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Topic: Servo Motor Power Issues (Read 50 times) previous topic - next topic


Hello, I am currently having some issues with a servo that is being used in a project I am working on. The servo (RMCS-2202 datasheet here) is moving erratically and on its own under certain power conditions. The servo is being powered off of two 12V 20Ah SLA batteries wired in series for a total voltage of 24 volts, and then stepped down to 12 VDC by a DC-DC converter manufactured by TRACO Power (TEP 100-2412WIR). When the servo is connected to this DC-DC converter it will move on its own through random rotations to the left or right, stopping occasionally before moving again. This happens only when the Arduino is sending commands to the servo. The Arduino is communicating with the servo through the I2C interface. I am reasonably certain that there is not an issue with the communication with the servo, as it works as intended when wired directly to one of the 12 V batteries in the battery pack (essentially center tapping the battery pack). I suspect that the issue is related either to the servo not getting enough current, electro magnetic interference from other components in the system, or noise from the DC-DC converter. The DC-DC converter can supply up to 8.4 A at 12 V and the servo has a stall current of 7 A so it should be adequate for this usage, but I haven't had a chance to measure the current directly under load. As of right now I am at a loss as to what exactly is the issue, and was hoping someone here might be able to shed some light on the situation and offer a potential solution. Thanks.


It might be related to the bursty nature of the load - many power supplies assume fairly constant
load currents, for instance don't handle sudden changes from 10% to 90% load well.  But I'd
measure the currents and voltages first.  You might just have poor wiring/connections for instance.
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