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DumHed
Experienced Roboteer
Joined: 29 Jun 2004
Posts: 1219
Location: Sydney
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I've been doing some serious work on my car for the last couple of days (trying out a new engine configuration), so I haven't had that much time for robot building, but today I picked up a long bolt for the flipper pivot, drilled the holes, and put it together.
The flipper moves really nicely, and the whole thing is very strong, but I'm not 100% sure on the flipper geometry yet.
Basically the ram is a bit longer than I need, but I don't have to use it's full throw if that's a problem.
My main concern is that as the flipper extends there's more and more leverage against the ram, so the lifting power will decrease.
That was always part of the plan though, because as the flipper activates it will have maximum power at the bottom of the stroke, with the power dropping off but the speed increasing as it lifts.
Hopefully that will get it to throw things pretty well, but if there's not enough power in the ram it might not get enough speed up.
Ahh well, only one way to find out
If it's not good enough I have the fatter, shorter ram to try, which would improve the geometry as well as having more power.
The downside to that is slower action, and more gas / air used for each flip. _________________
The Engine Whisperer
- fixer of things
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Tue Jan 11, 2005 11:09 pm |
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DumHed
Experienced Roboteer
Joined: 29 Jun 2004
Posts: 1219
Location: Sydney
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Found the datasheet (it's at work normally). Yeah they're not going to handle amazing current, but they let me test out the design and then decide on what I need.
The nicect feature of these though is that I can get lots of them for free
There are also a few tricks in the board design. One is that I can easily expand the board to run parallel FETs, and the other is that all components are on the same side, with nothing on the back of the board. This means that the whole thing can be clamped against a large alloy heatsink, or even a structural alloy chassis plate, saving weight and space.
So far I'm going to be using a single scooter motor, which won't be excessively loaded.
If I have problems though I'll shell out for some higher current FETs and modify the design if necessary.
The main aspect of this design though are:
modularity - each board will do one task, and be easily changeable
toughness - everything is isolated, and all FETs have overvoltage protection on the gate drive (in case they're used on much higher battery voltage)
simplicity - parts are easily replaceable and construction is quick
scalability - it's easy to add to the overall design to drive different things
I'm doing some smaller weapon control boards as well, and someone I work with has a microprocessor receiver / channel decoder / PWM driver board pretty much sorted, so soon I'll have a configurable full control system that's very easy and cheap to use.
Want one motor drive, steering, and 4 weapon outputs? Easy, just plug in the right boards. Want mixed tank control, a variable speed weapon, and a single output srimec? easy!
The trick now is to get it all working _________________
The Engine Whisperer
- fixer of things
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Thu Jan 20, 2005 9:12 pm |
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