A robot for automatic charging of drones

Abstract

The present invention discloses a robot for automatic charging of unmanned aerial vehicles. The robot includes an end effector and a position adjustment mechanism. The position adjustment mechanism can drive the end effector to move arbitrarily in the horizontal plane and rotate around the vertical axis. The end effector includes a mounting plate, a charging interface, a second pressure sensor and a distance sensor. The mounting plate is provided with two side edges at an angle of 90°; the two side edges serve as a first detection edge and a second detection edge respectively. The second pressure sensor is installed at both ends of the first detection edge; and the distance sensor is installed in the middle position of the first detection edge and the second detection edge. The charging interface is installed in the center hole of the mounting plate and faces downward. After the initial alignment, the present invention realizes high-precision alignment between the charging interface and the charging socket through the directional movement of the end effector and the cooperation of the two pressure sensors and the two distance sensors.

Description

Technical Field

[0001] The present invention belongs to the field of charging robots, and specifically designs a precisely positioned automatic charging robot for unmanned aerial vehicles and a driving method thereof. Background Art

[0002] Nowadays, the number of mobile robots is increasing. They are applied in different fields such as logistics, inventory, furniture assembly, education, etc. However, all mobile robots have a limited operation time, which restricts the range of activities of mobile robots. For indoor robots, this factor is not important because the increased workspace can be compensated by more docking stations. On the other hand, for outdoor robots that explore unknown areas (such as coal mine rescue robots), the operation time issue is crucial.

[0003] There are many studies on increasing the working range of mobile robots. One of the most effective ways is to apply renewable energy sources as the power source of the robot, such as solar energy. This makes the working range of mobile robots infinitely possible. However, it also has disadvantages, such as sensitivity to external conditions and low charging speed. The most common way to increase the walking distance of mobile robots is to increase the battery capacity. However, in this case, the size and weight of the mobile robot are also increasing dramatically. Another approach can be taken from the aviation and aerospace industries. In order to increase the range of an aircraft, it is necessary to use additional fuel tanks or refueling tankers. Based on this, this paper designs a new mobile charging robot that is simpler and cheaper than the original one, which can recharge the main robot and increase its range of activities. Summary of the invention

[0004] The object of the present invention is to provide a precisely positioned automatic charging robot for an unmanned aerial vehicle and a driving method thereof.

[0005] The present invention provides a robot for automatic charging of unmanned aerial vehicles, comprising an end effector and a position adjustment mechanism. The position adjustment mechanism can drive the end effector to move arbitrarily in the horizontal plane and rotate around the vertical axis. The end effector comprises a mounting plate, a charging interface, a second pressure sensor and a distance measuring sensor. The mounting plate is provided with two side edges at an angle of 90°; the two side edges serve as a first detection edge and a second detection edge respectively. The second pressure sensors are installed at both ends of the first detection edge; and the distance measuring sensors are installed in the middle of the first detection edge and the second detection edge. The charging interface is mounted on the mounting plate and faces downward. A square groove is provided on the top of the unmanned aerial vehicle that can be docked with the robot; the mounting plate can extend into the square groove.

[0006] The charging process of the robot for automatic charging of drones is as follows:

[0007] Step 1: The charged drone and the robot move relative to each other until the square groove is directly below the end effector.

[0008] Step 2: The drone being charged moves upward or the end effector moves downward until the mounting plate contacts the bottom surface of the square groove;

[0009] Step 3: Taking the orientation of the first detection edge on the moving block as the first target direction, the position adjustment mechanism drives the end effector to move along the first target direction; until one of the second pressure sensors detects a pressure value.

[0010] If the two second pressure sensors both detect pressure signals, there is no angle deviation of the charging interface.

