[FW] Tracked 4WD Lifter: Aegis

[R9000]

Alright, we're on CAD revision what, 50 now? xD Anyway, I spent a good amount of time on this one, so hopefully I've thought everything through. Everything I've modelled is either from measurements of components or material I'm going to cut to size and shape. I've got just about all of the electronics together now, and some of the other bits. The linac I'm using shouldn't be too hard to modify with the Turnigy SK3 brushless I've got, but I'll have to work out the exact placement for gears etc by eye when I get round to building it. For the lifting arm, I'm looking at getting some 10mm and 5mm steel pieces cut, which I can countersink, hacksaw or drill as needed. I'm planning for the scoop to be 4mm steel, but I really don't know if it'll be too heavy. Titanium's as possibility I guess, but I don't know if I can get a piece big enough, and I don't really want to go importing anything if I can help it. The linac can shift 300N as it is, so hopefully I'll have plenty of power and speed with the new motor. The scoop might need more than the four screws I've shown here. Also, I realize when fully extended, the linac motor hits the rear lifter axle, I might move the axle back a bit more to fix it, otherwise I'll just have to not push it back that far, or add some kind of limiter switch. The motor and the top of the lifter will have additional thin steel/HDPE armour too, but I'll look at just adding that on later.

The axles for the shovel mech are all 10mm diameter, and I'll be using nylock nuts and washers to keep everything nicely in place. The sides should be about 3mm steel too, but I think I'll go thicker if I've got the weight to play with. The rest will be 20mm HDPE (main frame) and 10mm HDPE (top and bottom). The top isn't really transparent, I just did that so the components are visible. On that note, as you can see, the LiPo is in one of the sides. It's about 500g, so I'm hoping it won't drag the centre of mass too far off, but I'll put something in the other side to compensate if it really becomes a problem. The side compartment was the only place it'd really sit comfortably, because I obviously want to get some foam padding in there too. You can see I'm sort of making the drive motor mounts integral to the chassis, which should hopefully screw together nicely with some barrel nuts. With regard to the wheels; they seem to fit well enough, and give enough clearance from the body to propel the robot without tracks, but I'm adding some tracks made out of some light bike chains I have with 3mm HDPE plates screwed on. The plates will have adhesive neoprene pads stuck on to give extra traction, and I might modify the wheels slightly to help them grip the tracks, but that remains to be seen, since the robot will run fine without them. You can see a breakdown of a section of track in the pictures, but I was too lazy to model it really intricately, much less bend it round the wheels in CAD. Long story short, the chains and screws will sit either side of the wheels, with the connecting plates contacting the outer face of the rubber tyres.

One thing I'm still a little unsure about is how easily the side armour will get chewed off by horizontal spinners. I can't support it through the wheel hubs because the screws won't reach, so it's just attached by two big HDPE blocks in the middle. Should I aim to make it thicker, or try and curve it back round to screw onto the front and back of the body? This'd be tricky with the tracks, but if it's necessary, I should be able to find a way to do it. Anyway, I'll be setting up the electronics tomorrow, getting all the connectors soldered on and testing everything, etc, so at least I'm making some progress. :P

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