MTS Series 793 - Manual (Page 20)

MTS Series 793 Tuning and Calibration
About Tuning
Introduction 20
How the Tuning Controls Work
To understand how tuning works, consider the analogy of taking a car on the
highway. The dashed line down the middle of the road is where the driver wants
to be—so this is the command.
This is an automated system that tells the driver if the car is following the
command and, if not, how far it is off and in what direction. As the car moves, the
road begins to curve. The driver does not respond immediately, so the command
(the desired path) and the feedback (the actual path) are starting to differ.
This difference (command minus feedback) is error. It is indicated by the shaded
triangle.
Note that error increases the longer the driver waits to correct it, that is, the larger
the difference between the desired path and the actual path.The driver turns the
steering wheel to adjust the car’s path. But there is a problem.
Note Assume the error detector is set to a value that represents the width of
the road. If the response is too slow or too quick, the error detector can
stop the program before you go off the road.