"gain direction" is a correct and usable phrase in written English.
It means to find or acquire guidance or purpose in one's actions or decisions. Example: After years of feeling lost and unsure about his future, John finally gained direction when he discovered his passion for photography.
Rotated input signals allow more excitation to be applied in the weak gain direction of the process and less excitation in the strong gain direction.
Two simple and practical test methods will be proposed that can enhance the model quality of low gain direction.
Comparing to existing results, this method does not require a priori knowledge about the sign of control gain direction.
The main idea is to use the high amplitude and high correlation test signals that excite the low gain direction more and that will not disturb process operation.
For this class of processes, it is essential to have good estimation of the very small difference between certain transfer functions, or, low gain direction.
For illustration, the proposed method is applied on a chemical distillation column and the result shows that it is optimal to amplify the low gain direction of the plant.
Simulation results show good accuracy of the proposed method in identifying low and high gain directions.
A new weighted direction variable is proposed to strengthen the interactions along the small gain directions, thus improving the identifiability and accuracy of the ill-conditioned model.
Some possible modifications to existing design methods are given for situations, where the dynamics are not aligned with the gain directions.
Using the reactor/separator system with two material recycles as a process example, a robust constraint handling controller is designed by confining the input into the large gain directions.
The optimization problem includes a search for both the Fourier coefficients and phases in the multisine signal, resulting in an uniformly distributed output signal displaying a desirable balance between high and low gain directions.
