knowledge is the best insurance.
1.The principle of Drone flight
The rotor like the wheel is an amazing invention.
The four-rotor uav has become a aerial photography machine, fulfilling the imagination of many ordinary people about the sky.
The rotors can fly and the people who have played the bamboo dragonfly should know that when the hand is rubbed and the bamboo dragonfly a spinning speed, it will produce lift, so that the bamboo dragonfly will take off.
In the same way, a multi-rotor drone is also spun by a motor that causes the propeller to rise and fly. For example, a four-rotor drone, when the combined lift of the four propellers equals the total weight of the plane, the lift of the plane is balanced with gravity, and the plane can hover in the air.
When I was A kid, I read comic books, and saw doraemon and daxiong dragon fly free to fly in the sky, especially want to be like them, can fly in the sky, overlooking the earth.
But if someone had invented the same bamboo dragonfly now, I would have been reluctant to wear it. Because the effect of flying is like this:
The propellers are spinning wildly, and people are spinning in the opposite direction…
According to Newton’s third law, when the rotor is spinning, it also exerts an opposing force (countertorque) on the motor, causing the motor to rotate in the opposite direction. That is why helicopters now carry a small tail, applying a force in the horizontal direction to counteract this reaction and keep the helicopter fuselage stable.
Back to four rotor aircraft, it also can produce such a force of propeller, so in order to avoid the plane crazy spin, the four four rotor aircraft propeller, the adjacent two propeller rotation direction is opposite.
As shown in the figure below, the triangle red arrow indicates the plane’s head orientation, the rotation direction of propeller M1 and M3 is counterclockwise, and the rotation direction of propeller M2 and M4 is clockwise.
When flying, M2 and M4 counterclockwise produced by reactive force (torque) and M1, M3 clockwise reaction force (torque) phase offset, the aircraft fuselage can remain stable, not like a big male rotates the “crazy”.
Not only that, but the back and forth of the multi-axis plane and the rotation flight are also controlled by the speed control of multiple propellers.
This is a good understanding that when the plane needs to raise the height, the four propellers accelerate and rotate at the same time, the lift increases and the plane goes up. When the plane needed to lower the altitude, the four propellers would slow down and the plane would go down.
The reason why it is emphasized is that it is important to maintain the relative stability of multiple rotor speed, so it is very important to maintain the posture of the aircraft body, and you will understand after watching it
It has been said that when the drones have the same rotational speed, the anti-torque of the aircraft has been offset and will not rotate.
But when it comes to the plane spin around, we can take advantage of the reactive torque, M2 and M4 two clockwise rotating motor speed increase, M1, M3 number two counterclockwise rotation of motor speed is reduced, because of the influence of the torque, the plane can produce a counterclockwise rotation.
The level Moving
Multi-axis plane and we usually take a plane, not perpendicular to the ground like jet propeller, so cannot directly produce horizontal force to move horizontally.
It won’t we, of course, and the above four rotor, when need according to the triangle direction arrow, M3, M4 motor propeller will improve the speed, at the same time, M1, M2 motor propeller speed reduction, due to the lift is greater than the front of the plane at the back of the plane, the plane of the posture will lean forward.
Tilted to the side of smooth inspect below, then screw lift produced in addition to offset the aircraft gravity in the vertical direction, also has a component in horizontal direction, the component of the aircraft with the horizontal acceleration, the plane so that it can forward flight.
On the contrary: when M1, M2 motor speeds up, M3, M4 motor decelerates, the plane will lean back and fly back.
In the same way, when the M1 and M4 motors accelerate, and the M2 and M3 motors decelerate, the plane tilts to the left, thus flying to the left.
When the M2 and M3 motors accelerate, and the M1 and M4 motor decelerate, the aircraft tilts to the right and then to the right.
Does this explain that the principle of multi-rotor flight is simple? ~
In fact, before the multi-rotor, people used more complicated fixed-wing aircraft and helicopters to make aerial photography.
However, the landing of the fixed-wing aircraft is very high and cannot be suspended.
While the helicopter is heavy and fast, its structure is very complicated and precise, and t housands of parts are very troublesome in terms of debugging and maintenance.