[0011] If only one second pressure sensor detects a pressure signal, the charging interface has an angle deviation; calculate the deviation angle Wherein, x is the distance value x measured by the distance measuring sensor on the first detection side; l represents the side length of the mounting plate. The position adjustment mechanism drives the end effector to rotate around the vertical axis by a deviation angle α; the rotation direction is determined according to the position of the second pressure sensor that detects the signal; if the second pressure sensor close to the second detection side detects a pressure signal, the rotation direction of the end effector is the direction in which the second detection side is away from the first detection side. If the second pressure sensor far from the second detection side detects a pressure signal, the rotation direction of the end effector is the direction in which the second detection side is close to the first detection side.

[0012] Step 4: The two distance measuring sensors detect the distance between themselves and the side wall of the square groove, and determine their position in the square groove and their relative position to the charging socket of the drone based on the two distance values ​​obtained. Based on the relative position, the position adjustment mechanism drives the end effector to move to the top of the charging socket of the drone being charged, so as to achieve docking of the charging interface on the end effector with the charging socket on the drone being charged.

[0013] Preferably, at least three first pressure sensors are arranged at different positions on the bottom surface of the mounting plate.

[0014] Preferably, in step 2, all the first pressure sensors detect pressure signals to determine whether the mounting plate has abutted against the bottom surface of the square groove.

[0015] Preferably, after step three is executed once, step three is executed again to ensure that the two second pressure sensors detect the pressure signal at the same time.

[0016] Preferably, the mounting plate is square, and there are four first pressure sensors in total, which are respectively mounted on four corners of the bottom surface of the square mounting plate.

[0017] Preferably, the charging interface and the mounting plate form a sliding pair in the vertical direction. The charging interface slides up and down under the drive of the push-pull power assembly. When the charging interface is pushed out, it can be inserted into the charging socket on the top of the drone below; when the charging interface is retracted, the bottom edge is higher than the bottom surface of the first pressure sensor.

[0018] Preferably, the charging socket is provided with two groups of sockets staggered at 90° along the circumferential direction; when the charging interface is plugged into any group of sockets, the drone can be charged.

[0019] Preferably, the position adjustment mechanism includes a planar drive module and a configuration ring. The planar drive module includes a vertical rotating motor, a moving block, a frame and a Y-axis guide frame. The frame and the upper frame form a rotating pair with a common axis vertically arranged, and are driven to rotate by a vertical rotating motor. The Y-axis guide frame and the frame form a first sliding pair; the moving block and the Y-axis guide frame form a second sliding pair. The Y-axis guide frame is driven by a motor in conjunction with a conveyor belt. The moving block is driven by a motor in conjunction with a lead screw nut. The configuration ring is fixed on the moving block. The mounting plate is installed below the configuration ring.

[0020] Preferably, the position adjustment mechanism further includes a driving component. The driving component is arranged between the mounting plate and the configuration ring. Three driving motors are evenly installed on the edge of the configuration ring along the circumferential direction. The driving component includes a driving motor, an upper rod and a lower rod. One end of the three upper rods is rotatably connected to the configuration ring and driven to rotate by the driving motor. The other ends of the three upper rods and one ends of the three lower rods respectively form spherical pairs; the other ends of the three lower rods and three different positions of the mounting plate on the end effector respectively form rotating pairs.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. After the initial alignment, the present invention realizes high-precision alignment between the charging interface and the charging socket through the directional movement of the end effector and the cooperation of two pressure sensors and two distance measuring sensors.

[0023] 2. The present invention provides a reliable connection between robots by using encoders and pressure sensors. The pressure data on the contact surface can be used to estimate the angular, vertical and horizontal deviations on the end effector.

[0024] 3. The present invention adopts an inverted drive, which is more compact than the traditional drive, making the robot more compact as a whole.

