homemade speed controlllers (for school project)
 

Has anyone ever made their own speed controllers for the robots?
Note this is for a School Project.

Re: homemade speed controlllers
 

Last time I checked I thought the rules said it was illegal, you must use a Victor 884 made by Innovation FIRST

Re: homemade speed controlllers
 

sorry, i dont care about whether its legal, but it could be a project for my electronics coursework, and i could test it on an old robot if i built it. Maybe i wont, i'm just interested in whether anyone has and if so how hard is it to do?

Re: homemade speed controlllers (for school project)
 

Stephen,

Power electronics is a fascinating subject. Yes, with some coaching and some hard work on your part, I think you could do it. Please PM me when you plan to start and we will start a new thread here. However, can we wait until after next week? I'm swamped right now...

Mike

Re: homemade speed controlllers (for school project)
 

It's false statements like this that get other teams in trouble.

Regardless, you shouldn't go around making a statement like the former; especially when it is explicitly stated in the rules that only Victor 884 speed controllers may be used.

<R22> Only Victor 884 Speed Controllers are permitted. Victor 883 and 885 Speed Controllers may not be used.

Re: homemade speed controlllers (for school project)
 

sorry i've changed the original post now...

Re: homemade speed controlllers (for school project)
 

I haven't built one, but the most developed plans for speed controllers I've found is the OSMC:

The official site for them is here: http://groups.yahoo.com/group/osmc/
You can buy kits to build them here: http://www.robot-power.com/osmc_info/

I've wanted to build one, but I don't have a need for a 50V, 160A speed controller. :)

Re: homemade speed controlllers (for school project)
 

he is asking how you can make one. he doesnt want to use it for Compitition

Re: homemade speed controlllers (for school project)
 

Back on track...

Does it need to go forward and reverse or only forward? It is pretty easy to make a forward only one actually.

Re: homemade speed controlllers (for school project)
 

havn't decided yet, it depends how hard it is to make one go backwards....
ideally yes
having im'ed mike betts, i'm probably going to be starting this in a couple of weeks (given other stuff gets sorted as well...) and there will m/p be a thread about it then

Re: homemade speed controlllers (for school project)
 

Hey now, no need to insult. I realize what he is asking; I posted the rule from the handbook to verify that the statement "Its legal, but you have to get it approved by FIRST." is indeed false. I posted it so someone reading this thread would not mistake his original statement as true, to avoid further confusion, and to make sure those skimming over the thread were fully aware that you cannot use homemade speed controllers in the FIRST robotics competition.

Re: homemade speed controlllers (for school project)
 

yes, hence why i edited the original post to remove the confusion. I thought you used to be able to do it and hence you still could, but i'm wrong and i accept that

Re: homemade speed controlllers (for school project)
 

[voice=codger]I was programming robots and wiring speed controllers before you young'uns were born.[/voice]

In 1981, I was the principal programmer for a group building a radio-controlled robot (featuring a TV camera and two-way audio) for an engineering open house event at the University of Illinois. The electronics guy designed and built a 16-step pwm speed controller, using a separate mechanical relay to switch between forward and reverse. We tested everything out using a single 12-volt car battery and it worked well, if a bit slow -- the motor and circuitry were intended for a 24 volt supply. When we were satisfied with the results, we added the second battery. It went fine until we gave it full throttle, at which point the speed control circuit caught fire.

One of the diodes neatly unsoldered itself from the board and broke the circuit before we could react. Replacing those diodes with heftier ones fixed the problem, and the Synton Amateur Radio Club Telepresence Robot worked fine thereafter.

