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Today, Xiaobian is popular for everyone to popularize the multi-rotor UAV flight "pre-preparation": UAV debugging, generally can refer to the following steps:
I. View the structure of the drone and estimate the impact on flight quality.
There are many types of drones, including the use of carbon fiberglass and other integrated molding bodies. There is a mechanism for fixing the motor at the arm end. This type of body has strong rigidity, but the weight of the body is large, the motor position is fixed accurately, and the vibration The source is mainly the variable speed rotation of the motor and the paddle. The body does not generate extra resonance, and the high frequency component is less. The body also uses a double-layer circular carbon plate as the center of the body, and the carbon rod arms are fixedly clamped in the double layer. In the circular carbon plate, the arm has a long overhanging length and is clamped and fixed at the arm end. This type of body has a weak rigidity, and the arm end motor clamping screw is easy to loose, so that the lifting surface of the paddle and the plane of the body The angle is generated. In addition to the variable speed rotation from the motor and the paddle, the loose clamping of the body arm and the motor will cause additional high-frequency resonance components. The body also has multiple carbon rods that are cross-fixed to form a “#†shape. The arm has a short overhanging length and is clamped and fixed at the arm end. This type of body has good rigidity and simple structure and light weight. The vibration source is mainly the variable speed rotation of the motor and the paddle, and the body does not generate any amount.
At the same time, carefully check the motor for low noise at low speed, check whether the motor and the base are loose, whether the motor is in good condition, and whether there is any swaying friction between the rotor and the stator. The flight control installation position or platform should be fixed to the body and there is no additional relative motion or vibration with the body itself. All of the above will worsen the vibration of the body.
The flight control installation position is as far as possible away from the airflow field generated by the high-speed rotation of the paddle, or the hood is installed to cover the flight control, and the influence of the airflow field on the air pressure sensor in the flight control is weakened, especially the design of the larger diameter blade design. Man-machine.
Second, test the response of the motor ESC, predict the impact on flight quality
Emphasis is placed on detecting the response of the motor's ESC to different frequency excitations and the synchronism of multiple motors. First, complete the ESC calibration, and then operate the remote control rocker at different frequencies (such as slow, medium, fast) to excite the ESC motor to see if the motor response can follow the excitation, with obvious delay or stuck and stuck. , check how the ESC handles the excitation signal at a given frequency, with or without filter protection, and short-term overload protection. Especially nowadays, due to the popularity of the agricultural drone market, many manufacturers undertake custom motor ESCs, but there are some problems in the performance matching of motor ESC products, which can not effectively exert the performance of the motor, and the drive motor is defective. Of course, sometimes because of the problem of custom motors, there are serious large inertia and nonlinear characteristics, which are not suitable for multi-rotor drones. In terms of detecting synchronism, you can use a remote control to connect all ESCs at the same time. Operate the remote control rocker at different frequencies (such as slow, medium, and fast) to excite the ESC to see if all motors can follow the excitation synchronously.
Third, install flight control
When installing the flight control for the first time, you can use the thicker and softer double-sided tape to stick the flight control to the center of the machine. Install the flight control position to avoid the power supply wiring around it and form a closed loop. After installing the flight control, follow the instructions for the flight control calibration, including sensor calibration, remote control calibration, flight mode settings, etc. After the calibration is completed, shake the attitude of the aircraft, and adjust the direction of the nose of the drone, and check whether the flight control measurement feedback is correct through the ground station. In addition, after searching for GPS in the outdoor, observe whether the number of stars is stable. When observing that the drone is stationary on the ground, the ground station displays whether the ground speed and vertical speed of the flight control measurement feedback are correct, whether there is a big jump, and whether the height value is stable and correct. If the above conditions are correct, it indicates that the sensor is correctly calibrated and the flight control status is good. 
