Infinite-Dimensional Pole-Optimization Control Design for Flexible Structures Using the Transfer Matrix Method

Author(s):  
Ryan W. Krauss

This paper presents an approach to control design for flexible structures based on the transfer matrix method (TMM). The approach optimizes the closed-loop pole locations while working directly on the infinite-dimensional TMM model. The approach avoids spatial discretization, eliminating the possibility of modal spillover. The design strategy is based on an iterative process of optimizing the closed-loop pole locations using a Nelder-Mead simplex algorithm and then performing hardware-in-the-loop experiments to see how the pole locations are affecting the closed-loop step response. The evolution of the cost function used to optimized the pole locations is discussed. Contour plots (three dimensional Bode plots) in the complex s-plane are used to visualize the pole locations. A computationally efficient methodology for finding the closed-loop pole locations during the optimization is presented. The technique is applied to a single-flexible-link robot and experimental results show that the optimization procedure improves upon an initial, Bode-based compensator design, leading to a lower settling time.

Author(s):  
Ryan W. Krauss ◽  
Wayne J. Book

The transfer matrix method (TMM) can be a powerful tool for modeling flexible structures under feedback control. It is particularly well suited to modeling structures composed of serially connected elements. The TMM is capable of modeling continuous elements such as beams or flexible robot links without discretization. The ability to incorporate controller transfer functions into the transfer matrix model of the system makes it a useful approach for control design. A limitation of the traditional formulation of the TMM is that it can only model feedback where the actuators and sensors are strictly collocated. The primary contribution of this paper is an algorithm for modeling noncollocated feedback with the TMM. Two cases of noncollocated sensors are considered (upstream and downstream). The approach is experimentally verified on a flexible robot that has one upstream and one downstream sensor in its feedback loops.


2018 ◽  
Vol 10 (7) ◽  
pp. 168781401878875
Author(s):  
Lu Sun ◽  
Guoping Wang ◽  
Xiaoting Rui ◽  
Xue Rui

The transfer matrix method for multibody systems has been developed for 20 years and improved constantly. The new version of transfer matrix method for multibody system and the automatic deduction method of overall transfer equation presented in recent years make it more convenient of the method for engineering application. In this article, by first defining branch subsystem, any complex multibody system may be regarded as the assembling of branch subsystems and simple chain subsystems. If there are closed loops in the system, the loops should be “cut off,” thus a pair of “new boundaries” are generated at each “cutting-off” point. The relationship between the state vectors of the pair of “new boundaries” may be described by a supplement equation. Based on above work, the automatic deduction method of overall transfer equation for tree systems as well as closed-loop-and-branch-mixed systems is formed. The results of numerical examples obtained by the automatic deduction method and ADAMS software for tree system dynamics as well as mixed system dynamics have good agreements, which validate the features of proposed method such as high computational speed, more effective for complex systems, no need of the system global dynamics equation, highly programmable, as well as convenient popularization and application in engineering.


1993 ◽  
Vol 115 (4) ◽  
pp. 490-497 ◽  
Author(s):  
An-Chen Lee ◽  
Yuan-Pin Shih ◽  
Yuan Kang

A general transfer matrix method (GTMM) is developed in the present work for analyzing the steady-state responses of rotor-bearing systems with an unbalancing shaft. Specifically, we derived the transfer matrix of shaft segments by considering the state variables of shaft in a continuous system sense to give the most general formulation. The shaft unbalance, axial force, and axial torque are all taken into consideration so that the completeness of transfer matrix method for steady-state analysis of linear rotor-bearing systems is reached. To demonstrate the effectiveness of this approach, a numerical example is presented to estimate the effect of three-dimensional distribution of shaft unbalance on the steady-state responses by GTMM and finite element method (FEM).


Author(s):  
Shuaijun Li ◽  
Bryan W. Karney ◽  
Gongmin Liu

Analytical models of three dimensional pipe systems with fluid structure interaction (FSI) are described and discussed, in which the longitudinal vibration, transverse vibration and torsional vibration were included. The transfer matrix method (TMM) is used for the numerical modeling of both fluidic and structural equations and then applied to the problem of predicting the natural frequencies, modal shapes and frequency responses of pipe systems with various boundary conditions. The main advantage of the present approach is that each pipe section of pipe system can be independently analyzed by a unified matrix expression. Thus the modification of any parameter such as pipe shapes and branch numbers does not involve any change to the solution procedures. This makes a parameterized analysis and further mechanism investigation much easier to perform compared to most existing procedures.


Author(s):  
Gangli Chen ◽  
Xiaoting Rui ◽  
Yuanyuan Ding ◽  
Hanjing Lu

A new approach for active vibration control design of multi-rigid-flexible-body systems based on transfer matrix method for multibody systems (MSTMM) is presented in this paper. The vibration characteristics are computed by solving homogeneous linear algebraic equations. Then, the augmented eigenvector and body dynamics equation are adopted to derive the state space representation by combining modal superposition method. Furthermore, Linear Quadratic Gaussian (LQG) control strategy is employed to design the control law. Compared with the conventional methods, the proposed method has the following features: without system global dynamics equation, high programming, low order of system matrix and high computational speed. Formulations as well as a numerical example are given to validate the proposed method.


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