A Flexible and Robust Large Scale Capacitive Tactile System for Robots

IEEE Sensor Journal, Vol. 13, Issue 10, 2013Capacitive technology allows building sensors that are small, compact and have high sensitivity. For this reason it has been widely adopted in robotics. In a previous work we presented a compliant skin system based on capacitive technology consisting of triangular modules interconnected to form a system of sensors that can be deployed on non-flat surfaces. This solution has been successfully adopted to cover various humanoid robots. The main limitation of this and all the approaches based on capacitive technology is that they require to embed a deformable dielectric layer (usually made using an elastomer) covered by a conductive layer. This complicates the production process considerably, introduces hysteresis and limits the durability of the sensors due to ageing and mechanical stress. In this paper we describe a novel solution in which the dielectric is made using a thin layer of 3D fabric which is glued to conductive and protective layers using techniques adopted in the clothing industry. As such, the sensor is easier to produce and has better mechanical properties. Furthermore, the sensor proposed in this paper embeds transducers for thermal compensation of the pressure measurements. We report experimental analysis that demonstrates that the sensor has good properties in terms of sensitivity and resolution. Remarkably we show that the sensor has very low hysteresis and effectively allows compensating drifts due to temperature variations

Smart Fabric sensors for foot motion monitoring

Smart Fabrics or fabrics that have the characteristics of sensors are a wide and emerging field of study. This thesis summarizes an investigation into the development of fabric sensors for use in sensorized socks that can be used to gather real time information about the foot such as gait features. Conventional technologies usually provide 2D information about the foot. Sensorized socks are able to provide angular data in which foot angles are correlated to the output from the sensor enabling 3D monitoring of foot position. Current angle detection mechanisms are mainly heavy and cumbersome; the sensorized socks are not only portable but also non-invasive to the subject who wears them. The incorporation of wireless features into the sensorized socks enabled a remote monitoring of the foot

Tactile Sensing over Articulated Joints with Stretchable Sensors

©2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.Presented at the World Haptics Conference (WHC), 2013, 14-17 April 2013.DOI: 10.1109/WHC.2013.6548392Biological organisms benefit from tactile sensing across the entire surfaces of their bodies. Robots may also be able to benefit from this type of sensing, but fully covering a robot with robust and capable tactile sensors entails numerous challenges. To date, most tactile sensors for robots have been used to cover rigid surfaces. In this paper, we focus on the challenge of tactile sensing across articulated joints, which requires sensing across a surface whose geometry varies over time. We first demonstrate the importance of sensing across joints by simulating a planar arm reaching in clutter and finding the frequency of contact at the joints. We then present a simple model of how much a tactile sensor would need to stretch in order to cover a 2 degree-of-freedom (DoF) wrist joint. Next, we describe and characterize a new tactile sensor made with stretchable fabrics. Finally, we present results for a stretchable sleeve with 25 tactile sensors that covers the forearm, 2 DoF wrist, and end effector of a humanoid robot. This sleeve enabled the robot to reach a target in instrumented clutter and reduce contact forces

A Large Area Tactile Sensor Patch Based on Commercial Force Sensors

This paper reports the design of a tactile sensor patch to cover large areas of robots and machines that interact with human beings. Many devices have been proposed to meet such a demand. These realizations are mostly custom-built or developed in the lab. The sensor of this paper is implemented with commercial force sensors. This has the benefit of a more foreseeable response of the sensor if its behavior is understood as the aggregation of readings from all the individual force sensors in the array. A few reported large area tactile sensors are also based on commercial sensors. However, the one in this paper is the first of this kind based on the use of polymeric commercial force sensing resistors (FSR) as unit elements of the array or tactels, which results in a robust sensor. The paper discusses design issues related to some necessary modifications of the force sensor, its assembly in an array, and the signal conditioning. The patch has 16 × 9 force sensors mounted on a flexible printed circuit board with a spatial resolution of 18.5 mm. The force range of a tactel is 6 N and its sensitivity is 0.6 V/N. The array is read at a rate of 78 frames per second. Finally, two simple application examples are also carried out with the sensor mounted on the forearm of a rescue robot that communicates with the sensor through a CAN bus

Electronic hardware design of a low cost tactile sensor device for physical Human-Robot Interactions

International audienceWe propose in this paper a low-cost method of Electrical Impedance Tomography (EIT) data acquisition from soft conductive fabric for the design of robots artificial skin. We use a simple multiplexer/demultiplexer circuit for retrieving the resistance field from the pair-wised electrical current injected and the output voltage measured from the conductive fabric. A microcontroller controls the current injection and voltage output patterns and the analog-to-numeric conversion from the tactile material. After explaining the EIT method, we present the electronics corresponding to the data acquisition and we analyze the material property. Results show that we can acquire and localize in real time spatial patterns of the tactile contact

Electronic hardware design of a low cost tactile sensor device for physical Human-Robot Interactions

International audienceWe propose in this paper a low-cost method of Electrical Impedance Tomography (EIT) data acquisition from soft conductive fabric for the design of robots artificial skin. We use a simple multiplexer/demultiplexer circuit for retrieving the resistance field from the pair-wised electrical current injected and the output voltage measured from the conductive fabric. A microcontroller controls the current injection and voltage output patterns and the analog-to-numeric conversion from the tactile material. After explaining the EIT method, we present the electronics corresponding to the data acquisition and we analyze the material property. Results show that we can acquire and localize in real time spatial patterns of the tactile contact

Development of a surrogate bruising detection system to describe potential bruising patterns associated with common childhood falls.

