COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering

Purpose – The purpose of the paper is to find a speed control structure with two degrees of freedom robust against drive parameters variations. Application of structure model following control (MFC) and fuzzy technique in the controller of PI type creates proper non-linear characteristics, which ensures controller robustness.

Design/methodology/approach – The use of proper structure with two degrees of freedom and non-linear characteristic introduced by fuzzy technique ensures the robustness of the speed control system. The paper proposes a novel approach to MFC synthesis to be performed in two stages. The first stage consists in the set value of P type controller of model and the process controller simultaneously should be designing by fuzzy technique. At the second stage of the synthesis consist in tuning parameters of process fuzzy controller by the swarm of particles method (particle swarm optimization) on the basis of a defined quality index formulated in the paper. The synthesis is performed using simulation techniques and subsequently the behavior of a laboratory speed control system is validated in the experimental setup. The control algorithms of the system are performed by a microprocessor floating point DSP control system.

Findings – Use of proper structure with two degrees of freedom of the non-linear fuzzy controller guarantees expected robustness and improves the dynamics of speed control significantly.

Research limitations/implications – The proposed structure of MFC was tested on a single machine under well-defined conditions. Further investigations are required before any industrial applications.

Practical implications – The proposed controller synthesis and its results may be very helpful in robotic system where changing of system parameters is characteristic for many industrial robots and manipulators.

Originality/value – The paper proposes an original method of synthesis of robust system with two degrees of freedom system validated by simulation and experimental investigations.