Quadcopters are becoming more widespread because they are incredibly stable, fast and fun to fly. Newer technologies have allowed development of smaller and cheaper quads with vast capabilities. While some quadcopters can give hobbyists endless fun of flying an RC toy, others with cameras are extremely popular for taking professional aerial photos or videos, surveillance and 3D terrain mapping.
All quadcopters follow the same mechanical design. A quad is a helicopter consisting of four motors with propellers or blades which give the quad its desired total torque. A gyroscope or accelerometer inside the housing make out how the quad is positioned in space by detecting it’s pitch, yaw and roll. This can be used to correct for any imbalances by adjusting the thrust for each motor individually and make the quad stable in air and hover in place. A pilot uses a transmitter to control the drone, letting it turn, spin, gain or lose altitude.
Main parts of a quadcopter include the frame, motors, propellers, Electronic Speed Control (ESC), flight control board, radio transmitter and receiver, battery and charger – the motors control the total mechanics and balance of the quadcopter; the remote control has a radio transmitter which is used to send adjustments to the antenna and receiver on the quadropter; the Flight -controller is the brain of the drone that controls speed and direction and communicates with the pilot (a software to monitor and control the quadcopter is usually programmed or supplied with the fight controller kit); a high capacity lightweight battery, typically Li-Po battery, supplies power to the motors and electronics; an ESC board varies speed and direction of a motor. Having a battery input and a three phase output for the motor, each ESC is controlled by a high frequency signal to adjust a motor’s speed quickly.
Today, quadcopters are even possible for novice pilots to fly because of breakthroughs in small micro controllers. Earlier, pilots had large workloads to control the rotational speeds and directions of four motors simultaneously with enough precision to balance the drone. But today, this task is done by computerized flight controllers with necessary algorithms which can make the on the fly decisions based on a pilot’ input via the radio controller sticks and controls.
Flight controllers are the most important part of quadcopter design. They can be of varying complexity and selected according to the type of quad and other functions. By programming and configuring a Flight Controller board using different software and calculation algorithms, the same quadcopter can fly differently. Many flight controllers allow different selectable flight modes such as a GPS lock mode, a self-leveling mode, and a manual mode.
Flight controllers often use a combination of an accelerometer and a gyroscope to calculate a good and useful orientation. Good drones also have some ancillary sensors like GPS or Altimeters for extra functionality. Many Inertial Management Unit (IMU) boards are available which combine these sensors. The sensors communicate with a small microcontroller via I2C or analog. Quadcopters often support GPS controls through smartphone, tablet or laptop to help track their whereabouts, follow pre-determined routes, and find their way back to their takeoff point in the event of low battery or when the connection between drone and the controller is lost. For instance, using a mobile app, users can just draw a route on the screen to make the quad follow a flight path using GPS coordinates. With GPS, a quad can even automatically correct for the wind and hover in place.
One of the important concern while designing a quadcopter is keeping small size and weight to simplify its structure and catering applications. While advances in electronics have allowed the production of cheap and lightweight quads with flight controllers, accelerometers, GPS and cameras, future quads will allow avoiding obstacles, cooperating with UAVs (unmanned aerial vehicles) and other vehicles, handling unpredicted flight conditions, tracking moving targets and cross-platform compliance.
Mentioned below are some practical reference designs on Quadropters including necessary documentation like hardware and software design files, user guides, schematics, and more.
- Quadropter For Ground/Air/Water UAV’s: Here is a quadcopter drone which is a very popular design for ground, air and water unmanned aerial vehicles (UAV) as well as motor control applications. It consists of a flight controller and four electronic speed controllers (ESCs), one for each motor. The flight controller is equipped with a radio to receive flight commands provided by the pilot and the inertial measurement unit (IMU). The IMU provides information (such as velocity and orientation) that are necessary for autonomous stabilization of the vehicle, using the internal accelerometer, gyroscope, and sometimes the magnetometer and GPS receiver. This design is based on a single Kinetis KV4x or Kinetis KV5x MCU which helps to drive four BLDC motors of ESC. More on this Reference Design
- Quadcopter Drone based on Cortex-M4 MCU: This reference design includes a real-time flight control board to help users develop flight applications with zero delays. The design is based on Nuvoton’s Cortex -M4 microcontroller supporting high speed ESC (400Hz). A proprietary 10-axis sensor algorithm system allows real-time control of flight dynamics with zero delays. Other components included are a joystick, a 2.4G RF module, and a section board with a Nu-Link-Me emulator that employs a Nuvoton’s Cortex -M4 development board. The system only needs to be connected to an airframe, voltage regulator, motor, rotors, and a portable lithium battery to begin flying. More on this Reference Design
- Arduino-based UAV Helps in 3D Mapping: ArduCopter is an open-source UAV platform based on Arduino. It is an advanced autopilot system for multicopters, helicopters, and other rotor vehicles for applications like 3D mapping. The design offers both enhanced remote control flight (via a number of intelligent flight modes) and execution of fully autonomous missions. Several web applications can be used to allow sharing flight data, videos or even allow web based control. Other features include automatic takeoff/landing and fail safety which detects when vehicle loses transmitter contact. A mission planner software can be used to set up the Copter without any programming. It can be used to point and click waypoints to automate the mission and provide a route for the Copter, and provide visual displays for vehicle state, settings and telemetry. More on this Reference Design
- Open-source RC Quadropter for Surveillance: The AeroQuad is an open source hardware and software project dedicated to the construction of remote controlled four-rotor helicopters, called quadcopters or quadrocopters for purposes such as surveillance, search and rescue, and agricultural applications like mapping of fields. The latest software also supports additional multicopter configurations. The AeroQuad hardware consists of the fully-featured STM32-based AeroQuad32 flight controller board or an Arduino microcontroller (Mega 2560 or Uno) as the flight controller board. Additionally, it comes with an AeroQuad shield with various sensors, such as an accelerometer, gyroscope, magnetometer (heading), barometer (altitude hold) ultrasonic sensors and GPS. The design supports multiple flight configurations, enhanced battery monitoring options, multiple flight options, multiple receiver options and camera stabilization support. More on this Reference Design