Well last Friday I planted the tomatoes into their big slabs. Then the mass measurements were all over the place. Without irrigation the mass should be monotonically decreasing, but it was making significant jumps. This was bad because I needed that mass data to run the irrigation timing algorithm. I figured out that the error was from the plant tray rubbing on the guides, piece of wood that keep the tray in the proper orientation when it’s being lifted for tare. The fundamental problem was I used one central piston for lifting, then as it came down it could twist and rub on the guides. This was sort of random so it could cause the mass reading to go up if it was fetching on something taking weight off the load cells. I tried a bunch of solutions, but the one that I put in today used 3d printed ramps on the tray and the lift plates that always try to slide the tray back into centered as it comes down. I used PETG plastic which is pretty slippery so hopefully that works. The proper solution of course is to use 2+ pistons for lifting each tray. I ordered some, but the delivery time was really long (1 month) so the temporary solution needs to work pretty well.
I got my PAR reading system working again. I was using a ADC on an arduino nano but the noise was really high for some reason. I switched it to a Phidgets VINT Hub and works great. I can’t recommend Phidgets enough. The stuff works really well with minimal fussing.
I also worked on tight doors for the ventilation openings. I made one that seals pretty tight using a neoprene gasket. The door slides up and down on bearings and then to seal I made 3D printed ramps so that pushing down on the door pushes it in towards the wall and seals. Actuation will be with a pneumatic piston since I already have the compressed air setup, but that’s a month a way too. For now I can just move it manually.
The tomatoes seem to be growing just fine despite the irregular watering this week. Some small fruits developing, plenty of flowers. I did have some leaves getting spotted, perhaps fungal issues. It has been very foggy here, which in the morning/night can lead to condensation.
Sun Aquasystems 