How do I determine the small movement torque of a servo? I have a project and the servo has plenty of torque to move the mechanism when the movement is large. However when I need to move the mechanism one or two degrees, there is insufficient torque.
The servo specifications only give large movement torque. Is there a specification for small movement torque such as one or two degrees?
Hi Marty,
From a mechanical perspective, servos should have the same amount of torque for small movements as for large movements. However, it is the integrated PID controller – and how exactly it is tuned – that determines if this is actually the case. For expensive servos, we’d expect the torques to be the same, but for cheaper servos, that may not be the case.
Also, many PID controllers are configured to have a certain amount of deadband – a range around the current position where small signal changes result in no action – to avoid torquing the motor unnecessarily for changes so small that the internal potentiometer cannot even read.
Unfortunately, manufacturers don’t usually give specific information about torques of small movements or resolutions of deadbands, and since the torque is determined by the controller more so than the mechanics, there isn’t a conversion equation either.
If you do want to make adjustments within a few degrees, we would recommend considering adding an external gearbox such as the ServoCity 5:1 Top-mount Gearbox for HS-785HB Servo: you might not need the additional torque it gives, but it will also multiply your precision by a factor of five.
Hope this helps,
Jeffrey
