closed loop on pressure

14 years 11 months ago #4954180 by DougWong
closed loop on pressure was created by DougWong
<P style="MARGIN: 0px"><A href=" dev.roboteq.com/dev1/ax3500closeup.shtml " target=_blank><STRONG>AX3500</STRONG></A><FONT face="arial, helvetica, sans-serif"> - </FONT><FONT face="arial, helvetica, sans-serif" color=#0000cc>position closed-loop</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0000cc>Is it feasible to use a pressure transducer feedback signal (amplified) intead of a potentiometer in closed-loop position mode?</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0033cc>We want braking force to be proportional to our demand signal - to control braking force by having the actuator push a brake lever and using hydraulic pressure as feedback to close the loop.</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0033cc>The dynamics are likely different than using a pot - the actuator doesn't move much to increase force, so we reallly want to control the actuator force, not its position. Force in our actuator is proportional to current - I assume PWM gives reasonable control of average current.</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0033cc>Has anyone tried this?</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0033cc>Do the PID tuning constants have enough range to accommodate this scenario?</FONT>
<P style="MARGIN: 0px"><FONT face="arial, helvetica, sans-serif" color=#0033cc>Is the PID loop fast enough for this application? (the pressure changes very quickly with very little movement of the actuator)</FONT>
<P style="MARGIN: 0px">

Please Log in or Create an account to join the conversation.

14 years 11 months ago #4957892 by cosma
Replied by cosma on topic Re:closed loop on pressure

As long as your transducer outputs a signal in the 0-5V range, you should be able to use it as you described. The PID loop executes every 16ms.

Please Log in or Create an account to join the conversation.

14 years 11 months ago #4974573 by DougWong
Replied by DougWong on topic Re:closed loop on pressure

Is it possible to use the controller simply as a PWM driver with no feedback?

We think by making the PWM output proportional to the demand signal, we will get proportional braking.

Please Log in or Create an account to join the conversation.

14 years 11 months ago #4983678 by cosma
Replied by cosma on topic Re:closed loop on pressure
<P style="MARGIN: 0px">You can configure the controller to operate in open loop.
<P style="MARGIN: 0px">
<P style="MARGIN: 0px">However, commands will be read and executed every 16ms.

Please Log in or Create an account to join the conversation.

Moderators: tonysantoni
Time to create page: 0.087 seconds