Chief Delphi - Holonomic Drive Mathmatics Discussion

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Re: Holonomic Drive Mathmatics Discussion

Quote:

1) That's three joystick ports taken, unless you start hacking up wires and getting some crazy soldering going. And joysticks cost money to get more and more each year (as I imagine it's hard to impossible to do such a thing and easily keep the joysticks in COTS form).

we did cut those sticks and wire them into one port..........not too much trouble!

and as for using more sophisticated programming......

in 2002 we didn't have the processing power to properly calculate the coordinates. we came up with the sticks! they worked awesome......but you could do it any way you choose.

my money is on sticks though.......cheap error-proof, effective!

Re: Holonomic Drive Mathmatics Discussion

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Originally Posted by ajlapp

Its a very simple and effective solution to a fairly complex problem. The only downside is that you would be unable to translate and rotate at the same time, which may or may not be worth the extra effort. If that is not a consideration then this would be hard to beat.

Re: Holonomic Drive Mathmatics Discussion

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Originally Posted by seanwitte

no you defintly could do that. for example. push the stick to the top right while rotating the stick counterclockwise. well a better way to say iot would be to rotate the stick counterclockwise with B as the axis. then according to

.........+...+
....A.../.....\...B
.......-........-

.......+........+
....C..\...../...D
.......-.....-

C would be at -, A towards -. D towards+.
right? with B still at neutral. so then the robot would be doing the same thing.
rotating counterclockwise with B at the axis.
so now comes the place where a little more imagination is req'd.
now move the stick the same way as before(b as the axis counterclockwise) but now move the axis of rotation a little closer to the A stick. so A-,C-,D+ but B is only slightly towards +.
guess what? the robot does the same thing. the axis it is rotating at is a little above B but a littel towards A too. and it is shuffling towards NE too. i think. i confused myself slightly. forgive me. its a friday night. but i just wanted to prove you COULD translate and rotate at the same time. NO problem. just a matter of driver getting used to.

Re: Holonomic Drive Mathmatics Discussion

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Originally Posted by greencactus3

Build it and prove me wrong. I'm certain that you will not be able to drive along a straight line while rotating at the same time. You may be able to approximate it but it would take a driver savant to keep track of the orientation and keep the translation along the same vector.

Re: Holonomic Drive Mathmatics Discussion

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Originally Posted by seanwitte

i wish i had the resources to do that but i cant. but yes i agree a driver would not be able to drive in a straight line while rotating. but why would he ever need to? the field has many obstacles, and when will you ever need to rotate and move in a straight line for a longer distance than a couple meters? and as for driver? its not hard. for example. a person who flies rc helicopters should have NO problem. there's no Z in this.

Re: Holonomic Drive Mathmatics Discussion

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Originally Posted by robotaddict

Now comes the interesting part, how on earth do you control this darn thing?! Sure you can move in any direction, but this would confuse any mortal driver. So I had the "brilliant" idea of using a gyro to give the robot absolute direction, that is when you push the stick away and it goes away, and vice versa, but in uncomplicating the drivers' job I have complicated my own.

This is exactly what Team 190 did with their 2005 robot. The field oriented controls allowed us to do things like rotate while translating in a straight line without causing a headache for the drivers. I am not a programmer, so I can't tell you how the code worked. I do know that we had trouble with processing speed, and that we had to convert all our trig functions to use integer math, but I don't know the details. Hopefully someone else from the team can fill you in.