Extension of the micro-class notes, the fifth issue | about the plant protection machine
On July 25th , the extension of the micro-classroom invited Guo Ning, the sales manager of Shanghai Topo Robot Co., Ltd., to share the things about the plant protection machine. Regarding the sharing content of the day, the extension of the agricultural small series has been compiled into class notes, which will facilitate the review and review of relevant knowledge in the later stage. Students should not forget to click on the top right corner to collect articles~
Plant protection drone background
The drone was first known as a model or aircraft. With the popularity of the market, more and more model enthusiasts and civil aviation practitioners participated in it, laying the initial technical foundation for the market. The injection of more capital has made the drone market grow rapidly, and the companies that have emerged are also uneven. Segments include entertainment aerial photography, positive photography mapping, and plant protection drones. The drone also has multiple types of rotors, single rotors, fixed wings, and vertical take-off and landing fixed wings.
The plant protection drone that we are talking about today is the first to be used for plant protection operations. It is a manned plant protection aircraft. It has the characteristics of large drug loading and high efficiency in single operation, but it is not suitable for small plot operations. With the maturity of Japan's Yamaha single-rotor plant protection drone technology and its introduction into China, many of our manufacturers have developed their own plant protection drones based on this. The earliest domestic plant protection drones are mainly single-rotor. However, with the multi-rotor MK flight control entering the country, multi-rotor drones have gradually become popular. Especially after the emergence of the multi-rotor market in Dajiang, the development of multi-rotor is more rapid, and the multi-rotor plant protection drone will also be shipped. Health.
Component of plant protection drone
Next, we talked about the components of the plant protection drone. We have always said that the plant protection machine is not a simple patchwork, but a reasonable mix of the system. The reasonable and effective combination of the various parts can make the flight and spraying effect better. The plant protection machine consists of four parts: one is the structural part, that is, the frame; the other is the power part, including the motor, ESC, battery, and paddle; and the third is the control part, covering different forms such as flight control, remote control, and ground station control. Control; Fourth, the spraying part, consisting of water pump, nozzle, etc.
§  Structure part - plant protection machine frame
The general frame structure design should take into account the elements of easy transportation, easy maintenance, durable skin and low cost. Of course, based on these design factors, different manufacturers have different design concepts, and the products they design are also very different. At present, we often see four-axis, six-axis, and eight-axis. Some can't be folded, and some can be folded horizontally or vertically. Depending on the wheelbase, different power packs can be used to achieve different loads. The most common is a load of 10 kg, with four or six axes.
First of all, the unfoldable frame has the advantage that the structural strength and rigidity can be made very high, but the disadvantage is that transportation is inconvenient. Secondly, the vertical folding frame can be carried easily and the connection structure can be minimized. However, if the center plate is not designed well, especially when using the straight paddle, the adjacent paddles will collide with each other when folded down. However, if you use a folding paddle, you will avoid this problem. Finally, the horizontal folding frame has a part of the folding part compared with the vertical folding frame, and it is more convenient to fold and unfold, which is also the reason why the horizontal folding frame is popular.
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Plant protection machine rack assembly precautions
First, the part that is not frequently disassembled, the screw is fixed as much as possible using the screw glue.
Second, as much as possible to ensure that all motor mounting surfaces are at the same height and kept in the same horizontal plane.
Many people often ask a question. If the folding parts have a certain angle, how can we ensure that the motor is at the same height? This problem is really difficult to answer. Theoretically, if the length of each arm is the same, the angle of the opposite of each folding member is the same, then the mounting plane of the motor and each arm are generated. The angle is the same. However, in practice, the processing precision of the folded parts is different, so the upper and lower angles are also different. At the same time, each arm is different, and the final result leads to a large cumulative error. Finally, our plant protection machine is difficult to fly, and the temperature of each motor is different. Individuals tend to be simplistic and less connected, and the stability will be better.
