Robot Building Tips

[i-fixed-it-44]

Tips Tips Tips we all need robot building advice...so post your,tips,ideas,and etc. here.It'll help newbies and others too.

[dimastero]

I suppose keeping your bots as symmetrical as possible is a good thing to start with... It's handy for getting your robot balanced, which really simplifies programming

[HaWe]

no - really?

[mattallen37]

You mean for a mobile robot? None of my robots are symmetrical, as it is impossible with a single NXT to make a robot 100% symmetrical.

[doc222]

Depends, Take a Biped"my main interest" It would have two legs, both the same. But one NXT in the center line(though it may move if needed depending on how it weight shifts). If we look at Humans and the animal as a insperation we see lots of symmetrical things pair/s of legs, two arms, tow ears and eyes. But only one head, one nose (but two nostriles). So if we say the center line is a point of symmetrics, then it is in balance or symmetrical.

Everthing has an exception and I have started to think that at least for Lego Bipeds to have greatest function perhaps only one arm is needed. Two creates alot of weight, most tasks performed are not so complex that two would have a greater function with two. If this one armed Biped was to be created than again the same symmetrical theroy could apply. It would be in the center.

Doc

[mattallen37]

My statement was more of a joke, though true. An NXT brick is not symmetrical, so only using one, there is no way to make a robot 100% symmetrical. Actually, as far as I know, there are no two NXTs that are identical, so I don't think that even if you used two it could be 100% symmetrical.

[sqiddster]

Also, each and every piece likely has a different number of atoms, and this will have to be measured to make a perfectly symetrical 'bot.

Ok, time for seriousness:
Tips...
1. If you like your 'bots to look good, a colour scheme is always nice.
2. It's a good idea to only use NXT motors when servo functionality is required. XL motors fit the bill in every other situation in which NXT motors would be used.
3. Although having heaps of gears and whatnot in a robot will make you feel smart, the closer the motor is to the output, the better.
4. Worm gears are your friend.
5. Axles are ridiculously flexible. Follow the lead of LEGO designers and use axle joiners with short axles as opposed to longer axles, if you can help it.

hope that was helpful...

[doc222]

One thing i see alot is: "Unsupported axles", No matter how close it is to a motor, all gears must be supported on both sides and never more than 2 spaces from, the counter gear. A few exception there are but in most cases a must. Even Tires and rims should be if possible, on any thing with wheels the axles flex this will add Canter to the wheel. wheels in a off canter ballance will have many issues with "going straight"

In a long gear train: Never change the angle of the out putting shaft without a gear reduction in a system that will have a greater load(working load). Even a 180* will loose alot of torque if it passes through even 1:1 Never gear up to go down. Again there acceptions to any thing.

Say you are getting power to point that needs about 24:1 reduction. But its not a straight shot. So you must have two places it will do two 90* bends. Its better to have a reduction of say 3:1 at the first 90*. 3:1 at the secound 90* and a final reduction at the PoC=point of connection of 3:1 wait thats 27:1(thats ok close enough). What this does is reduce "wrapping of a axle". It iss even better if you can use a progression, each angle change or a counter axle has slightly more reduction on down the line. If we look at one of the lattest Technic kits we are starting to see issues with long gear trains that have equal ratio/ ratios at each gear exchange and it is over loading some PF motors and the function is poor.

Like squid said if you can just mount as close as possible if not right on it, when you can.

[dad-and-adam]

One trick I use on just about every project is the 3-4-5 triangle. That is to say if two legs are 3 and 4 units long and the remaining side is 5 units it will be a 90 degree angle between the two shorter legs. Of course any multiples of 3, 4 and 5 (like 6,8,10) work as well.

dad-and-adam
(formerly Dad and Adam from the nxtasy forum) -I was going to change my user name more than that, but all the cool names were already taken (who would have throught "pinhead" was already being used).

[sqiddster]

Ahh, the old 3-4-5 triangle. But, remember kiddies, this is NOT 3 studs, 4 studs, 5 studs. It is really 4, 5, 6 studs, because the hinge points aren't at the end of the liftarm, but half a stud towards the centre on both sides.