Well, it's almost two years later (and about a week before we skip town!), and other than needing replacement diaphragms (normal maintenance) the original pump system is going strong.
However, the student who took over my wife's project after she graduated decided he needed higher gas-sparging rates so it was clearly time for (channeling Tim Allen) More Power:
Okay, so its hard to tell just from looking at them, but those are larger pump heads on larger DC motors, with a max flow rate of 15 liters/minute (the old ones topped out at 5). Conveniently, the bigger motors are more efficient, drawing only 0.8A at 12V (compared to 1.0A for the old ones), but their current spikes are even more monstrous.
I didn't have nearly as much time to work on this one, so it's a little less pretty (plastic cups protecting the tachometers instead of acrylic pipe, etc...) but it works perfectly. Also, especially after having built a similar system with the SMC03As, it was an absolute joy to work with the Jrks and the configuration utility. The GUI is very intuitive and the visual feedback is invaluable! It cut the system tuning time down by a factor of 20 at least!
I did run into one minor issue with the Jrks. I know its been brought up before that the Jrk acceleration parameter only limits increasing duty cycles, but lets them decrease to zero in a single PID cycle. I started running these pumps with 0.1uF caps and a slight acceleration limit, which worked fine for increasing the speed, but which would send my power supply into self-shutdown whenever I stopped the motors. I ended up having to go with 10uF caps to prevent this.
I can understand how it could be desirable for a robot to be able to emergency-stop (this could also be achieved with the Motor Off command), but in a lot of situations automatic smooth ramping of both increasing and decreasing speed would be really nice. Ideally acceleration and deceleration could be separate parameters. I understand that would be a pain, since you would need to run a firmware revision AND modify the configuration utility. As a quick fix, maybe you could create an alternative version of the firmware that applies the acceleration parameter both ways and let the customers decide which version to load.
Just a thought, and other than that minor detail I'm super-happy with the Jrks!