Recently I had a chance to really spend some time on it, and complete my self emptying mod. Posting here in a new thread so its more visible.
First I had to redesign and 3D print the Neato dirt bin so that I could make modifications to it to allow an external vacuum to suck out the contents (hatch on the top of the bin). This was especially difficult because the tolerances of the bin are really tight to get it latch properly, sit low enough to not interrupt the lidar, and for the filter to lock in.
Picture of bin model:
I then worked on the design of the base station. Essentially its just an arm that comes out from the back of the base station. The arm moves up and down via a 8mm threaded rod and a stepper motor. And then 2 static 8mm rods to keep it straight. At the end of the arm, there's a tapered box that the ShopVac hose is attached to.
One slight issue that I have decided to leave as is, the weight from the box at the end of the long arm makes it a bit front heavy. Especially when the shopvac hose is attached. Due to this, the arm bends down towards the front quite a bit. I think the solution here would be a stiffer arm and lighter front "box." However, it doesn't affect performance.
For the electronics, it's just an Arduino, dvr8825 Stepper Motor Driver, Buck boost converter (24V input to 5V output), limit switch, hc-sr04 distance sensor, and a "IoT Relay" for switching on the shopvac. After prototyping it all, I wired everything up on some perfboard and printed a little box for the electronics.
Code and models can be found here: https://github.com/SeanReg/Neato-Self-Empty
Short low quality video of shopvac activating -> cleaning -> turning off -> and then arm begins to move away:
https://streamable.com/4asn7l
Some pictures are below of the base station (I need to take better ones). It definitely isn't a "sleek" or "modern" design for the base station, but it works!