I have always been fascinated by robotics and the electronics under the hood that powers them. Building an Unmanned Aerial Vehicle (UAV) for autonomous flight and FPV has been one of my childhood dreams. Despite a few early unsuccessful attempts, I was yet to achieve this dream until now.
The UAV I chose to build falls into the category of multirotors. It is a replica of DJI Frame Wheel F450 quadcopter. A quadcopter is made up of a few basic components which are described below:
- Frame – the basic structure of the quadcopter. consists of 4 arms, center plate which doubles as a power distribution board and the screws that hold everything together. I decided to go for a replica of DJI Frame Wheel F450 frame.
- Motors – provides the driving force. A quadcopter needs 4 motors. I used 1000kv brushless motors for my build.
- Propellers – generates the propulsive force for the quadcopter. They come in various shapes and sizes. I have used 1045 propellers for my build.
- Electronic Speed Controllers (ESCs) – controls the speed and direction of the motors. A quadcopter requires 4 ESCs, one per each motor. I used 30A SimonK ESCs.
- Flight Controller – acts as the brain of the quadcopter. Controls the speed of motors allowing the quadcopter to maneuver in air. There are a number of both commercial and open source flight controllers in the market which includes KK Multicopter, MultiWii, APM, Pixhawk/PX4 and DJI Naza. I chose to go with APM.
- Radio/Transmitter – primary means of communicating with and controlling the quadcopter. I am using Flysky FS-TH9x (also known as Turnigy 9x). It is one of the most popular radios for aerial vehicles.
- Battery – provides power for all on-board electronics. A quadcopter battery needs to be both light weight and have sufficient capacity to provide adequate flight time.
- Accessories – mostly depends on the flight controller. Accessories for APM includes battery monitor, GPS and in-flight telemetry.
The components I used for my quadcopter build are summarized below:
Building the quadcopter was not complicated at all. Some motors and ESCs in the market comes with banana connectors out of the box. But the ones I chose did not, thus my initial task was to solder banana connectors to the motors and the ESCs. The connectors were soldered and protected with heat shrink tube as shown below:
Next step was to solder the ESCs and the power module to the central power distribution board.
And then the arms were attached to the center plate using screws.
A quadcopter has a few different configurations which includes Quad+, Quad-X and Quad-H (please refer this article for more information about these configurations). Order of the motors and their spin direction depends on the selected configuration. I have selected Quad-X configuration for my build, thus the motor order and spin directions should be as follows:
CW stands for ‘Clockwise’ and CCW stands for ‘Counter Clockwise’. Propellers also have CW and CCW variants, thus they also should be attached to the motors accordingly. Refer the following image on how to distinguish between CW and CCW propellers:
Official APM Documentation has detailed instructions on how to connect different on-board electronics to the APM. Each motor was connected to its corresponding ESC using banana connectors. The 3 wires were connected arbitrary since we can change the rotation direction later just by exchanging any 2 of the 3 wires. Then the ESCs were connected to the flight controller using APM’s output connections 1 to 4 (be mindful to connect signal, + and – pins in the correct order). Finally, the radio receiver was connected to APM’s input connections (1 to 8).
The assembled quadcopter looks like this:
Following steps needs to be completed before we can test the quadcopter:
- Bind Flysky 9x transmitter with its receiver (refer this video for instructions)
- Calibrate APM (refer this article for instructions)
Once the basic calibrations are done on the APM, it is safe to take it out for a test flight. Flying a quadcopter for the first time is not the easiest thing to do, but this video covers all the basics you need to know.
During my testing, I was able to get roughly 20-30 minutes of flight time on a single charge. Following video shows my quadcopter in action: