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Daniel's Robots - Hellfire Labs - Qld
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Daniel
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Joined: 30 Aug 2005
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Location: Gold Coast


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The axe is controlled by a 24V speed controller. So no to that idea.

And I have the Victor so I can control the speed of the axe when I return it. I've actually programed my radio so the axe will return at a maximum of 20% of full power.

Post Mon Mar 06, 2006 12:41 pm 
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Knightrous
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That's a pretty good idea with the return using 20% rates. I had some shocking issues with Xain tipping backwards and lifting the front (And drive motors) off the ground when the hammer returned. Relays to control a 24v EV was really bad. I'm considering a H-Bridge control to handle the current.

Will be cool to see an active hammerbot again, Fragmentor was awesome, but just never seemed to have much luck.
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Post Mon Mar 06, 2006 3:44 pm 
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Daniel
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Joined: 30 Aug 2005
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Location: Gold Coast


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Almost finished. Today I spent the day cutting and welding (very badly) bits of steel together to make 2 different keep away sticks. One I will use for wedges, drums, flippers and vertical spinners, and the other for horizontal spinners, thwack bots and Scoopy. The second keep away stick is a bit too big so I can only use the pick or Machetti blade, not the hammer or axe.

So many choices.

All I need to so now is solder up the battery connections and add spacers for the Machetti blade as its handle is thinner then the hammer, pick and axe handles.

Post Wed Mar 29, 2006 6:06 pm 
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Daniel
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Joined: 30 Aug 2005
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The event is over. I suppose it didn't do too bad for a first robot. Espicially since it was a back up robot in case Sidewinder didn't want to work.

Everything worked very well on Friday. The chain derailed a few times that day but no more then it did in the final test runs. The fight against Retread didn't go as I planned. I took off all the front attachments so I could have a longer reach and I used the axe as it could really mess up a can, like the fuel filled one sticking out of Retread. But Retread tapped out as I was moving in so I moved the hit sideways and just punched the axe through the flimsy top covers. I would have been nice to crush the butane can, but I'm not that mean since the hit was already late.
http://www.zippyvideos.com/8069600144639866/avenger_vs_retread/
After a quick mess around while Retread was being pulled from the arena I noticed that I lost one side of the drive. Once I got the robot back onto the pit talbe I found that the motor had fallen off the gearbox. So I ripped out the side of the robot and put the motor back on and decided to do the other side just to make sure nothing would go wrong against Reboot.

Well what ever I did between Friday and Saturday really rooted up the drive. I added the forks out the front as the have rails at the back to deflect Reboots drum but when I test drove the robot it wouldn't move. I seemed to have lost all my ground clearance somewhere. When I eye balled it on the table it seemed fine but on the floor it was shyte house to drive. I removed the bottom bolts from the forks so it would act like a hinged system which helped a bit.
I also changed to the pick. Not because I wanted to penatrate the top plate on Reboot, but because I wanted to be able to self right.
Which was lucky because I couldn't turn the robot during the start of the fight. Reboot just hammered me around the arena and I could do was self right and make holes in the floor. Once Reboot ripped off the forks the fight was more fun, although my ability to hit a moving target was no good. I only managed one good hit. The the chain came off, the drive problem got worse (all the body panels came loose) and I got rolled over.
http://www.zippyvideos.com/5811183334640896/reboot_vs_avenger/
The result was what I expected. Reboot is the robot I'm afraid of the most. But it still looked good.

Lots of chunks taken out of the chopping boards but nothing major. The screw being snapped in half and the pressed into the boards was kind of funny though. I'll need to get a picture of that.

Next was Inspector General. So bugger the front attachments, driving is more important. I switched to the axe because I like it and it sounds good. One of the batteries seemed to take a long time to charge but I put that down to being impatient. However the robot only lasted 10 seconds before going dead flat. It seems that Reboot killed one of my SLA's. What a bugger of a way to go out. I told Brett to beat the crap out of the robot and I went and had a sulk.

I borrowed so SLA's from Team Vertex on Saturday afternoon for a melee. I lasted about 15 seconds before I flipped my self while trying to hit No.5. I did better in a 3 way with Orbit and Marauder. They were both pulled out of the arena and I was left to cut a key board in half. I also remember hitting a scanner which fill the arena and my robot with glass. I was still pulling glass out of the robot that night.

On Sunday I rigged the robot to run NiMh packs and challenged Brett to a grudge match. I wanted to see what would happen it I had batteries that could last 3 minutes. Hat off to Brett for spending more then an hour fixing IG for that one fight. And it was a damn fun fight. I remember twice that Avenger sitting on top of IG, slaming the axe into his sides while he was slaming me into the wall on the opposite side of the arena. Oh, what fun. I need a video of that. Shame I lost that fight too.



Anyway, what I need to fix it the chain derailing and the drive problems. A spot of welding will fix the derailing and want to change the robot to four wheel drive to see if that will fix the driving problems. I'll do the drive train setup Helios style.

Post Tue Apr 04, 2006 11:07 am 
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andrew



Joined: 16 Jun 2004
Posts: 3110
Location: Castle Hill, Sydney. N.S.W


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yeah dude, that robot rocked so hard.

Once probs r fixed itll be alot of fun but i was very impressed at how powerful chain and motor setup was.

was cool
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Post Tue Apr 04, 2006 11:35 am 
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Daniel
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Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast


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I've been watching the videos on my fights and now I have a question for everyone.

