The main aim of the thesis is to contribute to a semi-autonomous active sensing system for needle tracking during percutaneous needle insertion. The objective is twofold: first to develop a system for acquiring ultrasound images, then to analyze these images in order to track the needle. The thesis is thus divided into two main lines of research: (1) investigate whether it is feasible to make a robotic system for acquiring ultrasound images using commercially available components; (2)

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... e how to track a needle using 2D ultrasound images and possibly other sensor information in real-time. In this thesis we have developed an ultrasound robotic system using the UR5 robot from Universal Robots, based on a set of requirements derived from the state of the art in the literature. The system has both force and haptic control. We developed and tested several novel methods for tracking a needle in an ultrasound image. In addition, a novel visual servoing method has been developed to ensure that the needle lies in the imaging plane of the ultrasound probe during insertions. The thesis concludes that it is feasible to make an ultrasound robotic system using commercially available components and shows that such a system meets the derived requirements. It also concludes that the novel needle tracking methods presented are both accurate and precise compared to previous methods presented in the literature. It is also shown that using velocity measurements from a needle insertion robot significantly improves the both the accuracy and precision, compared to only using ultrasound images. The visual servoing method shows promise for solving the alignment problem of keeping the needle in the imaging plane of the ultrasound probe. iii Preface