Third, to ensure that the plant's center of gravity is at its geometric center after the planter is assembled. Otherwise, the output of the motor will be inconsistent due to the unbalanced center of gravity, resulting in a decrease in the service life of the entire aircraft and an increase in the failure rate.
§     Power section
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Stable power output is the biggest guarantee for flight safety. When choosing power, many people will encounter problems. What kind of motor, what kind of paddle, what type of ESC, and how big the battery is, especially for the first time, it is more challenging. The more manufacturers come to choose the power package. For example, the K3000 , K5000 , and the 8 Series power kits and 6 Series power kits. Regardless of whether we choose the power mix or choose the power package of the manufacturer, the principle is that the power must have sufficient redundancy when fully loaded. Under normal circumstances, the full throttle takes off, and the throttle output of the aircraft must be below 70% , otherwise There is not enough redundancy to maneuver. This is also the reason why we often encounter the same rack with different power, and the effect of flying out is different.
Secondly, for power, it is not enough to ensure sufficient power. The dynamic balance of the motor and the paddle is better. Otherwise, the vibration of the motor and the aircraft may increase during the high-strength operation of the plant protection machine. More and more unstable issues, this is what many people often say, my plane started to fly very well, but with the use of it is not stable, the first few flights fly very well, but the effect of flying behind is very difference.
Finally, when installing the blade, expand the frame to observe the pitch of the paddle. Generally speaking, the pitch of the paddle is less than 0.2 times of the paddle diameter. The force of the paddle will be greatly reduced due to the vortex interference of the paddle tip, and on the other hand, the vibration of the paddle will be increased. As a result, the vibration of the aircraft is increased. The final result is that the aircraft we see is not stable and the battery consumption is fast.
§     Control section
The control part is divided into two large blocks, one is the flight controller that controls the aircraft, the other is the command control part, the remote control, the ground station control, etc. Next, we mainly talk about the flight controller.
Flying control is also known as the brain of the drone, which is the core of our technology. We can say that the multi-rotor aircraft cannot fly without flight control. The stable flight or hovering of a multi-rotor is achieved by controlling the speed of the motor to achieve a balance between torque, lift and drag. Of course, some people will say that there is another way to control the multi-rotor flight control by using the torque of the paddle to achieve different tension, so as to ensure the aircraft's hovering or stable flight.
Through its high-precision sensor, the flight control senses the attitude change of the aircraft, and then controls the acceleration and deceleration of different motors to stabilize the flight attitude of the aircraft. The general flight control is to achieve stable control of the aircraft through two-stage PID control. Generally consists of magnetic compass, GPS , accelerometer, gyroscope, barometer and so on.
The so-called magnetic compass is the direction of the direction, used to determine the orientation of the aircraft. By sensing the state of the accelerometer, of course, GPS is also used to measure the speed, and the flight speed of the aircraft is ultimately a fused data. On the other hand, the gyroscope is the attitude of the perceived aircraft. For example, how many degrees are in the roll direction, how much the pitch direction is shifted, how much the heading is turned, etc. are calculated by the gyroscope data. By knowing these data, the flight attitude of the aircraft is stably controlled. The barometer calculates the altitude of the aircraft by sensing the change in air pressure. For the attack, the GPS is also participating in the fixed height. Of course, every flight control has its own characteristics, and the control methods are different. It is precisely because these manufacturers have different flight mathematical models, that is, we often say that the algorithms are different and the adaptability is different.
§     Spraying part
Next, we talk about the spray part. Generally, the pumps we see have both brush and brushless. The nozzle is further divided into a pressure nozzle and a centrifugal nozzle. The pressure nozzle has a general plastic fan nozzle and a pressure cone nozzle. There are two types of centrifugal nozzles, quick release and non-quick release. The advantage of brushed water pump is that the cost is lower, but compared with the brushless water pump of the same power, the weight is heavier and the life is lower; in terms of the nozzle, the pressure nozzle is easy to cause blockage when we apply powder or emulsion, and centrifuge The advantage of the nozzle is that it is not easy to block, but the cost is higher compared to the pressure nozzle, and the wind resistance will be worse.
