robot driving using compass controll whit pid controller

[soheil6818]

hi all
i want to drive my robot and controll it by Compass(CMPS03)
the compass is working properly! means it shows an exact degree! but when i want to use it to turn my robot 90deg it has 10deg error! means if robot will stop at 90 deg , it stops at 100deg! how can i controll my robot motors to have a fix turning!
using atmega32, C language

 

[srikanthsamaga]

This is because you cannot stop the Robot very accurately(immediately) because of physical limitations.
Try to stop the motor a bit early, for ex now if you are stopping the motor at abt 85 deg, try to stop it at 80 deg.

 

[soheil6818]

will PID controller work for this problem?

 

[mishra12]

what kind of motor you are using for wheels ?

 

[soheil6818]

dc / 170rpm / torque 2N.m / brushed /
what do you mean by "what kind of motor you are using for wheels ? "

 

[mishra12]

when you are saying robot motor how would we know whether that motor is stepper or the one that you have used may be inertial force may have caused your robot accuracy in turning if you have used stepper motor it can be controlled in a great accuracy i mean that

 

[engshahrul]

I think, if you applying PID, this can be do.

Now, If you read 90 degree then you give command to stop the motor, it give delay and due tu mechanical or inertia, it will over that required degree.

If you put PID, the motor will slowly automatically before it reach 90 degree and ready to stop on required degree.