I been doing a project for Stroke Patient, it is related to a load cell to test the grip strength of the patient.
Project includes:
Arduino Mega 2560
Planetary dc motor (IG42-S14E DC12V 405RPM 6.5kg.cm)
13Amp 6V-30V DC Motor Driver
5kg Load Cell and module XFW-HX711
PWM doesn't control the force consistently I'm afraid.
You need to measure the current through the motor, that is linearly related to the torque of the motor.
You can then use a PID loop to set the torque by adjusting the PWM in a feedback loop.
However if the motor is stalled (stationary), then the relationship between PWM and force will be more
consistent. It will change as the motor warms up though.
MarkT:
PWM doesn't control the force consistently I'm afraid.
You need to measure the current through the motor, that is linearly related to the torque of the motor.
You can then use a PID loop to set the torque by adjusting the PWM in a feedback loop.
However if the motor is stalled (stationary), then the relationship between PWM and force will be more
consistent. It will change as the motor warms up though.
Is there a tutorial? cause i can't seem to find any related to it.
SoraJayson:
My motor driver is from Cytron Technologies. MD13S. Rare right?
it looks like a brushless motor driver, but your DC motor is ordinary. You probably you don't need this.
just use a logic level Mosfet and connect your load to the drain with a protection diode
if I am right brushless motors used in the applications where speed matters, such as a quadcopter
SoraJayson:
Is there a tutorial? cause i can't seem to find any related to it.
I doubt anyone else is doing this - is it being used stalled as I surmized? The only accurate way
is to measure the current, and even then you have some uncertainty related to static friction.
Stalled motors tend to heat up (no air cooling), so the friction can change, as will the response to
PWM (the windings increase in resistance). Measuring the current seems like the most repeatable
and sensible approach if consistency is important.