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+#let post_title = "Building a drone"
+#let post_preview_image = "top.jpg"
+#let post_summary = "Using a raspberry pi and 3d printer to build a drone from scratch"
+
+= Building a Drone
+
+I chose to build a drone from scratch for my AP Physics final project.
+We were given an open ended assignment to _build something cool_
+and I wanted a drone. My choice was much more ambitious than the course required,
+and took quite a while to complete.
+
+For the drones frame I finally had an excuse to purchase a 3d printer. I
+modelled the frame and arms modularly to support future upgrades and
+replacements from damage, reducing the cost of operation. Initially I
+was using some 3d printed torodial propellers due to their higher
+efficiency and lower sounds usage. Due to safety concerns of the
+propellers not withstanding tension at higher RPMs and exploding I
+switched to some generic acrylic propellers I bought. A challenge in
+designing the frame was leaving enough room to contain the volume of the
+wires. I went with the Elegoo Neptune 3 as the printer was open-source
+and had a much better cost-to-utility than proprietary printers such as
+the Ender series. I am not sponsored I just really like the printer.
+
+
+The flight computer was the most difficult part to program. Using an
+ultrasonic distance sensor, gyroscope, and accelerometer the drone has
+enough information to probably never crash. The autopilot is implemented
+on an Arduino UNO using a
+#link("https://en.wikipedia.org/wiki/Proportional%E2%80%93integral%E2%80%93derivative_controller")[PID Controller]
+for stabolization. The autopilot quality is currently impacted every time
+the drones mass distribution changes, which can be fixed with a reinforcement
+machine learning algorithm. For the higher level programming such as flight
+automation, video transmission and WiFi communications I used a Raspberry
+Pi Pico. There is also a 2.4GHz line of sight receiver for manual control.
+A future upgrade may contain a SIM card for near-infinite remote control
+connection, but drone regulations would make this difficult.
+
+The power system is the most physically challenging portion of the
+drone. The motors took 14.6 Volts, while the UNO microcontroller took 5
+Volts, and the Pico and most sensors run at 3.3 Volts. All of the power
+to the motors ran through the power distribution board, which I modified
+to also output the lower voltages and used Bidirectional Logic Level
+Converters to shift between 3.3 and 5V signals where needed. A potential
+flaw with having all the power coming from the same source is spikes in
+energy consumption to the motors may cause the microcomputers to receive
+too little power, which could be fixed with a capacitor. Luckily, I
+haven't experienced this yet as the 2C discharge rate on the 2.5Ah
+capacity battery is more than enough. Having a battery this big does
+mean it takes up about half the internal electronics volume and is half
+of the drones mass, but it can also maintain full throttle for half an
+hour making for long flights.
+
+The motors I used were a bit overkill for a 1.1kg drone, as going past
+20% throttle sends it shooting through the sky, which is not a bad
+issue to have. Here's the technical numbers behind that: I have
+propellers with a 6cm radius on motors with a 2450KV rating (2450 rpm
+per volt) and peaking at 14.6 Volts. From this the tip speed is ~225m/s
+under no load at max throttle, quite a lot more than what
+is safe or necessary to get into the air.