OK, I'm at a loss for words on this one. I'm looking for a word or phrase to describe the following situation...
I have an open loop control system that when I apply voltage \$A\$ I get output \$A_1\$. When I'm at state \$A_1\$ I apply voltage \$B\$ (\$B > A\$) I get output \$B_1\$. But when I apply voltage \$A\$ again I get output \$A_2\$ (\$A_2 \ne A_1\$).
I'm still not sure about hysteresis. I took some data on the system and attached a graph of what I'm seeing. The system is a camera with a liquid lens and a voltage source. The blue line represents starting at voltage step 126 and then starting to capture an image at each voltage from 127 to 143.
The red line represents setting the voltage to 144 and then capturing the same image moving from voltage step 143 to 127.
You can see that depending on which way I come from the results are different for the same voltage step.