Acceleration
14 years 7 months ago #27980840
by roboteq
Acceleration was created by roboteq
Is there a way to turn off the Acceleration parameter, or set it to something faster than 85ms (perhaps 20 ms or less)?
I'm building a control system, and using the AX2550 as an open-loop controller (that is, within a larger closed-loop system (because I have multiple sensors, etc.etc.)). The 85 ms acceleration is now the primary delay in my system. And as I understand it, the Acceleration parameter is a command delay. Is that correct? If so, can we make it not do that delay? That would be so great.
I'm building a control system, and using the AX2550 as an open-loop controller (that is, within a larger closed-loop system (because I have multiple sensors, etc.etc.)). The 85 ms acceleration is now the primary delay in my system. And as I understand it, the Acceleration parameter is a command delay. Is that correct? If so, can we make it not do that delay? That would be so great.
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- cosma
14 years 7 months ago #27989104
by cosma
That value cannot be made lower. What mode are you using the controller? If in analog mode, there may be a way to bypass this.
Replied by cosma on topic Re:Acceleration
That value cannot be made lower. What mode are you using the controller? If in analog mode, there may be a way to bypass this.
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14 years 7 months ago #27992704
by roboteq
Replied by roboteq on topic Re:Acceleration
I've been experimenting with analog and RS-232; not sure which one i'll choose. What is this analog bypass?
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- cosma
14 years 7 months ago #27993157
by cosma
Replied by cosma on topic Re:Acceleration
you will need to configure the controller in RS232 mode and in position mode with analog feedback. PID gains set to P=1, I=0, D=0
The trick here is that the command position is 0 (after reset with no other command received on RS232 port) and put your desired speed on the analog input.
The controller will see any value on the analog input as a position error and immediately attemp to correct by giving the output a value that is 0 (the command) minus the analog value multiplied by the P gain (=1 in this case).
This correction is done without the acceleration ramp.
The trick here is that the command position is 0 (after reset with no other command received on RS232 port) and put your desired speed on the analog input.
The controller will see any value on the analog input as a position error and immediately attemp to correct by giving the output a value that is 0 (the command) minus the analog value multiplied by the P gain (=1 in this case).
This correction is done without the acceleration ramp.
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14 years 7 months ago #27998620
by roboteq
Replied by roboteq on topic Re:Acceleration
We've been working on trying to eliminate signal delays as much as possible from our control system. Switching to the RS-232 interface with the ax2550 made a big improvement over our previous analog control so we would like to stick with it. We've done some measurements of the transfer function for various values of the acceleration parameter and it looks like this is going to be a stumbling block for us. We'd really like to have straight linear control of the motor. Would it be possible to include this option in the rs-232 interface? It would be a big help.
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- cosma
14 years 7 months ago #27999393
by cosma
Replied by cosma on topic Re:Acceleration
This would require some customization of the firmware. We can put it on the list of improvements for the next release keeping in mind that quicker response time will cause extra stress on the power stage.
Please contact us directly via <A href="dev.roboteq.com/dev1/contactus.html" target=_blank>www.roboteq.com/contactus.html for further discussion
Please contact us directly via <A href="dev.roboteq.com/dev1/contactus.html" target=_blank>www.roboteq.com/contactus.html for further discussion
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14 years 7 months ago #28082010
by roboteq
So pretending that the AX2550 is a continuous (and not discreet, which it is) system, do you think the following ascii control system diagram is a good representation of what is happening with the acceleration parameter (with the AX2550 in open loop mode)?
______ Vin dV ______ dV/dt _______ Vout
X--->| K1 |
>( )
>| +K2 |
>| integral |
.
>
|_____| - ^ |_____| |_______| |
|___________________________________|
dV/dt = +K2(Vin-Vout)
Replied by roboteq on topic Re:Acceleration
So pretending that the AX2550 is a continuous (and not discreet, which it is) system, do you think the following ascii control system diagram is a good representation of what is happening with the acceleration parameter (with the AX2550 in open loop mode)?
______ Vin dV ______ dV/dt _______ Vout
X--->| K1 |
>( )
>| +K2 |
>| integral |
.
>
|_____| - ^ |_____| |_______| |
|___________________________________|
dV/dt = +K2(Vin-Vout)
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