We often encounter the situation that the liquid is rolled up when the airplane is flying forward. Especially when the relative height of the nozzle and the motor is not good, the winding will be more obvious. This is because the eddy current disorder under the propeller causes the direction of the liquid to be unstable. Caused. In order to avoid these problems, the easiest way is to test the spraying of the liquid when the nozzle is different from the motor, and to continuously adjust the relative height to achieve the best results.
Precautions for assembling the plant protection machine
We often see different flight effects on the same aircraft using different flight controls, some suitable for Dajiang, and some suitable for extension. But these are only superficial phenomena, and the reasons are very complicated. So how do we solve these problems? What do we need to pay attention to during the assembly and assembly process? We know that many flight control systems now have internal shock absorption. Like DJI, T-A plant protection flight control has its internal damping. It involves its natural frequency, especially because of aircraft vibration and flight control. The frequency is similar or multiplier, and the half-frequency relationship causes the vibration to increase, that is, the resonance phenomenon causes the flight effect to be poor.
On the other hand, the output frequency of the flight control is inconsistent with the control frequency of the ESC, causing these problems. There is also a mathematical model of power inconsistency. Some paddles do not cause problems on a single plane. For example, when the heading of the remote controller is centered, the motor output of the positive and negative poles is too different. When a certain threshold is reached, it is still not guaranteed. The aircraft's stable hover, then the flight control defaults to the aircraft can not hover, causing the aircraft's spin problem. This threshold is somewhat set by the flight controllers, and some manufacturers are relatively small. It will also happen that we often say that flying with other flying controls is very good, and you can't fly with yours.
These problems are hidden in the flight control algorithm, so the phenomenon is consistent, but the reasons are very different, so as a plant protection company, our professional quality should also be improved. We have been saying that the plant protection machine is not a simple patchwork, but a systematic project, such as some large manufacturers, the flight control is the same as you use, but the flight effect is much better. Many people are copying their shapes, but the reason for doing so is not to understand. We often say that we must know more about it, otherwise we will have problems. We don’t even know where the problem is. It’s hard to solve it. In the end, it may be said that the flight control is not good and the ESC is not good. There are problems with the rack.
It is very likely that we are our own problems. When we assemble, we don’t pay attention to it. The power is not matched well. The installation of the flight control is not good. The strong electricity interferes with the weak electricity. So how do we solve these problems? What do we need to pay attention to during the assembly process?
For the plant protection machine, the deformation of the frame will inevitably occur during the flight. When deforming, the deformation of the material, the direction of deformation, etc., are all calculated when we design the aircraft. Generally speaking, a good airplane is calculated, not pieced together. A good match is achieved by the combination of load and load, frame structure, material and connector. When choosing a rack, we try to choose as few connectors as possible, carry it portable, and fold it. Of course, cost is also one of the considerations. After the power is matched, the disturbance of the tip vortex has a great influence on the flight stability of the aircraft. The high-strength operation of the plant protection machine and the high-temperature and high-humidity environment also make the requirements for each component of the plant protection machine higher.
Especially now, we are more concerned about the durability of flight control, ESC, and motor, but we do not know the durability and stability of the aircraft structure is very important, often we ignore a lot of these aspects. The rack does not cause irreparable deformation for a long time in continuous flight, which is often the basis for determining the durability of our aircraft structure. On the other hand, the dynamic balance of power is also very important. In the case of high-intensity operation, the dynamic balance is not good, which will lead to problems such as electric motor tuning and stalling. On the other hand, the force effect is also something we need to consider. Generally speaking, Motors with small KV values ​​will work better with large-sized paddles, but the corresponding maneuvering wind resistance is also worse, so we must consider the maneuverability and wind resistance while considering the force effect.
