Join us in becoming tech enthusiasts!
Author: Liu Zeyu
Source: www.dfrobot.com.cn
Recently, I’ve often seen children playing with a non-powered foam plane in the park. It glides quite far once thrown. Out of curiosity, I bought a small hand-thrown plane online to play with, which is perfect for flying in the park. However, I always feel that the flight time is too short and not satisfying enough. It would be great if it could be controlled wirelessly, so I decided to modify it into a remote-controlled plane.
This is the hand-thrown plane I bought online, with a wingspan of 34cm:
I initially decided to use the STC8 microcontroller for the modification. Actually, it can be modified with Arduino, but the peripheral circuit of Arduino’s main control Atmega328P is a bit more complex than that of STC8. Considering the size and weight for the onboard system, I chose to use STC8. There will be a post about using Arduino to modify a remote-controlled plane later, so stay tuned.
Then, I prepared to use two hollow cup motors to drive the plane. The speed difference between the two motors can change the plane’s direction, providing thrust while also allowing for steering, achieving two goals at once. I happen to have two hollow cup motors on hand, model 716, paired with 55mm propellers, which should provide enough power for the plane to take off.
Regarding the battery, I didn’t have a small battery on hand, so I bought a 100mah lithium battery online. It’s lightweight and sufficient for these two motors to fly for about 5-6 minutes. Additionally, small capacity battery chargers are more convenient for quick recharging during outdoor flights.
To charge the plane, I purchased a TP4056 lithium battery charging board, which has a micro USB interface, allowing me to use a power bank to charge the battery conveniently while not flying.
With the motors and battery ready, I can now start developing its control board. Since this is a remote-controlled plane, I need a transmitter for people to control the plane; an receiver to receive signals and control the motors. Therefore, a module is needed to transmit control signals. I selected a relatively inexpensive wireless chip LT8920, with a frequency range of 2.4G, and the manufacturer claims a distance of about 200m. This chip will be responsible for communication. In summary, the receiver will integrate the following components: STC8 microcontroller, wireless chip LT8920, power supply system, motor drive system. The transmitter will integrate: microcontroller, wireless chip LT8920, power supply system. With so many systems, making them small and lightweight is nearly impossible using a standard perforated board, so I designed a PCB to integrate all these circuits onto a small circuit board.
I want to make the entire circuit board as small as possible, so that it can be used for other planes in the future. Ideally, one board should be compatible with various models of hand-thrown planes. Next, I will explain the entire PCB, divided into the transmitter’s PCB and the receiver’s PCB. Since the receiver has a higher requirement for size, it is more complex, so I will first tackle the more challenging receiver part. Below is the schematic diagram of the receiver I have drawn. The core system is enclosed in a box, consisting of four core components. On the left is the microcontroller, which I use for the circuit as well as the communication circuit between the wireless module and the microcontroller, while on the right is the motor drive part and the power supply part.
After converting the drawn circuit diagram into PCB files and arranging the positions and wiring, the general shape has been determined.
The circuit board has two sides. I placed the microcontroller, motor drive, and power supply on one side, and the wireless module on the other side. Thus, the receiver part of the circuit board is completed. Its dimensions are 1.4CM wide and 1.78MM long.
Next, I will complete the circuit design for the transmitter. To enhance the control experience later, I added an ADXL345 gravity sensing module to the transmitter, allowing it to control the plane using either joystick control or gravity sensing.
Due to the addition of the gravity sensing function, the transmitter will have more components. However, the size restriction for the transmitter is not as strict, so it won’t pose much difficulty for the PCB design. The designed circuit diagram is as follows. On the left, from top to bottom, are the microcontroller part, joystick circuit part, and gravity sensing chip circuit part. The right side is simpler, with the peripheral circuit and power supply part for the wireless module LT8920.
To facilitate soldering, all components are placed on the same side. Since only two motors need to be controlled, I used a single joystick instead of the dual joystick design found on traditional remote controllers, making the overall size smaller and allowing for one-handed operation. The designed PCB is shown in the image:
I designed a placement slot for the battery on the back, and thus the overall design of the transmitter PCB is completed, with dimensions of approximately 6.8CM long and 3CM wide.
A few days later, I received the completed PCB board:
Using a hot air gun, I soldered some components:
After soldering, it looked like this:
Holes were drilled in the wings to install the motors.
Assemble the receiver onto the hand-thrown plane. Since there was no extra space on the hand-thrown plane, I removed the nose cover and installed the receiver inside. Connect the motors on both sides and install the battery.
Adjust the CG (center of gravity) of the hand-thrown plane. Generally, the CG of such planes is located at the front edge of the wing, about one-third back. Adjust the battery position so that the nose is slightly raised.
Now the overall modification work is completed, and it’s time to start debugging.
Burn the program into the transmitter and receiver, connect them to the battery, push the throttle stick, and observe the rotation direction of the two motors. The correct direction should be that the two motors rotate in opposite directions (to counteract the motors’ torque). If both motors turn in the same direction, please reverse any one of the motor’s two wires.
Move the joystick to the left and observe if the right motor increases speed while the left motor decreases speed. If the opposite occurs, modify the program or directly reverse the terminals of the two motors.
All debugging work is completed. The plane’s takeoff weight is 27g, and it can take off!
The plane is lightweight, so there’s no need to fear crashes. The motors mounted on the wings ensure they are not damaged during impacts with the ground. According to my actual flight tests, since the plane is too lightweight, it is suitable for flying in light winds or indoors. The 716 motor paired with the 55mm propeller, using a 100ma battery pack, has a flight time of about 5.5 minutes. The charging module purchased online can generally be fully charged in about 15 minutes, so bringing four batteries when going out allows for uninterrupted flying enjoyment. The plane during charging is shown below:
For friends with larger hand-thrown planes (my model has a wingspan of 34cm, which is relatively small), naturally, larger motors are needed for power. This board is also suitable, as the built-in driver module can drive motors with a maximum current of 2.8A, suitable for all motors below the size of 130, 180, 8520. Even larger planes can be easily powered. Thus, the entire modification process of the plane has been introduced. Below are some beautiful photos of outdoor flights as a conclusion!
*Feel free to share with your friends. If you need to reprint, please indicate the source and original author.
The official DFRobot mini-program has officially launched!
700+ open-source hardware one-stop selection
↓↓↓
——Recommended Activities——
Registration Link:
http://mc.dfrobot.com.cn/thread-280766-1-1.html
Project resources click here
Draw beautiful circuit wiring diagrams
New Raspberry Pi 4 | A pen with funny functions | Vibration mini robot
Flexible electronic skin is here | I accepted Captain America’s shield | Arduino mixed beverage machine
Offline sound quality praised electronic piano | Homemade fingerprint box
Makerspace NFC component management system
“Time” embedded in glass windows | “Drink more water” reminder
Cardboard robot cos Su Daqiang | Magic book flipping pages from afar
Laser cutting Chinese chess | Eternal tulip | Solar panel tracking the sun
LED heart lamp | [Must-Collect] 2018 Selected Project Collection!
NFC access control | micro:bit Dutch windmill
GameBuino game console | Weaving wind music interactive art installation
Beautiful works are worth having a “Look”
