Friday, 18 October 2013

A HOG drive, take 2 pt.2

I was going to update my Going Whole Hog post on LMR, but I have been pretty darn busy whenever I have internet acess, so I think I will just throw these pictures up here with a quick discription.

I finished up the chassis that I started in the last HOG drive post:

This one was slapped together (yeah, I know, you can tell) but I tried a couple of new things on it, compared to the first version: The new gimbal design, smaller, tougher, better. Mounting the battery on the front axle, giving it a much better C of G, as well as more weight on the front wheels, which prevents them from lifting up in a tight turn. Wider wheels with better grip, and a wider front stance, partially for the same reasons as the battery, and also for turning and tracking straight, I needed more grip.

Because it was slapped together, it wasn,t very strong, and I did not like a few things about it, asmyetrical steering because of the front swingarm not being parallel to the ground, general shoddyness on the build which caused it to fall apart whenever it hit something, that kind of thing. So I built a new one, from the ground up. The only thing structurely that is the same on this one is the rear gimbal, which proved to work great.

Learning from the lessons from the first two, I implemented better wheels, the battery on the front, the improved gimbal, and a stupidly sturdy frame. The frame is made up of 3 layers of studful technic beams arranged in the pattern you can see in the last pic. The top and bottem frame layers are identical, they are fastened together with friction pins, and have a layer of overlapping bricks in the middle fastening the two layers together. The two servos are fixed in place by the shape of the frame, and two rings of zip ties each. This seems to work rather well, and I have had no problems with them. The frame also has zip ties keeping it together in various places, making it extremly sturdy, I have crashed into too much stuff already, and it hasnt shown any signs of breaking or loosening. I also replaced the fan for the ESC, as during one of the previous versions of GWH, one of the fan blades had broken off making the fan unbalanced and very noisy. I ripped the fan you see off of a broken 2000W inverter.
At the moment it is still an RC beast, but hopefully soon I will mount some sonar on the front and a picaxe or arduino on it let it rip. The way these things are made, it has two throttles, one controling the speed of the motor, and the forward/backward servo/gimbal so I will let the microcontroler have control of the forward/backward servo and the steering servo, and keep the ESC throttle on manual RC control. This will let me have a panic kill switch, and also fine tune the speed for the amount of space it has to run on. So far I have only been able to run him around my kitchen and a little on the wood floor in the house, but I stopped on the wood floor because the rubber wheel leaves little rubber streaks.
Here are two videos of it running on my kitchen floor:

And a video that shows the basic movements that the servos do, along with how that changes the angle at which the hemisphere touches the ground.             

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