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September 26, 2011
Director of Creative Robotics Ltd
University of Sussex
Product ROB-12668 |
about 3 days ago
Ah! It seems that we did actually correct the ‘motion control example’ code with ‘Wheel1’ and ‘Wheel2’ and pull-ups enabled - we just didn’t upload the latest version to the website. Bad us. It is fixed now.
Thanks! The need for pull-ups is explained in the user guide but you are right to point out that it is an importnat detail that we should have made clearer. I have updated our product page with this info. We made an even worse mistake by not updating the code examples - the video and the motion control example both relate to the earlier version of the board where pull-up resistors were not required so I can see how that confuses thinge even more.
We will update the code examples, and correct the left/right wheel confusion - We should have stuck with ‘Wheel1’ and ‘Wheel2’ to match the schematic.
We appreciate the feedback, and we hope you enjoy using the shield.
Product ROB-12668 |
about 3 months ago
We scratched our heads over this when designing the boards and concluded that this was a better all round option because … if you want the cheapest version you can just buy a single cable, cut it in half and solder it to the board, or you can solder on a break out board to have the connector, or a cable splitter board to run pairs of wheels in sync.
News - Enginursday - Three Child… |
about 7 months ago
Not exactly OT, but at a tangent - I used to have a BBC micro computer and the BBC basic editor had an auto line numbering command. I once tried setting it to increment in steps of 1000 and got the error message “Don’t be silly”
Product ROB-11666 |
about 10 months ago
dbc - Sorry to hear you toasted your wheel. We will be opening up shipping to the US on CreateBots soon - Unfortunatly that might not help you much as our current shipping solutions to the US (FedEx) would end up costing you more than it would cost to just buy a replacement wheel from Sparkfun. It would only really be worth your while if you wanted to order a bunch of other parts from us as well (and we will be super happy if you decide to do that!)
Product ROB-11666 |
about 11 months ago
The short answer is .. quite a bit, probably a couple of degrees - these aren’t really designed for ultra precise motion jobs.
News - New Product Friday: HUB-e… |
Ok, looks like 5Kg is too much for them to handle - the bot starts to moves but the motors stall out pretty quick (running off 7.2V) - reducing the payload to 4Kg gets the bot moving but even then any attempt at skid steering is going to fail because of the additional loading this involves - I will repeat the experiment with the 180:1 versions and see what happens. I’ll put together a video, and write it up for our website.
Excellent question. My daughter and I are just filling up her cardboard box bot with stones in order to test it out - So far it just manages to move with a 5Kg load (4x 120:1 wheels running from 6xAAA NIMh batteries), but the batteries could do with a charge so I’ll report back in a few hours and put a vid of the results on our Youtube Channel
I’m going to guess that your battery, cam and controller are unlikely to be more than 5Kg so they whould work fine.
David - The wheels use an off the shelf gear motor so it is possible to change the ratio fairly easily (although it currently requires a slight modification to the gear motor shaft) You can potentially go as high as 1788:1 although I think there would be some issues with the torque being a little too high.
The encoder is built into the wheel rim, not the motor shaft, so changing gear ratios will not change encoder resolution. The only way to do this is with a different PCB/code disk design - possible, but not straight forward.
If you strip the tyre off you can get the hub to drive tank tracks. SFE don’t stock the track system at the moment (which isn’t our design) but I hope they won’t object if I point you to Solarbotics who do sell them: https://solarbotics.com/product/gmt/
Cool, we will try and post a few videos when we get the prototypes made (along with the Wheg attachement we also have in the works!) Great video by the way!
No public wish lists :(