Thermal optimization of a polyimide V-groove actuator for a walking micro-robot

The objective of this thesis was to develop a Finite Element Model for the Polyimide V-groove actuator (fabricated by T. Ebefors, Sweden). Extensive FEM simulations for this MEMS actuator were performed using ANSYS 5.6. An optimization module was used to improve the performance of the existing design. A substantial improvement in the performance was observed for the proposed design. In short, this research established a methodology that can be extended for modeling and simulation of other MEMS devices. A computer simulated FEM model for heat and deflection analysis was validated for two configurations of the Polyimide V-groove Actuator (i.e. a Serpentine Heater Configuration and a Polysilicon Heater Configuration). Some differences between the simulated and experimental results (reported by T. Ebefors) were noted in the low frequency domain. The role of various parameters including thermal conductivity and wall temperature has been investigated to eliminate these discrepancies. To improve the performance of the actuator, different design geometries were proposed and each design was simulated for various frequencies. Significant performance improvement was observed for the case of uniform diaphragm thickness at the V-groove bottom . The optimization module of ANSYS was used for optimizing the thickness of the silicon diaphragm (referred to as single variable optimal design ). Steady state analysis showed that there is an improvement in the deflection and the force developed for the single variable optimal design over T. Ebefors\u27 design. Transient analysis showed improvement in the cooling characteristics of the single variable optimal design over T. Ebefors\u27 design. In the second optimization exercise (referred to as overall optimization ), all the dimensions of the V-grooves were used as design variables. A three times increase in the deflection was observed in the overall optimal design as compared to the single variable optimal design. Also, there is a three times reduction in the maximum force developed by the overall optimal design. Transient analysis revealed that the overall optimal design has better cooling characteristics compared to the single variable optimal design. Hence, for an application where the applied force is not a critical factor, the overall optimal design would be suitable, e.g. if a lightweight mirror is mounted on the end of the actuator, the mirror can be moved through a larger distance. For micro robotics applications, the optimal design with a single variable could be useful, where the load carrying capacity of this design is superior

A Novel Human Machine Interface for Advanced Building Controls and Diagnostics

A new generation of Human Machine Interfaces (HMI) for building automation systems is needed to allow facility managers to leverage the potential of advanced controls and diagnostics. In this paper we will describe a design process and the end product, a novel HMI prototype. This novel system is an integration of advanced algorithms, an underlying software architecture, building equipment, and the human operators that use it. Recent developments in building controls and diagnostics techniques promise to improve occupants comfort while minimizing energy consumption. Advanced diagnostics algorithms can not only detect equipment failures and anomalous behaviors but also estimate the energy and comfort impact of faults. New sophisticated control schemes regulate a building based on past and future conditions rather than a static model. They can also automatically adapt to equipment failures to maintain the highest comfort given the available resources. There are several hurdles that must be overcome to effectively deploy these techniques. The perceived algorithmic difficulty of these approaches and the absence of proper tools to leverage them create a gap between what we know is computationally possible and operators in the field. One of the biggest problems is that current Building Management Systems (BMS) are not designed to natively support these advanced capabilities. As a part of the Department of Energy (DoE) sponsored Energy Efficient Building Hub (EEBHub), a team led by UTRC prototyped a new HMI that natively supports a variety of advance features. Within the EEBHub, several academic and industrial teams are experimenting with new technologies to reduce the energy footprint of buildings. In collaboration with these teams, UTRC integrated novel diagnostic and control techniques with building automation infrastructure to better understand the possibilities of a new HMI for building applications

DETC2008-49335 PRODUCT FAMILY COMMONALITY SELECTION THROUGH INTERACTIVE VISUALIZATION

ABSTRACT High dimensionality and computational complexity are curses typically associated with many product family design problems. In this paper, we investigate interactive methods that combine two traditional technologies -optimization and visualization -to create new and powerful strategies to expedite high dimensional design space exploration and product family commonality selection. In particular, three different methods are compared and contrasted: (1) exhaustive search with visualization, (2) individual product optimization with visualization, and (3) product family optimization with visualization. Among these three, the individual product optimization with visualization methods appears to be the most suitable one for engineer designers, who do not have strong optimization background. This method allows designers to "shop" for the best designs iteratively, while gaining key insight into the tradeoff between commonality and individual performance. The study is conducted in the context of designing a UTC product using an in-house, system-level simulation tool. The challenges associated with (1) design space exploration involving mixed-type design variables and infeasibility, and those associated with (2) visualizing product family design spaces during commonality selection are addressed. Our findings indicate a positive impact on the company's current approach to product family design and commonality selection

Study of a honeycomb-type rigidified inflatable structure for housing

This paper presents a parametric study aimed at uncovering general design principles that govern the structural performance of honeycomb-type rigidified inflatable structures (RIS) as load-bearing wall systems for use in residential housing. This study involves the use of finite element modeling and optimization. A series of honeycomb-type RIS wall systems, each comprising different honeycomb cell sizes, are examined. The problem at hand is stated in the form of minimizing material volume subject to: permissible stress, maximum allowable deflection, and membrane thickness. The optimization results help identify optimal design configurations for given sets of loading conditions and material properties. The effects of various design parameters, such as cell size, material properties, and membrane thicknesses, are discussed. The performance of honeycomb-type RIS wall systems is compared with that of rectilinear-type RIS wall systems, which were studied previously. The work presented makes a significant step in establishing the feasibility of RIS for housing applications

IMECE2003-43722 THERMAL MANAGEMENT OF A POLYIMIDE V-GROOVE LEG ACTUATOR FOR A WALKING MICRO-ROBOT

ABSTRACT A model for a Polyimide V-groove leg actuator with a Polysilicon type heater was simulated using ANSYS 5.6. Potential areas for improvement were identified. These include the relative expansion of the Polyimide within the V-groove during the heating cycle, and the heat conduction path during the cooling cycle. Various geometries were investigated, and results were compared with a Plane Wall V-groove design. Significant Net Gain was observed for the case of uniform diaphragm thickness at the V-groove bottom. Considering the simplicity of fabrication of this case, the uniform diaphragm Vgroove geometry appears worthy of further investigation