Climbing on vertical concrete structures like bridge pylons or dams is still a great challenge for autonomous robots. This paper presents the traction- and friction control system of the wheel-driven wall-climbing robot CROMSCI and its impact on navigation safety. This robot applies negative pressure adhesion and driven wheels for propulsion. The main challenge is to produce sufficient high forces for carrying and accelerating the robot contrarily to gravity which is inhibited by different factors. Slippery of the wheels e.g. must be minimized due to abrasion and uncontrollable movements of the robotic system. This is done by measuring upcoming forces and taking them into account for a traction control system. Another problem may occur because of shear forces between the wheels lowering the transferable forces in rolling direction. Furthermore, also the seals influence robot locomotion due to a certain driving resistance. This paper will present these control elements and prove their functionality and impact on driving safety via experimental results.
This study presents a Finite Element (FE) model of the human hand-arm system to compute modal parameters. The FE model is calibrated by considering natural frequencies obtained from experimental vibration analyzed by using Operational Modal Analysis (OMA) and transmissibility. Modal and harmonic analyses of the FE model are performed for two boundary conditions. The first one considers fixed shoulder condition while the second one introduces the trunk in order to permit motion of the shoulder. The results show that the natural frequencies of the second model are comparable with those determined from measurements. The results of the present study suggest that improved finite element models of the human hand-arm system may reveal hand-arm injury mechanism, the understanding of which may assist in deriving appropriate frequency weightings for the assessment of different components of the hand-arm vibration syndrome.
This paper proposes a novel alternative interface system that enables a user to control an electrical device without his/her hands. The system reads the operational intentions of the user from his/her tongue motions. Although the tongue is the most maneuverable organ besides the hands, it is difficult to detect its motions noninvasively. W e develop a multiple electrode array, which is attached to the anterior neck so as to register myoelectric signals related to tongue motions, and we also develop a motion classification algorithm based on SVM . The proposed system detects 7 tongue motions: right, left, upward, downward, forward, backward and neutral with 90% accuracy. Moreover, this system is integrated with the cursor pointer of a PC. Operability tests based on Fitts' law are conducted with three able-bodied persons, and the results valid ate the proposed system.
This paper presents measurement results of the performance of an electrostatic actuator aiming for an application in artificial muscles of autonomous robots and power assist suits. The actuator consists of multiple stacked parallel electrodes connected by flexible hinges. The unique structure will allow for both large force and long strokes like biological muscles. We performed two experiments using different prototypes: measurement of the spring characteristics, and measurement of the contraction ratio, the actuation energy density and the responsiveness. The spring characteristics ensure the structure of the actuator prevents the electrostatic force from decreasing beyond necessity. In the second measurement, the performances of the prototype were compared with typical performances of biological muscles.
The fault diagnosis of wind farms has been proven to be a challenging task, and motivates the research activities carried out through this work. Therefore, this paper deals with the fault diagnosis of a wind park benchmark model, and it considers viable solutions to the problem of earlier fault detection and isolation. The design of the fault indicator involves data-driven approaches, as they can represent effective tools for coping with poor analytical knowledge of the system dynamics, noise, uncertainty, and disturbances. In particular, the proposed data-driven solutions rely on fuzzy models and neural networks that are used to describe the strongly nonlinear relationships between measurement and faults. The chosen architectures rely on nonlinear autoregressive with exogenous input models, as they can represent the dynamic evolution of the system over time. The developed fault diagnosis schemes are tested by means of a high-fidelity benchmark model that simulates the normal and the faulty behaviour of a wind farm installation. The achieved performances are also compared with those of a model-based approach relying on nonlinear differential geometry tools. Finally, a Monte-Carlo analysis validates the robustness and reliability of the proposed solutions against typical parameter uncertainties and disturbances.
This paper presents 3D sensing and mapping method for a mobile robot that is equipped with an arm-type sensor movable unit and a laser range finder (LRF). The arm-type sensor movable unit is mounted on the robot and the LRF is installed at the end to change its position. Changing the height of the sensor by keeping flat is also possible for the system. It may be difficult for moving robot to apply mapping algorithms such as the iterative closest point (ICP) because sets of the 2D data at each sensor height may be distant in a common surface. This paper proposes a method for this kind of sensing by using an interpolation. Dynamic programming was applied to compute corresponding sensing points for the ICP. Several experimental results provide validity of proposed methods.
