Pose, posture, formation and contortion in kinematic systems

The concepts of pose, posture, formation and contortion are defined for serial, parallel and hybrid kinematic systems. Workspace and jointspace structure is examined in terms of these concepts. The inter-relationships of pose, posture, formation and contortion are explored for a range of robot workspace and jointspace types

Line-symmetric motion generators

When a rigid body is axially reflected through a moving line, its image undergoes a so-called line-symmetricmotion. The space comprising all possible line-symmetric motions that share a common initial line is a four-dimensional submanifold, denoted M4, in the special Euclidean group SE(3). Recently, we showed that M4 may be used to characterize motions of a line-symmetric body that are free of self-spin and sliding, thus lending itself to applications such as remote center of motion devices for minimal invasive surgery and haptic interfaces. Aiming at designing robot mechanisms for these applications, we present in this paper a systematic enumeration of line-symmetric motion generators (LSMGs), i.e., robot mechanisms that generate the line-symmetric motion manifold M4, following a procedure based on symmetric space theory. LSMGs present a ubiquitous line symmetry of their joint axes, thus offering a new understanding of the line-symmetric motions

Kinematically Redundant Octahedral Motion Platform for Virtual Reality Simulations

We propose a novel design of a parallel manipulator of Stewart Gough type for virtual reality application of single individuals; i.e. an omni-directional treadmill is mounted on the motion platform in order to improve VR immersion by giving feedback to the human body. For this purpose we modify the well-known octahedral manipulator in a way that it has one degree of kinematical redundancy; namely an equiform reconfigurability of the base. The instantaneous kinematics and singularities of this mechanism are studied, where especially "unavoidable singularities" are characterized. These are poses of the motion platform, which can only be realized by singular configurations of the mechanism despite its kinematic redundancy.Comment: 13 pages, 6 figure

Double Circular-Triangular Six-Degrees-of-Freedom Parallel Robot

This paper describes a new structure of a six-DOF parallel robot. First, a known planar three-DOF double-triangular structure is modified by replacing the stationary triangle with a circle. It increases the work envelope considerably especially when rotational motions are required. The ability for unlimited rotational motion allows extending the structure into six-DOF by using two sets of stationary circles and moveable triangles. Each set can actuate the moving triangle in a planar three-DOF motion and hence actuate a line connecting the centers of the movable triangles in four-DOF. The robot's end-effector is attached to a link along this line while rotation about and translation along this line are obtained by the additional rotational DOF of the movable triangles. The solution of the direct kinematics of this six-DOF manipulator is given in a closed-form and it is shown that at most, four different solutions exist

Super-resolution far-field ghost imaging via compressive sampling

Much more image details can be resolved by improving the system's imaging resolution and enhancing the resolution beyond the system's Rayleigh diffraction limit is generally called super-resolution. By combining the sparse prior property of images with the ghost imaging method, we demonstrated experimentally that super-resolution imaging can be nonlocally achieved in the far field even without looking at the object. Physical explanation of super-resolution ghost imaging via compressive sampling and its potential applications are also discussed.Comment: 4pages,4figure

Rotational Mobility Analysis of the 3-RFR Class of Spherical Parallel Robots

none4noSpherical parallel manipulators (SPMs) are used to orient a tool in the space with three degrees of freedom exploiting the strengths of a multi-limb architecture. On the other hand, the performance of parallel kinematics machines (PKMs) is often affected by the occurrence of different kinds of singular configurations. The paper aims at characterizing a class of SPMs for which all singularities come to coincide and a single expression is able to describe all the singular configurations of the machines. The study is focused on a class of SPMs with 3-RFR topology (Revolute-Planar-Revolute pairs for each of the three limbs) addressing the mobility and singularity analysis by means of polynomial decomposition and screw theory. The neatness of the equations that are worked out, expressed in a robust formulation based on rotation invariants, allows a straightforward planning of singularity free tasks and simplifies the synthesis of dexterous machines.openCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, MassimoCorinaldi, David; Carbonari, Luca; Palpacelli, Matteo-Claudio; Callegari, Massim

