David J. Cappelleri

Efficient Pareto Frontier Exploration using Surrogate Approximations

In this paper we present an efficient and effective method of using surrogate approximations to explore the design space and capture the Pareto frontier during multiobjective optimization. The method employs design of experiments and metamodeling techniques (e.g., response surfaces and kriging models) to sample the design space, construct global approximations from the sample data, and quickly explore the design space to obtain the Pareto frontier without specifying weights for the objectives or using any optimization. To demonstrate the method, two mathematical example problems are presented. The results indicate that the proposed method is effective at capturing convex and concave Pareto frontiers even when discontinuities are present. After validating the method on the two mathematical examples, a design application involving the multiobjective optimization of a piezoelectric bimorph grasper is presented. The method facilitates multiobjective optimization by enabling us to efficiently and effectively obtain the Pareto frontier and identify candidate designs for the given design requirements.

Transcriptome transfer produces a predictable cellular phenotype

Cellular phenotype is the conglomerate of multiple cellular processes involving gene and protein expression that result in the elaboration of a cells particular morphology and function. It has been thought that differentiated postmitotic cells have their genomes hard wired, with little ability for phenotypic plasticity. Here we show that transfer of the transcriptome from differentiated rat astrocytes into a nondividing differentiated rat neuron resulted in the conversion of the neuron into a functional astrocyte-like cell in a time-dependent manner. This single-cell study permits high resolution of molecular and functional components that underlie phenotype identity. The RNA population from astrocytes contains RNAs in the appropriate relative abundances that give rise to regulatory RNAs and translated proteins that enable astrocyte identity. When transferred into the postmitotic neuron, the astrocyte RNA population converts 44% of the neuronal host cells into the destination astrocyte-like phenotype. In support of this observation, quantitative measures of cellular morphology, single-cell PCR, single-cell microarray, and single-cell functional analyses have been performed. The host-cell phenotypic changes develop over many weeks and are persistent. We call this process of RNA-induced phenotype changes, transcriptome-induced phenotype remodeling.

Design of a PZT Bimorph Actuator Using a Metamodel-Based Approach

The design of a variable thickness piezoelectric bimorph actuator for application to minimally invasive surgery is proposed. The actuator is discretized into five segments along its length, where the thicknesses of the segments are used as design variables in the problem of optimizing both the force and deflection at the tip. Metamodeling techniques are used to construct computationally inexpensive approximations of finite element simulations and to rapidly explore the design space and the Pareto frontier. A prototype device and experimental verification of the analytical results are also discussed.

Designing open-loop plans for planar micro-manipulation

This paper describes a test-bed for planar micro manipulation tasks and a framework for planning based on quasi-static models of mechanical systems with frictional contacts. We show how planar peg-in-the-hole assembly tasks can be designed using randomized motion planning techniques with Masons models for quasi-static manipulation. Finally, we present simulation and experimental results in support of our methodology

The Robotic Decathlon: Project-Based Learning Labs and Curriculum Design for an Introductory Robotics Course

This paper presents a series of novel project-based learning labs for an introductory robotics course that are developed into a semester-long Robotic Decathlon. The last three events of the Robotic Decathlon are used as three final one-week-long project tasks; these replace a previous course project that was a semester-long robotics competition. The course assessment shows that this new approach enhances student learning with respect to the standard lecture/test style of teaching, and that the three shorter final project tasks make the course easier to manage and more enjoyable for the students.

Caging micromanipulation for automated microassembly

This paper introduces the concept of caging micromanipulation for use in automated open loop microassembly tasks. Utilizing a caging transport motion primitive along with rotational and translation primitives, we demonstrate full control of the state of the part. Additionally, a framework for planar microassembly task planning is provided based on the A* algorithm. It is used to determine the optimal assembly sequences and part starting locations in the workspace. We also describe a test-bed suitable for planar micro, meso-scale, and nano-scale manipulation and assembly tasks and present simulation and experimental results of this work.

Automated Assembly for Mesoscale Parts

This paper describes a test-bed for planar micro and mesoscale manipulation tasks and a framework for planning based on quasi-static models of mechanical systems with intermittent frictional contacts. We show how planar peg-in-the-hole assembly tasks can be designed using randomized motion planning techniques with Masons models for quasi-static manipulation. Simulation and experimental results are presented in support of our methodology. We develop this further into a systematic approach to incorporating uncertainty into planning manipulation tasks with frictional contacts. We again consider the canonical problem of assembling a peg into a hole at the mesoscale using probes with minimal actuation but with visual feedback from an optical microscope. We consider three sources of uncertainty. First, because of errors in sensing position and orientation of the parts to be assembled, we must consider uncertainty in the sensed configuration of the system. Second, there is uncertainty because of errors in actuation. Third, there are geometric and physical parameters characterizing the environment that are unknown. We discuss the synthesis of robust planning primitives using a single degree-of-freedom probe and the automated generation of plans for mesoscale manipulation. We show simulation and experimental results of our work.

Towards Mobile Microrobot Swarms for Additive Micromanufacturing

In this paper, a novel approach to achieving the independent control of multiple magnetic microrobots is presented. The approach utilizes a specialized substrate consisting of a fine grid of planar, MEMS-fabricated micro coils of the same size as the microrobots (≤ 500 μm). The coils can be used to generate real magnetic potentials and, therefore, attractive and repulsive forces in the workspace to control the trajectories of the microrobots. Initial work on modelling the coil and microrobot behavior is reported along with simulation results for navigating one and two microrobots along independent desired trajectories. Qualitative results from a scaled-up printed circuit board version of the specialized substrate operating on permanent magnets are presented and offer proof-of-concept results for the approach. These tests also provide insights for practical implementations of such a system, which are similarly reported. The ultimate goal of this work is to use swarms of independently controlled microrobots in advanced, additive manufacturing applications.

A magnetic thin film microrobot with two operating modes

Magnetic principles have proved successful for untethered submillimeter microrobotics, although challenges still exist in areas of propulsion and control. This paper presents the design, analysis, and performance results for a bimorph thin film magnetic microrobot utilizing the magnetostrictive principle as a secondary oscillating operation mode. The microrobot is no larger than 580 µm in its planar dimension and its total thickness is less than 5 µm. As a robot with magnetic material, it can be operated in a pushing/pulling mode in orthogonal directions for movement in a plane, while its powered with an external magnetic field as low as 1 mT. For the secondary oscillating operation mode utilizing the magnetostrictive principle, in-plane strain is induced, resulting in bending and blocking forces on the robot. These forces are theoretically calculated to prove enough drive force can be generated in this mode. The design is further abstracted and translated into a piezoelectric cantilever FEM model to confirm the theorectical results. Microrobot fabrication and test-bed development based on this analysis is shown, which enabled us to participate in the final competition in the 2010 NIST Mobile Microrobot Challenge, with good performance in the dash and freestyle events. Finally, we discuss the testing results in various dry and fluid environments along with recommendations for future investigation and improvements. Keywords: microrobot, magnetostrictive, bimorph

Modeling and global trajectory tracking control for an over-actuated MAV

This paper deals with an original micro aerial vehicle (MAV) design, the Omnicopter MAV. It has two central coaxial rotors with fixed-pitch propellers and three perimeter mounted ducted fans with servo motors performing thrust vectoring. Compared with traditional rotary wing MAVs that have inherent underactuation, the Omnicopter possesses some advantages in mobility, for example, lateral translation with zero attitude and hover with nonzero attitude. The trajectory tracking control design, global stability analysis, and control allocation are demonstrated through numerical simulation. The advantage of zero attitude translation is illustrated through experimental results. Graphical Abstract