Hi there LV'ers
I have a few motion control problems that are, to quote ' doin my head in'.
I have a system that uses both encoder and analog feedback at varying times during the program operation. This all seems to work fine with the system configuring and re-configuring the analog/encoder etc what ever is required.
My system is then to perform two task under analog control, one is to simply drive to an analog feedback value and hold, the other is to cycle between two analog feedback values.
The main part of the problem that I have is the setting of PID parameters using the MAX autotune facility. This autotune feature works fine with encoder feedback with values in the range of 10 .. 250 for the 3 main PID parameters. When this same task is performed with analog feedback the machine drives at high velocity and comes in with values of 32767 for the PID parameters - clearly an error.
If we try to set the PID parameters for analog feedback manually we come up with a few values in the 10 .. 100's range for the parameters and the motor sort of behaves itself except when we try a simple cycle between two values in the MAX 1-D interactive screen. The one direction move say to 200 (whatever's) works fine, a cyclic move from 200 to 600 will cycle the motor very hard and not actually stop on the desired values etc.
These problems seem as though they are all PID problems and I just can't work out why I can't auto tune on the analog feedback. The transducer we are using is a load cell, although I have changed this to an LVDT just to ensure there wasn't a noise problem on the signal.
Thanks for any help
wayne
---------------------------------------------------------------------- Wayne Galbraith School of Civil and Resource Engineering The University of Western Australia 35 Stirling Highway Crawley 6009
Tel - (08) 9380 3788 email - [EMAIL PROTECTED] ----------------------------------------------------------------------
