Overload/Overcurrent-protection for servos

Hello everyone!

I'm building a robot that uses 12 cheap hobby servos as actuators. For steering this robot, I am using this servo driver from Adafruit

A big problem with this board is that there is no overload or overcurrent protection. If one of the servos is stuck in a certain position mechanically (e.g. by pressing the actuator against a unmovable part), it starts to draw much current as there is no torque control which eventually leads burning the servo and its destruction.

To prevent this, I would like to implement some kind of overcurrent protection. Does someone know any ready-to-go solution or even a board for this purpose? I know I could build my own solution by measuring each servo current and attaching a relais to the power source. However, a ready-made board would simplify this task a lot and would be better in terms of the robot's weight.

I know there are some servos with inbuilt overload protection, but they are too expensive as my robot uses 12 of them.

Thanks a lot!

ardudu001:
If one of the servos is stuck in a certain position mechanically (e.g. by pressing the actuator against a unmovable part),

Wouldn't it be simpler to ensure that your code cannot command any servo to go too far?

...R

I am assuming your servos are all on the same power source. You can measure the current with a Hall sensor and since your software knows what is operating it can determine when the current is to high. Measure the DC current using Acs712 Hall Effect-Based Linear Current Sensor and arduino. Acs712 can measure current precisely and accurately if properly managed. The more servos you have running concurrently the less accurate this will be.

ardudu001:
Hello everyone!

I'm building a robot that uses 12 cheap hobby servos as actuators. For steering this robot, I am using this servo driver from Adafruit

A big problem with this board is that there is no overload or overcurrent protection. If one of the servos is stuck in a certain position mechanically (e.g. by pressing the actuator against a unmovable part), it starts to draw much current as there is no torque control which eventually leads burning the servo and its destruction.

To prevent this, I would like to implement some kind of overcurrent protection.

Polyfuse per servo, plus 1k series resistor in each servo control line?

Robin2:
Wouldn't it be simpler to ensure that your code cannot command any servo to go too far?

...R

I think the issue is mechanical blockage that the software isn't able to predict...

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