- Sun Feb 05, 2012 9:51 pm
#139306
StaticDet5 wrote: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 Power is applied and withdrawn from the motor regardless of where it is in the driving cycle.I'm glad I asked, thx for the info ! That's different from what I had believed, though in restrospec it makes sense. If the cyclic rate is high enough the time delay between triggering and firing wouldn't be that noticable and it's less $$s to make it that way.
StaticDet5 wrote: This is one of the things I'm hoping to change. One of my current design projects is to determine when the gearbox is at it's lowest potential energy state (spring relaxed). I'm trying to figure out a proper sensing methodology on the gearbox. I'm actually back to my original idea of detecting motor load.A lot will depend on the motor chosen. If it's overspec'ed the motor may be relatively loafing along even when compressing the spring thus making it hard, in practice, to disintinguish between the 2 states. But a strong motor would cost more $$s than picking a just adequate motor so perhaps the difference btw loaded and unloaded states can be distinguished ... amongst the noise caused by the commutation. I do think you'd have better luck measuring current vs measuring voltage (battery or motor) though. If you attempt the latter you will need some adaptive thresholds as I'd bet that the difference in battery voltage, loaded vs unloaded will be less than that of battery charged vs discharged. Best thing I can think of to recommend is to come up with some test program(s) for Arduino and use it as a low budget O-scope. Collect as many samples as you can, of battery voltage and perhaps motor current, with charged and discharged batts and see if you can devise an algorithm to determine the cycle changes.
StaticDet5 wrote: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.Barring success in using voltage or current to do cycle detection (or the time it'll take to figure it out), I'm sure a good way can be found to do it with a "switch" of some sort. The best way to do this detection depends a lot on the space available though my gut feel is to use some optical method.
StaticDet5 wrote:On the inadvertent gearbox cycling:FETs, due to their high gate impedance, can be prone to false triggering when the voltage across them changes rapidly. Adding the resistor mentioned is good practice ... just in case. I'd only do more than this if testing showed there was good reason to do more. And afterall this is Arisoft and not a real firearm (or real steel as the AS community calls it). An AD is less likely to cause injury, provided one follows the normal safety rules.
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.
StaticDet5 wrote: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 definitely want to see pics when you're all done ! Damn man, you'll have me digging into boxes to drag out my project pistol vs getting packed to move.