[0025] 4. The mobile robot of the present invention has strong adaptability and can be applied to a variety of scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the overall appearance of the present invention;

[0027] Figure 2 is a three-dimensional diagram of a planar driving module in the present invention;

[0028] Figure 3 is a stereogram of the configuration ring in the present invention;

[0029] Figure 4 is a schematic diagram of a driving component in the present invention;

[0030] Figure 5 is a stereoscopic diagram of the end effector of the present invention;

[0031] Figure 6 is a bottom schematic diagram of the end effector in the present invention;

[0032] Figures 7a-7d It is a schematic diagram of the alignment process of the charging interface and the charging base of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] like Figure 1 , 2As shown in Figure 3, a robot for automatic charging of unmanned aerial vehicles includes a planar drive module 1, a configuration ring 2, a drive component 3 and an end effector 4. The planar drive module 1 includes a vertical rotation motor 1-1, a moving block 1-2, a frame 1-3, two belts 1-4, three guide rods 1-5, a ball screw 1-6 and two Y-axis guide frames 1-7. The frame 1-3 and the upper frame form a rotating pair with a common axis vertically arranged. The vertical rotation motor 1-1 is installed on the frame and is located directly above the frame 1-3. The output shaft of the vertical rotation motor 1-1 is fixed to the frame 1-3 and is used to control the rotation of the planar drive module 1 around the vertical axis. The two belts 1-4 are installed on multiple pulleys on both sides of the frame 1-3; the movement of the moving block 1-2 on the X axis is controlled by belt drive. Eight pulleys are installed on the frame 1-3 to cooperate with the two belts 1-4. Two of the wheels are active parts, and the remaining six wheels are driven parts. The two wheels of the active part are connected by a guide rod 1-5 and controlled by a driving motor. The driving motor is installed on the outer side of the active wheel. A Y-axis guide frame 1-7 is installed on the belt 1-4, which is fixed to the belt 1-4 and connected to the moving block 1-2. A driving motor is installed on one of the Y-axis guide frames 1-7. The moving block 1-2 is connected to the Y-axis guide frame 1-7 in the form of a ball screw 1-6, that is, the belt 1-4 drives the Y-axis guide frame 1-7 to move horizontally, and controls the movement of the moving block 1-2 in the X-axis direction. At the same time, a hole is opened above the moving block 1-2, which is connected to the guide rod 1-5 on the Y-axis guide frame 1-7 to ensure that the moving block 1-2 will not deflect. At the same time, a hole is opened on the Y-axis guide frame 1-7, which is connected to the guide rod 1-5 on the frame 1-3 to ensure that the Y-axis guide frame 1-7 will not deflect during movement.

[0035] The planar driving module 1 provided in this embodiment is only an example, and other existing planar driving modules 1 that can realize two-degree-of-freedom movement on a horizontal plane and rotation around a vertical axis can also be used.

[0036] like Figure 3 As shown, the configuration ring 2 is fixed at the bottom of the moving block 1-2; the planar driving module 1 controls the movement of the configuration ring 2 on the X-axis and Y-axis and the rotation around the Z-axis. Three motor slots are evenly arranged along the circumference on the edge of the configuration ring 2, which are used to fix and install three drive motors respectively.

[0037] The driving component 3 includes a driving motor, an upper rod 3-1 and a lower rod 3-2. One end of the three upper rods 3-1 is fixed to the output shafts of the three driving motors respectively. The other ends of the three upper rods 3-1 are connected to one end of the three lower rods 3-2 respectively through ball hinges; the other ends of the three lower rods 3-2 and three positions uniformly distributed along the circumference of the axis of the mounting plate 4-3 on the end effector 4 respectively form a revolute pair.

[0038] like Figure 5 and 6 As shown, the end effector 4 includes four first pressure sensors 4-1, two second pressure sensors 4-6, two distance measuring sensors 4-2, a mounting plate 4-3, a push-pull power assembly 4-4 and a charging interface 4-5.

[0039] The mounting plate 4-3 is square; four first pressure sensors 4-1 are respectively mounted on the four corners of the bottom surface of the square mounting plate 4-3. Two adjacent side edges on the mounting plate 4-3 are respectively used as the first detection edge and the second detection edge. Two second pressure sensors 4-6 are respectively mounted at both ends of the first detection edge; two distance sensors 4-2 are respectively mounted in the middle of the first detection edge and the second detection edge.

