CKI-01: Analytical and Experimental Studies into the Identification and Control of Intelligent Structural Systems
• Prof. A. M. Abdel-Ghaffar
• Prof. Sami F. Masri
• Prof. Richard K. Miller
• Mr. Isao Nishimura
• Prof. James L. Beck
• Prof. Thomas K. Caughey
• Prof. Wilfred D. Iwan
The active control of large structural systems is a subject of growing worldwide interest. A testament to the depth and breadth of this interest is the convening of, and the international participation in, the first "U.S. National Workshop on Structural Control Research" which was recently held on the campus of the University of Southern California under the auspices of the National Science Foundation. The proceedings of this Workshop furnish extensive information on the myriad research issues that need much more attention before the full potential of active control approaches can be fully exploited in the structural engineering field.
This report presents some of the results of an ongoing analytical and experimental study into the control of building-like structures subjected to nonstationary random excitations such as earthquakes. The structural model used resembles a 5-story building about 2.5 meters high. The building model was subjected to a variety of direct-force excitations. The control algorithm used employs an adaptive structural member at a pre-determined location in the model in order to attenuate the structural response relative to the moving building foundation. An electromagnetic actuator is used to generate the required control forces in the "smart" member. Among the key features of the algorithm under discussion are:
1. Only one active controller is required to attenuate the vibration response contributed by the first three modes; the damping factor is increased from virtually zero to about 20%.
2. Only two sensors are needed for this algorithm; this leads to simpler instrumentation and a more robust system.
3. Due to the optimization procedure used to select the controller location, a significant amount of damping augmentation is obtained from a relatively small amount of control energy.
4. The whole design procedure was demonstrated; special attention was devoted to the time lag problem of the active controller and the stability of the system. As part of the design phase of this study, a system identification procedure was used to develop a suitable reduced-order mathematical model. The results of a simulation study using this identified model are compared to experimental measurements. Problems encountered in the experimental phase of the study are reported and discussed. It is shown that (1) the algorithm under discussion is capable of reliably controlling the motion of the test structure under arbitrary dynamic environments, and (2) the features of the algorithm make it a promising candidate for application to large civil structures.
2. Active Brace Control (Analytical Part)
3. Active Brace Control (Experimental Part)
A. Free Vibration Test of Speciment Structure (1)
B. Free Vibration Test of Speciment Structure (2)
C. Finite Element Analysis of Specimen Structure
D. Test of Open Loop Transfer Function of Controller
A detailed discussion of some analytical issues related to active control algorithms is provided in Appendix I.
- Optimal Location of Control Devices
- Acceleration Control
- Effect of Time Delay on Structural Control
Development of Online System Identification for Structure
• Mr. Yasuo Takenaka
• Mr. Norihide Koshika
• Mr. Hiroshi Ishida
• Mr. Kazuhiko Yamada
• Mr. Masatoshi Ishida
• Mr. Kazuhide Yoshikawa
• Mr. Yoshiki Ikeda
• Mr. Narito Kurata
An on-line system identification procedure was developed based on extended Kalman filter, which removes noise from a system and observation, and estimates the best vector. This procedure can be classified as a parametric method in the time domain and can be considered as one of the adaptive filtering techniques. Kalman filter can make a scale of a system and observation small, and it does not require a large computer. This report describes the fundamental theory of this method, the numerical tests of the newly developed code, and the application to the experimental tests conducted by CUREe.
2. On-Line System Identification Procedure
3. Numerical Test
4. Application To Experimental Test
Also listed as Report No.: CK91-04 (February 1991)