Some issues with Line Follower Robot

I'm working on a Line Follower Robot project. I'm using 5 sensors with digital value for programming part which means that now i'm not using PID control for my robot. However there are some issues with my robot :

  1. My robot can follow the line well when it runs at medium speed but when i increase the speed it can't turn at the sharp corners.In fact, it does turn a little bit before stopping because out of track. I have tried adding "delay()" to my program but it still doesn't work.

  2. I'm wondering that which is the best way for setting up speed for robot when it turns. Because there are several ways to set up speed for robot when it turns such as : one motor runs faster and the other runs slower, one motor runs and the other stops , one motor keep going forward and the other goes reversely.
    I'm now using "one motor runs faster and the other stops".

Please help me troubleshoot these problems. Thanks a lot !!!

Please read the forum guide in the sticky post. This will tell you all the information we will need you to provide if we are to have any chance of helping you with your problems. We need schematics, code, links to data sheets of all components and so on.

I have tried adding "delay()" to my program but it still doesn't work.

The fact that you thought adding delay() would help indicates that you are completely out of your depth with this project. What other Arduino projects have you successfully completed before this project?

High speed can be achieved only with smooth transitions between different directions. A bot or motor cannot stop immediately, instead the controller must respect a maximum applicable acceleration/deceleration. So it's a bad idea to fully stop one wheel during a turn. You can add some look-ahead, so that the bot knows when to slow down before bending.