Of course, there are still many people who don't know how to choose when they choose the plant protection flight control accessories. First, we need to know what kind of flight effect we want to achieve. Secondly, we need to know what the function and function of each component is, for example, the height is high. Radar, he can not only realize the imitation flight, but also improve the height setting effect. The digital transmission can not only see the data but also realize the self-planning route through the ground station. The role of the RTK is not only to improve the positioning accuracy of the level, but also to improve our Height setting effect. For example, if you want to be able to fly with high precision and full autonomous, you must choose accessories such as rtk , digital transmission, and radar. When assembling the plant protection machine, we are more concerned with the compatibility and matching between the components. Only by choosing a reasonable combination can we achieve good results.
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About the black technology of the plant protection machine
At present, the development direction of plant protection machines is towards intelligent and automated. Many people will also say that the intelligentization of plant protection will only make the employees become less important, and the operation process is too intelligent. These people are just porters. However, some people say that plant protection manufacturers are growing wildly, but the gap in the market lies in flying hands. The shortage of flying hands has caused a large number of plant protection aircraft to idle. The shortage of flying hands is also because the operation of the aircraft is still very complicated. It takes at least one month for a person who has never been in contact to learn from being able to work independently. This has led more and more manufacturers to develop aircraft in the direction of intelligence.
Simple operation, simple requirements for flying hands, so that a large number of flying hands can be quickly filled. However, the intelligence also makes the requirements for aircraft sensors higher, the higher the requirements of intelligence, the requirements for flight control, the power requirements will be higher, and the self-checking function of the aircraft should be improved accordingly. Ability to avoid obstacles, automatic dispensing, filling, active obstacle avoidance, aircraft motor temperature, number of revolutions to be able to monitor in real time, etc.; it can also make the flight control more scalable, the aircraft more intelligent will also make The requirements of flying hands are getting lower and lower. There are still many people who are implementing self-service landing and landing platforms, realizing automatic battery replacement, automatic dosing and other operations. The addition of these technologies will make the drones take off their wings and use cutting-edge technology to drive the growth of agriculture.
The above is all about the plant protection machine. If you have any problems in the process of using the extension flight control and the experience in the actual operation process, you can share it with us and help us further optimize the product. To provide you with better and more practical products.
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question Time
1. Why after changing the flight control, spin phenomenon occurs when the plane took off.
Teacher Guo: If there is a problem of take-off self-selection, you can check it from three points:
First, does the remote control calibrate the median?
Second, whether the motor is installed in balance
Third, whether the magnetic compass is calibrated
2 , the extension of the flight control LED indicator light sometimes appears red light, and sometimes the blue light is long, but not bright.
Teacher Guo: If you encounter this problem during flight, it is recommended to send the LED indicator to the after-sales test to find out the specific cause of the problem.
3. What is the reason for a lack of motor power output?
Teacher Guo: This problem will occur in three situations. First, whether the ESC has been calibrated at the same time. Second, whether the flight control output has a problem. Third, the flight control and ESC connection lines pass through the distribution board. A signal resistance is large, resulting in signal attenuation, which can also cause the above problems, which can be eliminated by the exclusion method.
4 , the effect of the expansion of the flight control with the expansion of the power package flight is better than other power sets, what is the reason? Will the P80 's power kit match the difference?
Teacher Guo: The effect of the expansion and control of the flight control with the extension of the power package will be better, because the program of the ESC has been modified, and the matching of the flight control is better. At the same time, the motor, the ESC and the blade have also been matched. P80 's power package effect is also good, we also have customers in use, P80 blade and motor dynamic balance effect is better, so the body vibration will be greatly reduced, at the same time, force, response, reaction speed is also better It is also good to match the expansion and control flight control.
Warm little stickers
In the coming year, the expansion of the micro-classroom will launch online courses from time to time. We will invite relevant experts such as pesticides and agricultural machinery to station in the micro-classroom. I hope everyone will pay more attention to it. Regarding the plant protection power system, if you have any questions, or if you want to know more about other aspects of the drone, you can pay attention to the official message of the “ Top-Up Agriculture †subscription.
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