InstantForum.NET v4.1.4RoboticsConnection User Forumhttp://www.roboticsconnection.com/userForums/info@roboticsconnection.comThu, 04 Dec 2008 14:58:59 GMT20http://www.roboticsconnection.com/userForums/Topic74-9-1.aspxJerry,</P><P>Ha! That's cool! :) Yeah, my little 7lb. Yorkie steers clear from my robots, and is smart enough to jump up in a chair. :)</P><P>Also, we used to use a ball caster on our older Botster platform, and while it worked well on hard, flat surfaces, you could forget about driving on carpet. Hence, the reason we went w/ the caster wheel for the Stinger design.</P><P>Thanks for the pics!</P><P>Best Regads!Sun, 24 Feb 2008 11:26:28 GMTjsummerourhttp://www.roboticsconnection.com/userForums/Topic74-9-1.aspxI bet the diff-drive demo from the terk project at cmu is just pushing the motors forward at a constant velocity. I check. Well here's what the bot is starting to look like. No sensors are on it yet since I want the bot to travel on a straight line first. <br><br>[img]http://www.nfnnet.org/qwerk/jnqwerkbot2.jpg[/img]<br><br><br>My pup does not know what to make of the bot, here's a shot from the robot's persepctive:<br>[img]http://www.nfnnet.org/qwerk/dog6.jpg[/img]Sun, 24 Feb 2008 09:16:34 GMTjerrynhttp://www.roboticsconnection.com/userForums/Topic74-9-1.aspxHey Jerry,<P>Hmm...There's a few reasons why you would have these troubles:</P><OL><LI>The aluminum caster pivot isn't centered with the hole in the chassis, where the caster collar sticks through, and the set screw for the caster collar is rubbing against the chassis. You can alleviate this by loosening the two bolts that secure the caster pivot to the frame, center it, and tighten it back down.</LI><LI>You may need a little lithium grease between the caster pivot and the pivot hub.</LI></OL><P>We've driven the Stingers around a line following course over, and over, and over again, w/o any troubles. So, look closely at the suggestions above, and I'm sure you be able to fix it right up. :cool:</P><P>Also, are you using PID velocity/distance control w/ the Serializer? If so, it should be traveling straight as an arrow. Otherwise, it will probably arc (not due to the caster).</P><P>Best Regards!Sat, 23 Feb 2008 13:08:26 GMTjsummerourhttp://www.roboticsconnection.com/userForums/Topic74-9-1.aspxJust finished the stinger platform. The caster seems to be causing the bot<br>no to travel in a straight line. The code is driving the motors with the same power level and velocity. The bot tends to veer to the left(front of the platform facing away from me). Has anyone experimented with a ball caster<br>on the stinger?Fri, 22 Feb 2008 21:37:35 GMTjerryn