Synthesis Of Robust Feedback Controllers Research Articles

Two-stage continuous biomethane production from enzymatic hydrolysate of agave bagasse: Modelling, identification and control

An AM2 model modification is proposed by including the parameter identification and a robust feedback control synthesis. The contribution is shown by experimental proof-of-concept. The AM2 model is modified with the aim of including the CODs changes in the effluent near the steady state with the inlet CODt concentration changes at a fixed flow rate. The parameter identification is experimentally implemented on-line and computationally performed via the Levenberg–Marquardt algorithm. To this end, an experimental set-up was carried out each from a two-stage biomethane production process stage as an instrumented and automated bioreactor. Afterward, robust feedback control is implemented for each stage. For the first stage, the VFA productivity maximum is defined as the control goal whereas the biomethane maximum flow is the aim on the second stage. The feedback control is robust against kinetics and parametric uncertainties such that the biogas production reaches biomethane maximum production. In this sense, the contribution shows the biomethane production can be optimized through enzymatic agave bagasse hydrolysate.

Specification Guided Automated Synthesis of Feedback Controllers

The growing use of complex Cyber-Physical Systems (CPSs) in safety-critical applications has led to the demand for the automatic synthesis of robust feedback controllers that satisfy a given set of formal specifications. Controller synthesis from the high-level specification is an NP-Hard problem. We propose a heuristic-based automated technique that synthesizes feedback controllers guided by Signal Temporal Logic (STL) specifications. Our technique involves rigorous analysis of the traces generated by the closed-loop system, matrix decomposition, and an incremental multi-parameter tuning procedure. In case a controller cannot be found to satisfy all the specifications, we propose a technique for modifying the unsatisfiable specifications so that the controller synthesized for the satisfiable subset of specifications now also satisfies the modified specifications. We demonstrate our technique on eleven controllers used as standard closed-loop control system benchmarks, including complex controllers having multiple independent or nested control loops. Our experimental results establish that the proposed algorithm can automatically solve complex feedback controller synthesis problems within a few minutes.

Robust performance results for discrete‐time systems

The problems of robust performance and feedback control synthesis for a class of linear discrete‐time systems with time‐varying parametric uncertainties are addressed in this paper. The uncertainties are bound and have a linear matrix fractional form. Based on the concept of strongly robust H∞‐performance criterion, results of robust stability and performance are developed and expressed in easily computable linear matrix inequalities. Synthesis of robust feedback controllers is carried out for several system models of interest.

Shifted Quadratic Guaranteed Cost Bounds for Robust Controller Synthesis

This paper presents three novel shifted quadratic guaranteed cost bounds for analysis and synthesis of robust feedback controllers. Numerical examples are given to compare the robust stability and performance tradeoffs of these controllers with controllers based upon scaled Popov synthesis.