Person:

Rosen, David W.

Permanent Link

https://hdl.handle.net/1853/71643

Associated Organization(s)

Organizational Unit

George W. Woodruff School of Mechanical Engineering

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Publication Search Results

Now showing 1 - 10 of 17

Lagrangian Duality in 3D SLAM: Verification Techniques and Optimal Solutions

(Georgia Institute of Technology, 2015) Carlone, Luca ; Rosen, David W. ; Calafiore, Giuseppe ; Leonard, John J. ; Dellaert, Frank

State-of-the-art techniques for simultaneous localization and mapping (SLAM) employ iterative nonlinear optimization methods to compute an estimate for robot poses. While these techniques often work well in practice, they do not provide guarantees on the quality of the estimate. This paper shows that Lagrangian duality is a powerful tool to assess the quality of a given candidate solution. Our contribution is threefold. First, we discuss a revised formulation of the SLAM inference problem. We show that this formulation is probabilistically grounded and has the advantage of leading to an optimization problem with quadratic objective. The second contribution is the derivation of the corresponding Lagrangian dual problem. The SLAM dual problem is a (convex) semidefinite program, which can be solved reliably and globally by off-the-shelf solvers. The third contribution is to discuss the relation between the original SLAM problem and its dual. We show that from the dual problem, one can evaluate the quality (i.e., the suboptimality gap) of a candidate SLAM solution, and ultimately provide a certificate of optimality. Moreover, when the duality gap is zero, one can compute a guaranteed optimal SLAM solution from the dual problem, circumventing non-convex optimization. We present extensive (real and simulated) experiments supporting our claims and discuss practical relevance and open problems.
Ultralight-but-robust automotive vehicle with strong, lightweight, next-generation material

(Georgia Institute of Technology, 2011-05-31) Choi, Seung-kyum ; Rosen, David W. ; Neu, Richard W.
Tissue support for suprachoroidal surgery

(Georgia Institute of Technology, 2010-09-24) Rosen, David W. ; Melkote, Shreyes N. ; Mathai, George ; Olsen, Timothy
ITR/PE+SY digital clay for shape input and display

(Georgia Institute of Technology, 2007-11-30) Book, Wayne J. ; Rossignac, Jarek ; Mynatt, Elizabeth D. ; Allen, Mark G. ; Goldthwaite, John Randall ; Rosen, David W. ; Glezer, Ari
Designing Platforms for Customizable Produces and Processes in Markets of Non-Uniform Demand

(Georgia Institute of Technology, 2007) Williams, Christopher Bryant ; Rosen, David W. ; Mistree, Farrokh ; Allen, Janet K.

The foremost difficulty in making the transition to mass customization is how to offer product variety affordably. The answer to this quandary lies in the successful management of modularity and commonality in the development of products and their production processes. While several platform design techniques have emerged as a means to offer modularity and commonality, they are limited by an inability to handle multiple modes of offering variety for multiple design specifications. The Product Platform Constructal Theory Method (PPCTM) is a technique that enables a designer to develop platforms for customizable products while handling issues of multiple levels of commonality, multiple product specifications, and the inherent trade-offs between platform extent and performance. The method is limited, however, by its inability to handle multiple design objectives and its reliance on the assumption that demand in the market is uniform for each product variant. The authors address these limitations in this paper by infusing the utility-based compromise Decision Support Problem and demand modeling techniques. The authors further augment the PPCTM by extending it use to a new domain: the design of process parameter platforms. The augmented approach is illustrated through a tutorial example: the design of a product and a process parameter platform for the realization of a line of customizable cantilever beams.
Manufacturing Cellular Materials Via Three-Dimensional Printing of Spray-dried Metal Oxide Ceramic Powder

(Georgia Institute of Technology, 2007) Rosen, David W. ; Williams, Christopher Bryant