[0040] The charging interface 4-5 is installed in the center hole of the mounting plate 4-3 and faces downward. The charging interface 4-5 and the mounting plate 4-3 form a sliding pair in the vertical direction. The charging interface 4-5 slides up and down under the drive of the push-pull power assembly 4-4. The push-pull power assembly 4-4 uses a cylinder. The cylinder is connected to the air pump installed on the mounting plate 4-3 through a reversing valve to control the push-out and retraction of the charging interface 4-5. When the charging interface 4-5 is in the pushed-out state, it can be inserted into the charging socket on the top of the drone below; when the charging interface 4-5 is in the retracted state, the bottom edge is higher than the bottom surface of the first pressure sensor 4-1, thereby avoiding affecting the detection of the first pressure sensor 4-1.

[0041] The materials of the upper rod 3-1 and the lower rod 3-2 are polylactic acid (PLA) and hollow aluminum tube, respectively. The first pressure sensor 4-1 and the second pressure sensor 4-6 are both conductive rubber pressure sensors, which use conductive rubber as a sensitive element. When the contact contacts an external object and is pressed, the conductive rubber is compressed, causing its resistance to change, thereby changing the current flowing through the conductive rubber. The charging port 4-5 is made of hard aluminum, which is stronger and can withstand a current of 18A.

[0042] The working range of the end effector 4 is 110 mm on the positive and negative x-axis, 110 mm on the positive and negative y-axis, and 60 mm on the positive and negative z-axis.

[0043] An encoder is installed behind the rotating shaft of each drive motor. The phase pulse of each revolution is directly given to the PLC and read through the PLC's high-speed measurement port. The PLC can read the number of pulses at a certain time through interruption. After simple multiplication and division operations, the number of pulses in one minute can be calculated, which is equivalent to how many revolutions.

[0044] Each drive motor is powered by a power module; the power module consists of a battery and two DC-DC regulators. The battery output voltage is 22.7-29.8VDC. The drive motor requires 12VDC and the Intel NUC requires 19VDC. DC-DC regulators are used to reach these voltages. The charging interface 4-5 in the end effector 4 is charged by the battery to deliver energy.

[0045] The top of the drone that cooperates with the charging robot is provided with a square groove; the depth of the square groove is greater than or equal to the thickness of the mounting plate 4-3. A charging socket matching the charging interface 4-5 is provided at the center of the square groove. The side length of the square groove is 5 times the side length of the mounting plate 4-3. The charging socket is provided with two sets of jacks staggered 90° along the circumferential direction; when the charging interface is plugged into any set of jacks, the drone can be charged. As a result, the charging interface has a correct charging posture every 90° rotation.

[0046] like Figures 7a-7d As shown, the working process of the charging robot is as follows:

[0047] Step 1: The charging robot obtains the current route and position of the UAV being charged, and automatically approaches the UAV being charged while being mounted on the power system. The power system is an aircraft used to carry the charging robot for flight.

[0048] Step 2: The power system carries the charging robot to hover above the UAV being charged.

[0049] Step 3: The electronic compass in the charged drone transmits the current position information to the charging robot through the Bluetooth module. The charging robot compares the information with its own position information and makes adjustments. The vertical rotation motor 1-1 on the plane drive module 1 rotates forward until the position information of the plane drive module 1 is roughly aligned with the position information of the charged drone. At this time, the square groove on the charged drone is located directly below the end effector 4. Since the size of the square groove is larger than the end effector 4, the accuracy requirement for this alignment is relatively low, which can be achieved by the flight of the charged drone under the guidance of the communication and positioning system; it can also be guided by machine vision.

[0050] Step 4: The three drive motors on the configuration ring 2 rotate synchronously forward, driving the end effector 4 to descend, so that the bottom surface of the end effector 4 extends into the square groove of the drone being charged and presses against the bottom surface of the square groove; when the first pressure sensors 4-1 all contact the bottom surface of the square groove of the drone being charged and sense current, it means that the end effector 4 is in contact with the drone being charged on the Z axis, and the drive motor stops rotating. If the end effector 4 moves downward to the limit position, the four first pressure sensors 4-1 do not all sense current, then the drive motor on the configuration ring 2 reverses, the drive component 3 moves, the end effector 4 rises, and the charging robot moves back to the top of the drone being charged and aligns again.