Child abuse is a leading cause of fatality in children aged 0-4 years. An estimated 1,700 children die annually as a result of child abuse of which threequarters (75.7%) of the children were younger than 4 years old1. Infants (younger than 1 year) had the highest rate of fatalities among the group. Many of the serious injuries and fatalities could have potentially been prevented if clinicians and child protective services were able to better distinguish between injuries associated with abuse versus those caused by accidents. Missed cases of child abuse have been shown to be as high as 71% of all admitted cases, where children are presented at hospitals for their injuries and not evaluated as being abused 2. Additionally, when child abuse is legally pursued for criminal charges, a little more than half of the cases move forward to prosecution as opposed to being screened out for reasons including the need for further investigation or insufficient evidence 3. Therefore there is a need to provide clinicians, child protective services and law enforcement personnel with improved knowledge related to the types of injuries that are possible from common household accidents that are often reported to be the underlying cause of injury in child abuse. Bruising is an early sign of abuse, and can be an effective indicator of child abuse. Although not life threatening, bruising injuries or bruising patterns provide a “roadmap” documenting a child’s exposure to impact. Previous research has relied upon the use of instrumented anthropomorphic test devices, or test dummies, to investigate injury risk in common childhood falls and accidents in addition to head injury and bone fracture risk in children 4-7. However, the ability to predict bruising patterns occurring in association with falsely reported events in child abuse does not exist, and could prove extremely useful in the distinction between abusive and accidental injuries. This study required the modification of an existing pediatric test dummy to allow for the prediction of potential bruising locations and bruising patterns in children during common household fall events that are often stated as false scenarios in child abuse. The scope of this project included the development of a “sensing skin” that was adapted to a commercial pediatric test dummy. This modified test dummy was then used in mock laboratory experiments replicating common household injury events while the “sensing skin” measured and recorded levels of impact force and locations of impact on the human surrogate. The data from the “sensing skin” was acquired and compiled in a computerized visual body map image displaying the areas of contact or impact locations. This body map image provided a “roadmap” of the human surrogate’s contact exposure during the specific fall event and defined a compatible impact roadmap–specific event combination. Impact roadmap–event combinations for various common household falls provide an indication of where potential bruising could occur. This knowledge of potential bruising patterns could aid clinicians in distinguishing between abusive and accidental injuries for specific fall types

Sculptured computational objects with smart and active computing materials

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2001.Includes bibliographical references (leaves 325-328).This thesis presents the creative, technological, and philosophical means and methodology, by which technology artists and researchers can materially and sculpturally transform physical computing technology from hard, remotely-designed, plastic shells, into intimately created, sensual computing objects and artifacts. It asserts that the rigid, square, and prefabricated physical materials of computing technology are a fundamental technological and artistic limitation to anyone who wishes to sensually transform physical computing technology, or develop a rich artistic vocabulary for it. Smart and active sculptural computing materials are presented as a solution to this problem. Practically, smart computing materials reduce the number of separate, rigid, and square prefabricated parts required to create physical computing objects. Artistically, active sculptural computing materials give artists and designers the ability to directly manipulate, shape, experiment with, and therefore aesthetically understand the real, physical materials of computing technology. Such active design materials will also enable creative people to develop a meaningful artistic relationship between physical form and computation. The total contributions of this thesis include a proposal for a future three-dimensional design/technology practice, a portfolio of sensually transformed expressive computational objects (including new physical interfaces, electronic fashions, and embroidered musical instruments), and the smart and active sculptural computing materials and processes (in this case smart textiles), which make that transformation possible. Projects from the design portfolio include: The Triangles, and its applications; Electronic Fashions, including the Firefly Dress and Necklace, New Year's Eve Ball Gown, and Serial Suit; The Musical Jacket; Electronic Tablecloths; and a series of Embroidered Musical Instruments with embroidered pressure sensors. Contributions from the supporting technical area include: the first fabric keypad (a row and column switch matrix), a new conductive yarn capable of tying and electrical/mechanical knot, an advanced process for machine embroidering highly conductive, flexible and visually diverse electrodes, an empirical model of complex impedance sensing, and a definition of and test for the machine sewability and flexibility of yarns. These contributions are presented in three sections: 1) the supporting arguments, and philosophy of materiality and computation behind this work, 2) the design portfolio, and 3) the supporting technical story.by Margaret A. Orth.Ph.D