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Hardware

Overview

A drone is a computer system with a collection of subsystems and the ability to issue commands in order to change the global state (eg move). We can issue commands to the drone by manipulating a control interface which then converts our commands into radio signals (eg a radio controller), which a receiver on the plane then relays to our flight controller. Alternatively, we can utilize a computer to generate the same commands and define flight patterns via software. When controlling the drone manually, radio dropouts/loss of signal can occur. Likewise, when flying pre-programmed missions we also need a manual overrides, for example if another aircraft is in the vicinity. For both scenarios, we incorporate mission planning to have pre-defined fallbacks and safety protocols. Then we can have the drone execute a plan/return to a known good point (RTL) in case of loss of control or an emergency.

Broadly a drone has:

Flight control system

  • Flight controller -- your drone's brain, which contains an IMU (Inertial Measurement Unit), which estimates what direction is up/the current state. This allows the flight controller to compute our goal state and by extension what thrust the motors need to provide to maintain flight.
  • Flight controller interface -- a board which allows the FC to communicate with hardware and other sensors. On most small drones this will be integrated.
  • DroneCAN -- this is a common interface/protocol (CAN) for sensors and other devices to communicate.
  • Receiver -- this relays messages from a transmitter (radio controller) to pilot the drone.
  • Compass -- Most flight controllers will have one built in, to provide a frame of reference using the local magnetic field. More advanced designs often combine the results of multiple compasses to reduce noise and normalise the results. Remember to calibrate!
  • Barometer -- this provides a backup altitude reference while in flight. Many flight controllers will have one built in.
  • GPS -- this provides the primary navigation data. GNSS (integrating results from other satellite systems) improves our redundancy and reduces variance. RTK is an advanced form of GPS which provides even higher resolution, but requires custom equipment.

Power/flight system

  • Battery -- A large 6S LiPo provides a decent amount of power (~1/2 hour) in the field.
  • Electronic Speed Controller -- this receives signals from the flight controller to regulate voltage states (eg control the motors). DShot is a popular protocol.
  • Power management unit -- this tracks voltage/amperage to estimate battery health and by extension remaining flight time.
  • Motors / propellers / frame -- Your choice here. Carbon fiber provides a lot of rigidity but figuring out how to position elements so that their forces cancel out/are in phase is an important area of building airframes.

Communication/control

Laptop/tablet to run your control layer + chat with the backend.

  • Telemetry radio -- SiK is a common starter here, but more powerful radios and repeaters can dramatically improve the range and the amount of data that can be transmitted.
  • WiFi -- we can also interface with the drone over a local or remote network.
  • USB -- you will be required to connect the flight controller to your computer (eg run Ardupilot in serial mode) at some point.
  • Transmitter -- for manual control of a drone in the field via radio.

Sensors/payloads

Potential options:

  • Companion computer -- to run your control layer locally and relay telemetry data/state.
  • Cameras -- Sony ILX-LR1 is camera built specifically for mapping with a manual shutter, 1/8000 shutter speed, a 61MP sensor and an ISO range of 100-32000.
  • Infrared sensors -- Teledyne makes sensors used in many popular drones.
  • Lidar -- By observing patterned laser light across a space, we can calculate the orientation and distance of any reflections. This is valuable for detecting terrain and 3d imagery.
  • Radar -- We can embed millimeter wave radar and use this to estimate distance as well.
  • Optical flow -- this employs computer vision to estimate distance by computing the amount of pixel change and by extension velocity from a pinhole camera.

NDAA

As of 2024, NDAA hardware is required for drone operations in the United States in certain locations. BlueUAS is a program to certify hardware and simplify the procurement process.

  • Cube Orange+ -- This ecosystem requires more tinkering with settings, but the hardware available is standardized, making it a good general choice. Comes with ADS-B, an important safety tool. Supports RTK capture and injection.
  • 3DR -- US made drone and radio hardware.
  • NWBlue -- NDAA drone hardware vendor.
  • ModalAI -- PX4 developer kits, with support for running TFLite models on device.
  • Wingtra -- Advanced VTOL surveying drone platform.
  • Ebee-X -- Advanced surveying drone platform.

Non-NDAA

  • Holybro -- Very up to date hardware that implements the Ardupilot and PX4 specs, with an ecosystem of sensors similar to the above.
  • NewBeeDrone -- California drone supplier.
  • Heewing Cruza -- VTOL with good endurance.
  • Argus ROC WING VTOL -- Similar to the Cruza, with a H7 controller.
  • Emlid -- tools for capturing GPS data.