exposed to the outside of the machine body. In addition, the microphone can be isolated from the sound from the outside of the drone, and the noise collected outside the drone can be prevented from being collected.

If the drone's body is loose, the output signal of the accelerometer attached to the drone will be abnormal. Therefore, an acceleration sensor may be used as the relaxation sensor 530. The acceleration sensor may be mounted exclusively for detecting the relaxation of the airframe, 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.

The mounting position of the relaxation sensor 530 is arbitrary, but it is desirable that the loosening sensor 530 be mounted at a position where it can effectively detect looseness and rattling of the airframe. In the drone body according to the embodiment described above, the frames having the first and second support arms are paired vertically, and the upper and lower frames are connected by columns. Each of the vertically paired frames has a reinforcing beam to form a trapezoidal three-dimensional space. The relaxation sensor 530 is arranged inside this trapezoidal three-dimensional space. More specifically, the body 50 is arranged in the trapezoidal three-dimensional space, and the relaxation sensor 530 is arranged 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. In 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 suppression component is mounted. Therefore, when the 6-axis gyro sensor 505 also serves as the relaxation sensor, the relaxation sensor is arranged in the body 50 and below the mounting portion of the vibration suppression component.

[Evacuation behavior]
When the structural parts of the drone body having the frame are loosened or rattled, the body makes an abnormal noise. The abnormal sound may be a sound in a frequency band different from the normal state, or may be a sound generated suddenly or irregularly. This abnormal noise is detected by a relaxation sensor 530 (see FIG. 11) composed of the microphone, an acceleration sensor, and the like, 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 an evacuation action.

The evacuation action is either emergency return, emergency landing, or emergency stop, and the flight controller 501 causes the flight controller 501 to perform any of the above evacuation actions according to the degree of abnormal noise, that is, the strength of the abnormality detection signal of the relaxation sensor 530. If the noise is relatively slight, make an emergency return, if the noise is moderate, make an emergency landing, and if the noise is strong, make an emergency stop. Emergency return is, for example, returning to the original position where it took off and landing. An emergency landing is an on-the-spot landing. An emergency stop is to stop all propeller drive motors and cause them to crash on the spot. It's safer to crash the drone than to get it out of control.

As one of the evacuation actions, hovering may be performed once, and if the abnormality detection signal by 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 even during hovering, either emergency return, emergency landing, or emergency stop is performed depending on the strength of the abnormality detection signal.

When taking the evacuation action, the flight controller 501 stops the pump 106 to stop the spraying of the drug. Further, the flight controller 501 may operate the LED 107 and the warning light 521 to visually display the emergency situation, and may operate the buzzer 518 and the speaker 520 to acoustically display the emergency situation.

As described above, according to the embodiment of the airframe according to the present invention, when looseness or rattling of the airframe structural parts occurs, the relaxation sensor detects this and outputs an abnormal signal. Since the drone takes an evacuation action by the output of the abnormal signal, it is possible to avoid in advance the trouble caused by the deterioration of various control accuracy caused by the loosening and rattling of the airframe structural parts. The above-mentioned defects include departure from the planned flight path, variation in flight altitude, variation in attitude control and speed control, and in some cases, collision with an obstacle, but according to this embodiment. , Such a problem can be avoided.

As described above, as an example of this description, an agricultural chemical spraying drone has been described as an example, but the technical idea of the present invention is not limited to this, and can be applied to all drones.

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

Claims (10)

It has an airframe and a plurality of propeller drive motors mounted on the airframe to individually rotate and drive a plurality of propellers, and the airframe is an airframe having a frame for supporting the plurality of propeller drive motors. hand,
It is equipped with a relaxation sensor that is attached to the airframe and outputs an abnormal signal when it detects looseness or rattling of structural parts of the airframe including the frame.
When the relaxation sensor outputs the abnormal signal during flight, hovering is performed, and when the relaxation sensor does not output the abnormal signal during the hovering, the operation state is restored.
When the relaxation sensor outputs the abnormal signal during hovering, any one of a return operation of returning to the takeoff point and landing, a landing operation of landing on the spot, and an emergency stop operation of stopping the plurality of propeller drive motors. Perform the operation of
A flying object having an angular velocity sensor as the relaxation sensor and outputting the abnormal signal when vibration in a predetermined frequency band is detected by the angular velocity sensor during the hovering .
The flying object according to claim 1, wherein the relaxation sensor is a microphone, and outputs the abnormal signal when the microphone detects an abnormal noise.
The flying object according to claim 2 , wherein the abnormal noise is a sound in a frequency band different from the sound in the frequency band generated in a normal state.
It has an airframe and a plurality of propeller drive motors mounted on the airframe to individually rotate and drive a plurality of propellers, and the airframe is an airframe having a frame for supporting the plurality of propeller drive motors. hand,
A relaxation sensor for detecting looseness or rattling of structural parts of the airframe including the frame is attached to the airframe.
When the relaxation sensor outputs an abnormal signal, an evacuation action is performed.
The frame includes one first support arm and two second support arms that extend diagonally symmetrically from the middle of the length direction of the first support arm, and both ends of the first support arm. An air vehicle that supports the propeller drive motor at a portion and a tip portion of the second support arm, respectively.
The flying object according to claim 4, wherein the two second support arms extend from the first support arm in a direction in which their respective tip portions expand.
The flying object according to claim 5 , wherein the frame has a reinforcing beam that connects the two second support arms at an intermediate position in the length direction.
The frame having the first support arm, the second support arm, and the reinforcing beam is arranged vertically, and the upper and lower frames are connected by columns, and the first support arm, the second support arm, and the like. The flying object according to claim 6 , wherein a trapezoidal three-dimensional space is formed by the reinforcing beams, and the relaxation sensor is arranged in the three-dimensional space.
The aircraft according to any one of claims 4 to 7 , wherein the evacuation action is either an emergency return, an emergency landing, or an emergency stop.
The propellers are arranged at a total of four locations in front, back, left and right in a plan view, and the distance between the left and right propellers is wider than the distance between the front and rear propellers. The air vehicle according to any one of claims 1 to 8 , wherein the aircraft is arranged.
The flying object according to claim 9, wherein the component mounting portion has layers in the vertical direction, and the relaxation sensor is arranged in a layer below the layer on which the vibration suppression component is mounted.

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