Wallfollowing with PID-Control

[Torwald]

Hello,

I try to realize a robot moving through a labyrinth. I finished the algorithm, but with the electronic detail i have some Problems.
The hole thing is realized in Simulink/Matlab. My Problem:

I try to realize a Wallfollowing with PID-Controll. But it doesent works. If i follow only one site is no Problem. But changing from the left site wallfollowing to a right site wallfollowing doessent works.

Can someone help me? I need only this wallfollowing plan in simulink!

Thanks Torwald