Copper Chaperone for Cu/Zn Superoxide Dismutase is a sensitive biomarker of mild copper deficiency induced by moderately high intakes of zinc

BACKGROUND: Small increases in zinc (Zn) consumption above recommended amounts have been shown to reduce copper (Cu) status in experimental animals and humans. Recently, we have reported that copper chaperone for Cu/Zn superoxide dismutase (CCS) protein level is increased in tissues of overtly Cu-deficient rats and proposed CCS as a novel biomarker of Cu status. METHODS: Weanling male Wistar rats were fed one of four diets normal in Cu and containing normal (30 mg Zn/kg diet) or moderately high (60, 120 or 240 mg Zn/kg diet) amounts of Zn for 5 weeks. To begin to examine the clinical relevance of CCS, we compared the sensitivity of CCS to mild Cu deficiency, induced by moderately high intakes of Zn, with conventional indices of Cu status. RESULTS: Liver and erythrocyte CCS expression was significantly (P < 0.05) increased in rats fed the Zn-60 and/or Zn-120 diet compared to rats fed normal levels of Zn (Zn-30). Erythrocyte CCS expression was the most sensitive measure of reduced Cu status and was able to detect a decrease in Cu nutriture in rats fed only twice the recommended amount of Zn. Liver, erythrocyte and white blood cell CCS expression showed a significant (P < 0.05) inverse correlation with plasma and liver Cu concentrations and caeruloplasmin activity. Unexpectedly, rats fed the highest level of Zn (Zn-240) showed overall better Cu status than rats fed a lower level of elevated Zn (Zn-120). Improved Cu status in these rats correlated with increased duodenal mRNA expression of several Zn-trafficking proteins (i.e. MT-1, ZnT-1, ZnT-2 and ZnT-4). CONCLUSION: Collectively, these data show that CCS is a sensitive measure of Zn-induced mild Cu deficiency and demonstrate a dose-dependent biphasic response for reduced Cu status by moderately high intakes of Zn

The impact of hyperbaric oxygen therapy on serological values of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF)

<p>Abstract</p> <p>Background</p> <p>Hyperbaric oxygen (HBO) therapy is an effective adjunct treatment for ischemic disorders such as chronic infection or chronic wounds. It combines hyperoxic effects with the stimulating potential of post-therapeutic reactive hypoxia. As its crucial effects, stimulation of fibroblast growth, induction of collagen synthesis and the initiation of angiogenesis are discussed. Angiogenesis is a multistage process resulting in the growth of blood vessels. It includes degradation of extracellular matrix, proliferation and migration of different cell populations and finally formation of new vessel structures. This complex chain of procedures is orchestrated by different cytokines and growth factors. Crucial mediators of angiogenesis are basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF); their <it>in-vivo </it>function is still not fully understood.</p> <p>Methods</p> <p>Forty-three patients suffering from sudden sensorineural hearing loss or tinnitus were treated with HBO. The therapy included 10 sessions of 90 minutes each, one session a day. Serological levels of bFGF and VEGF were assessed by enzyme-linked immunosorbent assays performed according to the manufacturer's instructions on day 1, 2, 5 and 10 of HBO therapy and were compared to mean values of the control group, related to the patient's age and sex, and their development observed over the ten days of HBO.</p> <p>Results</p> <p>There was no sex- or age dependency of bFGF observed in the present study, whereas under HBO our results showed a significant mitigation of the bFGF concentration. In the present data, there was no connection between the VEGF concentration and the patients' ages. Women showed significantly higher levels of VEGF. There was no significant change of VEGF concentration or the VEGF/bFGF ratio during HBO. All scored results varied within the range of standard values as described in the current literature.</p> <p>Conclusions</p> <p>A significant effect of HBO on serum concentrations of bFGF and VEGF was not verified in the present study. Additional application of exogenous growth factors in conjunction with HBO was not obviously linked by a coherent cause-and-effect chain as far as wound healing is concerned.</p

Should mechanical dyssynchrony be assessed in patients with implantable cardioverter-defibrillators?

Cardiac Dysfunction and Arrhythmia