This question is kinda dumb but
Just a basic power problem
I’m trying to build a torsion test
but i cant afford a torque cell
so our group decides to use current and voltage sensor to see if we can detect the change of current and voltage and somehow convert them into force?
So will the current flow or voltage change as the stepper motor try to break a piece of wood stick?
or is there other way to detect force?
Unless you are using the stepper motor as a hammer, how would it break a piece of wood?
Paul
Paul_KD7HB:
Unless you are using the stepper motor as a hammer, how would it break a piece of wood?Paul
we just need it to break cereal stem, i dont know if stepper motor would be enough
The current in a stepper motor does not vary with load - they provide full torque all the time.
The current of a DC motor does vary with the load - assuming the voltage is fixed.
...R
Not necessarily, You'll get constant torque throughout the operation. Stepper motor will be enough to cut cereal stems but not wider wooden sticks.
I think I’d look at a different approach , you will effectively get a snap as the motor moves , a current spike that is fast and hard to measure and includes motor losses etc .
If you had a slowly turning mechanism - motor and say worm gear and use something like a light spring or a strain gain to measure the slowly increasing force .
Have a look at how this is done with testing say metal bars .
Torque is force X distance from fulcrum . Have a google for definitions of force , torque , power
f129luke:
This question is kinda dumb but
Just a basic power problemI’m trying to build a torsion test
but i cant afford a torque cell
so our group decides to use current and voltage sensor to see if we can detect the change of current and voltage and somehow convert them into force?So will the current flow or voltage change as the stepper motor try to break a piece of wood stick?
or is there other way to detect force?
With DC motors the current is a pretty good linear function of torque, with steppers current is by definition
constant and no use at all for measuring torque (steppers are the wrong motor type for this).
Robin2:
The current in a stepper motor does not vary with load - they provide full torque all the time.The current of a DC motor does vary with the load - assuming the voltage is fixed.
...R
The current is not dependent on the voltage (to first order) if the torque is fixed. The speed and voltage
are related (although some voltage is lost to heat in the windings).
MarkT:
The current of a DC motor does vary with the load - assuming the voltage is fixed.
The current is not dependent on the voltage (to first order) if the torque is fixed.
I was trying to cover the situation where the voltage would be deliberately varied by the user - which would defeat any attempts at relating current to torque.
...R
I did a test earlier,
I have a motor with unknown current and voltage (i got this stepper motor from other people, and cant find much information about this motor)
And i use a *current and voltage sensor which can measure up to 26VDC and 3.2A. (according to the page below)
and i test it out, the chip work just fine when I used it on LED bubble
Then i use the same set up to measure the motor, the chip goes really hot right after i run the program and i feel like its going to burn out
But the only power source i attached is 12V and 1A, i don't understand why it goes that hot.
Sensor: Zio Current and Voltage Sensor - INA219 (Qwiic) - SEN-15176 - SparkFun Electronics
f129luke:
I did a test earlier,I have a motor with unknown current and voltage (i got this stepper motor from other people, and cant find much information about this motor)
And i use a *current and voltage sensor which can measure up to 26VDC and 3.2A. (according to the page below)
and i test it out, the chip work just fine when I used it on LED bubbleThen i use the same set up to measure the motor, the chip goes really hot right after i run the program and i feel like its going to burn out
But the only power source i attached is 12V and 1A, i don't understand why it goes that hot.
Sensor: Zio Current and Voltage Sensor - INA219 (Qwiic) - SEN-15176 - SparkFun Electronics
If you really want people to help you, please supply a block diagram showing how you have everything connected. What are you using to control the stepper motor? How do you have it connected to the Arduino? What code are you using to run the stepper motor?
Paul
f129luke:
Then i use the same set up to measure the motor, the chip goes really hot right after i run the program and i feel like its going to burn out
Have you set the current correctly? What did you set it to? Yes the chip will run very hot if
the current is more than 1A or so, since its thermally limited to 1.7A or so even with the heatsink.
But the only power source i attached is 12V and 1A, i don't understand why it goes that hot.
That's upto 12W, so more than enough to get a tiny SMT chip hot! 0.5W in a small component will
get it pretty warm.
Sensor: Zio Current and Voltage Sensor - INA219 (Qwiic) - SEN-15176 - SparkFun Electronics
MarkT:
Have you set the current correctly? What did you set it to? Yes the chip will run very hot if
the current is more than 1A or so, since its thermally limited to 1.7A or so even with the heatsink.That's upto 12W, so more than enough to get a tiny SMT chip hot! 0.5W in a small component will
get it pretty warm.
thx for the answer.
I did not set anything with the current, just default.
What i don't understand is
The chip says can run up to 26V, and the only power source is 12V
Then will it burn out the chip?
And the power source only serves 1A(So I guess the motor can only grab 1A current from the motor, no more than 1A), then how does it burn out the chip which can run up to 3.2A?
(Just a basic circuit problem i don't get)