Semi-active control

As a final example of a MR fluid controlled adaptronic system, the smart prosthesis knee developed by Biedermann Motech GmbH [178-181] is presented. This system shown in Fig. 6.91 is a complete artificial knee that automatically adapts and responds in real-time to changing conditions to provide the most natural gait possible for above-knee amputees. The heart of this system is a small magnetorheological fluid damper that is used to semi-actively control the motion of the knee based on inputs from a group... 

Magnetorheological fluid actuators provide technology that enables effective semi-active control in a number of real-world applications. Automotive applications of MR fluid are significant and growing rapidly. Annual production of MR fluid is now on the order of hundreds of tons. It is estimated that more than one hundred thousand MR fluid devices are presently in use. This number is expected to rise into the millions as more automotive platforms adopt MR fluid based real-time controlled motion control systems. Due to their simplicity, low power, and inherent robustness, MR fluid devices have proven themselves in a wide variety of commercial applications. 

Carlson, J.D. Innovative Devices That Enable Semi-Active Control. Proc. 3rd World Conf. on Structural Control, Como, Italy, April 2002, F Casciati, ed., John Wiley, Chichester (2003), pp 227-236... 

The dynamic response of civil engineering structures subjected to earthquake excitation can be reduced by using passive control systems such as energy dissipation devices (e.g. viscous dampers, etc.). The advantage of these systems with respect to active and semi-active control systems consist in the fact that they don t require any power supply, therefore are quite reliable and they require least maintenance. 

Semi-Active (Adaptive-Passive) Systems Refer to an adjustable passive vibration control scheme, that is, the passive treatment can adjust itself in response to changes in the structure. For example, the stiflfiiess, damping coefficient or other variables of the passive control scheme can change automatically so that optimal vibration mitigation is induced. These variable components, also known as tunable parameters of the control system, are re-tailored via a properly developed semi-active control algorithm. Being more versatile than passive control techniques and more affordable (in terms of cost and energy consumption) than active control schemes, has made semi-active control methods very popular. 

Eikus, B., Abe, M., Fujino, Y. (2002). Investigation of semi-active control for seismic protection of elevated highway bridges. Structure Engineering, 24(3), 281-293. doi 10.1016/ 80141-0296(01)00095-5... 

The main objective of this chapter is to find the optimal values of the base isolation system as a kind of passive control device, and that of the STMD system as a kind of semi-active control device using genetic algorithms (GAs) and fuzzy logic to simultaneously minimize the buildings selected responses. A comprehensive literature review of these systems is provided in the main relevant sections of each system. 

Pourzeynali, S., Mousanejad, T. (2010). Optimization of semi-active control of seismically excited buildings using genetic algorithms. Sci-entia Iranica, Transaction A. Civil Engineering (New York, NY), 77(1), 26-38. 

S5mians, M. D., Constantinou, M. C. (1999). Semi-active control systems for seismic protection of structures A state-of-the-art review. Engineering Structures, 21, 469-487. doi 10.1016/ S0141-0296(97)00225-3... 

Jansen, L. M., Dyke, S. J. (2000). Semi-active control strategies forthe MRdamper A comparative study ASCE. Journal ofEngineeringMechan-ics, 126, 795-803. doi 10.1061/(ASCE)0733-9399(2000)126 8(795)... 

Karamodin,A., Kazemi, H. (2010). Semi-active control of structures using neuro-predictive algorithm for MR dampers. Structural Control and Health Monitoring, 17, 237-253. 

Ikeda, Y. (2004). Active and semi-active control of buildings in Japan. Journal of Japan Association for Earthquake Engineering, 4(3), 278-282. 

Figure 1. Example of active (or semi-active) control system (active mass damper)...

Control algorithms available in the literature map control force required to an equivalent voltage and then supply that voltage into the damper. This inverse mapping of force to voltage makes the choice and development of control algorithms more complicated. Semi-active control algorithms... 

Ali, S. F., Ramaswamy, A. (2008). GA optimized FFC driven semi-active control for phase II smart nonlinear base isolated benchmark building. Structural Control and Health Monitoring, 15, 797-820. doi 10.1002/stc.272... 

Jung, H. J., Choi, K. M., Spencer, B. F. Jr, Lee, I. W. (2005). Application of some semi-active control algorithms to a smart base isolated building employing MR dampers. Structural Control and Health Monitoring, 13(2-3), 693-704. doi 10.1002/stc.l06... 

Leitmarm, G. (1994). Semi-active control for vibration attenuation. Journal of Intelligent Material Systems and Structures, 5, 841-846. doi 10.1177/1045389X9400500616... 

Xu, Z. D., Shen, Y. P., Guo, Y. Q. (2003). Semi-active control of structures incorporated with magnetorheological dampers using neural-networks. Smart Materials and Structures, 72(1), 80-87. doi 10.1088/0964-1726/12/1/309... 

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