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This study presents model and analysis of a robust one-dimensional stick–slip transportation of an object, on dry contact with an oscillating platform suspended by nonlinear leaf spring. The oscillating platform is designed and modeled such that the elastic spring constant is direction dependent. A recursive analytical solution algorithm is proposed to solve nonlinear system dynamics. The system and the input force parameters are both investigated with goal to optimize the average velocity of the object. Both experimental and analytical results showed that the stick–slip motion is highly nonlinear and sensitive to the system and input force parameters. Moreover, the simulations showed that it is feasible to design a platform with robust sets of parameters (natural frequencies) and further use the input force parameters (amplitude and driving frequency) to tune for desired average velocity, under given dry friction conditions.

This research utilizes the advancement of multi-polymer jetting technology to construct structures from composite layers using polymer materials, and with goal to interpolate intermediate tensile properties that meets the application requirement without compromising the design form. The research hypotheses that the tensile properties of a uniformly layered composite can be linearly interpolated from the mass ratios composing its structure. The hypothesis was tested and validated on standard specimens composed of two polymer materials sandwiched in ultrathin layers. The linear regression analysis between mass ratios and the tensile properties exhibits strong coefficient of determinations for the fitted data $$R_{{\text{reg}}}^2$$ and the proposed linear model $$R_{{\text{hyp}}}^2$$ which were obtained for yield strength, elasticity modulus, maximum strength, and strength at break. The tensile elongations measured at the maximum strength and the rapture strength undergo significant fluctuations that make their regression less linear with the mass ratio. Finally, the elongation at yield remains constant regardless of mass ratio.

The paper presents a novel design of multi-fingered end-of-arm-tooling mechanism for handling micro–meso scale objects. More particularly, the research aims to develop a compliant prosthetic manipulator designed for rapid 3D manufacturability. The microgripper is constructed from a multiple compliant 5-beam mechanism arranged symmetrically to provide three-dimensional manipulation. Comprehensive one dimensional and three dimensional finite element modeling simulations are conducted including geometrical optimization, structural and dynamic analysis with and without grasping an object, modal and buckling analysis. The results showed capability to tune the structural responses to attain fine to coarse displacement allowing grasping of irregular shapes. Preliminary experimental results showed that using electromagnetic actuation as a source of force input to a 3D printed gripper introduces asymmetrical nonlinear response between the reaction force and displacement measured at the fingertip. Future improvement will involve investigating the effect of the digital printing and force feedback control methods to regulate fingertip displacement.

This article develops algorithms for the characterization and the visualization of micro-scale features by using a small number of sample points, and with a goal to mitigate for the measurement shortcomings which are often destructive or time consuming. We implement the algorithms to rapidly examine the microscopic features of a Microelectromechanical System (MEMS) surface. Such images are highly dense; therefore, traditional image processing techniques might be computationally expensive. The contribution of this research include first, we develop local and global algorithm based on modified Thin Plate Spline (TPS) model to reconstruct high resolution images of the micro-surface’s topography, and its derivatives by using low resolution images. Second, we obtain a bending energy algorithm from our modified TPS model, and use it to filter out image defects. Finally, we develop a computationally efficient Windowing technique, which combines TPS and Linear Sequential Estimation (LSE), to enhance the visualization of images. The Windowing technique allows rapid image reconstruction based on the reduction of inverse problem.

This manuscript presents methodologies followed in the construction and packaging of a 3-D microelectromechanical system (MEMS) Fourier transform (FT) spectrometer based on integrated heterogeneous microassembly and packaging systems. We develop procedures, assembly, and packaging work-cells configured for sequential active alignment of miniaturized optical components. Component-to-system-level tolerance analysis is introduced to compensate for the misalignments associated. Furthermore, an inverse methodology based on the self-alignment of fibers is presented to counter the shifts resulting from the fiber packaging process.

The design of many thermal Microelectromechanical (MEMS) actuators is often based on finite element analysis, but lacks analytical insight. In this paper we report a novel electro-thermal microgripper and a comprehensive thermal modeling of a general 5 lineshape microbeam’s actuator using 1-D steady state heat equations. Because of the variety of microgripper fabrication technologies and their applications, different thermal boundary conditions are considered for lifted off and attached grippers. Parametric and nonparametric electrothermomechanical identification models for silicon on insulator microgripper, fabricated on 100 μm device layer, are obtained.

