Sharif Digital Repository

Due to possible distortion contained in frequency-domain data, system identification methods based on data-matching alone do not guarantee stable models. This is a model of a linear system from its frequency response data. It is an improvement and an extension of previous work. The method first identifies a matrix-fraction description of the transfer function matrix of the system from data. Then, through forming a multivariable observable or controllable canonical form, the method separates and replaces the unstable subsystem by a stable subsystem having approximately the same frequency response. Finally, it calculates the Markov parameters of the resulting model and obtains a state-space... 

Recently, receptance coupling substructure analysis (RCSA) is used for stability prediction of machine tools through its dynamic response determination. A major challenge is the proper modelling of the substructures joints and determination of their parameters. In this paper, a new approach for predicting tool tip FRF is presented. First, inverse RCSA formulation is extended so that the holder FRFs can be identified directly through experimental modal tests. The great advantage of this formulation is its implementation in arbitrary point numbers along joint length. Therefore, in comparison with previous inverse RCSA approaches, a more realistic joint model can be considered. In addition, due... 

Analytical and numerical system identification (system ID) techniques of smart structures with piezoelements are introduced and compared in this paper. Simplicity and low cost of numerical system ID methods developed here make them beneficial in control design and implementation as well as in optimization of location and size of actuators and sensors of the smart structure. The accuracy of these techniques is then verified using analytical system ID, which derives the dynamic model of the structure from differential equations. In the first numerical system ID technique, Finite Element Method (FEM) is employed to model the dynamic system and to obtain the Frequency Response Function (FRF).... 

In this paper, a robust control system is developed for a flexible beam with piezoelectric actuators (called Smart Beam). The active control system of smart beam satisfied desired properties for all admissible measurement and plant noises, disturbances and model uncertainties. Thus it is the best candidate for sensitive industrial, medical and etc. robot arms and bases a new concept in the use of smart structures in robotics. The Frequency Response Function (FRF) of the smart beam was obtained from a Finite Element (FE) model. The corresponding transfer function was derived from the □ synthesis and several control schemes were then designed to suppress the vibration. Results showed the...