Comparison and Application of Metrics That Define the Components Modularity in Complex Products

As the content and variety of technology increases in automobiles, the complexity of the system increases as well. Decomposing systems into modules is one of the ways to manage and reduce system complexity. This paper surveys and compares a number of state-of-art components modularity metrics, using 8 sample test systems. The metrics include Whitney Index (WI), Change Cost (CC), Singular value Modularity Index (SMI), Visibility-Dependency (VD) plot, and social network centrality measures (degree, distance, bridging). The investigation reveals that WI and CC form a good pair of metrics that can be used to assess component modularity of a system. The social network centrality metrics are useful in identifying areas of architecture improvements for a system. These metrics were further applied to two actual vehicle embedded software systems. The first system is going through an architecture transformation. The metrics from the old system revealed the need for the improvements. The second system was recently architected, and the metrics values showed the quality of the architecture as well as areas for further improvements.

Piezoelectric T-Beam Microactuators

This paper introduces a novel T-beam actuator fabricated by a piezoelectric MEMS fabrication process. ICP-RIE etching from the front and back of a bulk PZT chip is used to produce stair stepped structures through the thickness with complex inplane shapes. Masked electrode deposition creates active and passive regions in the PZT structure. With a T-shaped crosssection, and bottom and top flange and web electrodes, a cantilevered beam can bend in-plane and out-of-plane with bimorph actuation in both directions. One of these T-beam actuators is fabricated and experimentally tested. An experimentally validated model predicts that the cross-section geometry can be optimized to produce higher displacement and blocking force.

Meta4acle: Generating Compelling Metaphors for Design

Metaphors have successfully been used by new product development and design teams to help frame the design situation and communicate new products to stakeholders. Yet, the process of finding a compelling metaphor often turns upon stumbling upon it or a flash of insight from a team member. We present Meta4acle: a Metaphor Exploration Tool for design that suggests possible metaphors to make the process more one of ‘seeking out’ than ‘stumbling upon’ an effective metaphor. The tool takes data about the project in the form of a title, domain and key associations required of the metaphor and returns suggestions from a database of possible metaphor sources. We built a Meta4acle prototype and evaluated it with positive results for three existing design case studies. We present plans for its full implementation and evaluation.

High Yield Assembly of Compliant MEMS Snap Fasteners

Heterogeneous assembly at the microscale has recently emerged as a viable pathway to constructing 3-dimensional microrobots and other miniaturized devices. In contrast to self-assembly, this method is directed and deterministic, and is based on serial or parallel microassembly. Whereas at the meso and macro scales, automation is often undertaken after, and often benchmarked against manual assembly, we demonstrate that deterministic automation at the MEMS scale can be completed with higher yields through the use of engineered compliance and precision robotic cells. Snap fasteners have long been used as a way to exploit the inherent stability of local minima of the deformation energy caused by interference during part mating. In this paper we assume that the building blocks are 2 1/2 -dimensional, as is the case with lithographically microfabricated MEMS parts. The assembly of the snap fasteners is done using μ3, a multi-robot microassembly station with unique characteristics located at our ARRI’s Texas Microfactory lab. Experiments are performed to demonstrate that fast and reliable assemblies can be expected if the microparts and the robotic cell satisfy a so-called “High Yield Assembly Condition” (H.Y.A.C.). Important design trade-offs for assembly and performance of microsnap fasteners are discussed and experimentally evaluated.

An Investigation on the Profile of Microlens by the Thermal Reflow Process Due to Surface Tension and Gravity

Microlens and its mold fabricated by thermal reflow using photoresist have been widely used for forming patterns in different scales. When the photoresist solidifies from melting condition, for example by the reflow process, its profile is formed based on the balance between surface tension and gravity. This research is aimed to investigate the influence of surface tension and gravity on the profile of microlens in thermal reflow process. Theoretical analysis based on the interaction between surface tension and gravity of liquid droplet is first investigated. The result showed that the height to diameter ratio (h/D), or the sag ratio, of the liquid droplet is affected by the Bond number (Bo), a number defined as the ratio of gravity to surface tension. The sag ratio is not sensitive to Bo when Bo is small but the ratio decreases as Bo increases if Bo is over the critical number. Based on the analysis, the critical number for the AZ4620 photoresist on a silicon substrate is 1, corresponding to the critical radius of droplet R = 2,500μm. When the size of the droplet is less then the critical size, the profile is mainly controlled by the surface tension and thus the sag ratio is about the same regardless the size. The profile, in contrast, is highly affected by the gravity if the size of the droplet is larger then the critical size. The sag ratio decreases exponentially with respect to Bo in this case. Experiments are also designed and conducted to verify the analysis. Experimental result showed that the sag ratio of the photoresist reduces to 0.065 from 0.095 when Bo increases from 0.0048 to 0.192. The results showed that the trend is consistent to the theoretical model.

