Hartmut Witte

ISB recommendation on definitions of joint coordinate system of various joints for the reporting of human joint motion-part I: ankle, hip, and spine

The Standardization and Terminology Committee (STC) of the International Society of Biomechanics (ISB) proposes a general reporting standard for joint kinematics based on the Joint Coordinate System (JCS), first proposed by Grood and Suntay for the knee joint in 1983 (J. Biomech. Eng. 105 (1983) 136). There is currently a lack of standard for reporting joint motion in the field of biomechanics for human movement, and the JCS as proposed by Grood and Suntay has the advantage of reporting joint motions in clinically relevant terms. In this communication, the STC proposes definitions of JCS for the ankle, hip, and spine. Definitions for other joints (such as shoulder, elbow, hand and wrist, temporomandibular joint (TMJ), and whole body) will be reported in later parts of the series. The STC is publishing these recommendations so as to encourage their use, to stimulate feedback and discussion, and to facilitate further revisions. For each joint, a standard for the local axis system in each articulating bone is generated. These axes then standardize the JCS. Adopting these standards will lead to better communication among researchers and clinicians.

Anatomic guidelines for the prevention of abdominal wall hematoma induced by trocar placement.

A knowledge of the parietal structures of the abdominal wall is necessary to minimize risks of operative procedures like laparoscopy. For means to prevent intraoperative bleeding and the occurrence of abdominal wall hematoma, we studied the course of the inferior epigastric arteries and the ascending branch of the deep circumflex iliac artery in 21 human cadavers. The abdominal wall structures were dissected and the distances of the arteries in relation to anatomic structures such as the umbilicus, pubic symphysis, superior ischial spine and lower edge of the rib-cage were measured. Comparison of the morphometric results obtained with the location of 36 trocar incision sites recommended in the common literature yields the information that about half of these incision sites incur the risk of injuring the arteries.

Structural Characterization of the Whisker System of the Rat

Vibrissae or tactile hairs, commonly known as whiskers, are the mechanical gates of special mechano-sensitive organs. In terrestrial mammals, they carry various functions, especially object determination and texture discrimination. We hypothesise that the characteristic morphology and structure of whiskers is a primary morphological condition for their mechano-sensitive functions. To constitute mathematical models on the systematic but different mechanical behavior of the main types of whisker hairs (micro vibrissae, macro vibrissae, straddlers), information is lacking on the distribution of properties in a field of all three types of hairs, taken from one and the same animal. Referring to sets taken from five individuals, geometry data is provided as one complete set for a female rat (Rattus norvegicus). Due to measurements of diameters along the length, the shape of whiskers in rats is confirmed to resemble a cone, which may be overlaid by some convexity or concavity. Additionally, the surface and internal structure of different vibrissae were examined by scanning electron microscopy. The cuticle of the rat whisker consists of flat scales, overlapping like roofing slates. A cross section reveals up to 20 superposed layers of cuticular scales. The longitudinal dimension of one scale is shorter in whiskers compared with body hairs. A hollow medulla is observed from the base to approximately half of the overall length, which is then partially filled by compact tissue, until it disappears completely near the tip. An extraordinarily thick cortex probably rules the characteristic bending features, and the multilayer cuticle probably has a mainly protective function.

Locomotion in Nocturnal Prosimians

Napier and Napier (1967), whose categorization has often been criticized and sometimes modified, but never replaced, divided the prosimians into the following locomotor categories: slow climbing (and bridging), branch running and walking, vertical clinging and leaping.

Transfer of biological principles into the construction of quadruped walking machines

In the wide range of possible biological and technical solutions for legged terrestrial locomotion, quadrupeds represent a compromise between lightweight construction, dynamic stability, and usage of self-stabilizing effects and minimization of neural control. Several biomechanical features indicate that mammals form interesting and preferable paradigms for the construction of walking machines, even if their morphology and locomotory functions in some issues seem to be more complicated than that of the phylogenetically older amphibians and reptiles.