Re: homemade speed controlllers (for school project)
 

Wow,
It must be the last week before ship as everyone is on edge. Stephen, Mike Betts is a good source for control. You do need to come up with a list of what you want to do. Do you need fine control of speed, direction control, full torque with speed control, etc. If you just want to change speed and don't care about anything else, you can find lots of variable voltage circuits that might work and are easy to build for beginners. You might want to hook up with an amatuer radio club for some added help. There is some really active clubs in Britain

Re: homemade speed controlllers (for school project)
 

cheers al! you are one of the people everyone knows and respects here :)
it would seem so (in relation to your first sentence), i have just found out that one of my mates is really into building remote controlled planes :o (and hes on the robotics team....)
ANyway, after the builds finished etc you'll hear from me more :)
stephen

Re: homemade speed controlllers (for school project)
 

There is some great information on speed controllers and design at:

http://www.mcmanis.com/chuck/robotic...sc2/index.html

In fact I recommend the entire site for those interested in robotics and electronics.

Jason

Re: homemade speed controlllers (for school project)
 

I wanted to try some experiments with small motors and a processor
producing PWM signals. I found a nice H bridge circuit at Digi-Key,
the LMD18200 from National. You feed it a pwm signal and power
for up to 3A at 12-55 volts. Of course you need a heat sink and some
filter caps at those levels.

Re: homemade speed controlllers (for school project)
 

i saw a couple of weeks
i mean a few weeks more from now.... seem to have got overloaded with other stuff ...

Re: homemade speed controlllers (for school project)
 

if you know how to use a servo, and understand the concept of resistors and how to read the lines you can make a clumsy mechanical real easy.

Re: homemade speed controlllers (for school project)
 

The problem with that is that you are not pulsing electricity, you are converting electricity into heat. The lower the voltage (speed) the higher the heat. You are making a constant power draw. The difference is the ratio of heat energy to kinetic energy.

So what I'm basically sayingis generally speaking a mechanical speed control will run down the battery faster than an electronic one, and it will get very hot. Electronic is better.

Re: homemade speed controlllers (for school project)
 

So what I'm basically sayingis generally speaking a mechanical speed control will run down the battery faster than an electronic one, and it will get very hot. Electronic is better.[/quote]
yea i know but its so simple. not sure he said he was going to use a battery actually. if its unlimited power supply and littel heat isnt a problem id just make a mechanical.

Re: homemade speed controlllers (for school project)
 

What type of motor do you want to use and what am I going to use this motor for is the most important question that you probably need to know. Moving a heavy object involves the use of a motor that we all know and love. Moving an object with percision would benefit most from either a stepper motor or a servo motor. If you want a motor that is going to last a long time brushless is the way to go.
Here is a website that I obtaind from searching google about speed controllers:Website

Re: homemade speed controlllers (for school project)
 

Hi again all

an update
I decided to make something easier for my school project, however there is a couple of people from the lower year who would like to make a couple, for this event. http://www.extremefightingmachines.c...cambridge.html
Basically we don't wnat to use any of the first equipment due to how expensive and precious it is, so we will be using a remote controlled car reciever, and a couple of home made speed controllers. The reciever gives out a pwm output to whatever it drives, and we used it beforein a previous featherweight, but with 2 victors.
So firstly, we need to decide how much current and what motors etc it will drive. They will most probably be window screen wiper motors, from a local junkyard. Anyone who would like to help and suggest stuff is most welcome, and it would be great to see a FIRST team thrash the destruction style teams :)
Denman

Re: homemade speed controlllers (for school project)
 

Stephen,
I am not sure how your cars are laid out but in the US, the motor drives both wipers and is relatively powerful. I would guess it may run stall current as high as the Chalupa or Drill motor, about 100 amps. Your homemade controllers should be designed to handle that much current.

Re: homemade speed controlllers (for school project)
 

The game looks fun

good luck!

Re: homemade speed controlllers (for school project)
 

Stephen,
One option might be to use a chopper circuit from a cordless drill. An example is DeWalt part number 152274-10, Switch, VSR, available at www.dewaltservicenet.com for US$41.14. You would have to make mechanisms to actuate the trigger and reversing switch, but that might be simpler and cheaper than building your own compact high-current motor speed controller.

Good luck.

Re: homemade speed controlllers (for school project)
 

last year we used some from a ford fiesta, they ran fine on a victor 554... the may not be a robot to put them in now.... depends what happens on this wednesday, as we havn't started on it. but we'll see
Right now i'm just researching some basic therory