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Discussion Starter · #1 ·
Hey guys,

John here I'm new to the RC world and I've been meaning to get into it for a while so here I am.

Basically I'm building a RC Warthog from the games franchise Halo.


I did come here about a week ago to do a post and spent about half an hour writing it only to have when I click post it disappeared. I got a bit frustrated and went away and found the answers to most of the questions I wanted to know.

Anyway just so you get an Idea I'm using 4 200w electric bicycle motors and 3 24v lithium ion batteries. It's going to be about 190cm long 96cm wide and 74 cm high. Just small enough to fit in the tray of my ute. I was planning to do this full scale and build an actual vehicle but I'm too poor haha.

A few problems I've had and have overcome so far.

1. The electric motors are brushless sensored motors. So they have 3 phases then a + and - and 3 more phases for the hall sensors. 8 wires in total. The Control boxes on the bikes I got them from don't work and they only spin forwards. I spent ages looking for ESC that would be powerfull enough but couldn't find anything to power them all. Basically I came up with I would buy new bike control boxes to power them. I will need two boxes per wheel one for forwards one for backwards.

2. Now I've decided I have to use the bike control boxes I need to come up with a way to connect them to the Remote control. I thought well they will probably be controlled by a pot (Potentiometer - Basically two variable resistors that change the output voltage from 0 to 24 ) in the throttle. I thought well I could control it with a servo just spinning the knob on the pot. When I pulled it apart I found out it was controlled by a hall sensor. A hall sensor uses two magnets on either side of it to decide how much voltage to let though.
After much thinking on how much work it's going to be to move two magnets around the sensor using a servo and worrying if one of the magnets falls of it, will just drive off in a straight line until it hits something.
Anyway eventually while I was working on a water distiller at work ( I'm a small appliance service technician ) It uses a cradle relay ( A cradle relay uses an electromagnet to hold a strip of metal against it then the current flows though two bits on the end of it )to keep it turned on. I thought why cant I just put one magnet on one side to make sure it turns off then an electro magnet on the other side to make it turn on and once I get my spacing right I'll have my throttle.

3. Forwards and backwards. So I'm going to use an electro magnet to power the hall sensor. I'll just explain this for one wheel. I'll have two control boxes one which will spin the motor forwards and the other reverse. I will have two electro magnets which will be controlled by a traditional brushed ESC when I make the ESC spin the motor forwards it will power one of the electromagnets when I make it spin in reverse it will spin the other one. I will stick some diodes ( A components that only allows current to flow in one direction) in the lines so it only powers one electromagnet at a time.
When electromagnet powers one hall sensor it will power one box and makes the motor spin in one direction.

4. Wheels basically I've got the hubs and I'm going to put them inside some 8 inch rims. It's just going to involve a bit of welding and some time on the lathe. My fire brigade captain has an old golf buggy with 8 inch rims which I'm going to pillage and I bought some tyres last night off ebay 16x6-8's they look real mean with a chunky knobby pattern.

5. Steering. Now I went and talked to an RC guy about this because I need it to do some pretty specific things. 1. Normal car steering. 2. Four wheel steer. 3. Four wheel crab steering. How I'm going to do this.... Not sure yet. My idea's are connect two servos up to a fancy pants remote that can control them in those ways then have the servos move other things on the car that will control the steering. What I mean is move possibly some hydraulic levers to control the steering. Or I might just have to make up a circuit that controls it by spinning electric motors.

That's about it for now any suggestions would be welcome

Cheers for reading John
 

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Wow I will be following this build I'm a big halo fan have you got any photos of what you've done so far?are you copying the warthog suspension its an out there setup
 

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Discussion Starter · #3 ·
No photos at the moment. All I've really done is get the Electric motor hubs off of the electric bikes. I'm still in the designing stage and I want to have all the electronics down before I start building anything. I've bought lots of stuff and I'll put a picture up of my tyres as soon as I get them. I'm even getting them delivered to my work address because I'll get them faster :D

As the day has continued I've come closer to working out how I'm going to do the steering. I thought servos are too small and I remembered at work we sell massage chairs and they have Linear actuators that extend the calf rests. I know I have two that work (The guy who fixes them gave them to me because I sorta collect this type of thing) they are 110v Dc. The motors on them are practically identical to some 12v ones I have aswell. So I've started thinking about how I'm going to design a board to make them move the way I want them too and after about half an hour in I had a thought about the servos again. I just thought sheesh it would be so much easier if I could just use them. I had a quick google and found it's not going to be that hard to turn a regular 12v dc brushed motor into one. So thats what I'm going to do. Without getting too technical it's basically I connect a potentiometer to the end and run the motor control though a H-Bridge... and Kazammm I've got a 100kg+ Servo. I'll have to make two but that won't be a problem. I've got a million 12v DC motors laying around.

As for copying the suspension Probably not. WETA workshop in Newzealand have built a full size one. I've actually touched it Yewwww.. Haha and I'll probably be doing something simmilar to them. I could go the whole functional way and have a real fancy suspension set-up but since I'm trying to make it look like the warthog I'm just going to do something that's I supposed concealed.

I'm just going to keep posting I'm excited about this and my girlfriend gets bored when I start talking in my electrical jargon.

I will take some photos when I get something done :)
 

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Very cool love to see how it turns out
 

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Discussion Starter · #5 ·
Just found an awesome PCB that all I have to do is hook up a Pot to the drive motor after I've geared it down then Plug is straight into the RC receiver way easier then my H-bridge idea. Manily because I'd have to buy a servo and pull it apart as well to get the controls from the Rc receiver. Anyway here's a link for anyone in the future who's going to do a big project like this http://www.rcpowerservo.com/rc-power-servo/.
 
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