How to make a 3pi make smooth and sharp turns

I am using my 3pi to solve a hexagonal maze formed by black lines. I read the User manual properly and used the braking techniques provided in it for making the bot move on hexagonal turns. the technique is efficient at slower speeds but results in extreme jerks and abrupt brakes leading to significant errors. Any help would be be appreciated regarding how can this be controlled and the 3pi be made to turn at the sharp turns without these abrupt brakes and also the deviations.
I have been using the speeds of 1/2 of the max speed.



Could you describe the problem you are having in more detail? Do you just want to get rid of the abrupt braking, or is it causing the 3pi to not function correctly? In my experience, when speeding up the 3pi, it helps to have stronger PID coefficients immediately after a turn to help the 3pi find the line again. During this time, it helps if you make it so the 3pi cannot detect turns again for a small amount of time, so it does not incorrectly detect the same intersection twice. You can weaken the PID coefficients after a brief period (you might need to experiment to find a good amount of time).

You might try having the 3pi turn as soon as it detects the intersection instead of stopping the motors first. You can see an example of this in the “LVBots May 2014 maze solving competition” blog post. The course in this competition was arranged on a grid with only 90-degree turns, but Ben’s 3pi (the first place winner) does not stop before making turns (although it does slow down slightly).

If you could post a video demonstrating the problem and your code, I might be able to offer more advice.


Respected Sir

Thankyou for your reply Sir and I went on with gradually deaccelarating the 3pi and at turns, ending up with a speed of 25% of the full duty cycle.I guess, there is no problem with PID coefficients since the 3pi followed the line correctly. Although my 3pi is not working again which I have posted in another post but for knowledge I would like to know if there is any other possible way of speeding up my 3pi at turns.

Without seeing your 3pi in action, it is hard for me to give more advice on speeding up the turns. I am sorry you are having problems programming your 3pi now. If you can post a video demonstrating the problem after your 3pi is working again (and maybe your code too), I might be able to offer some alternative solutions.