Enemy HELP

hey guys i need help i am using the robot from unity and i want it to chase me and i have done that but the robot can walk though walls i dont know how to stop that from happening so i asked you guys.

  Thanks
      skully412

You could add a box collider to the wall and then activate it as is a trigger then, make a script that upon enter turns character around. Sorry cant help you much more without a detailed description.