QUOTE(jesse @ Mar 5 2009, 09:59 AM)
Lynxmotion seems to be US based... a bit too high tech for my needs, i think... plus, it's gonna be very expensive too...
anyway, i've recently visited a shop doing some NXT classes. According to them, NXT is quite "brittle"... any fall or hard knocks might result in some lego parts falling off.... unless i do something (forgot the term he used) to strengthen the joints by adding more lego parts...so the total cost would definitely be more than 1 set of NXT...
sigh...
anyway, i found this recently:
www.youtube.com/watch?v=s7leJ3Sti_g
wonder if i can mod/hack it to do what i want....
Added on March 5, 2009, 10:09 amThanks ian90!
Thanks for the tip... Vex Robotics seemed cool....and the VEXplorer is precisely the kind of robot/vehicle that I want... I was actually thinking of building the NXT into something like the VEXplorer...
sadly, the VEXplorer is out of stock....sigh... anyone knows where to get one locally or have one for sale?
anyway, i need to install this cable sometime end of march.... in the mean time, i'm still trying to find out how to mod/hack the toy i found...
VEX is wheel-base robot, lynxmotion is legged base. Toyrus midvalley used to have a few unit of NXT, keep inside the glass cabinet near the counter.
With no background in robot construction and design, and deadline within 3 weeks, NXT is the best solution. I wonder how big (and weight) of your cables? You may have already notice, Lego are made with smooth plastic surface, it won't give you enough traction to cross your obstacle, especially the second pic. Though NXT do have these small rubbers for traction, it wouldn't be enough. You will need to add non-lego item to add traction (ie small and flexble rubber, e.g. eraser, rubberband, balloon, etc)
For your obstacle course, your robot primary locomotion should be wheel-base, and optional locomotion is some form of legged locomotion. Wheel will give you the thrust and forward motion. Legged would be optional if you have to clear tall obstacles.
Other design consideration, is the degree of motion (freedom) of your robot. It will give you the no. of servo motors required, and thus no. of NXT set you need.
Say, you have the minimum of:
1. forward, backward (1 servo)
2. left, right (1 servo)
3. clamp (1 servo)
Additional motion (option 1):
4. Manipulator (extension of arm, say 1 joint) (1 servo)
5. Crawl, climb ability (at least 2 servo)
Or (option 2):
4. Manipulator (extension of arm, say 1 joint) (1 servo)
5. Additional wheel base (1 or 2 axle, which gives you 6, 8 wheels typical terrain vehicle) (1-2 servo)
Which sum up, you would need 2 sets of NXT. (3 servo is too limited to create anything creatively awesome

) With the weight of 2 NXT, and 10 batteries, it should give you a steady robot and traction. Btw, you would need spare batteries, rechargable preferably.
2x NXT = RM 2798
1x quick charger + 4 rechargable battery = RM 150-200
additional rechargable battery (16 pcs) = RM 200+
Total = RM3148 - RM 3198
There are better options, i.e. direct order from VEX or lynxmotion. Then again, 3 weeks are not enough to build this type of robot.
Anyway, the point is:
It is waaay cheaper to use a long stick, 1 pair of sore arms, a stiff shoulder to do the job than spending >RM3k for ineffective robot. Worst case, the batteries run out, or by some other means, the RM3k robot stuck inside. Still you need a long stick to retrieve, or break the ceiling (additional $$).
It is good to introduce new idea, trying new initiative. But not within 3 weeks. Give it a deserving duration, at least 1-2 years, start from scratch and customize your robot to your needs.
This post has been edited by Aurora: Mar 9 2009, 09:24 AM