Modelling and Simulation of a Cantilever-Paddle Beam Under the Effect of Capillary, Shock, and Electrostatic Forces

In this paper, we present a mathematical model and analysis for a microbeam fixed at one end and coupled to a microplate at its other end under the effect of capillary, shock and electrostatic forces. The model considers the microbeam as a flexible structure, the plate as a rigid body. First, we subject the system to capillary force via a drop of fluid which is trapped underneath the microplate. We derive closed-form solutions to the static and eigenvalue problems associated with the microbeam-microplate system. We then subject the system to shock loads for both case (capillary and electrostatic forces). The Galerkin procedure is used to derive a set of nonlinear ordinary-differential equations that describe the microsystem dynamics. We investigate the influence of the fluid volume ratio and the applied DC voltage on the microbeam response. We find that the effect of capillary force has much more dominant role compared to shock and electrostatic forces.

Micropump With Six Vibrating Membranes: Design Analysis

In this study, a novel design of multiple vibrating membrane micropump has been investigated. The micropump is composed of six membranes and three nozzle/diffuser elements. The membranes were vibrated out-of-phase simultaneously to create pressure difference in the pump chamber. The characteristics of this micropump were analyzed using the finite volume method. The commercial computational fluid dynamics software, FLUENT, with the dynamic mesh algorithm was employed to study velocity field and flow rate during the operating cycle. The simulation results showed that the movement of these membranes combined with the rectification behavior of three nozzle/diffuser elements can minimize back flow and improve net flow in one direction. The average mass flow rate from the micropump increased when the maximum membrane displacement and membrane frequency increased. However, the average mass flow rate from the micropump decreased when pressure head increased. Increases in maximum pressure head were associated with increases in membrane frequency.

Behavior-Form Double Directions Creative Conceptual Design Model and Its Quotient Space Implementation

This paper presents a novel indirect matching approach between the function layer and the form layer to enhance the capability for the FBS method to obtain the creative conceptual design results. Firstly, the basic operation actions set, which is composed of the basic operation actions obtained by decomposing each function in the lowest level of the function decomposition tree in the FBS model into the sub-functions, in the function layer is regrouped dynamically. This behavior regroup process has introduced the new design variables into the conceptual design process and leads the behavior creativity to produce. On the other hand, considering the multi-functions for each basic structure to have and representing these functions with the basic operation actions, then the basic operation actions set in the form layer is set up. Dynamic regrouping this set in the form layer, the new design variables has been introduced into the conceptual design process, and leads the form creativity to produce. Through the above behavior-form double directions creative process, the solution scope of the conceptual design is enlarged obviously. Therefore, the method present in this paper has enough capability to obtain the creative conceptual results. Furthermore, the model presented in this paper is represented with the quotient space mathematically. The case study has shown that in the function layer, through adjusting the attribute function, which determines the partition grain of the basic operation actions set in the function layer or in the form layer, the new behaviors can be generated.

Task-Space Control Design and Performance Evaluation for a 6DOF Stewart Nanoscale Platform

A 6DOF Stewart platform using piezoelectric actuators for nanoscale positioning objective is designed. A measurement method that can directly measure the pose (position and orientation) of the end-effector is developed so that task-space on-line control is practicable. The design of a sensor holder for sensor employment, a cuboid with referenced measure points, and the computation method for obtaining the end-effector parameters is introduced. A control scheme combining feedforward and feedback is proposed. The inverse model of a hysteresis model derived by using a dynamic Preisach method is used for the feedforward control. Hybrid control to maintain both the positioning and force output for nano-cutting and nano-assembly applications is designed for the feedback controller. The optimal gain of the feedback controller is searched by using relay feedback test method and genetic algorithm. In experiment, conditions with/without external load employed with feedforward, feedback, and feedforward with feedback control schemes respectively are carried out. Performance of each control scheme verifies the capability of achieving nanoscale precision. The combined feedforward and feedback control scheme is superior to the others for gaining better precision.

Novel Linearly Tunable MEMS Capacitors With Flexible Moving Electrodes

In conventional MEMS parallel-plate capacitor designs, the moving electrode is commonly modeled as a rigid plate with flexible boundary conditions provided by a set of supporting beams. Such a capacitor generates limited tuning ratio up to 1.5 and its capacitance-voltage response is nonlinear. This paper presents novel designs where the moving electrodes are fixed-edge flexible plates. The plate displacement is selectively limited by a set of rigid steps, located between two electrodes, to generate a smooth and linear response and high tunability. Three different step heights are considered in the design and the linearity of the C-V curve is maximized by modifying the geometry of the plate, and changing the location and order of steps. Since the analytical solution for coupled electrostatic-structural physics in this case does not exist, ANSYS® FEM simulation is performed to obtain the C-V curves and optimize the design. Two designs with different electrode shapes, rectangular and circular, are developed. For rectangular-plate capacitors, tunabilities ranging from 120% to 140% and high linearity are achieved. Circular-plate designs, on the other hand, generate lower tunabilities and an extremely linear region in C-V curves. Design methodology introduced in this research is not limited to proposed geometries and can be extended to different topologies to obtain a combination of high tunability and linearity.