By comparison, more than simple rotor flight principle, the fuselage structure is more simple, reliable, consumers can quickly get started flying without too much debugging and maintenance, so many rotor aerial soon occupied the market.
2.several major systems of Drone
As we have learned in middle school biology class, the human body can be divided into sports system, nervous system, respiratory system and digestive system.
Like the human body, a complete multi-rotor aerial uav can also be divided into the following major systems: flight control system, remote control system, power system, map transmission system, cloud platform, aerial photography camera.
(1)Flight control system
The Flight control system can be seen as the brain of a drone, whether it is hovering or flying, or in which direction it flies, and is dictated by Flight control.
How does flight control manage to maintain a posture? This is because flight controls contain “cerebellum”, which means there are several sensors, and the basic flight control includes the following sensors:
GPS: to obtain the latitude and longitude information of the aircraft, to determine its own position;
Barometer: used to measure current atmospheric pressure to obtain altitude information of the aircraft;
IMU: an inertial measurement unit, which includes a triaxial accelerometer and a triaxial gyroscope to measure the angular velocity and acceleration of a plane in a three-dimensional space, and then work out the posture of the object.
Compass: used to distinguish the plane’s orientation in the world coordinate system, which is to link the southeast northwest to the front and rear of the aircraft.
A flight control
With the development of science and technology, now also adds some aerial drones on more sensors, such as ultrasonic measuring accuracy height near the ground, in the absence of GPS indoor light flow help plane positioning hover.
After collecting the information from the above sensors, the flight control will fuse the data, determine the location, posture, orientation and other information of the aircraft, and then make a decision on how to fly.
(2)Remote control system
The remote control system includes the remote control of the ground and the receiving module of the aircraft. In addition to pitch (pitch), roll (roll), heading (yaw) and accelerator (throttle) two rocker four channels, also includes flight mode, control yuntai rotation, control switch camera taking pictures, and other functions. These instructions are transmitted to the aircraft via the remote control’s launch system and received by the receiving module on the plane. The current mainstream radio signal is 2.4G signal.
Remote control and receiver
The power system includes the electric tuning, motors, blades, and power batteries of the uav.
Electrical tone: a full – term electronic governor, converting the direct current of the power battery into three alternating current that can drive the motor directly. After receiving the flight control instruction, the motor speed can be controlled to realize the change of the tilt Angle of the aircraft.
Motor: current mainstream motor is brushless motor, the function of the motor is by turning, driving the propeller to turn, thus providing lift.
Blade: the blade is fixed on the motor shaft, rotating with the rotation of the motor, bringing lift to the uav and realizing the flight.
Power battery: the aerial photography uav is currently using lithium polymer as the motive force, and several pieces of core together in parallel, to provide the power for the flight.
Blade, electric, motor
(4)Figure the system
As the name suggests, the image that is seen on the plane is transmitted to the screen in front of the user. In addition to the image, the image transmission also transports the flight data of the aircraft. So the user can see the real-time image and height and speed information on the display and APP. Graph transmission usually USES 5.8 G, 2.4G frequency band.
There are two kinds of graph transmission and digital map transmission, and the digital image in aerial aerial uav is more popular with consumers because of high quality and distance.
In the digital map, the LightBridge technology in Dji is the most effective, but recently Amimon CONNEX of Israel has also introduced a low-latency digital map, which does not know the effect.
Figure the system
If you have ever tried to walk on a mobile phone, you will find that there is a shaking in the picture. The shaking of the plane’s fuselage will also cause the jiggling of the frame, so as to eliminate the jitter, there will be a cloud platform. The cloud is used to capture data through the triaxial accelerometer and triaxial gyroscope, and to calculate the tilt Angle and reverse correction position to maintain the camera level.
Triaxial yuntai can eliminate the upward jitter, for this three yuntai motor, such as the plane tilted to the right, yuntai backward tilt to the left, keep the relative level with the ground, so as to realize the image stabilization.
Some aerial drones contain cameras, while others require a GOPRO or other camera. Special aerial camera with ordinary cameras are basically the same, just because of the aerial is usually far from the camera distance, subject with object distance, the characteristics of the large depth of field, the aerial camera with wide Angle, prime lens.
These major systems are basically the classification of the early model.
Maybe with the development of uav technology.
