I am not understanding autotuning. I enter position and speed, a travel of 23 inches.I send it to the start position and tell it to go. The axis moves anout an inch and stops. No errors. Same thing running in reverse.
So I decided to get some plots for tuning from the plot manager. I set up negitive absolute move to 3 inches (I am scaled) and positive to 26 inches. When I run it I get a great plot. The gains are quite different from foward to reverse. Do I get a plot foward and reverse, then click the autotune button and apply the gains or what. I am a bit confused here. Any sugestions to get the autotune wizzard to work.
The beginning and ending points that you specify in the autotuning are just points that define the valid range within which the autotuning is allowed to move the axis. The auto-tuning will not actually move the entire distance. It will only move as far as needed to to get enough data. On a hydraulic cylinder, this is typically an inch or so, just as you saw.
Since the auto-tuning wizard has absolutely no idea how your system is going to behave, it offers the option to move the system to the starting (or ending) position, and assumes that you have specified a safe range for the auto-tuning.
The autotuning asks you to enter positions and an output voltage, not speed. If you click the help button on the page in which you enter the positions and oputput voltage, it will explain what the output voltage does. If your systme is non-linear with respect to the output voltage going to your valve, you may want to auto-tune it at the voltage that your system is expected to run at.
A single-rod hydraulic cylinder behaves quite differently in the forward and reverse directions, hence the differnet gains. RMCTools uses a Positive Feed Forward and Negative Feed Forward to take care of this difference. The other gains are ratioed by the ratio of the feed forwards.
If you use plots that you have taken yourself, take one of each direction, then in the tuning wizard, choose “Use an existing plot”, click OK, then choose "Positive and Negative direction plots, then in the boxes below, choose the plot that corresponds to the direction. Then the tuning wizard will calculate the correct gains and feed fowards for both directions.
My guess is that your system will tune nicely if you just complete the auto-tuning as it is.
The help topics from the tuning wizard are a little unclear. I will fix them to be more clear.