Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Lintilla - NMO - Vic
Robot Stats
Team name: NMO
Robot name : Lintilla
Team location : Victoria
Robot weight(Class): Feather weight
Type of Robot: Thwackbot
Drive system : 2 18Volt DSE Andrew mods
Type/size of wheels : Bunnings red wheels
Speed/motor control:
Power: 18V CP 2400's
Armour: Steel, UHWM, Rubber
Radio: Spektrum
Fri Jan 19, 2007 11:10 am
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
So some questions for people.
What is the thinnest mild steel we can get away with these days against spinners?
I'm hoping the answer is 5mm. I know that copbra is 6mm and I think that some parts of spyder are 10mm or something.
Here's a concept drawing I've been working on for a few days
Fri Jan 19, 2007 11:11 am
Spockie-Tech Site Admin
Joined: 31 May 2004
Posts: 3160
Location: Melbourne, Australia
"Shape" is probably important to the question of how thin the armour is required to defend against a spinner.
If you put a nice flat solid wall in the way of a high velocity bullet, you are going to get maximum energy absorbtion and hence damage.
A thinner angled traingulated angled structure will deflect a portion of the energy in another direction, destabilising the spinner and preventing you from experiencing the "jumped in front of a train" effect.
Think about force vectors and diverting the flow (like Judo) rather than taking the punch in the face. Spyder's body and wedge shapes are good examples of this.
A parallelogram shaped body with braces in the triangle corners for your thwack bot will give you a chance of diverting horizontal spinners as well as swecondary wedges that will work either way up. There was an American thwack bot that was built like this, but I forget its name right now. I think Gary knows it.
It may be more likely to be "caught" by vertical spinners, but as long as you leave the extremeties of the triangles empty, that would be air-armour.
Your dual-pipe walls look like they would be very structurally strong too, but are going to divert any hits above the 1/4 and below the 3/4 mark *into* the center join area rather than away from you. _________________ Great minds discuss ideas. Average minds discuss events. Small minds discuss people
Fri Jan 19, 2007 12:44 pm
Daniel Experienced Roboteer
Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast
If you want a steel tube for armor, steal a street sign. That's what Hellbringer was made out of.
But your better off deflecting hits rather then trying to absorb them. Just make some trapazoidal panels and weld them around the outside at 45 - 30 degrees. And at 30 degrees a 3mm thick panel looks 6mm thick to a hozrizontal spinner.
As for a thwack bots, try to get the wheels as close to the center of gravity as possible. Don't put the wheels in the center of the chasis but closer to the hammer and put all the batteries and electronics on the other side. That way it will naturally lift off the ground when spinning. Also I used 18V drills with 150mm wheels and 24V batteries in colorful version of Avenger and it had a mean thwack attack. As it spun the chasis and axe would lift so that the balance was perfect and the center of gravity was directly over the wheels.
http://www.youtube.com/watch?v=TBUkZ2yqzK8
Fri Jan 19, 2007 1:00 pm
Rotwang Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1589
Location: Vic
Twrex or something likes that, and I agree about the centre of gravity thing, both versions of bane have the weight on the wheels.
Jolt doesn’t seem to respect angled armour the way it should, the holes in IG are in a smooth angled area where you would think it would deflect and its sliced through the tough stainless. 1.6mm isn’t thick enough, the laminated section on IG’s back held up well.
The 3 mm on the front of bane also held up well to Jolt and Orbit.
The VD’s are potentially more of a problem to the horizontal thwack as they can flip if they can grip the edge. Angling this area is a must. _________________ Satisfaction is proportional to effort and results.
Fri Jan 19, 2007 2:49 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Ok revisions after what people had to say. I had some 40mm OD tube in the shed but that won't do. Changed to 63mm OD 50mm ID pipe for armour. that's 6.5mm wall thickness.
Moved motors closer to the axe. looking at about 11 Kg's without the axe at this stage.
Fri Jan 19, 2007 6:08 pm
Rotwang Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1589
Location: Vic
You might need to triangulate the axe handle or move the motors further apart to being the handle between them to support the handle.
The 6.5 mm wall thickness might be strong enough to support the axe handle but there is a good chance it will get very wobbly after a hard fight.
Obviously that will make the body wider and add weight but the wider track gives more leverage to get the Axe moving, less top speed in the spin though. _________________ Satisfaction is proportional to effort and results.
High performance drive Custom control electronics Siaxially symmetrical morphology Titanium armor _________________ Satisfaction is proportional to effort and results.
Fri Jan 19, 2007 7:48 pm
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Been thinking about how to make the bot translate while spinning. IE move around the areana. The 2 ways I thought of was some sort of very hard to build, expensive, unreliable speedcontroller / processor on the 2 drive motors or a third drive motor with a cam on it made out of a red wheel. http://robowars.org/forum/album_pic.php?pic_id=1388
I had thought that if the bot had a cam run off a drill motor then it should be a simple matter of just turning the motor on and the bot would move in an almost straight line.
What does everyone think?
Wed Jan 31, 2007 7:51 am
NMO Experienced Roboteer
Joined: 16 Jun 2004
Posts: 486
Location: Melbourne
Joined: 30 Aug 2005
Posts: 2729
Location: Gold Coast
When the broken red wheel lifts off the ground it won't have much load on it so it will be spinning faster then the other wheels. Then when it hits the ground again the load will be put back onto it and it'll slow down again, but probably slower then the drive motors. So it'll be spinning faster then the drive motors and then slower then the drive motors. Although I have no idea much of an effect it will have on the translation. As long as it averges out it should be fine.
I like it. Give it a go and see what happens.
How is the rubber going to stay on the wheel after you cut it? Would it be better to make a wheel out of MDF for a test run?
Wed Jan 31, 2007 8:23 am
Ali
Joined: 06 Mar 2005
Posts: 92
Location: Scotland
Look for a US robot called Cyclone Bot , Im almost sure its got some sort of movement while spinning but im afraid im not sure how its done . _________________ If practice makes perfect and no one is prefect, Then why practice?
Wed Jan 31, 2007 8:30 am
Rotwang Experienced Roboteer
Joined: 15 Jun 2004
Posts: 1589
Location: Vic
The 3rd wheel idea is what I was working towards.
Move the centre hole on the wheel and spring load it so it parks in the up direction then sync the 3rd wheel speed to translate.
Controlling the speed of the other 2 wheels cant be done quick enough.
Tyres don’t grip and inertia in mechanicals causes problems even if electronics can deliver theoretically correct power to motors. _________________ Satisfaction is proportional to effort and results.
Wed Jan 31, 2007 9:15 am
Valen Experienced Roboteer
Joined: 07 Jul 2004
Posts: 4436
Location: Sydney
I was looking at cyclone bot style of things and i think a controller can be done just with a counter on the wheels.
As for update speed, you can vary the power to the wheels with the ibc at 50hz assuming you need 4 "power settings" per revolution to translate you get 12.5 rps or 750 rpm.
your speed whilst translating is governed by the rate at which you can slow down and speed up the wheels. _________________ Mechanical engineers build weapons, civil engineers build targets
Wed Jan 31, 2007 9:22 am
dyrodium Experienced Roboteer
Joined: 24 Aug 2004
Posts: 6476
Location: Sydney
I bet rotational translational movement is quite possible using stepper motors. _________________ ( •_•)
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