Understanding Tribot Operation

[tcwan]

Hi,
I finally managed to build the Tribot http://mindstorms.lego.com/en-us/suppor ... ribot.aspx using only the 9797 Set parts.
The front assembly is quite a challenge, since the 9797 Set didn't have many of the parts used for the front assembly, and as I didn't quite understand how the claw drive mechanism worked from looking at the instructions since I'm not very mechanically inclined. Finally (through trial and error), I realized that the perpendicular 4 tooth gears (the one that looked like 4 rounded beads) need to have their axles intersect through a single point beyond the ends of the rods (making a 90 deg angle). Maybe I'll get around to posting the instructions after I managed to understand how to use LDD properly.

Anyway, after having built the Tribot, I'm trying to understand how it is supposed to work. I'm guessing that it works something like the following:
1. The ball and holder is located on a map with lines leading to it.
2. The Tribot uses the light sensor to do line following to locate the ball holder
3. The touch sensor is triggered when it bumps against the ball.
(Here it gets a bit confusing, the ball is light, the bump bar would lift the ball up from the stand, possibly pushing it off entirely, and the touch sensor disengages at that point)
4. Somehow the Tribot knows that it has found the ball, and activates the claw mechanism to close in on it.
5. If the claw manages to catch the ball, it would press against the touch sensor and activate it.
6. The Tribot engages homing behavior (to drop it off at some destination).

My questions are:
a. How would the Tribot ensure that Step #3 works reliably? Is it expected that the ball would sometimes pop out of the holder and it would've failed?
I constructed the holder using the 1x6 studded (rectangular) grey beams arranged in a 7x7 square, so I don't know if it is more slippery compared to the actual 8527 ball holder.

b. What is the purpose of the Sound sensor and Ultra-sonic (distance) sensor? Are they intended for use in any specific scenario?

[tcwan]

This is my first time using LDD, so I hope I got it right.
(LDD is a pretty amazing software package. It is almost a full-function CAD!)
Unfortunately I couldn't combine the sections together to make the completed Tribot in LDD.
Something in the way that LDD detects object interference, etc.

[Edit: Version 1.01, I forgot to change the friction-peg (blue) in the rear wheel assembly to a frictionless-peg (beige),
there are insufficient number of friction pegs in the 9797 Set]
[Edit2: Zipped the lxf file]

[mightor]

Did the forums not allow you to upload the .lxf file? If this is the case, I can add that type.

Edit: I added the lxf file extension.

- Xander

[tcwan]

Did the forums not allow you to upload the .lxf file? If this is the case, I can add that type.

Edit: I added the lxf file extension.

- Xander

Hmm. I tried to reupload a revised version (1.01), but it still complains that .lxf extensions were not allowed.

[h-g-t]

I can't get anything to load unless it is a .zip file.

Try zipping it up then post it again.