Robot Challenge

Hi. I built the Tribot ball catcher thingy with similar results. I think the ball is not heavy enough for this to work reliably. when the bot hits the ball the touch sensor is not reliably pushed since the bumper simply kicks the ball away. If you hold the ball sligthly with a finger on the top I find that the catch rate goes up significantly.

I will try something tonight and use the ultrasonic sensor to slow the bot down as it reaches the ball. I am hoping this will help stop the bot in the right place rather than rely on the touch sensor.
 

Thanks! Good to know I'm not the only one having problems with this robot. Will be interested to hear if you make progress. If you do, please post a picture on brickshelf or somewhere, if helpful, and link in a comment here.
 

Ok. Some progress. I took out the touch sensor and moved the ultrasonic sensor lower on the horizontal axcis so that it can still ping the ball as it gets closer. I added a loop based on ultrasonic sensor output and set the loop to terminate when object is closer than 10cm. I then moved the command to move forward into this loop and set the move to occur in increments of .5 rotations. Now I can ge tthe bot to move forward slowly and stop more or less where it should consistently. I think this is the way to go but I'd like to refine my loop such that it starts fast and then slows down as it gets nearer. I will need to learn more about counters and variables etc. Good luck. (Pics to come)
 

try it

in official Programming Guide (NXT Tribot)

page --> 13

Port A
- Power:100 --> 50
- Duration:0.5 --> 1 seconds

screensnap
http://photos1.blogger.com/blogger/347/367/400/bot-2.jpg
 

sorry about my ignorance. is there a URL for the official programming guide or is this a printed book that I must buy? Thanks
 

Do you mean the guide to building the Tribot? It comes with the NXT set. The first part is printed, and the rest you can view in the software that comes with the NXT.
 

Ofcourse I have that. I was referring to what p3p3 said above (in official Programming Guide NXT Tribot) but rereading it I think it refers to what is supplied in the box and on the CD. Regards
 

Yes, I think that is what he is referring to.
 

I've got a tribot challenge for those who want a challenge. Can you make a tribot that tells weather the ball it picks up is red or blue? (You have to modify the tribot grabber to do this.) I was able to do it. Can you?
HINT: You can find out how to use the light sensor to tell between the two colors on the NXT CD-rom. you go to the Robo Center and click Machines. Then you click RoboArm-T56. After that click Recognize Colors and then click programming guide. It will tell you how to tell between red and blue using the light sensor.

Good Luck! :)