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Looking for linear motion suggestions

There is no assumption of more additional complexity for a PWM motor controller. Just a more predictable speed curve

Think about it this way - PWM is just a voltage regulation technique. By controlling the duty cycle you control the voltage. So really what you're suggesting wouldn't be any different from what OP has already tried, unless there is a feedback mechanism to adjust the PWM output dynamically.
 
Think about it this way - PWM is just a voltage regulation technique. By controlling the duty cycle you control the voltage. So really what you're suggesting wouldn't be any different from what OP has already tried, unless there is a feedback mechanism to adjust the PWM output dynamically.

PWM allows more linear low speed, speed regulation than simply varying the voltage. Because you are using the same voltage just varying the duty cycle the power of the motor does not just fade away at low rpm. SO yes, it is different
 
PWM allows more linear low speed, speed regulation than simply varying the voltage. Because you are using the same voltage just varying the duty cycle the power of the motor does not just fade away at low rpm. SO yes, it is different

Hehe :) Typically there is a capacitor bank in front of the PWM source. That capacitor bank is "topped off" during the "on" cycles, and is discharged during "off" cycles. Resistive loading of the circuit results in a voltage drop, and that voltage drop will be maintained as long as the duty cycle is below 100% (and/or below the max voltage of the source). In a typical motor controller feedback from the tach or encoder is used to compensate for loss of RPMs under load - primary control of the duty cycle is calculated in response to throttle demand, but loss of RPMs will additionally increase the duty cycle to compensate.

Now in a switching power supply (adjustable or non-adjustable) there is also feedback, but it's the voltage itself. Power supply will compensate for a voltage drop, which to a point will keep the RPMs constant, but will not be as accurate as RPM-based feedback.

To sum it up, it's not different.
 
You are correct, this is for a variable speed valve actuation. Speed control is the key here, position is not.

Confused,
First it was vertical lift of 100 lbs with 12 inch range and now it is variable speed valve actuation.
Likely can not give details on the net but a few more hints would be nice.

Since it for the day job I'll assume low cost hacks not acceptable.
Is it a product? Will long term availability of the system parts be a concern?
Have motion control systems in the field and in the shop built 40+ years ago. Now some fail (that sucks) and I am glad I designed around standard parts, mounts and connectors and controls.
(Along with please, please document the electrics and label the wires to the print)
I tell people to think that this machine may well outlive you and someone will have to fix it. Do you want them to love you or pee on your grave.
All this adds costs. A lot of cost.
A long life design or handful of years throwaway and tradeoffs? Five million cycle warranty or three months?
Bob
(I warned you many more questions)
 
I just remembered a while ago I bought a cheap one axis cnc controller. Something like $50. Supposedly it can home and control speed/position of one servo or stepper and has a few inputs and outputs. It fits in a 1/16 din space.
 








 
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