Mixing
From Combat Robot
About Mixing and Coupling:
Simple radio control systems have a direct relationship between the transmitter inputs and the receiver outputs. On such systems, if you move the stick for input channel 1 on the transmitter only the device plugged into receiver output channel 1 responds. Computerized transmitters (like the Futaba T6X) allow for much more complex relationships between the transmitter inputs and the receiver outputs. Moving the stick for transmitter input 1 on such a system may result in multiple receiver outputs responding, at differing rates and in differing directions!
Why bother with all this digital magic? The simple answer is ease of control. A single stick on the transmitter may be used to control power to both sides of the robot for forward and backward motion. A second transmitter stick can then 'mix' its input with that from the first stick to speed up one side of the 'bot and slow or reverse the other to turn or spin the 'bot around. This differential control is much more precise and natural than the alternative 'tank steer' method.
Two transmitter inputs that have an influence on both their own and each other's receiver outputs is Mixing, while a single transmitter input impacting multiple receiver outputs without itself being influenced by the other involved inputs is Coupling.
Computerized transmitters typically offer elevon mixing, which mixes channels 1 and 2 and is commonly used in combat robots. They may also offer V-tail mixing for channels 2 and 4, and flaperon mixing for channels 1 and 6. The transmitter sticks actually assigned to control the steering and throttle functions on a robot are determined by a combination of mixing and transmitter mode.
Mixing may also be accomplished with a separate electronic mixer that plugs in between the receiver and transmitter. These devices are more limited than computerized transmitters, which makes it more difficult to resolve robot control problems.
See also: 4QD guide to robot control
