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Tenzer, Yaroslav

This article presents a new approach to the construction of tactile array sensors based on barometric pressure sensor chips and standard printed circuit boards (PCBs). The chips include tightly integrated instrumentation amplifiers, analog-to-digital converters, pressure and temperature sensors, and control circuitry that provides excellent signal quality over standard digital bus interfaces. The resulting array electronics can be easily encapsulated with soft polymers to provide robust and compliant grasping surfaces for specific hand designs. The use of standard commercial off-the-shelf technologies means that only basic electrical and mechanical skills are required to build effective tactile sensors for new applications. The performance evaluation of prototype arrays demonstrates excellent linearity (typically <1%) and low noise (<0.01 N). External addressing circuitry allows multiple sensors to communicate on the same bus at more than 100 Hz per sensor element. Sensors can be mounted with as close as (3 \times 5)-mm spacing, and spatial impulse response tests show that linear solid-mechanics-based signal processing is feasible. This approach promises to make sensitive, robust, and inexpensive tactile sensing available for a wide range of robotics and human-interface applications.

In this paper we present the design, fabrication, and testing of a robot for automatically positioning ultrasound imaging catheters. Our system will point ultrasound (US) catheters to provide real-time imaging of anatomical structures and working instruments during minimally invasive surgeries. Manually navigating US catheters is difficult and requires extensive training in order to aim the US imager at desired targets. Therefore, a four DOF robotic system was developed to automatically navigate US imaging catheters for enhanced imaging. A rotational transmission enables three DOF for pitch, yaw, and roll of the imager. This transmission is translated by the fourth DOF. An accuracy analysis was conducted to calculate the maximum allowable joint motion error. Rotational joints must be accurate to within 1.5° and the translational joint must be accurate within 1.4 mm. Motion tests were then conducted to validate the accuracy of the robot. The average resulting errors in positioning of the rotational joints were measured to be 0.28°-0.38° with average measured backlash error 0.44°. Average translational positioning and backlash errors were measured to be significantly lower than the reported accuracy of the position sensor. The resulting joint motion errors were well within the required specifications for accurate robot motion. Such effective navigation of US imaging catheters will enable better visualization in various procedures ranging from cardiac arrhythmia treatment to tumor removal in urological cases.

Current commercial force-torque sensors are sensitive and accurate, but are also typically expensive and fragile. These features limit their use in cost-sensitive applications and unstructured environments such as people's homes. This paper presents a new design for an inexpensive and robust force-torque sensor that uses microelectromechanical system barometer transducers. The new design results in a six-axis force-torque sensor with an R2 greater than 0.90 for Fx and Fy, and an R2 greater than 0.98 for Fz, Mx, My, and Mz during compound loading. Furthermore, this sensor can be assembled in two days with off-the-shelf components for less than 20 USD.