VICTOR RESPONSE DELAY? - AGAIN

[yoyodyne]

Al,

I agree that a lot of the delay just has to be mechanical but I would think that even while the armature starts to back off and then the gear teeth disengage and the chain starts to slack (whatever the right terminology is) there would be some hint of system response as soon as the wheels start to slow down but maybe that doesn't even happen for over 100ms. I think that if the gyro response was delayed (although I don't understand how it could be delayed that much unless there are assembly problems as Gdeaver has suggested) then that might explain part of what I am seeing as well. I have an experiment in mind that I will try to carry out sometime this weekend. Basically what I was thinking of doing is to first drive a turntable with a VEX motor with the gyro on it and directly connect a grayhill 256 count per turn shaft encoder and also put a tab on the turntable and have it run through an optical interrupter limit switch. Then set up some simple code to turn it back and forth at different rates and see what the gyro and the shaft encoder are saying. The optical interrupter would give the truth data on the actual orientation. It seems to me that I should be able to see what the lag of the gyro (and shaft encoder to boot assuming there may be issues with that driver). The other experiment on the output side will be to toggle a digital output when the PWM value is changed and see how long it takes to show up on the PWM output. Others have posted that for PWM 1-12 it can be on the order of 50ms. So I will try with PWM1 and PWM 15 to get that data. I imagine there will be a lot of jitter in the delay for PWM1 to PWM 12 so it would be nice to automate that measurement some how and get some statistics - that is probably a bridge too far but a couple of my old standby HP Universal Time Interval Counters could record and dump that kind of data.

Then, if I have those measurements and especially if the PWM output has low jitter using the PWM 15 (Kevin Watson's Timer 3 code) then I could drive the turntable with a VEX gear train and chain to get a real world feeling for the mechanical linkage delays. Being a DSP/communications systems EE type I am really a fish out of water on the mechanical side and I just don't have a good gut feeling for what to expect there.

I'll post whatever data I get.

As for Philmont, I would really like either or both of my sons to go and I wouldn’t mind tagging along! Sea Base and Northern Tier seem to be more of an interest.

Thanks again,

Greg