The gearbox is run directly by the electric motor. Currently there is no cycle interrupt, or even cycle sensing. Power is applied and withdrawn from the motor regardless of where it is in the driving cycle. This is one of the things I'm hoping to change. One of my current design projects is to determine when the gearbox is at it's lowest potential energy state (spring relaxed). I'm trying to figure out a proper sensing methodology on the gearbox. I'm actually back to my original idea of detecting motor load.
Let me break it down further:
An AEG gearbox (typically) consists of a toothed compression cylinder, backed with a heavy duty spring. This spring provides the power to launch the BB. The compression cylinder is driven by a "sector gear"
. This gear is driven, in turn, by two other gears, and finally meets the motor at the pinion gear.
The motor is energized (typically by closing open switch contacts), which drives the gears. The sector gear engages gear teeth on the cylinder, compressing the spring. The sector gear only has teeth on half of the gear surface that makes contact with the compression cylinder. Once it "runs out" of teeth, the sector gear spins rapidly, and the cylinder flies forward. At this point, the activity in the motor changes dramatically (the motor has gone from being under a maximum load to almost zero load). I'm wondering if I can detect that state.
The reason goes beyond just detection of the motor cycle. If I can regularly detect the "load state" of the motor, it gives another indicator of the "health" of the gearbox. A change in load can signal a variety of issues in the gearbox.
The issue that I currently have is trying to figure out when the gearbox has cycled. I was hoping to use a small neodymium magnet and Hall effect sensor combination, but the location that I originally picked is unsuitable. The location was as distant from the electric motor as possible, and still on the gearbox. I'm wondering if I could put the same magnet (or even a larger one. My current one is an 1/8th of an inch) in the sector gear to determine the location of the gear. It won't give me any kind of measurement of the electrical load of the motor, but it will give me a definitive indicator of the gearbox state. Even if I can determine the state of the gearbox, I'd still like some insight into the electrical load of the motor.
On the inadvertent gearbox cycling:
Years ago I switched to using Dean's connectors for all of my power needs. The only disadvantage to them is that they can be difficult to disconnect or reconnect. There are times where intermittent connection is made during the connection process. I'm wondering if this intermittent contact can induce triggering phenomena through the circuit. Right now, I don't have a way to test this. I do need to consider a way to prevent this, if this is the case. When I'm walking around again, I'm going to try to replicate the circumstances, scientifically.
My current project is something I can plug away at with my leg in the air. I'm going to try to tackle the video display portion of the project.
I've got two uOLED displays from 4D systems (The uOLED 96 and the uOLED 160). Eventually I'd like to be able to use either display, but I'm going to work on the 96 first (
http://www.4dsystems.com.au/prod.php?id=77).
I've tried using existing libraries, but I'm getting compile errors. I'm guessing that the libraries I'm looking at are not supported by the current generation of the Arduino compiler (1.0). Instead, I'm going to begin experimenting with my own code, and possibly start a new line of code.
Again, thanks for the interest and contributions. It's really moving this project forward.