Raspberry Pi + new hybrid drone

Product design reasons

I went to design a product of Raspberry Pi+ because of the recruitment and selection of the school’s maker training camp on October 7th, and the topic of the selection was:
"Creative Design with Raspberry Pi or Arduino"
, please think about a cost For electronic products not exceeding US$200, at least one Raspberry Pi or at least one Arduino development board must be used. The product should be able to perform specific functions, help specific people, and solve specific problems. The work should not be similar to existing products, such as simple bracelet alarm clocks and desk lamps. The work should conform to the college student innovation and entrepreneurship competition.
And my design is the new multifunctional hybrid drone below

product design

The role of the original
1. Raspberry Pi
As a small card-type computer, the Raspberry Pi serves as the core center for receiving information post-processing analysis and controlling other originals. It mainly supports the Python language (because I don’t know much about the Python language, Therefore, the source code of the control system of the new type of drone is not given here. I will improve it after I understand Python in the future)
2.
A very core problem in the unmanned automatic flight of the GPS receiver is to solve where I am. The question of where to go. Among them, positioning is involved, and here is the on-board GPS mentioned by Mr. Han in the 68th section of Jin class action.
3.
Under the control of the Raspberry Pi, the ultrasonic sensor can identify the surrounding obstacles, move the ultrasonic rangefinder back and forth, and transmit the collected signals back to the data processing center, and the data processing center will display the measured distance. Realize the obstacle avoidance function of the aircraft. (The same, the source codehere will beimproved in the future)
4. Motor and its blades
Here you can directly use four 9600 rpm motor 1045 type blades.
Baidu gave a rough calculation formula for the lift of the propeller: (propeller)the square of thediameter and pitch speed (rad/s) 1 empirical coefficient of atmospheric pressure (0.25) = tensile force (kg).
Calculate the 4 motors can carry 22.297 kg, but because there are only two motors when accelerating, the actual load should be only About 10 kg (the US$200 limit really limits the power of the motor)
5. The steering
gear The steering gear is used to execute the instructions to the Raspberry Pi, and in this aircraft, the front and rear motors are put down (the four-rotor The aircraft is converted into a fixed-wing aircraft), adjust the embedded vertical tail swing to control the flight direction of the fixed-wing aircraft, this requires 4 (two control tails, two control motors)
6. The battery is
used to meet the needs of the motor and enhance the endurance.

(This is a hand-drawn sketch of a simple design concept) (Quad rotor state)

work process:

When there is a need (logistics, firefighting, patrol monitoring, etc.), first check the aircraft, then design a route with the computer, and then start the aircraft. The aircraft will first rise from the quadcopter state to the specified height according to the originally designed route. The Raspberry Pi instructs the steering gear to put down the fixed-wing power motor and transform it into a fixed-wing form, which can achieve high-speed flight. When it reaches the destination point, it reversely transforms into a quad-rotor state and descends to a specified height for operation.
**
(Fixed wing form)
(Note: 1. In order to maintain the propeller's tension balance, the diagonal propeller steering is opposite. When converted to the fixed wing form, the Raspberry Pi command adjusts the rotation of the front and rear power motors to be the same
. 2. Due to the plane Front and rear asymmetry, the speed of the four motors is not necessarily the same before the four-rotor flight, and needs to be fine-tuned after a balance experiment.
3. The fluid surface of the aircraft can increase its lift and enhance its sliding ability)

Function and cost budget

Function brief introduction:
Before introducing the functions, let’s briefly list the advantages and disadvantages of
fixedwing and multi-rotor.Fixed wing:
advantages (1) long flying distance and large cruising area;
(2) fast flying speed;
(3) high flying height;
(4) ) The route can be set to fly automatically;
(5) The recovery point coordinates can be set to automatically land.
Disadvantages (1) Cannot hover to obtain continuous images of a certain place;
(2) Can only fly according to a fixed route and not flexible enough;
(3) The operation is more difficult, which also leads to high risks;
Multi-rotor:
Advantages (1) Small size, Light weight, low noise, good concealment, suitable for multi-platform and multi-space use;
(2) It can take off and land vertically without a catapult or launcher for launching, and can hover, fly sideways, and fly upside down;
(3) Flying Low altitude, strong maneuverability, and strong ability to perform special tasks;
Disadvantages 1) Slow flight speed. It cannot be achieved for the lens that requires high altitude and high speed.
(2) The flying distance is short. Due to technical limitations (remote control), if you want to increase the shooting distance, you can let the remote control stand on the car, which can increase the shooting radius.
Therefore, it can be seen that the combination of fixed wing and multi-rotor can be improved in terms of maneuverability (which is not available in fixed wing) and can be improved in performance such as speed and degree of freedom (which is not available in multi-rotor) and , The use of Raspberry Pi to automatically track flight can solve the problems of limited manpower, receiver signal limitation and manpower operation. In order to solve the problems that will occur during automatic flight, I installed an ultrasonic sensor. This is the method I saw in the CDSN community (Mainly it is much cheaper than lidar). This can be done by programming the Raspberry Pi to build a UAV obstacle avoidance system (this one will be compiled after I learn Python), and a GPS is installed in order to realize automatic flight For the locator, considering the battery life issue and the voltage and power required by the motor, the battery of the Raspberry Pi should not be enough, so a new battery was added.
Cost
Raspberry Pi (4B) 230 yuan
GPS receiver 50yuan
ultrasonic sensor 50yuan
motor 155 4=620yuan
blade 11 4=44yuan
steering gear 11*4=44yuan
battery 38yuan
other building materials (including body materials, pallets, etc.) 50 yuan
Total: 1088yuan<$200

Summary and thanks

During this design process, I checked and learned many other excellent blogs on CSDN, and learned some knowledge in fields that were not covered before. In this design, I also clearly discovered that a simple design often contains a combination of many basic knowledge behind it. At present, this design is just a concept. The internal programming of the Raspberry Pi and the algorithms for its function operation are all I have not designed it yet. Of course, I will solve these technical problems one by one after I have learned professional knowledge in my future university studies. Then I will share with you all the related problems and gains encountered in the process of solving. share together.
PS: Finally, I passed the selection of the maker training camp!