In the future, it will also develop the “obstacle avoidance system”, “deformation system”. (or already?)
Let’s look forward to it
3. appearance introduction of drone
Today’s we’ll give a brief explanation of what the various parts of the drone do. Take the DJI Phantom 4 as an example.
The consumer class aerial drone is mostly four-axis and six-axis, and the motor on each axis drives the propeller to rotate to generate lift, and thus fly. At present the mainstream of the motor is a brushless motor, the motor is divided into the stator and rotor, the following is the motor stator winding coil, driven by magnetic field permanent magnet steel rotation of the rotor, motor turned up.
The left side is the rotor and the right is stator
Do you often hear people ask whether this motor is 2212 or 2312? What does that mean? It’s the size of the motor. For example, the Sprite 4 motor is 2312, which indicates that the diameter of the motor stator is 23mm and the stator height is 12mm. The larger the first two, the wider the motor, the higher the larger the number of motors.
Careful friends will find Phantom 4 3°outward tilt of motor, this design can make the 4 direction more flexible.
The common propeller is made of plastic, carbon fiber, and 2, 3 leaves. The elf 4 USES two blades of paddle. Why not three blades? Because the simple increase of leaf number does not increase the lift, and also consider the resistance, the battery discharge capacity and other factors.
The propeller is also used in four digits for size, for example, the elf 4 USES 9450 blades, and the first two represent the diameter of the blades, and the latter two represent the pitch of the blades.
There are also different ways of installing propellers, and the consumption class aerial drones have the following ways to install propellers.
Screw fixed blade
Use screws to fix the blade, usually in model aircraft.
The rotation of the propeller is fixed to the motor through the thread, and in the process of the rotation of the motor, the force of the rotation will tighten the blades, but in some cases the risk of ejection will be found.
The quick release oar
Such as self-tightening oar thread damage or stop motor due to blocked steep, can lead to blade fly out from motor (shot), so the latest aircraft tend to use a higher reliability of quick release OARS, such as the elves 4 with a quick release OARS.
3. LED lamp
The consumer class aerial drone usually has LED lights below the arm, which are not just for decoration but for great use.
In flight in front of the red LED lights have played an important role in aircraft position and the helicopter, the rear lights show that real-time status of the aircraft, aircraft normally slow green light flash, for example, is out of control when the yellow lights flash, slow flash a red light when low battery.
4. electrically controlled
After pulling the battery out of the elf 4, you can see from the battery store that some of the circuit boards, this is the electrical palette for the aircraft, are used to control the current size of the motor.
Unmanned aerial vehicle (uav) electronic equipment is also afraid of water, like mobile phone, after the water will affect the warranty, so with a waterproof label in the fuselage, the water turns red, if this label is red when the maintenance, can affect the warranty. So don’t fly on rainy days or foggy days. Take care to prevent flooding back to the south.
5. Ultrasonic/visual positioning/visual obstacle avoidance
The two large circular holes in the center above are ultrasonic modules, using the ultrasonic principle to accurately determine the height in low altitude. The two smaller circles on both sides are the visual positioning module, which is similar to two eyes, using image recognition technology to enable it to hover indoors.
Ahead of the elves 4 feet on the shelf, we also can see two small “lens”, this is the key to the elves 4 obstacle avoidance, based on the three-dimensional imaging of the two lenses, elves 4 can achieve visual obstacle avoidance. Currently, there are several technologies for uav avoidance, including visual obstacle avoidance, Intel realsense technology and ultrasonic avoidance technology.
The part that connects the camera and the fuselage is called a cloud platform, and the cloud can keep the camera stable during flight, removing the jiggling of the frame. Spirit 4 makes some of the clouds in the fuselage, making the entire fuselage smooth.
Images in order to ensure the implementation of all directions stabilization, yuntai respectively three axis: pitch, roll, and heading, each axis has a motor, for use in the plane tilted image to remain stable.
7. Remote control
In fact, during the earliest flight, the remote control for flying drones was almost always like this:
While looking at a lot of buttons, shifter lever is very cool, but with difficulty is also high, which switch need to be set, what functions corresponding to the throttle calibration schedule to such operations as itself. The use of such a remote control often runs up to dozens of pages and stumped new people.