In this article we present STARbot, a bioinspired legged robot capable of multiple locomotion modalities by using large deformation of its skeleton. We construct STARbot by using origami-style folding of flexible laminates. The long-term goal is to provide a robotic platform with maximum mobility on multiple surfaces. This paper particularly studies the quasistatic model of STARbot's leg under different conditions. We describe the large elastic deformation of a leg under external force, payload, and friction by using a set of non-dimensional, nonlinear approximate equations. We developed a test mechanism that models the motion of a leg in STARbot. We augmented several foot shapes and then tested them on soft to rough grounds. Both simulation and experimental findings were in good agreement. We utilized the model to develop several scales of tri and quad STARbot. We demonstrated the capability of these robots to locomote by combining their leg deformations with their foot motions. The combination provided a design platform for an active suspension STARbot with controlled foot locomotion. This included the ability of STARbot to change size, run over obstacles, walk and slide. Furthermore, in this paper we discuss a cost effective manufacturing and production method for manufacturing STARbot.

This paper focuses on robotic technologies and operational capabilities of multiscale robots that demonstrate a unique class of Microsystems with the ability to navigate diverse terrains and environments. We introduce two classes of robots which combine multiple locomotion modalities including centimeter scale Discrete and Continuous robots which are referred here by D-Starbot and C-Starbot, respectively. The first generation of the robots were obtained to allow rapid shape reconfiguration and flipping recovery to accomplish tasks such as lowering and raising to dexterously go over and under obstacles, deform to roll over hostile location as well as squeezing through opening smaller than its sizes. The D-Starbot is based on novel mechanisms that allow shape reconfiguration to accomplish tasks such as lowering and raising to go over and under obstacles as well as squeezing through small voids. The CStarbot is a new class of foldable robots that is generally designed to provide a high degree of manufacturability. It consists of flexible structures that are built out of composite laminates with embedded microsystems. The design concept of C-Starbot are suitable for robots that could emulate and combine multiple locomotion modalities such as walking, running, crawling, gliding, clinging, climbing, flipping and jumping. The first generation of C-Starbot has centimeter scale structure consisting of flexible flaps, each being coupled with muscle-like mechanism. Untethered D-Starbot designs are prototyped and tested for multifunctional locomotion capabilities in indoor and outdoor environments. We present foldable mechanism and initial prototypes of C-Starbot capable of hopping and squeezing at different environments. The kinematic performance of flexible robots is thoroughly presented using the large elastic deflection of a single arm which is actuated by pulling force acting at variable angles and under payload and friction forces.

This paper presents a new method that evaluates the manufacturability of microoptical systems. A statistical, kinematic link model is applied to compute the deviations of optical paths due to the positional and angular misalignments of optical components. The deviation of optical paths is a main source that deteriorates the performance of an optical system, hence it is very important to quantify how misalignments accumulate and propagate from one component to another. This method was applied to evaluate the optical performance of an assembled, chip-scale Fourier Transform (FT) microspectrometer. The microspectrometer was prototyped by using the microassembly of heterogeneous optical components. The statistical model computes the optical paths of two beams that travel through an input fiber, a beam splitter, moving and fixed mirrors, and a detector. Its results were used to determine the tolerance budgets for the fabrication and assembly processes of micro optical components.

Microgrippers based on electrothermal actuation were designed and fabricated using the deep reactive ion etching (DRIE) process with 100mum thick silicon on insulator (SOI) wafer. The design requirements are restricted to basic manipulation tasks such as pick and place, and nonprehensile manipulation. This paper explores several electrothermal end-effectors which have been fabricated for serial and parallel microassembly. The end-effectors include three main building blocks: 1) Integrated and symmetrical actuators of V and U shapes. The symmetrical expansions on Chevron and hot arms allow combination of forward translations that amplify angular motion at the tips of a gripper. 2) A joule heating element based on a resistive V-shape electrothermal actuator. In 3D microassembly, the joining of a micropart is essentially performed by providing an integrated microheater device. 3) A force or position feedback sensing block based on self-straining or electrostatic principle. The integrated sensor can be calibrated for both position and force measurements. Serial heterogeneous assembly of meso and micro-scale objects is demonstrated using a 3D microassembly station. Black-box dynamical models for microgrippers are derived using experimentally obtained data, and performance variations due to the way the microgrippers are mounted onto the robot are discussed.