The paper is focused on a way of determining the roughness coefficient for organic glass with high end optical properties; the way is in between classical and dynamic light scattering providing results of samples related to a reference called etalon, made from the same material or materials with similar properties and with different 3D dimensions.
Hydrodynamics of impingement flow is a key partner of heat transfer analysis of run-out table (ROT) steel cooling. Velocity and pressure profiles before and after impingement of long circular free-surface industrial water jets (Re = 16,669-50,068) was numerically studied and also wetting front propagation and size of impingement zone were computed. The turbulent models represented impingement water flows over surface better in good agreement with the experimental data at the ROT facility. Higher velocity gradient was obtained for long turbulent jets indicating enhanced heat transfer at impingement zone. The effect of local pressure on saturation temperature changes predication of boiling heat transfer correlations up to 9% which is noticeable for ROT cooling. Impingement zone was found smaller respect to the estimation used in ROT modeling obtained from short jets experiments. For twin jets, simulation show calm interaction of low flow rate water jets with no splashing in accordance with the experiment. Water film thickness in interaction zone is elevated toward jet-jet axis.
In this paper, the effects of open circuit fault on the grid parameters such as active power, reactive power, voltage and the compensator rating of a fixed speed wind farm are investigated. To evaluate effects of open circuit fault, a wind farm that consists of six fixed speed wind turbines connected to capacitor banks, transformers and transmission lines is simulated using MATLAB/SIMULINK Toolbox and Aerospace/Environment and Power System Block-sets. The results reveal that after occurrence of single phase open circuit fault, the grid remains stable but the power quality is reduced because of voltage fluctuations.
Rolling contact fatigue (RCF) unavoidable mode of failure observed in two surfaces which are rolling with relative to each other. Rolling contact fatigue is the name given to crack growth and material damage generated as a result of high loads transmitted between two surfaces. An understanding of rolling contact fatigue failure mechanism and a prediction of lifetimes are of interest to both manufacturer and researcher. Subsurface originated cracks have been recognized as one of the main modes of failure for rolling contact fatigue (RCF) of bearings. Numbers of investigators have attempted to determine the physical mechanism involved in rolling contact fatigue of bearings and proposed models to predict their fatigue lives. This paper attempts to cover the most widely used life models used in RCF.
This paper investigates the aerodynamic lift and drag of the ANSAT helicopter fuselage prototypes using Computational Fluid Dynamics. The CAD model of the fuselage was meshed using an unstructured grid and computed using a viscous flow model under the assumption of steady flow conditions. To account for the influence of the helicopter rotor an actuator disk model was used and the results were compared with computations for the isolated fuselage. The contributions to the total drag of the individual helicopter fuselage components were also studied using different turbulence models. The key components of the fuselage drag were identified.
Multifingered robot hands have the potential to execute dexterous and fine manipulation of multiple objects. This paper analyzes the grasp stability of two spatial objects to enhance the dexterity of the hands. The stability is investigated using the potential energy method, in which the grasp is replaced with a linear spring model. A grasp stiffness matrix is analytically derived by including the contact surface geometry (metric tensor, curvature, and torsion) and contact condition (frictionless sliding contact and frictional rolling contact). The grasp stability is evaluated using the eigenvalues of the matrix, and the displacement mode of the grasp is derived by its corresponding eigenvectors. The effectiveness of this analysis is demonstrated through numerical examples.
In this paper, the key technique of a new kind of EPC network, called Barcode-EPC network, is discussed. It takes advantage of Barcode reader distributed anywhere and connectivity to the Internet of EPC Network. Employs the architecture of EPC Network and track of ONS, an Object Naming System belong to EPC Network, to parse the IP of an object with Barcode. The method of designing and implementing a new EPC Network also is discussed in this paper and case study is introduced for supporting the extensibility on Barcode in EPC network.