[0051] Step 5: Use the direction of the first detected edge on the moving block 1-2 as the first target direction ( Figure 7a U direction in the planar driving module 1), the moving block 1-2 on the planar driving module 1 drives the end effector 4 to move along the first target direction until one of the second pressure sensors 4-6 detects a pressure value; at this time, it is considered that one of the angles is against the side wall edge of the square groove.

[0052] If both second pressure sensors 4-6 sense current, it means that the coordinate axis of the planar driving module 1 of the charging robot is aligned with the coordinate axis of the charged drone, and the charging interface does not need to perform attitude adjustment.

[0053] If only one second pressure sensor 4-6 senses current, it means that the charging interface has an angle deviation relative to the charging socket on the drone being charged; the distance sensor 4-2 located on the first detection edge detects the current distance value x; the controller calculates the deviation angle Wherein, l represents the side length of the mounting plate 4-3. The vertical rotation motor 1-1 on the planar driving module 1 drives the end effector to rotate the deviation angle α, and the rotation direction is determined according to the position of the second pressure sensor 4-6 that detects the signal; if the second pressure sensor 4-6 close to the second detection edge contacts the side wall of the square groove, the end effector rotates forward ( Figure 7c The positive rotation is the rotation direction of the second detection side away from the first detection side. If the second pressure sensor 4-6 away from the second detection side contacts the side wall of the square groove, the end effector rotates in the opposite direction ( Figure 7c The reverse rotation refers to the rotation direction in which the second detection side approaches the first detection side.

[0054] Step 6: Repeat step 5 to confirm that the two second pressure sensors 4-6 detect signals at the same time; at this time, it is considered that the posture of the charging interface is correct.

[0055] Step 7: The two distance measuring sensors detect the distance between themselves and the side wall of the square groove, and determine their position in the square groove according to the two distance values ​​obtained (since the length and width of the square groove are consistent, the distance between the end effector and the two adjacent side walls of the square groove can be obtained according to the distance values ​​measured by the two distance measuring sensors, and then the position of the end effector in the square groove can be determined), as well as the relative position between themselves and the charging socket of the drone. According to the relative position, the planar drive module 1 drives the end effector to move to the top of the charging socket of the drone being charged.

[0056] Step 8. The charging port in the end effector extends out and docks with the charging socket to start charging the drone.

