# Torque controlled servo

#### Sam Kuiper

Joined May 31, 2017
4
Hi AAC,

For a project for school in am looking for a servo with wich you can read the torque.
I need this for a toys testing setup. The toys need to be rotated at least 180 degrees or until the torque has reached 0.34 Nm.
I thought the best sollution was a servo that can read the torque but i can't find it anywhere so i hope you can help me.

Sam Kuiper
from The Netherlands

#### kubeek

Joined Sep 20, 2005
5,768
I guess you might need to use two separate things, a servo and something to measure the torque. Since your torque setpoint is allways the same you could use something as simple as a spring and a switch, and just calibrate it to trigger at your desired value.

#### Sam Kuiper

Joined May 31, 2017
4
I guess you might need to use two separate things, a servo and something to measure the torque. Since your torque setpoint is allways the same you could use something as simple as a spring and a switch, and just calibrate it to trigger at your desired value.
Thanks for the reply, I will defenitly look into this

#### Sensacell

Joined Jun 19, 2012
2,917
Theoretically, the current consumed by a DC motor can be proportional to the torque produced.

Things get tricky when you consider the inertia of the motor.
Say you run the motor up to a point and cut the power- theoretically zero current, but now the energy stored in the rotating motor armature creates forces that can get really large, at zero current.

Running the motor slowly can mitigate this, but gear trains can introduce all kinds of non linearity.

Joined Jul 18, 2013
23,915
Hi AAC,

For a project for school in am looking for a servo with wich you can read the torque.
I need this for a toys testing setup. The toys need to be rotated at least 180 degrees or until the torque has reached 0.34 Nm.
I thought the best sollution was a servo that can read the torque but i can't find it anywhere so i hope you can help me.

Sam Kuiper
from The Netherlands
An example of the rotation device would help as to show if any mechanical arm or leverage is present etc.
Max.