A teleoperation system to control the humanoid robot using an RGB-D sensor

This paper presents a concept design of the work algorithm for a teleoperation control system of a humanoid robot. The humanoid robot control system needs to stabilize the robot in a vertical position in order to prevent the robot from falling. The process of design of the control system includes the design of position filter to detect the unstable positions. The application of such a control system enables to control the humanoid robot using motion capture technology

Konzept einer berührungslosen Lagerung für Rotations-Blutpumpen

A crucial challenge for the function of implantable blood pumps for long-term use is the hemocompatibility. Essentially, the mechanical damage of blood cells and the formation of blood clots have to be avoided. Therefore not only a well-guided blood flow alongside the pump has to be ensured, but also the rotor bearing has to be designed with special attention. In this thesis a concept of a contact-less rotor bearing for rotational blood pumps is developed. Following the standard engineering design processes, the boundary conditions for the use of miniature axial-flow pumps are defined and potential solutions are presented. After the evaluation of the principle solutions a hydrodynamic and/or magnetic bearing is proposed. The solution of a hybrid bearing implementing both principles is selected. However, the magnetic component is purely derived from the existing magnetic face coupling. Different embodiment variations of the hydrodynamic bearing are shown and discussed. The spiral groove bearing (SGB) yields the best results considering the given requirements. The theoretical background is outlined and a SGB is designed. Subsequently, the hydraulic performance of the bearing is assessed. Using flow visualisation techniques the flow within the grooves is analysed. Tracer particles show a fully developed velocity field. There is no acceleration of the flow within the grooves and the fluid moves evenly towards the centre. Computational fluid dynamics show pressure gradients, velocity vectors as well as shear stress distribution inside the SGB. A stationary vortex at the groove entrance is clearly visible. Hence, there is barely a fluid exchange between the bearing and its surroundings. A theoretical characterisation of the start-up behaviour on an ersatz-model provides information on the minimal gap width and the minimal rotational speed for a contact-less operation. Summary and discussion of the results conclude this thesis. Further studies are suggested in a final outlo

Konzept einer berührungslosen Lagerung für Rotations-Blutpumpen

A crucial challenge for the function of implantable blood pumps for long-term use is the hemocompatibility. Essentially, the mechanical damage of blood cells and the formation of blood clots have to be avoided. Therefore not only a well-guided blood flow alongside the pump has to be ensured, but also the rotor bearing has to be designed with special attention. In this thesis a concept of a contact-less rotor bearing for rotational blood pumps is developed. Following the standard engineering design processes, the boundary conditions for the use of miniature axial-flow pumps are defined and potential solutions are presented. After the evaluation of the principle solutions a hydrodynamic and/or magnetic bearing is proposed. The solution of a hybrid bearing implementing both principles is selected. However, the magnetic component is purely derived from the existing magnetic face coupling. Different embodiment variations of the hydrodynamic bearing are shown and discussed. The spiral groove bearing (SGB) yields the best results considering the given requirements. The theoretical background is outlined and a SGB is designed. Subsequently, the hydraulic performance of the bearing is assessed. Using flow visualisation techniques the flow within the grooves is analysed. Tracer particles show a fully developed velocity field. There is no acceleration of the flow within the grooves and the fluid moves evenly towards the centre. Computational fluid dynamics show pressure gradients, velocity vectors as well as shear stress distribution inside the SGB. A stationary vortex at the groove entrance is clearly visible. Hence, there is barely a fluid exchange between the bearing and its surroundings. A theoretical characterisation of the start-up behaviour on an ersatz-model provides information on the minimal gap width and the minimal rotational speed for a contact-less operation. Summary and discussion of the results conclude this thesis. Further studies are suggested in a final outlo

Mechanical stress activates platelets at a subhemolysis level : an in vitro study

A feasibility study is performed to quantify sheep platelets (PLTs) and to identify the relationship between PLT count and hemolysis as a consequence of mechanical stress. Six adult, healthy Dorset sheep have been used for in vitro blood sampling test procedures in a hemoresistometer device (HRM). In each experiment, blood of the same animal was exposed to six different shear rates. Free hemoglobin levels and PLT count for each shear rate were detected. In all animals (A-F), hemolysis increased significantly between the shear rates of 2325 and 3100/s (P < 0.05) and the mean PLT count dropped immediately (contact, low shear) 40% in the beginning, between the shear rates of 0 and 775/s (P < 0.05). PLT count increased slightly as soon as hemolysis started. At higher shear rates, hemolysis increased and PLTs reduced further. Precise counting of PLTs indicates that PLTs are consumed dramatically at very low shear (by contact) and further by applied mechanical stress when hemolysis is obvious. A repetition of these tests with human blood could indicate species differences