CreFroD wrote:Hello! For solar-powered robot design, I need very efficient, low power motors being able to give 0,5-0,7 Nm torque at 53 RPM. The operation voltage is 6.6V. I haven't seen any brushless motors lower than 30Kv. If I understand it correctly, I need 53/6.6=8,5Kv motor. Is such motor physically possible? Can I take higher Kv motor and drive it slowly, like drone gimbals do? Would torque increase proportionally? I have seen many threads on this topic, but they were about high power (>300W) motors for helicopters/multicopters working at speeds much higher, than 50 RPM. Thank you for help!
yes, there shouldn't be much issue driving a higher kv motor at those lower speeds, though it will require a more robust controller than a low kv motor (less inductance/back emf = harder for the controller to 'control' the motor.
There's also little issue driving a motor at below its rated power level - in your case, ~4W vs 90W rated for the aforementioned unit.
You could also use a gymbal motor, that may be a better option overall. 4W shouldn't be an issue, and you should be able to find one that can provide your desired torque levels.
A servo motor with its 'end points' removed may also be a good option. You can use a voltage divider in place of its pentameter to trick its brian into continuously rotating. A simple arduino program can use the pentameter's actual outputs to get an accurate position feedback too, feed that through a simple PID controller and bias the voltage divider accordingly and you have a simple and (possibly, idk how much a .7NM servo costs) cheap closed loop position control.