John P. Swensen

Learn More
— Traditionally, visual servoing is separated into tracking and control subsystems. This separation, though convenient , is not necessarily well justified. When tracking and control strategies are designed independently, it is not clear how to optimize them to achieve a certain task. In this work, we propose a framework in which spatial sampling kernels –(More)
Active cannulas, so named because of their potential medical applications , are a new class of continuum robots consisting of precurved, telescoping, elastic tubes. As individual component tubes are actuated at the base relative to one another, an active cannula changes shape to minimize stored elastic energy. For the first time, we derive the differential(More)
Visual servoing typically involves separate feature tracking and control processes. Feature tracking remains an art, and is generally treated as independent of the underlying controller. Kernel-based visual servoing (KBVS) is a categorically different approach that eliminates explicit feature tracking. This chapter presents an experimental assessment of the(More)
— Needle insertions serve a critical role in a wide variety of medical interventions. Steerable needles provide a means by which to enhance existing percutaneous procedures and afford the development of entirely new ones. Here, we present a new time-varying model for the torsional dynamics of a steerable needle, along with a new controller that takes(More)
Needle insertions underlie a diversity of medical interventions. Steerable needles provide a means by which to enhance existing needle-based interventions and facilitate new ones. Tip-steerable needles follow a curved path and can be steered by twisting the needle base during insertion, but this twisting excites torsional dynamics that introduce a(More)
In this paper, we examine the static connectivity of 2D and 3D arrays of spherical cells with conductive paths, and the associated power dissipation in the individual cells. Herein, we use the term "cellular material" to describe the ensemble of many cells, in contrast to the more traditional use of the term for foams and honeycomb materials. Using a(More)
The proposed research effort explores the development of active cells—simple contractile electro-mechanical units that can be used as the material basis for larger articulable structures. Each cell, which might be considered a 'muscle unit,' consists of a contractile Nitinol Shape Memory Alloy (SMA) core with conductive terminals. Large numbers of these(More)
While techniques exist for the rapid prototyping of mechanical and electrical components separately, this paper describes a method where commercial additive manufacturing (AM) techniques can be used to concurrently construct the mechanical structure and electronic circuits in a robotic or mechatronic system. The technique involves printing hollow channels(More)
This paper introduces a concept that allows the creation of low-resistance composites using a network of compliant conductive aggregate units, connected through contact, embedded within the composite. Due to the straight-forward fabrication method of the aggregate, conductive composites can be created in nearly arbitrary shapes and sizes, with a lower bound(More)