Lately, there has been lot of new gimbals with Direct Drive, thanks to work done by people like Alex and others. Of course, the first group that made DD servo available to mass has been DJI. They truly deserve accolade and they are still the performance champ.

First of all, I would like to clarify that Servo is nothing more than motor with positional feedback. Even the DD gimbal using motors gets its positional feedback via IMU that is mounted on the gimbal. Whether they are DD or not, they are all Servos. I know that people like to equate servo with typical hobby servo, but that is not true.

At least in hobby realm, for long time, we were limited by available motor (brushed), size requirement and available voltage(typically 5v due to transistors) While speed was nice, it was not as critical as torque and smaller size, so highly geared servos were made, has become standard. In greater motion control industry, servos are used to control many machinery. lot of them are direct drive, while most are belt or gear driven . Some uses screw drive to achieve higher torque/gearing effect. In fact, it is very rare that servo is used in direct drive application unless you need speed more than torque. In our application though, we do get pretty good assist from gravity by having perfectly balanced system, we reduce the inertia down to its frictional component.


anyway, as we all know, acceleration of starting motor depends on...Continue Reading