Design of a smart truss
Background
One of the more critical applications of trusses is their use in space, where their application ranges from instrument booms to robot arms. These trusses are subject to stringent requirements on aspects such as weight, reliability and precision. The use of modern (composite) materials makes these structures light, but, due to their stiffness, more susceptible to lightly damped vibrations which might affect the performance of the system. Think, for example, of high-precision sensors mounted to the extremities of such trusses.
Recent developments in the field of smart materials, that is, materials that respond to external electrical stimuli, allow for a tightly integrated truss design where a number of truss members can be made active allowing them to deform. Actuators and sensors can be integrated as collocated pairs leading to additional advantages in the formulation of the control problem. The controlled expansion and contraction of the truss members should be able to actively counter the vibrations to which the structure is subjected. The active truss could in the end be lighter than the passive design, while meeting the same design specifications.
The successful damping of the structure relies heavily on an efficient, effective and, ideally, robust control system, both in terms of performance and stability. The system will inherently possess a large number of degrees of freedom and choosing a suitable reduction scheme is necessary to obtain a feasible model.
Description of the MSc assignment
The research will start with a literature study. A number of research programs have been completed or are still ongoing in the field of active structures, which will be used as a starting point in the present work. Additionally, several (optimal) control strategies will be studied and based on the expected advantages and disadvantages a choice will be made. The emphasis will be on the development of a suitable and feasible control system.
The whole design will be tested through the use a reference model whereby a conventional truss, with known vibration response, is modified to contain smart actuators. Both the active and passive trusses will be built to obtain the experimental data.
The performance of the truss with the active control system will be compared to the reference design and the results will be evaluated to see if improvements are worthwhile.
Goal of the assignment
The student will design a smart truss designed to actively damp base excitations in a certain frequency range. The design will employ novel smart actuator and control theory applications. The design will be built and evaluated experimentally for reference purposes.
Schematic drawing of the reference truss
Schematic drawing of an active truss member
Potential application: The SPIRIT space interferometer where (micro)vibrations are detrimental to [source: http://www.nasa.gov/centers/goddard/news/topstory/2004/0915s
Mentors
- dr. Mostafa Abdalla
- ir. Roeland De Breuker
- prof.dr.. Zafer Gürdal
- prof.dr.ir. Bob Mulder