Claims

1. A robot for automatic charging of drones, characterized by: The robot comprises an end effector (4) and a position adjustment mechanism; the position adjustment mechanism can drive the end effector (4) to move arbitrarily in a horizontal plane and to rotate around a vertical axis; the end effector (4) comprises a mounting plate (4-3), a charging interface (4-5), a second pressure sensor (4-6) and a distance sensor (4-2); the mounting plate (4-3) is provided with two side edges forming an angle of 90°; the two side edges serve as a first detection edge and a second detection edge respectively; the second pressure sensor (4-6) is installed at both ends of the first detection edge; the distance sensor (4-2) is installed in the middle of the first detection edge and the second detection edge; the charging interface (4-5) is installed on the mounting plate (4-3) and faces downward; a square groove is provided on the top of a drone capable of docking with the robot; the mounting plate (4-3) can extend into the square groove; The charging interface (4-5) and the mounting plate (4-3) form a sliding pair in the vertical direction; the charging interface (4-5) slides up and down under the drive of the push-pull power assembly (4-4); when the charging interface (4-5) is in an extended state, it can be inserted into a charging socket on the top of the drone below; when the charging interface (4-5) is in a retracted state, the bottom edge is higher than the bottom surface of the first pressure sensor (4-1); The position adjustment mechanism comprises a planar drive module (1) and a configuration ring (2); the planar drive module (1) comprises a vertical rotation motor (1-1), a moving block (1-2), a frame (1-3) and a Y-axis guide frame (1-7); the frame (1-3) and the upper frame form a rotation pair arranged vertically on a common axis, and are driven to rotate by the vertical rotation motor (1-1); the Y-axis guide frame (1-7) and the frame (1-3) form a first sliding pair; the moving block (1-2) and the Y-axis guide frame (1-7) form a second sliding pair; the Y-axis guide frame (1-7) is driven by a motor in conjunction with a conveyor belt; the moving block (1-2) is driven by a motor in conjunction with a lead screw nut; the configuration ring (2) is fixed on the moving block (1-2); and the mounting plate (4-3) is mounted below the configuration ring (2); The position adjustment mechanism further comprises a driving component (3); the driving component (3) is arranged between the mounting plate (4-3) and the configuration ring (2); three driving motors are evenly mounted on the edge of the configuration ring (2) along the circumferential direction; the driving component (3) comprises a driving motor, an upper rod (3-1) and a lower rod (3-2); one end of the three upper rods (3-1) is rotatably connected to the configuration ring (2) and driven to rotate by the driving motor; the other ends of the three upper rods (3-1) and one ends of the three lower rods (3-2) respectively form a spherical pair; the other ends of the three lower rods (3-2) and three different positions of the mounting plate (4-3) on the end effector (4) respectively form a rotation pair; The charging process of the robot for automatic charging of drones is as follows: Step 1: The charged drone and the robot move relative to each other until the square groove is located directly below the end effector (4); Step 2: The drone being charged moves upward or the end effector (4) moves downward until the mounting plate (4-3) contacts the bottom surface of the square groove; Step 3: With the orientation of the first detection edge on the moving block (1-2) as the first target direction, the position adjustment mechanism drives the end effector (4) to move along the first target direction until one of the second pressure sensors (4-6) detects a pressure value; If both second pressure sensors (4-6) detect pressure signals, there is no angle deviation in the charging interface; If only one second pressure sensor (4-6) detects a pressure signal, then there is an angle deviation in the charging interface; the deviation angle is calculated. ; Wherein, x is the distance value x measured by the distance measuring sensor (4-2) on the first detection edge; l represents the side length of the mounting plate (4-3); the position adjustment mechanism drives the end effector (4) to rotate around the vertical axis to a deviation angle α The rotation direction is determined according to the position of the second pressure sensor (4-6) that detects the signal; if the second pressure sensor (4-6) close to the second detection edge detects the pressure signal, the rotation direction of the end effector is the direction in which the second detection edge is away from the first detection edge; if the second pressure sensor (4-6) away from the second detection edge detects the pressure signal, the rotation direction of the end effector is the direction in which the second detection edge is close to the first detection edge; Step 4. The two ranging sensors detect the distance between themselves and the side walls of the square groove, and determine their own position in the square groove and their relative position to the charging socket of the drone based on the two distance values ​​obtained; based on the relative position, the position adjustment mechanism drives the end effector to move to just above the charging socket of the drone being charged, thereby achieving docking of the charging interface on the end effector with the charging socket on the drone being charged.

2. A robot for automatic charging of drones according to claim 1, characterized in that: At least three first pressure sensors (4-1) are arranged at different positions on the bottom surface of the mounting plate (4-3).

3. A robot for automatic charging of drones according to claim 2, characterized in that: In step two, all the first pressure sensors (4-1) detect pressure signals to determine whether the mounting plate (4-3) has pressed against the bottom surface of the square groove.

4. The robot for automatic charging of drones according to claim 1, characterized in that: After step 3 is executed once, step 3 is executed again to ensure that the two second pressure sensors (4-6) detect the pressure signals at the same time.

5. A robot for automatic charging of drones according to claim 2 or 3, characterized in that: The mounting plate (4-3) is square; there are four first pressure sensors (4-1) in total; the four first pressure sensors (4-1) are respectively mounted on the four corners of the bottom surface of the square mounting plate (4-3).

6. The robot for automatic charging of drones according to claim 1, characterized in that: The charging socket is provided with two groups of jacks staggered at 90° along the circumferential direction; when the charging interface is plugged into any group of jacks, the drone can be charged.

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