Control for tracked vehicles in the form of a single joystick. It is designed for LEGO 8879 Power Functions IR Remote. The presented construction is the best and most functional mechanism of this type that I managed to build. The biggest problem is to obtain rigidity of the structure, so that it can move the pilot potentiometers without any problems. This solution seems to be the best for me at the moment. The symmetry of loads is important here, not necessarily related to the symmetry of the entire structure. If the resistance caused by friction is too great on one side of the structure, then the ratio will be limited to one pilot potentiometer.
LXF file
Lego Digital Designer project
 

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Control for a tracked vehicle