Designing Prosthetic Hands With Embodied Intelligence: The KIT Prosthetic Hands

Hand prostheses should provide functional replacements of lost hands. Yet current prosthetic hands often are not intuitive to control and easy to use by amputees. Commercially available prostheses are usually controlled based on EMG signals triggered by the user to perform grasping tasks. Such EMG-based control requires long training and depends heavily on the robustness of the EMG signals. Our goal is to develop prosthetic hands with semi-autonomous grasping abilities that lead to more intuitive control by the user. In this paper, we present the development of prosthetic hands that enable such abilities as first results toward this goal. The developed prostheses provide intelligent mechatronics including adaptive actuation, multi-modal sensing and on-board computing resources to enable autonomous and intuitive control. The hands are scalable in size and based on an underactuated mechanism which allows the adaptation of grasps to the shape of arbitrary objects. They integrate a multi-modal sensor system including a camera and in the newest version a distance sensor and IMU. A resource-aware embedded system for in-hand processing of sensory data and control is included in the palm of each hand. We describe the design of the new version of the hands, the female hand prosthesis with a weight of 377 g, a grasping force of 40.5 N and closing time of 0.73 s. We evaluate the mechatronics of the hand, its grasping abilities based on the YCB Gripper Assessment Protocol as well as a task-oriented protocol for assessing the hand performance in activities of daily living. Further, we exemplarily show the suitability of the multi-modal sensor system for sensory-based, semi-autonomous grasping in daily life activities. The evaluation demonstrates the merit of the hand concept, its sensor and in-hand computing systems

Aufbau, Charakterisierung und Ansteuerung eines Beleuchtungs-Moduls zur Simulation variabler Unterwasser-Lichtspektren unter Verwendung von Hochleistungs-Leuchtdioden

In dieser Bachelor-Arbeit wird die Realisierung eines LED-Moduls zur Erzeugung von variablen Lichtspektren beschrieben. Weiterhin sind die Implementierung einer Steuerungssoftware und die optische Charakterisierung des Moduls Themen der Arbeit. Das Ziel des Aufbaus ist es, Unterwasserlichtfelder im Wellenlängenbereich von 400 bis 750 nm zu simulieren. Die gesamte Strahlungsleistung des Moduls beträgt 8;5W auf einer Fläche von 10 cm × 20 cm. Für den Aufbau sind 72 1W-LEDs von 24 verschiedenen LED-Typen auf zwei Lüfter-gekühlten 10 cm × 10 cm großen Kühlkörpern montiert. Die individuelle Ansteuerung der LED-Typen erfolgt über eine Hardware mit 32 einzeln dimmbaren Kanälen mit einer Auflösung von 12 Bit. Jeder Kanal ist mit einem 350mA-Konstantstrom Tiefsetzsteller verbunden, an welchen LED-Stränge mit einer Strangspannung von bis zu 10;5V angeschlossen werden können. Die Ansteuerung der Module erfolgt über einen I2C-Bus. Die Software zur Ansteuerung wurde in Python 2.7 geschrieben und umfasst eine graphische Benutzeroberfläche. Es ist möglich jede LED-Gruppe einzeln zu steuern. In einer Datenbank sind die kalibrierten Spektren der einzelnen LEDs hinterlegt, dadurch können durch die Software Intensitäten für eine optimale Anpassung an vorgegebene Spektren berechnet werden. Eine weitere Funktion ist die Umsetzung von Tageszeit-abhängigen Lichtspektren. Um ein möglichst homogenes Lichtfeld zu erhalten wird ein Spiegelkanal und eine diffusstreuende Acrylglas-Scheibe verwendet. Dies ermöglicht eine gute Effizienz bei einer maximalen Abweichung der spektralen Inhomogenität von <5 %

ENVILAB: Measuring phytoplankton in-vivo absorption and scattering properties under tunable environmental conditions

Optical remote sensing of phytoplankton draws on distinctive spectral features which can vary with both species and environmental conditions. Here, we present a set-up (ENVILAB) for growing phytoplankton under well-defined light, temperature and nutrient conditions. The custom-built light source enables creation of light with spectral composition similar to natural aquatic environments. Spectral tuning allows for light quality studies. Attenuation is monitored with a spectrometer in transmission mode. In combination with automated spectrophotometer and fluorimeter measurements, absorption and excitationemission-fluorescence spectra are recorded. The set-up opens the door for systematic studies on phytoplankton optical properties and physiology

The quasi-free-standing nature of graphene on H-saturated SiC(0001)

We report on an investigation of quasi-free-standing graphene on 6H-SiC(0001) which was prepared by intercalation of hydrogen under the buffer layer. Using infrared absorption spectroscopy, we prove that the SiC(0001) surface is saturated with hydrogen. Raman spectra demonstrate the conversion of the buffer layer into graphene which exhibits a slight tensile strain and short range defects. The layers are hole doped (p = 5.0 − 6.5 × 1012 cm−2) with a carrier mobility of 3100 cm2/Vs at room temperature. Compared to graphene on the buffer layer, a strongly reduced temperature dependence of the mobility is observed for graphene on H-terminated SiC(0001) which justifies the term “quasi-free-standing.

Constitutive expression and regulated release of the transmembrane chemokine CXCL16 in human and murine skin

The CXC-chemokine ligand 16 (CXCL16) is expressed as a transmembrane adhesion molecule and can be released as a chemoattractant. Both functions are carried out by binding of CXCL16 to its receptor, CXC-chemokine receptor 6 (CXCR6). We here provide early evidence that CXCL16 is expressed in situ by epidermal keratinocytes of normal skin on messenger RNA and protein level and released into the wound exudate upon injury. Cultured human and murine keratinocyte cell lines (HaCaT and PAM212, respectively) as well as primary keratinocyte cultures constitutively express transmembrane CXCL16 on the cell surface. Soluble CXCL16 is released by its limited proteolytic cleavage involving the disintegrin-like metalloproteinase (ADAM)10 but not the closely related ADAM17, as shown by specific inhibitors and small-interfering RNA knockdown experiments. This shedding of CXCL16 is reduced by serum starvation but enhanced by cell stimulation with ionomycin or by UVB irradiation. Soluble CXCL16 from keratinocytes was shown to bind and activate CXCR6, and marked expression of this receptor was found on a subpopulation of T cells in the dermis. Thus, CXCL16 is constitutively expressed on the surface of human epidermal keratinocytes, released upon cell activation or photodamage and may then target CXCR6-expressing T cells in the dermis