Biomimetic robotics should be based on functional morphology

Due to technological improvements made during the last decade, bipedal robots today present a surprisingly high level of humanoid skill. Autonomy, with respect to the processing of information, is realized to a relatively high degree. What is mainly lacking in robotics, moving from purely anthropomorphic robots to ‘anthropofunctional’ machines, is energetic autonomy. In a previously published analysis, we showed that closer attention to the functional morphology of human walking could give robotic engineers the experiences of an at least 6 Myr beta test period on minimization of power requirements for biped locomotion. From our point of view, there are two main features that facilitate sustained walking in modern humans. The first main feature is the existence of ‘energetically optimal velocities’ provided by the systematic use of various resonance mechanisms: (a) suspended pendula (involving arms as well as legs in the swing phase of the gait cycle) and matching of the pendular length of the upper and lower limbs; (b) inverted pendula (involving the legs in the stance phase), driven by torsional springs around the ankle joints; and (c) torsional springs in the trunk. The second main feature is compensation for undesirable torques induced by the inertial properties of the swinging extremities: (a) mass distribution in the trunk characterized by maximized mass moments of inertia; (b) lever arms of joint forces at the hip and shoulder, which are inversely proportional to their amplitude; and (c) twisting of the trunk, especially torsion. Our qualitative conclusions are three‐fold. (1) Human walking is an interplay between masses, gravity and elasticity, which is modulated by musculature. Rigid body mechanics is insufficient to describe human walking. Thus anthropomorphic robots completely following the rules of rigid body mechanics cannot be functionally humanoid. (2) Humans are vertebrates. Thus, anthropomorphic robots that do not use the trunk for purposes of motion are not truly humanoid. (3) The occurrence of a waist, especially characteristic of humans, implies the existence of rotations between the upper trunk (head, neck, pectoral girdle and thorax) and the lower trunk (pelvic girdle) via an elastic joint (spine, paravertebral and abdominal musculature). A torsional twist around longitudinal axes seems to be the most important.

A novel PDMS micro membrane biosensor based on the analysis of surface stress

The biological and medical application of biosensors is more and more important with the development of technology and society. Detection of cells and biological molecules utilizing biosensors based on the analysis of surface stress would facilitate inexpensive and high-throughput test and diagnosis. This paper presents a biocompatible surface stress-based polydimethylsiloxane (PDMS) micro membrane biosensor. Each biosensor chip consists of two available PDMS micro membranes, one acts as active membrane and the other as reference. Biosensors were functionalized using different functional materials respectively: MUA (11 Mercapto 1 undecanoicacid), MUO (11 Mercapto 1 undecanol) and DOT (Dodecane thiol). Two biosensor test systems were built based on a white light interferometer and a fiber optic interferometer respectively. Finally, testing experiments using Escherichia coli (E. coli) were performed based on the biosensor test systems we built. The results of the experiments showed that the MUA is a better functional material to functionalize the biosensor membranes than MUO and DOT for E. coli detection, some properties of E. coli, such as healthily living and dead status, can be analyzed based on the PDMS micro membrane biosensors.

Legs evolved only at the end

Talking about legged locomotion often evokes the idea that animals using such devices are perfectly adapted to this kind of motion and should be copied by robotics. The aim of this contribution is to show that the evolution of legs comes late in phylogeny, be it in arthropods or vertebrates. Neural control of legs in vertebrates has to deal with conservative arrangements ‘invented’ for axial locomotion of metameric organisms. The structure of this paper is to show the importance of axial driven propulsion in vertebrates without legs, with legs and only at the end how limbs move the body in eutherian mammals.

Comparing the effect of different spine and leg designs for a small bounding quadruped robot

We present Lynx-robot, a quadruped, modular, compliant machine. It alternately features a directly actuated, single-joint spine design, or an actively supported, passive compliant, multi-joint spine configuration. Both spine configurations bend in the sagittal plane. This study aims at characterizing these two, largely different spine concepts, for a bounding gait of a robot with a three segmented, pantograph leg design. An earlier, similar-sized, bounding, quadruped robot named Bobcat with a two-segment leg design and a directly actuated, single-joint spine design serves as a comparison robot, to study and compare the effect of the leg design on speed, while keeping the spine design fixed. Both proposed spine designs (single rotatory and active and multi-joint compliant) reach moderate, self-stable speeds.

Characterization of Statical Properties of Rat's Whisker System

This contribution describes mechanical properties of the whisker system of rats. The motivation for the work was to achieve a better understanding of the functionality of this remarkable sense organ by defining structure-function-correlations. Special features of the different types of whisker are interpreted in terms of their morphological background, e.g., object recognition and texture discrimination. The whiskers are found to be conical in shape. Theoretical considerations of rod types reveal certain advantages of conically shaped rods over cylindrical rods. There is a difference in deformation, with the higher values applying to conical rods. Whiskers have a very flexible tip which is sensitive to very small forces. Uniaxial bending tests using actual whiskers were performed to characterize the static parameters. From experimental data obtained, the spring constant, the Youngs modulus and the flexural stiffness are calculated. Youngs modulus is one standard parameter for the characterization of materials. It was found that this can be regarded as constant along the whiskers with an average value of 7.36 GPa. Flexural stiffness was found to depend on the hair diameter and decrease from base to tip. The short vibrissae exhibit the lowest flexural stiffness, which means they are sensitive to very small forces. The experimental results obtained might well be used as a basis for the optimization or the construction of bioinspired technical sensor systems.