Omron’s Adjustment of Disturbance Overshoot (ADO) response is a unique technology used to adjust the response of temperature controller to different types of disturbances.

The ADO algorithm monitors the deviation of PV from the setpoint. Once the error is larger than the disturbance judgement width the algorithm is triggered. As the deviation returns to within the disturbance rectification band the algorithm sequence comes to an end. In this way it is possible to distinguish between “larger” disturbances and background process noise.

When activated ADO is able to adjust the response of the controller by ensuring that the appropriate amount of integral action is discharged so that the process value response can be tailored to return to the setpoint in minimum time with the smallest overshoot. Disturbance gain parameter controls how much the controller reacts to disturbances and Disturbance time constant controls the speed of recovery. The default values for disturbance gain is set to 0.65 and disturbance time constant to 1.  

The graph below shows the different responses to the same disturbance.

• The yellow trace was when the loop was tuned to give rapid response with some overshoot
• The purple trace is when the loop was tuned to give no overshoot
• The blue trace shows the case where ADO was used with standard tuning