Georg Bretthauer

A new ultralight anthropomorphic hand

In this paper a very lightweight artificial hand is presented that approximates the manipulation abilities of a human hand very well. A large variety of different objects can be grasped reliably and the movements of the hand appear to be very natural. This five finger hand has 13 independent degrees of freedom driven by a new type of powerful small size flexible fluidic actuator. The actuators are completely integrated in the fingers which made possible the design of a very compact and lightweight hand that can either be used as a prosthetic hand or as a humanoid robot hand. A mathematical model for the expansion of a flexible fluidic actuator is given and the mechanical construction and features of the new anthropomorphic hand are illustrated.

A new anthropomorphic robotic hand

This paper presents the new robotic FRH-4 hand. The FRH-4 hand constitutes a new hybrid concept of an anthropomorphic five fingered hand and a three jaw robotic gripper. The hand has a humanoid appearance while maintaining the precision of a robotic gripper. Since it is actuated with flexible fluidic actuators, it exhibits an excellent power to weight ratio. These elastic actuators also ensure that the hand is safe for interacting with humans. In order to fully control the joints, it is equipped with position sensors on all of the 11 joints. The hand is also fitted with tactile sensors based on cursor navigation sensor elements, which allows it to have grasping feedback and the ability for exploration.

A hydraulically driven multifunctional prosthetic hand

In this paper a new prosthetic hand is presented that closely approximates the grasping abilities of a human hand. A large variety of different objects can be grasped reliably and the movements of the hand appear to natural. This five-finger hand has 15 degrees of freedom driven by small sized flexible fluidic actuators. The drives are within the fingers allowing a very compact and lightweight hand. Also, a concept for the control of different grasp types is presented. The characteristics of the new hand are illustrated.

Image reconstruction of the subbasal nerve plexus with in vivo confocal microscopy.

PURPOSE To overcome the anterior corneal mosaic (ACM) phenomenon in in vivo confocal laser scanning microscopy (CLSM) and to reconstruct undistorted images of the subbasal nerve plexus (SNP), facilitating morphometric analysis in the presence of ACM ridges. METHODS CLSM was performed in five healthy volunteers. An original image processing algorithm based on phase correlation was used to analyze and reduce motion distortions in volume scan image sequences. Three-dimensional tracing of the SNP was performed to reconstruct images containing only the SNP layer, with nerve fibers clearly visible even in ACM areas. RESULTS Real-time mapping of the SNP revealed the presence of ridges with K-structures underneath them in all cases. The occurrence of K-structures correlated directly with development of ACM observed by slit lamp and resulted in massive deformation at the level of Bowmans membrane, seriously interfering with examination of SNP structures. The average elevation of ACM ridges was 20.6 μm (range, 8.7-34.0 μm). The novel method presented permitted reconstruction of the SNP layer in regions of ACM. CONCLUSIONS The described method allows the precise analysis and elimination of motion artifacts in CLSM volume scans, in conjunction with the capability to reconstruct SNP structures even in the presence of severe ACM. The robustness and automation of the described algorithms require ongoing development, but this will provide a sound basis for extended studies of corneal nerve regeneration or degeneration and for use in clinical practice.

Detection of time-delayed interactions in biosignals using symbolic coupling traces

Directional coupling analysis of bivariate time series is an important subject of current research. In this letter, a method based on symbolic dynamics for the detection of time-delayed coupling is presented. The symbolic coupling traces, defined as the symmetric and diametric traces of the bivariate word distribution, allow for the quantification of coupling and are compared with established methods like mutual information and cross recurrence analysis. The symbolic coupling traces method is applied to model systems and cardiological data which demonstrate its advantages especially for nonstationary data.

Development of an anthropomorphic hand for a mobile assistive robot

In this paper the mechanism, design, and control system of a new humanoid-type hand with human-like manipulation abilities is discussed. The hand is designed for the humanoid robot which has to work autonomously or interactively in cooperation with humans. The ideal end effector for such a humanoid would be able to use the tools and objects that a person uses when working in the same environment. Therefore, a new hand is designed for anatomical consistency with the human hand. This includes the number of fingers and the placement and motion of the thumb, the proportions of the link lengths, and the shape of the palm. The hand can perform most of human grasping types. In this paper, particular attention is dedicated to measurement analysis, technical characteristics, and functionality of the hand prototype. Furthermore, first experience gained from using hand prototypes on a humanoid robot is outlined.

Invariant Trajectory Tracking With a Full-Size Autonomous Road Vehicle

Safe handling of dynamic inner-city scenarios with autonomous road vehicles involves the problem of stabilization of precalculated state trajectories. In order to account for the practical requirements of the holistic autonomous system, we propose two complementary nonlinear Lyapunov-based tracking-control laws to solve the problem for speeds between ±6 m/s. Their designs are based on an extended kinematic one-track model, and they provide a smooth, singularity-free stopping transient. With regard to autonomous test applications, the proposed tracking law without orientation control performs much better with respect to control effort and steering-input saturation than the one with orientation control but needs to be prudently combined with the latter for backward driving. The controller performance is illustrated with a full-size test vehicle.

Comparison of surface EMG monitoring electrodes for long-term use in rehabilitation device control

In this paper different types of electrodes for long-term surface EMG recording are compared to a reference electrode that is established for clinical use. The electrode materials include four different polymers with conductive load and a fabric of threads coated by a conductive layer. Different criteria are used to evaluate surface EMG recording: the signal quality, including signal-to-noise (SNR) ratio, and impedance in long-term monitoring. The aim of the study is to find an EMG electrode that allows for both silicone liner and textile integration for control of rehabilitation devices for quadriplegics with a partial residual function of the upper limb and for multifunctional prosthetic hands. Besides electrical properties, the biocompatibility and the wearing comfort have to be considered to achieve a wide acceptance by the patients. Except for one evaluated electrode, the signal quality of the four different surface electrodes is comparable to commercial Ag/AgCl gel electrodes in long-term monitoring.

Autonomic Control in Patients Experiencing Atrial Fibrillation After Cardiac Surgery

Background: Atrial fibrillation (AF) occurs in 20–40% of patients after open heart surgery and leads to an increased morbidity and prolonged hospital stay. Earlier studies have demonstrated that depressed baroreflex function predicts mortality and major arrhythmic events in patients surviving myocardial infarction. Cardiac surgery per se leads to decreased baroreflex sensitivity (BRS) and heart rate variability (HRV). Hence, the present study was aimed at analyzing the impact of the cardiovascular autonomous system on the development of postsurgical AF.

A NEW CLASS OF FLEXIBLE FLUIDIC ACTUATORS AND THEIR APPLICATIONS IN MEDICAL ENGINEERING

In this paper a new class of flexible fluidic actuators are presented. The new actuator consists of thin plastic films filled with air or fluid and of a control unit. They have different features from conventional pneumatic and hydraulic actuators. These features are a high flexibility designed into their mechanical construction, the possibility of making very complex movements, a lightweight construction and very low manufacturing costs. The mathematical models for the expansion and contraction behaviours of these actuators are derived, and the results obtained by experiment are discussed. In addition, two typical applications in the medical engineering field are also described.