Reference processing in Two-Degree-Of-Freedom Control: Separation, Independence or Optimality

PI-Fuzzy controllers for integral plants to ensure robust stability

“…Since, the main tasks in control, high performance in setpoint tracking and effective regulation in the presence of disturbance inputs, are accomplished with some difficulty by means of PI and PID controllers, one typical approach is to develop two-degree-of-freedom (2-DOF) controllers which have advantages over those with only one degree of freedom [4,7,52,53]. Still, the main drawback of 2-DOF controllers is that although they ensure regulation, the reduction of overshoot is paid for by slower setpoint response.…”

Stable Genetic Adaptive Control by Using a 2-DOF Control Scheme

“…Indeed, the stability of the closed-loop is proved under weak feasible conditions on the parameter evolution. This benefit is obtained by using a certain implementation of a 2-DOF control law introduced in [16,17]. In this way, stability is mainly guaranteed by an internal fixed feedback controller while the tracking performance is achieved by genetically modified external compensators.…”

“…In this section we concentrate on the basic 2-DOF control law implementation introduced in [16,17] and displayed in There are several implementations of the general two degree of freedom controller. However, as pointed out in [19], not all of them possess the same closed-loop properties.…”

Tracking Performance and uncertainty: Performance Degradation Equivalence between 1-DOF and 2-DOF control configurations

“…The ideas presented in this communication are based on a previous work [7], where the configuration and structure of the parts of the controller that operate in open loop are characterized for the special case of a quadratic criterion performance specification. The resulting optimal, as well as independent, controller structure ranges all achievable 2-DOF designs.…”

“…See [4], [5], [6], and [7] among others. However, even the advantages of the 2-DOF over the 1-DOF configuration are well documented [5], a generic analysis of the reference tracking problem incorporating the effect of plant model uncertainty has not been completely addressed.…”