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I want to build a little RC car. I'm thinking Tank steering. I have a standard transmitter/receiver - the type that outputs 1 to 2 ms pulses. I think I need a mixer. Would this one work? The price seems almost to good.
How do you intend to tank steer an RC car? It's not a car if it has tank treads and if it's a car you use a sub micro servo for steering and a mini esc for the throttle motor. Would help if you could flesh out your intent better.
It would be a 3 wheeled car steered by the difference in speed between the 2 independently driven motors. The third wheel just holds it up.
I think this device takes the RC pulses for velocity and steering and modifies 2 outputs to accomplish steering.
In that case it will work fine. Keep in mind, unless you're using a straight ball caster for the third wheel you're going to have feedback issues with two drive wheels, it takes a certain amount of torque and time to re-orient something like a wheel caster, and that will drastically change how you drive the primary motors.
Yes, I did it with the original lego robotics kit, it definitely makes it squirly, enough so that you can control turning to the point where you can do decent controlled turns, you really need a ball caster, but that's for sensorless turning. If your motors are low speed high torque the problem will be less, as this is a follower though I doubt it will be an issue although a ball caster would give you slightly better control. Tuning the V mixer and the ESCS to get you good solid control of forward/reverse may be a bit tricky, but again it's based on the sensors so fine degree of control isn't required.
ronv; I dont know if this is what you think it is. As far as I can tell it has a single perpose. Googling "v tail mixer" comes up with all kinds of stuff even DIY info. Andy
Thanks guys!
I found a neat little wheel that is like a regular wheel in the normal direction and lateral rollers in the other direction so it can turn easily.
Thanks again for all the help I would have been a long way down the road to a dud.
Thanks guys!
I found a neat little wheel that is like a regular wheel in the normal direction and lateral rollers in the other direction so it can turn easily.
Thanks again for all the help I would have been a long way down the road to a dud.
If you place a motor with such a wheel sticking out of the vertices of an equilateral triangular base (ie, 120 degrees apart), and drive the motors in various speeds and directions, you can move the platform in any direction.
A similar kind of wheel, called a "Mecanum Wheel":
Allows you to do something similar - but is typically used on a four wheel platform. You basically can make a wheeled "vector translation" platform with either of these wheels.
They're not really meant to be used in a "caster" style configuration - but it might be worth trying anyhow...
Nice links cr0sh, especially the mecanum wheel, I've seen warehouse forklifts that have a variation of them and they can move in any direction at any time including rotate in place.
Nice links cr0sh, especially the mecanum wheel, I've seen warehouse forklifts that have a variation of them and they can move in any direction at any time including rotate in place.
...they are mentioned in the Mecanum Wheel wikipedia link I posted as one of the companies that bought rights from the US Navy for $2,500 in 1997; what I don't understand is how, when the Navy acquired the patents in the 1980s - that they didn't become government property, and thus "public property", for use by anyone (this is -supposed- to be the way things work; I'm not naive enough to believe this is always true, but it still sticks in my craw as a citizen of this country)...?
Mythbusters has one, I'd love to get a job driving one, you could probably thread a needle with em once you're proficient.
I'm not sure about your statement of 'that's how it's supposed to work' there's nothing in the constitution that allows all government documents to be property of the people, or that anything owned by the government is public property, by that logic it would be legal for any citizen to go up to an army barracks and demand to be allowed to drive a tank and they'd just have to had you the keys =) But that's a totally separate subjects!
I'm not sure about your statement of 'that's how it's supposed to work' there's nothing in the constitution that allows all government documents to be property of the people, or that anything owned by the government is public property, by that logic it would be legal for any citizen to go up to an army barracks and demand to be allowed to drive a tank and they'd just have to had you the keys =) But that's a totally separate subjects!
All I meant is that typically, at least for government research - the results of the research become (or should become) taxpayer "property" - freely available by all citizens to view and use, since our tax dollars supported its funding. I would think that certain procurments of IP would fall under that kind of umbrella as well, but I guess they don't - I just think they should. I don't think I, as a citizen, should have to pay twice to gain access to the ability to use such property that I've already technically paid for once via taxes.
Then again, there's the argument that I should only get the amount of "access" I paid for - which would be inconsequentially small as a single taxpayer, of course. Then again, do we only gain such a small amount of fire or police protection...? There's argument about that, too - of course.
I don't think as a taxpayer I am saying we should be able to run willy-nilly doing whatever with "equipment" bought with our dollars; I do think we should have the right to know what we have bought (up to and including so-called "black funded" projects - but that's another debate) - but the actual use of such would, for the majority of situations - be restricted.
For IP though - whether developed via taxpayer funding, or acquired via such funding - the taxpayer shouldn't have to purchase it twice, which seems the situation here (unless Airtrax and the others who purchased it aren't US companies? In that case, charging them for access is fair).
With that said - $2500.00 as a payment, on the whole - for such a technology - is fairly cheap, if you ask me (even though I think ideally it should be "free"). Something I find interesting is that while they mention other companies as having bought the technology, they only named Airtrax; I've never seen another company who has sold such products based on the technology (though I do know of a hobby robotics company that sells such wheels as custom parts). Who were the others? Were none of them able to turn a profit from their IP purchase? Is Airtrax the only manufacturer of such machines left - or is the US Government the only purchaser of their machines?
Lots of questions - not expecting an answer for any of them...
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