Has anyone else noticed that robots they have built with the wheels at the back of the robot drive better when compared to robots with the wheels at the front?

It was something that peeved me off with Avenger and The Aggressor and my brother noticed it with the newer Hellbringer. You can see it during the grudge match with IG. I had trouble driving up to IG to hit him with the axe because the robot is slow and won't drive straight but I retreated back across the arena very fast and straight.
Its a shame I can't afford the chopping boards to rebuild it with the wheels at the back so I could test my theroey.

Post Fri Apr 14, 2006 10:19 am 
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Glen
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yep, cause when you accellerate with a rear wheel machine all the weight shifts back onto the wheels making it a really nice to drive. i just stick them in the middle and try to get the thing to balance over the wheels now, get the best of both worlds.

or you could just do the half assed lazy thing and get a gyro in there Razz
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Post Fri Apr 14, 2006 11:51 am 
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Totaly_Recycled
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Yes all our bots drive better back wards lol its probaly got to do with traction from the weight getting lifted on to thedrive wheels under acceleration .the same way its easier to spin the wheels on a rear wheel drive car in reverse as opposed to going fowards.

Post Fri Apr 14, 2006 11:56 am 
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DumHed
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yep, remember the conversation we were having a while back about weight transfer?
That's exactly what's happening.
The wheel's torque effect tries to lift the front and shift weight to the back.
The result is of course that rear wheels get heaps of traction, and front wheels get poor traction.
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Post Sat Apr 15, 2006 7:56 pm 
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Daniel
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Joined: 30 Aug 2005
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Location: Gold Coast


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quote:
Originally posted by DumHed:
yep, remember the conversation we were having a while back about weight transfer?
That's exactly what's happening.
The wheel's torque effect tries to lift the front and shift weight to the back.
The result is of course that rear wheels get heaps of traction, and front wheels get poor traction.


Front wheels? Rear wheels? You do know Avenger and The Aggressor have two wheels? And I did say the 2 wheels version of Hellbringer.

I understand that weight transferance will change loads. I know with a two wheeled robot that has the wheels at the front, the moment created around the center of gravity under acceleration will lower the down force onto the two wheels. However it will never be enough to continuly lift the wheels as in your argument in the other thread, as as soon as the wheels lift then there will be no acceleration and the wheel would drop. The end effect if the robot would sit there bouncing. That doesn't sound plausable. Not unless your getting to an equlibrium point between acceleration and down force, hence slower acceleration..
Its also the fact that the robot would never drive straight in that direction. It would start on a large curve and eventualy spiral it a turn on the spot. We have seen this in 4 seperate robots. Under the weight lifting theroey once the robot begins to loose down force on the 2 wheels, if the center of gravity was off to one side then 1 wheel would have more down force then the other and the robot would always turn in that direction. Unfortuantly for that idea with the testing we did on Hellbringer the turning effect was always 50% in either direction. It was the same with Avenger and Loki.
Anyone care to explain how the direction is always random? Have a bit of a think about first.

Post Sat Apr 15, 2006 8:23 pm 
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Totaly_Recycled
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I get the same efect with the cheese, at the moment its basicly ballanced over both drive wheels and the weight distributionfrom side to side is more or less even .but it also takes off randomly .My theory is that a combination of random efects come in to play .One motor might start slightly before the other at times mabbe one wheel some times has a small bit of grit or other obstacle to over come etc .A slight over acceleration on one side will have the added effect of over ballancing the robot throwing its weight and giveing it more momentum in that direction so it continuses following an arc .
Even the fact if a wheel jumps slightly under rapid acceleration , that would instantly throw the weight on to the opposite wheel which would get more traction and make it go in the oposite direction .
I dont think there is one simple explanation for what happens in this case .

Post Sat Apr 15, 2006 9:27 pm 
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DumHed
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I'd say that slight differences in motor turn on time and differences in the ground would cause the random take off directions.

I realise that we're talking about two wheeled robots here, but those wheels are either at the front or the back, so they're front wheels or back wheels - and they'll have the same effects as the corresponding wheels in a 4 wheeled robot.
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Post Sun Apr 16, 2006 12:55 am 
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kkeerroo
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Here is some stuff my brother forgot to add in his haste to reply. I can't say anything about either Avenger or Loki as I have never been allowed to drive them but here are the 2x 100w scooter version of Hellbringers characteristics:
Driving "backwards" is not a problem.
Driving "forwards" the robot would accelerate slowly but travel in a straight line for 1-2m before going into a spin.
There is no way to predict the direction the robot would spin.
Once the robot has started to spin the only way to stop was to center the controls and wait for the robot to stop completly.
Turning the opposite direction when entering or during a spin didn't help.
A gyro only helped at lower speeds.
With the lightweight pneumatic flipper add-on the robot would spin immediatly clockwise at more than twice the speed that it could while turning.
The above clockwise only spin was due to an offset ball transfer unit.
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Post Sun Apr 16, 2006 9:47 am 
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Glen
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i think the slack in the drive also has a lot to do with it, if you reduce the power on cobra itll spin off to whatever side there is more "foward slack" in i guess i would call it for lack of a better word. thats probably the worst thing with the dewalts in that they have so much slack...

its interesting anyway
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Post Sun Apr 16, 2006 11:19 am 
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Knightrous
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Just a quick question. The K-Mart cutting boards you used to build Avenger, what size do they come in and how much are they?
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Post Mon Jun 19, 2006 8:25 pm 
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