HK segmentation of 3D micro-structures reconstructed from focus

This paper presents an evaluation of HK segmentation on 3D micro-structures reconstructed from focus. Due to the necessity of 3D shape and surface structure information for a precise micromanipulation, shape of the object is recovered using shape from focus (SFF). In the SFF procedure, using an image sequence, composed of images captured at different focusing levels, focused image of the micro-structure and its shape are acquired. Then the resulting shape, also called range image, is used in HK segmentation method to extract surface curvature information. Experimental results show that this technique works for both synthetic and real data

3D reconstruction, classification and mechanical characterization of microstructures

Modeling and classifying 3D microstructures are important steps in precise micro-manipulation. This thesis explores some of the visual reconstruction and classification algorithms for 3D microstructures used in micromanipulation. Mechanical characterization of microstructures has also been considered. In particular, visual reconstruction algorithm (shape from focus - SFF) uses 2D image sequence of a microscopic object captured at different focusing levels to create a 3D range image. Then, the visual classification algorithm takes the range image as an input and applies a curvature-based segmentation method, HK segmentation, which is based on differential geometry. The object is segmented into surface patches according to the curvature of its surface. It is shown that the visual reconstruction algorithm works successfully for synthetic and real image data. The range images are used to classify the surfaces of the micro objects according to their curvatures in the HK segmentation algorithm. Also, a mechanical property characterization technique for cell and embryo is presented. A zebrafish embryo chorion is mechanically characterized using cell boundary deformation. Elastic modulus and developmental stage of the embryo are obtained successfully using visual information. In addition to these, calibrated image based visual servoing algorithm is experimentally evaluated for various tasks in micro domain. Experimental results on optical system calibration and image-based visual servoing in micropositioning and trajectory following tasks are presented

Model-based vs. model-free visual servoing: A Performance evaluation in microsystems

In this paper, model-based and model-free image based visual servoing (VS) approaches are implemented on a microassembly workstation, and their regulation and tracking performances are evaluated. A precise image based VS relies on computation of the image jacobian. In the model-based visual servoing, the image Jacobian is computed via calibrating the optical system. Precisely calibrated model based VS promises better positioning and tracking performance than the model-free approach. However, in the model-free approach, optical system calibration is not required due to the dynamic Jacobian estimation, thus it has the advantage of adapting to the different operating modes

Novel parameter estimation schemes in microsystems

This paper presents two novel estimation methods that are designed to enhance our ability of observing, positioning, and physically transforming the objects and/or biological structures in micromanipulation tasks. In order to effectively monitor and position the microobjects, an online calibration method with submicron precision via a recursive least square solution is presented. To provide the adequate information to manipulate the biological structures without damaging the cell or tissue during an injection, a nonlinear spring-mass-damper model is introduced and mechanical properties of a zebrafish embryo are obtained. These two methods are validated on a microassembly workstation and the results are evaluated quantitatively

Çift taraflı kontrol sistemlerinin biomedikal alanda uygulamaları

Hareket kontrol sistemleri tasarlanırken, (a) çevre ile ya da herhangi bir sistem ile etkileşimi olmayan serbest hareket sistemleri, (b) çevre ile veya başka sistemler ile belirli fonksiyonel etkileşimi olan kısıtlı hareket (constrained motion) sistemleri dikkate alınmalıdır. Her iki durumda da kontrol, istenen sistem konfigurasyonu sağlamayı amaçlamaktadır. istenen sistem konfigurasyonu; yörünge takibi, etkileşim kuvvet kontrolü, empedans kontrolü gibi, bilinen sistem görevlerinin yapısını oluşturma açısından aynıdır. Ele alınan tasarım, belirli fonksiyonel ilişkileri korumak zorunda olan bir çok sistemde uyglanmaktadır. Bu çalışma, çift taraflı sistemerin bahsettiğimiz kontrol yöntemi ile kontrolü ve benzetim sonuçlarını sunmaktadır