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Controlling the Beast

Hands manipulate the radio-control for toy
Not all controllers are made equal

Controlling the beast

Basic quadcopter controls

A RC Quadcopter is piloted via a transmitter radio’s joysticks and switches. These instructions are then transmitted and received by a receiver on the quadcopter. The quadcopter flight controller serves as the central station where all incoming information is processed. An advanced attitude sensor or 3-axis gyro provides continuously updated flight status while the flight receiver relates instructions from the flight transmitter operated by the pilot. Mixing the pilot’s signals with output from its electronic gyros, the flight controller algorithm calculates and signals the ESCs which in turn determines the speed of individual motors. Even with proper instructions, it's still up to the power of the rotors and the stability of the structure to execute flight requirements.

Standard transmitter & receivers

Consistent signal clarity at longer distances is vital for reliable quadcopter operations but stiff competition in transmitter brands is a breeding ground for overstated specifications. It’s one thing if you are dealing with a $50 toy that weighs a little more than a paper airplane. It’s a whole different matter if you don’t want to jeopardize $3,000 of equipment. Toy transmitter range is usually about 100 metres, sometimes more. If you go beyond this range you may never see the little quadcopter again because the controls are usually stuck in the throttle up position when a pilot looses contact. Although hobby grade 2.4GHz transmitter such as the ones used on the CX-20 Auto Pathfinder quadcopter are rated for 300-500 metres or more, the real distance is only about 300 metres. Without an established standard for testing, a manufacturer can easily claim a 1km range when the signals is only working 90% of the time. Even if a transmitter is functioning at 95% reliability per minute in a 200 metre distance, you will likely loose signals in every other 10 minute flight. For the most part, a failsafe ‘Return to Home’ function is able to save and recover your quadcopter from signal loss. However, prerequisites include having proper GPS calibration for specific locations, establishing GPS based home position prior to takeoff, maintaining all satellite connections and hoping no trees/buildings are in the way. With these real world concerns, it's best to integrate a reputable transmitter and receiver with reliable signals than to be overly dependent on GPS based ‘Return to Home’ functions.

Reliable long distance transmitter & receivers

To address safety and to safeguard your long term investment, a reliable transmitter and receiver set up is an indispensable element of any professional aerial video platform. To service long range operations, a new generation of advanced transmitters such as the Spektrum DX8 and Futaba 14SG employ a combination of cutting-edge technology in the 2.4GHz bandwidth. Frequency hopping technology enables the transmitter to hop amongst bandwidths with the least amount of traffic. Advanced algorithms on multiple receivers or antennas are implemented at different locations for signal path diversity. And, as a last line of defense, these faster transmitters can recover from signal loss within a fraction of a second (as opposed to 3-4 seconds on standard 2.4GHz transmitters), way before the failsafe ‘Return to Home’ function kicks in.

A note on open source Arduino

Open source Arduino flight controllers might be a tempting format for individuals who are interested in adding customized features for research. But generally speaking, the most desirable user-friendly features are already integrated on leading flight controllers. Even from the point of view of an experienced hobbyist, Arduino presents an extremely difficult challenge. Integration may take months and the outcome is often disappointing because a massive amount of tuning is required.


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