I am using pololu dc motor #4847 for a simple set up. a penetrator is attached to the shaft of the motor, and it is pushed into a bucket of soil and the motor is attached to a UR5 robotic arm. (12 v, pololu motorshiled VNH5109). The problem is that the motor stops rotating at 1.3 A and 70 kg.mm (torque is monitored using UR5)
Based on the motor description, this is way below it stall torque ( 290 kg.mm, 5 A).
I am not sure what I am missing here that the motor is not using its full potential.
If you are measuring only 1.3A, you are likely limiting that current somewhere (for instance, your power supply might be limiting you). Separately, that 1.3A is about a quarter of the motor’s stall current and you are getting about a quarter of the stall torque, so that is as expected and also roughly the limit you should use to avoid damaging the motor.
Thank you Patrick for the response,
I just had the motor directly connected to a power supply to have the set up simpler. The stall current I get is around 2 A, which is way less that 5 A reported. Does this make sense? Or should I be looking at maximum power instead (2.6 A)?
At stall, the motor is basically just a resistor, and the current satisfies Ohm’s Law (I = V/R). The resistance of item #4847 is such that it will draw approximately 5A if it’s stalled while powered at 12V. If you’re measuring something significantly less than this, the likely explanation is your power supply is limiting the current somehow. What is your power supply?
Alternatively, is it possible you have a different motor, like the 12V medium-power version which has an extrapolated stall current of 1.8 A? I can check that for if you post a picture showing the label engraved in the motor case.