For the first flight, select the default parameters, take off in the attitude mode, and after the takeoff is normal, the attitude will hover after a period of time. Pay attention to whether the sound of the motor is normal during flight, whether the sound is abrupt or not, and whether there is a sharp sound. This flight data focuses on the accelerometer and gyroscope data. Considering the vibration of the body and the angular velocity vibration, the flight control installation method is suitable. Look at the angular velocity loop tracking situation, consider the response of the ESC motor (including the delay time, whether the response within the flight time is consistent, whether there is no motor reaction status), consider whether the angular velocity loop tracks the existence of static difference, and determine whether the ESC motor is Severe large inertia nonlinear system. Check the angular velocity loop and the angle loop for overshoot and oscillation. The tracking effect is obvious.
All of the above issues need to be considered when modifying control parameters. If the vibration is too large, first consider the state of the body, ensure that the paddle plane is consistent, the mechanical installation part is not loose, and the motor is not faulty. After that, if the vibration is still too much, consider installing a cushion. Installing the cushion will significantly improve the accelerometer measurement noise, but the improper stiffness of the installed cushion will cause the angular velocity measurement noise to deteriorate. When taking off, there will be a tendency for the motor to accelerate and decelerate with self-oscillation, so after installing the cushion Pay close attention to the motor response when taking off, and choose a cushion with appropriate stiffness. To what extent is the body state adjusted to perfection? Main reference: The high-frequency component of the acceleration measurement is low and the smooth gyroscope curve.
In the case that the acceleration and angular velocity measurements are acceptable, the parameters of each control loop are debugged, and the angular velocity loop is adjusted according to the first, and then the order of the angular loop, the speed loop, and the position loop is sequentially performed from the inside to the outside. Firstly, the angular velocity loop is debugged. If the overshoot and the oscillation are large, the sensitivity value is appropriately reduced. If the actual angular velocity response does not reach the expected value, the sensitivity value is appropriately increased. If the static difference is too large, the tracking effect is not obvious, indicating that the nonlinear characteristic is obvious. Appropriate increase of inertia coefficient, larger inertia coefficient will lead to greater inertia of the system, flight is not smooth, too large will cause shock; if there is overshoot and shock, but the degree of overshoot is small, while the angular velocity noise is not large, the data quality is better The oscillating suppression coefficient can be appropriately increased without lowering the sensitivity value, that is, the overshoot is reduced without lowering the system response. If the oscillating suppression coefficient is too large, not only will the oscillation not be suppressed, but also the deteriorating oscillation will occur; each change value is in the original value. Based on the change of 5%-10% on the basis of debugging. Debug to no overshoot and oscillation. If there is no static difference, check the tracking response time. If the response time is too large, the sensitivity value and the oscillation suppression coefficient can be improved at the same time to improve the response. The procedure can be improved, and the response of the motor must be considered. The output control amount and the angular velocity response are mainly viewed, and the response of the motor to the large control amount, the small control amount, the fast change control amount, and the slow change control amount is considered. If the motor itself is a nonlinear system with large inertia and the matching with the ESC is not high, it is necessary to closely check the stability of the system during the improvement of the response process. And adjust the system's highest angular velocity value and linear acceleration value according to the response of the motor. To what extent is the angular velocity loop adjusted? Main reference: 1, no deterioration of the original measured acceleration and angular velocity noise; 2, no overshoot or overshoot is small, no continuous oscillation; 3, response time is within 100ms; 4, small rudder static difference is small. It should be mentioned here that the larger parameters of the heading are more likely to cause the vibration noise of the body to be aggravated. In this case, the lower requirements for the heading tracking characteristics can be selected, and the flight quality is not greatly affected. 
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The drafter of soft solder test method national standards of GB/T28770-2012.
The drafter of lead free solder-chemical composition and type industry standards of SJ001-2007.
Be good at the heart, be sure to do it - talk about the "pre-preparation" of the multi-rotor drone
Editor's note: "I want my eyes to fly to the sky, to see the world under my feet." This may be the original intention of the birth of drones ; in 2020, the demand for Chinese plant protection drones is 100,000, which may be The standard of “scientific and technological agriculture†in the big agricultural country. Drones make us overlook the world, become the promoters of agricultural technology, and even save lives. We understand its role, but we don't know how it takes off accurately and safely. Fourth, take off for the first time, check the body state, determine the direction of debugging