BIAS - APMonitor Option

 Type: Floating Point, Input/Output
 Default Value: 0.0
 Description: Additive correction factor to align measurement
              and model values for Controlled Variables (CVs)

BIAS is additive factor that incorporates the difference between the current measured value and the initial condition of the controller. FSTATUS determines how much of the raw measurement is used to update the value of MEAS. A feedback status of 0 indicates that the measurement should not be used and the BIAS value is kept at the initial value of 0. A feedback status of 1 uses all of the measurement in updating MEAS. A feedback status in between 0 and 1 updates MEAS with a fractional contribution from LSTVAL and the new measurement. The value of BIAS is updated from MEAS and the unbiased model prediction (Model_u).

 BIAS = MEAS - Model_u

The BIAS is added to each point in the horizon and the controller objective function drives the biased model (Model_b) to the requested set point range.

 Model_b = Model_u + BIAS

The value of BIAS can also be set to an external value by setting the option apm_option(s,a,'cv.BIAS',value) and setting FSTATUS to 0 (OFF).

See also Estimation Objective Tuning