Adjusting Continuous Wheel

Question

Hi people,

I need some help here to adjust my continuous wheel I got with adventure bot. When it runs on tile or concrete floor it works just fine. When when it run on carpet floor, it can go forward and backward, but when I try to do a left or right turn, the wheel appears to slip and couldn't turn. I'm thinking of doing a adjusting the torque but I'm not sure os this the first place to go for. Perhaps there is a better way to solve this? If adjusting torque is the way to go, how much should I adjust it by?

Thanks

CochranRobotics · Answer

The screws on the servos don't adjust the torque. They adjust where the stop point is. By adjusting these you can get both servos to stop at the same reading making it easier to program. Different wheels that will work well on carpet and flat flooring is the way that you could solve this.

thetechguru · Answer

You can also try putting thick rubber bands (I find the ones that they use to hold broccoli stalks together at the grocery store work perfectly for this) as tires ti give the wheels some more grip as a short term solution before buying different wheels. Alan

DJ Sures · Answer

Hi philip! You indeed came to the right place. Robots aren't really designed for carpet - specially if you're experimenting with vision tracking and other features that require precision. If you wish to continue working on carpet, the robot is very light and therefore the wheels will spin. As previously suggested, adding elastic bands to the wheels may help with carpet. If you want to know more about the continuous rotation servos, there are question mark buttons next to the close buttons. Pressing the question mark button on the continuous rotation movement panel will bring you to its help page here: https://synthiam.com/Tutorials/Help.aspx?id=12 On that page, you will find a tutorial. The shortcut is here: https://synthiam.com/Tutorials/UserTutorials/190/1

CardboardHacker · Answer

If it is thick carpet, then the back leg might be getting caught, which could be causing the left and right turning problem.

Philip W · Answer

Thanks guys, I'll give the rubber band solution a tried first. There is another problem I've just observed, when I let the bot run forward (presumably both wheels are on full PWM mode because I haven't made any adjustments yet), one of the wheel spins faster then the other or one of the wheel had been put together off centered (as it constantly diverge to one side). I tried switching IO pin the wheel is plug into to see if that makes a difference (i.e. initially D0 for left wheel and D1 for right wheel, now D0 for right wheel and D1 for left wheel), I still observe the same problem. Therefore this leads me to believe the wheels weren't calibrated to each other. So I'm wondering how should I calibrate the wheels? Or is there a PID controller or something along that line for wheel speed adjustment to compensate for this? Thanks again.

DJ Sures · Answer

Please read my previous response.

Philip W · Answer

@DJSures I've followed your video at calibrating the wheels. But I can't get both wheels to align, the situation are as follows: 1) a) I set the slower wheel's stop value at 108, turn the potential-meter until it stops as per the video. b) Then I adjust the faster wheel's stop value. Here is where the problem comes in. I manage to narrow it down to between 101 or 102. When I calibrate it to 101 the bot will swift to the left, but when I calibrate it to 102 the swift to the right. So no matter which value I choose the bot will either swift to either side. 2) When I test the wheels by driving the bot in reverse, both wheels travels at a greater speed difference then when I test the bot driving forwards, although both wheel's reverse value are the same. Any thoughts on how can I fix this problem? Thanks again!

Dave Schulpius · Answer

As far as the forward and reverse speeds being different I think that is normal. Most Motors that I work with travel at different speeds depending on the direction that they are going.

Philip W · Answer

@Dave thanks for your comment, I personally don't do much work with continuous motors so I wasn't aware of it until you brought it up. I'm glad to know, I was going to get a motor with encoders in it so I could have a PID controller or something like that to adjust the speed. Probably I'll hold that thought for now.

Thanks again.

Philip W

Upgrade to ARC Pro