Decentralized Vibration Control in a Launch Vehicle Payload Fairing

Author(s):  
Kenneth D. Frampton

The vibro-acoustic environment inside a launch vehicle payload fairing is extremely violent resulting in excessive development costs for satellites and other payloads. The development of smart structures and active noise and vibration control technologies promised to revolutionize the design, construction and, most importantly, the acoustic environment within these fairings. However, the early promise of these technologies has not been realized in such large-scale systems primarily because of the excessive complexity, cost and weight associated with centralized control systems. Now, recent developments in MEMS sensors and actuators, along with networked embedded processor technology, have opened new research avenues in decentralized controls based on networked embedded systems. This work describes the development and comparison of decentralized control systems that utilize this new control paradigm. The controllers are hosted on numerous nodes, possessing limited computational capability, sensors and actuators. Each of these nodes is also capable of communicating with other nodes via a wired or wireless network. The constraints associated with networked embedded systems control that the control systems be relatively simple computationally, scalable and robust to failures. Simulations were conducted that demonstrate the ability of such a control architecture to attenuate specific structural modes.

Author(s):  
Tao Tao ◽  
Isaac Amundson ◽  
Kenneth D. Frampton

The early promise of centralized active control technologies to improve the performance of large scale, complex systems has not been realized largely due to the inability of centralized control systems to “scale up”; that is, the inability to continue to perform well when the number of sensors and actuators becomes large. Now, recent advances in Micro-electro-mechanical systems (MEMS), microprocessor developments and the breakthroughs in embedded systems technologies, decentralized control systems may see these promises through. A networked embedded system consists of many nodes that possess limited computational capability, sensors, actuators and the ability to communicate with each other over a network. The aim of this decentralized control system is to control the vibration of a structure by using such an embedded system backbone. The key attributes of such control architectures are that they be scalable and that they be effective within the constraints of embedded systems. Toward this end, the decentralized vibration control of a simply supported beam has been implemented experimentally. The experiments demonstrate that the reduction of the system vibration is realized with the decentralized control strategy while meeting the embedded system constraints, such as a minimum of internode sensor data communication, robustness to delays in sensor data and scalability.


2001 ◽  
Author(s):  
Kenneth D. Frampton

Abstract Although the application of active control to vibrations has been investigated from many years, the extension of this technology to large-scale systems has been thwarted, in part, by an overwhelming need for computational effort, data transmission and electrical power. This need has been overwhelming in the sense that the potential applications are unable to bear the power, weight and complex communications requirement of large-scale centralized control systems. Recent developments in MEMS devices and networked embedded devices have changed the focus of such applications from centralized control architectures to decentralized ones. A decentralized control system is one that consists of many autonomous, or semi-autonomous, localized controllers called nodes, acting on a single plant, in order to achieve a global control objective. Each of these nodes has the following capabilities and assets: 1) a relatively limited computational capability including limited memory, 2) oversight of a suite of sensors and actuators and 3) a communications link (either wired or wireless) with neighboring or regional nodes. The objective of a decentralized controller is the same as for a centralized control system: to maintain some desirable global system behavior in the presences of disturbances. However, decentralized controllers do so with each node possessing only a limited amount of information on the global systems response. Exactly what information each node has access to, and how that information is used, is the topic of this investigation.


2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000040-000045
Author(s):  
Bhal Tulpule ◽  
Alireza R. Behbahani

Abstract This paper describes the results of the risk reduction testing task recently completed by Embedded Systems LLC under the Air Force SBIR contract {5} titled “Improved Full Authority Digital Engine Control (FADEC) System”. The objective of this program has been to develop a hierarchical, distributed architecture for future propulsion FADEC and aerospace control systems with flexible, scalable and reconfigurable Smart Nodes (SN) built with high temperature capable devices. A key part of this program is the design, development and validation of the System On Chip (SOC) chipset in high temperature (225 Deg. C) SOI (Silicon On Insulator) technology ASIC (Application Specific Integrated Circuit) devices. The SOC chipset designed by Embedded Systems LLC provides the scalability and reconfigurability that enables the Smart Node to interfaces with most sensors and actuators found in FADEC and other aircraft control systems. The analog portion of this 2-chip SOC chipset fabricated by Honeywell using their SOI process is working properly. The digital portion of the SOC chipset, currently implemented in a commercial temperature FPGA (Field Programmable Gate Array), contains important computational functions needed for reconfiguring the SOC and performing complex control functions, such as real time control of an actuator, The risk reduction task was therefore focused on verification and validation of these key functions in a real environment before converting the design into an ASIC. The recent successful demonstration of the real time actuator control capability has minimized the risks and cleared the way for the digital ASIC implementation. The complete high temperature SOC chipset is expected to be available in late 2016.


Author(s):  
Britta Späh ◽  
Rudolf Sebastian Schittenhelm ◽  
Stephan Rinderknecht

Locations of sensors and actuators have major impact on the characteristics of control systems. In this paper a procedure for sensor and actuator placement for vibration control systems is presented. Two different performance criteria are used in order to find optimal positions for the system under consideration. One is considering observability and controllability only, the other one includes knowledge about a disturbance and the control objective. Both criteria are applied to a clamped plate resulting in different optimal sensor and actuator positions. The resulting configurations are investigated by comparison of optimal feed forward and H∞ feedback control of the system with identical disturbances and control objectives but different sensor and actuator positions. The required control effort and achieved amplitude reduction are employed to rate the different performance criteria that were used to determine the sensor and actuator positions. It is shown that, by placing sensors and actuators on the basis of an adequate performance criterion, increased control performance in terms of amplitude reduction per control effort is achieved.


2020 ◽  
Vol 53 (2) ◽  
pp. 2634-2641
Author(s):  
Vinicius Lima ◽  
Mark Eisen ◽  
Konstatinos Gatsis ◽  
Alejandro Ribeiro

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