Dear Pololu,
Could you order premium replacement tyres for Pololu Wheel 42x19mm to be made of soft polyurethane? (about 20 or 30 Shore scale) That would be a great help in high-traction application like mini-sumo!
Thx!
RiO,
That’s been on our to-do list for a while. Our initial strategy was to find stock tires and to make a custom hub that worked with our motors. That let us get complete wheels faster, but it means we don’t control the mold or material for the tire. Fang and Paul are visiting our suppliers in China right now; I’m hoping they’ll come back with information that will let us accelerate the tire development.
- Jan
Jan,
Is there any chance that such advanced tires will be available by February? I have a competition coming up in March and need to decide on the wheels design soon.
I’m not sure. We’re working on getting our own tires molded, but the first ones are not for the 42x19 wheels, and we might need to go back and forth a few times to get things right, so I don’t have any good estimate for availability.
- Jan
This is an old post but I believe I am having the same traction issues as the original poster and want to find out if there are alternative tires for the 42x19mm wheels. I’m using the Pololu wheel encoders so I need to stick with the custom Pololu hub.
Here is a link to a journal entry showing the problem I’m having on smooth surfaces: wp.me/p493sy-ap
The encoder and PID control are working perfectly so at this point I can only attribute the problem to traction.
Any help much appreciated.
Maybe there is something I can coat the wheels with to increase friction? In the end I think they just need to be a lot softer.
Hello.
Could you tell me what your code does? Are the encoders the only thing that affect navigation, or are there other sensors that affect it? Could you post your code?
You might also try cleaning your wheels. We have found that clean wheels can significantly help with traction issues.
- Grant
You can view the code here: github.com/solderspot/WallieBot … WallBot_v3
I’ve verified that the encoders work by just hand turning them and looking at the tick counts. The motor logic is straight forward and I’ve also verified that the adjustments match what the PID controller is setting. But at the end of the day the wheel tick counts are generally never off by more than two (except for the start maybe) so regardless of anything else the wheels should have travelled the same amount.
The tires are as clean as you’d reasonably expect from traveling across floors. They have thick chunky threads so I’m guessing there is not a whole lot of surface contact area and it might be uneven too. I’ve also noticed, from the very first version of the bot, that there is a lot of vibration as it travels. The bot probably needs to have a lot more weight to get the best out of these tires…
Some of our engineers were able to use those wheels in the past for dead reckoning contests. In the contests, the robots kept track of both position and heading, which has advantages when trying to keep the robot going straight. Unfortunately, if you still feel the tires are not getting enough traction, we do not carry any other tires for those wheels or any similar sized wheels to replace them.
By the way, your project is cool. If you feel like sharing it (or any other cool projects you have), feel free to post about them in the Share your Projects section of our forum.
- Grant
Thanks, Grant. I’ll update if I figure out more about the traction issue. For now I’m going to focus on the Zumo bot and then compare both to see how they perform relative to each other.
All the best,
Tom.