We wanted to a battery-powered PCB quadcopter is remotely controlled on the Blynk app. Acceleration and angular velocity measurements are made by an LSM6DSO breakout board and displayed on the app. The drone is powered by a single cell battery, and the motors are driven by the ESP32 through H-bridge drivers.
Our ESP32 wiring incorporates reset and boot switches to enable easy code uploading. The ESP32-S2 was chosen due to its ability to directly wire a USB port to the chip without the need of a UART IC. A LED is included to visually verify the ESP32 is receiving proper voltage.
Schematic for one of the four brushless DC motors. The wiring for the other motors is similar but the H-bridges are wired to different pins on the ESP32.
The drone's motion is controlled by four brushed DC motors. Brushed motors controlled by an H-bridge allow for easy integration onto a PCB, unlike brushless DC motors. This particular H-bridge allows for directional and speed control of the motor via PWM signals from the ESP32.
The drone is powered by a 3.7V LiPo battery. Due to the fluctuations in battery voltage over its use a voltage regulator ensures a consistent 3.3V to the ESP32. To maximize the power of the motors, the voltage of the battery is wired to power the four motors since at full charge the battery will have a voltage of around 4.2V. The motors were chosen so that they would stay powered despite the battery voltage dropping over its use time.
To collect flight data an IMU is attached to measure acceleration and angular velocity in all three axes. To read the data on the ESP32 we are using the I2C protocol through the SCL and SDA pins on the ESP32.
The board edge was created in SolidWorks and imported to capture the drone shape. The LiPo battery and IMU holder are 3D printed attaching to the mounting holes on the bottom of the board (light blue regions). The board edge geometry pushes the center of mass towards the center of the drone; the battery can then be positioned to adjust the center of mass to provide a more stable flight.
H-bridge layout issues led to us reordering boards but long shipping times forced us to solve our H-bridge issues with external boards. By soldering deadbugged H-bridges to the PCB and mounting them with 3D printed brackets, I was finally able to control the four motors on our drone.