In this paper we develop an array of pressure control units that locally and selectively pressurizes the wafer for better uniformity of thickness removal during the chemical mechanical planarization (CMP) process. A real-time metrology measurement determines where on the wafer the microactuator array should be activated in order to improve the overall uniformity of the wafer surface. We developed a new micro surface actuation mechanism comprising an array of piezoelectric bending discs sandwiched in a single multi-layer package. We obtained scalable manufacturing and packaging methods that do not only reduce the mechanical misalignment tolerances of such arrays, but also improve their electrical interconnect reliability under harsh environments. The finite element models showed that an individual disc in the array can generate local contact pressure. CMP experiments showed that such locality controlled the material removal rate on silicon wafer. A microactuator unit in an array delivered precise displacement and large pressure outputs measured for a wide range of input voltages. The static and dynamic responses of the microactuator were linear, and had a fast response to voltage input, making it suitable for high speed distributed pressure compensation during the CMP process.

Microassembly is an enabling technology to build 3D microsystems consisting of microparts made of different materials and processes. Multiple microparts can be connected together to construct complicated in-plane and out-of-plane microsystems by using compliant mechanical structures such as micro hinges and snap fasteners. This paper presents design, fabrication, and assembly of an active locking mechanism that provides mechanical and electrical interconnections between mating microparts. The active locking mechanism is composed of thermally actuated Chevron beams and sockets. Assembly by means of an active locking mechanism offers more flexibility in designing microgrippers as it reduces or minimizes mating force, which is one of the main reasons causing fractures in a microgripper during microassembly operation. Microgrippers, microparts, and active locking mechanisms were fabricated on a silicon substrate using the deep reactive ion etching (DRIE) processes with 100-um thick silicon on insulator (SOI) wafers. A precision robotic assembly platform with a dual microscope vision system was used to automate the manipulation and assembly processes of microparts. The assembly sequence includes (1) tether breaking and picking up of a micropart by using an electrothermally actuated microgripper, (2) opening of a socket area for zero-force insertion, (3) a series of translation and rotation of a mating micropart to align it onto the socket, (4) insertion of a micropart into the socket, and (5) deactivation and releasing of locking fingers. As a result, the micropart was held vertically to the substrate and locked by the compliance of Chevron beams. Microparts were successfully assembled using the active locking mechanism and the measured normal angle was 89.2°. This active locking mechanism provides mechanical and electrical interconnections, and it can potentially be used to implement a reconfigurable microrobot that requires complex assembly of multiple links and joints.

The performance of any micro-comronent affects the overall performance of the system especially in the micro-level. In this research work, the thermal and structural performances of microgripper based on silicon are studied. The present study is part of a larger effort in developing, modeling and characterization procedures toward understanding the behavior of microgripper. This is essential to develop better control algorithms and to facilitate the study of robot arms dynamic on gripping performance. The structural stiffness and failure of microgripper in static loading are characterized for two actuation modes: in-plane and off-plane. Moreover, building block attempts are introduced for dynamical modeling of microgripper/sensor/and environment. The electromechanical system model of sensor is experimentally identified and utilized in identifying the performance of hypothesized lumped models of microgripper.

The steady state temperature profiles of U- and I-shaped electrothermal microactuators are analytically derived. The temperature profiles could be used to evaluate the performance sensitivity of the microactuator due to various parameter changes. In this work, the analysis assumes an unpackaged silicon microactuator with an air gap between the actuator and substrate and the profiles are evaluated for various input voltage amplitudes. It was found that at low voltage inputs the temperature profile is exponential in nature with the failure being due to thermo-structural stresses and/or structure melting. At voltages larger than a critical value, a combined sinusoidal and exponential temperature profile is observed with the failure being strongly due to structural melting as well. However, higher voltage excitation causes a fully distributed sinusoidal temperature profile. In this mode, failures occur at different locations and due to high localized thermal stresses causing the temperature to exceed the material melting point. The behavior of U- and I-shaped microactuators based on silicon on insulator (SOI) fabrication and femtosecond laser micromachining was experimentally examined with the results corroborating the conclusions drawn from the analysis.

The Thin Plate Splines (TPS) theory is modified and employed in the reconstruction of 2D 1/2 unfolded micro-topographical surfaces. The modified TPS allows the reconstruction of MEMS structures based on sampled digital elevation model (DEM). The developed algorithms are implemented in MATLAB and applied to restore bad samples, enhance surface reconstruction, and compensate for surface irregularities for micromachining purposes. In addition, the restored surface reveals the scale components of the real surface (roughness, waviness and form). The irregularity of meso, micro and nano surfaces is then characterized into slope, curvature, strike, dip, azimuth and energy surfaces. It is concluded that the simplicity, differentiability of TPS and roughness components relaxation make the proposed theory advantageous on reconstruction and characterization of micro surfaces for a variety of applications.