Part 2 -- Quadcopter? Is it really the answer?

GitHub

 Lessons learnt from the pilot project was not to underestimate the learning curve of making a new system from scratch

, the fact that almost no UAVs uses a bare-metal LoRa to fly should have been a flag since the beginning of the previous project. And therefore, the ESP32-Wrover-cam was ultimately selected for the next development of my personal project which aims to make a cheap, totally commercial-off-the-shelf UAV capable of acting as “an eye in the sky” while it can be stored inside a small bag or a pocket. 

The initial prototype was again, made using straws and cardboards. The frame is configured to be in an H-shape to ease the iterations too, and this Quadcopter uses 4 720 coreless motors, each equipped with a 55m propeller, powered by a single 1s (or 3.7V) Lithium Polymer battery. 

The initial idea was to use ESP-NOW to transmit both video and control transmissions, however, the custom GCS which uses an ESP32S3 did not work due to its large power requirements, and so, the initially fully-physical GCS was switched into an webserver-based GCS written in HTML.

When the link was finally established, a new problem occurred, this time it’s regarding the loading of the UAV, which is too heavy to lift itself. The airframe was then switched to a wood-based frame configured in H-shape. The propellers were also changed to 65mm propellers to provide more lift on a similar RPM. At this point, another problem was found, the ESP32 is too power-consumptive that every time the motor reached around 50% of its total power/throttle, the whole ESP32 was turned off. The solution was to switch the battery to one with a much higher discharge rate. A single step down to 3.3V mini560 voltage regulator along with some capacitors were also attached to decrease power surges that may damage the ESP32. It was also used to prevent the ESP32 from shutting down again. Another major component change was the motor speed controller, initially it uses a bunch of TIP141 BJTs, it was later changed to IRLZ44NS Mosfet to ensure a much smoother motor speed switch.

However, even with these new changes, the power problem still persists, and so the decision was to roll back to the initial idea of using STM32 and LoRa since both draws less current compared to the power-hungry ESP32