An Introduction to the Special Issue on Advanced Control Methods: Theory and Application

The special Issue “Advanced Control Methods: Theory and Application” intents to collect and present high-erudite papers aiming theoretical as well as practical matters dealing with complex systems and advanced control methods designated for their steering. From the system theory point of view, most technological processes belong to the class of nonlinear lumped or distributed parameter systems. It is well known that control of such processes often represents a very complex problem. The control problems are due to the process nonlinearities, its distributed nature, and, high sensitivity of the state and output variables to input changes. In addition, the dynamic characteristics may exhibit a varying sign of the gain in various operating points, time delay as well as non-minimum phase behaviour. Evidently, processes with such properties are hardly controllable by conventional control methods based on the usage of controllers with fixed parameters. Their effective control then requires application of advanced methods. These methods have been developed in the past decades and are based on different principles. Generally, none of these methods is universal, and, for control of a process the most appropriate is only one of them. From this perspective, a research of various applications is useful and desirable. The aim of this special issue is to highlight greatly significant recent developments on the topics of analysis and control of such systems, covering the scale from purely theoretical articles to real-life applications. The performance of dynamic property of the mount is influenced by multiple factors and strongly depends on the working conditions. This means that the modal parameters of powertrain mounting system would make changes under different operating conditions. A novel approach to simulate the actual working condition is proposed in the testing of dynamic stiffness in the paper by I. Jin, J. Zhang and X. Guan entitled “Theoretical Calculation and Experimental Analysis of the Rigid Body Modes of Powertrain Mounting System”. Then the mechanical model of powertrain mounting system based on dynamic stiffness is established in this paper as well. In order to examine the rationality and accuracy of the computational model based on dynamic stiffness; experimental modal analysis is performed by multiple means and methods in this paper. Through the contrast analysis, advantages and disadvantages of these methods are illustrated and it is shown that using the method of Operational Modal Analysis could obtain more accurate and more reliable results. Based on the experimental and evaluation results, it is shown that there is smaller relative error and higher fitting degree between the calculation results based on dynamic stiffness and the results obtained from operational modal analysis. Moreover, the proposed method also enjoys satisfactory consistency with the actual working condition. The paper “Feedforward Model Based Active Force Control of Mobile Manipulator using MATLAB and MD Adams” by the authors S. Abdulah, M. Mailah and C. T. H. Hing highlights the potentials of using a feedforward model based Active Force Control (AFC) as a disturbance rejection scheme in the motion control of a mobile manipulator (MM). The AFC part creates a force or torque feedback within the dynamic system to allow for the compensation of the sudden disturbance introduced into the system prior to relaying the signal to the conventional outer-loop position controller employing a resolved acceleration control (RAC) configuration, thereby increasing the robustness of the MM system. The proposed AFCbased model also shows a faster computational performance by manipulating the estimated inertia matrix (IN) of the system instead of considering the entire system dynamic model. A feedforward element in the form of a simplified model of the dynamic system is implemented to complement the IN for a better trajectory tracking performance of the system. The simulation was performed and the results were compared with the computed torque WSEAS TRANSACTIONS on SYSTEMS Libor Pekař, Filippo Neri