bturep
commented
5 years ago The simplest way to deal with this mechanically would be to sheath the inside servo's mounting head in a hardened plastic tube. The inside diameter of the outer-ring's pivot hole would have to be drilled out to accomodate the combined outside diameter of servo mounting head+sheath.
This strategy has the advantage of requiring and easily sourced material.
This would isolate one servo head from the other electrically.
tygamvrelis
Undesired behaviour was observed when both servos were sent control signals while mounted to the lamp. This behaviour is not observed when they are sent control signals while dismounted. We noticed that the mounting heads of the servos are metallic, and figured it's possible that the servos are interfering with each other through the mounting mechanism.
We made the following observations:
Case 1: Both servos are mounted to the lamp and powered on, but are not given a control signal No motion.
Case 2: Outer servo is mounted to the lamp, and is powered on and given a control signal. The inner servo is disconnected Outer servo moves as desired.
Case 3: Inner servo is mounted to the lamp, and is powered on and given a control signal. The outer servo is disconnected Inner servo moves as desired.
Case 4: Both servos are mounted to the lamp and powered on. They are both sent a control signal to go to 0 degrees The inner servo was definitely going haywire in this case. I recall that the outer servo was fairly stable.
The root cause of this issue needs to be diagnosed. It would be ideal if we could solve it through circuitry (e.g. grounding the lamp) rather than something mechanical (e.g. using different mounting material). We did not try grounding the lamp since we measured a voltage of about 1.5 volts on the mounting head of each servo (powered by 5 V supply) and weren't sure if the mounting heads are floating or if they're being driven to that voltage by circuits inside the motors.