Cellular materials, metallic bodies with gaseous voids, are a promising class of materials that offer high strength accompanied by a relatively low mass. Unfortunately, existing manufacturing techniques constrain a designer to a predetermined part mesostructure, material type, and macrostructure. In this paper, the authors document their design rationale for the selection of the Three-Dimensional Printing (3DP) additive manufacturing process as a means to fabricate metallic cellular materials. This is achieved by selectively printing a solvent into a bed of spray-dried metal oxide ceramic powder. The resulting green part undergoes reduction and sintering post-production processes in order to chemically convert it to metal.
Analysis of Mesostructure Unit Cells Comprised of Octet-truss Structures

(Georgia Institute of Technology, 2006-08) Johnston, Scott R. ; Rosen, David W. ; Reed, Marques ; Wang, Hongqing Vincent

A unit truss finite element analysis method allowing non-linear deformation is employed to analyze a unit cell comprised of n3 octet-truss structures for their stiffness and displacement compared to their relative density under loading. Axial, bending, shearing, and torsion effects are included in the analysis for each strut in the octet-truss structure which is then related to the mesostructure level (unit cell). The versatility of additive manufacturing allows for the fabrication of these complex unit cell truss structures which can be used as building blocks for macro-scale geometries. The finite element calculations are compared to experimental results for samples manufactured on a Stereolithography Apparatus (SLA) out of a standard resin.
Design of a Graded Cellular Structure For an Acetabular Hip Replacement Component

(Georgia Institute of Technology, 2006-08) Johnston, Scott R. ; Rosen, David W. ; Wang, Hongqing Vincent

The state-of-the-art porous coatings become more and more popular in uncemented prostheses to make bone grow into implants for biological fixation. In this paper, graded cellular structures are proposed for uncemented prostheses to enhance stability on implant-bone interfaces. As an example study, the authors develop a new acetabular implant with gradient porosity for hip replacement. A gradient porous acetabular component with cellular structure could match the bone’s elasticity. Material is adaptively distributed from high porosity at the bone-implant interface to solid metal at the joint’s articulating surface. The new acetabular prosthesis would replace metal-on-polyethylene bearing with metal-on-metal bearing for less wear. The design problem of acetabular component is formulated and a requirement list is elaborated. A detailed design of the prosthesis with a graded cellular structure is presented. The design concept is validated with a comparison to the existing products according to the design requirements.
Design Synthesis of Mesoscopic Cellular Structures With Unit Truss Approach and Particle Swarm Optimization Algorithm

(Georgia Institute of Technology, 2006-08) Williams, Chris ; Rosen, David W. ; Wang, Hongqing Vincent

Cellular material structures have been engineered at the mesoscopic scale for high performance and multifunctional capabilities. However, the design of adaptive cellular structures - structures with cellular configurations, sizes, and shapes designed for a specific geometric and loading context - has not been sufficiently investigated. In this paper, the authors present a design synthesis method with the use of unit truss approach and particle swarm optimization algorithm to design adaptive cellular structures. A critical review is presented to show the pros and cons of the new design synthesis method and an existing homogenization method. The research extends the application of additive manufacturing in the design of new materials for high performances and benefits its long-term growth.
Design of General Lattice Structures for Lightweight and Compliance Applications

(Georgia Institute of Technology, 2006-07) Rosen, David W. ; Johnston, Scott R. ; Reed, Marques

The primary goal is to design parts with lattice mesostructure and demonstrate that they have better structural and/or compliance performance, per weight, than parts with bulk material, foams, or other mesostructured approaches. Mesostructure refers to features within a part that have sizes between micro and macro-scales, for example, small truss structures, honeycombs, and foams. The versatility of additive manufacturing allows for the fabrication of these complex unit cell lattice structures which can be used as building blocks for macro-scale geometries. A method and software system have been developed to synthesize lattice mesostructure parts and compliant mechanisms in 2D and 3D. Underlying the synthesis method is a new analytical model of unit lattices, used to compose larger structures. Axial, bending, shearing, and torsion effects are included in the analysis for each strut in the lattice structure which is then related to the mesostructure level (unit cell). A unit lattice finite element analysis method allowing nonlinear deformation is employed to analyze a unit cell comprised of n[3] unit structures for their stiffness and displacement compared to their relative density under loading. Aerospace and biomedical applications are demonstrated.