Extended Abstracts

Y. Menguc, et al., “Soft Wearable Motion Sensing Suit for Lower Limb Biomechanics Measurements,” International Workshop on Soft Robotics and Morphological Computation. 2013.Abstract

Motion sensing has played an important role in
the study of human biomechanics as well as the entertainment
industry. Although existing technologies, such as optical or
inertial based motion capture systems, have relatively high
accuracy in detecting body motions, they still have inherent
limitations with regards to mobility and wearability. In this
paper, we present a soft motion sensing suit for measuring lower
extremity joint motion. The sensing suit prototype includes a
pair of elastic tights and three hyperelastic strain sensors. The
strain sensors are made of silicone elastomer with embedded
microchannels filled with conductive liquid. To form a sensing
suit, these sensors are attached at the hip, knee, and ankle areas
to measure the joint angles in the sagittal plane. The prototype
motion sensing suit has significant potential as an autonomous
system that can be worn by individuals during many activities
outside the laboratory, from running to rock climbing. In this
study we characterize the hyperelastic sensors in isolation to
determine their mechanical and electrical responses to strain,
and then demonstrate the sensing capability of the integrated
suit in comparison with a ground truth optical motion capture
system. Using simple calibration techniques, we can accurately
track joint angles and gait phase. Our efforts result in a
calculated trade off: with a maximum error less than 8%, the
sensing suit does not track joints as accurately as optical motion
capture, but its wearability means that it is not constrained to
use only in a lab.

C. J. Walsh, A. H. Slocum, and R. Gupta, “Preliminary evaluation of robotic needle distal tip repositioning,” Proc. SPIE, vol. 7901. pp. 790108, 2011. Publisher's VersionAbstract
Advances in medical imaging now provide detailed images of solid tumors inside the body and miniaturized energy delivery systems enable tumor destruction through local heating powered by a thin electrode. We have developed a robot for accurately repositioning the distal tip of a medical instrument such an ablation probe to adjacent points within tissue. The position accuracy in ballistics gelatin was evaluated in a 2D experimental setup with a digital SLR camera that was fixed to a rig that also contained the gelatin. The robot was mounted to the rig in such a way that the stylet was deployed in a plane parallel the camera's lens. A grid paper attached to the back of the box containing the gelatin provided a stationary reference point for each of the pictures taken and also served as a coordinate system for making measurements. The measurement repeatability error was found by taking a stylet tip position measurement five times for two different pictures and found to be 0.26 mm. For a stylet with a radius of curvature of 31.5 mm and a diameter of 0.838 mm, the targeting accuracy was found to be 2.5 ± 1.4 mm at points that were approximately 38 mm lateral from the cannula axis.
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