In every country, large steel bridges, such as cable-stayed bridges, are actively being constructed, and the number of such bridges has been progressively increasing. These bridges are often inspected using drones, but inspection techniques have not been established because of strong winds and thunder. Therefore, robots capable of working in difficult environments are desired. In the present study, a prototype of a rotary actuator system combining two iron disks and two electromagnetic-vibration-type actuators was fabricated. A new operation principle was developed that drives the system using the reaction force of the vibration-type actuator. Two shape memory alloy coils and two friction pads were integrated into the system to enable it to carry out turning operations, which were successfully demonstrated. The proposed actuator system can thus move in any direction. In addition, with this actuator system, both slide-on-ceiling and wall-climbing motions are possible.
SummaryPod-driven ships have high performance both for energy saving and for utility as stern thruster, but they also have the difficulty in designing maneuverability. It is accordingly important to estimate the steering quality indices as accurately as possible in the early stage of design. This report deals with the steering quality indices by analyzing zigzag experiments of several pod-driven ships presented in the paper by M. D. Woodward, et al. The indices obtained are summarized in the graphs using the key parameter made of strut area and the graphs indicated here will be useful in the practical design of a new pod-driven ship. As the result of the consideration, it is found that pod-driven ships have small damping moment similar to that of conventionally propelled cargo ships and tankers with rudder. Through this study, it is also revealed that increase of strut area enables improvement of course-keeping quality.
This paper proposes a new type of a magnetic actuator that operates on a resonance energy of a mass-spring model by using an electromagnetic force. The magnetic actuator is moved by the difference in an inertia force during one period of vibration. Experimental result demonstrates that a horizontal speed of the magnetic actuator was 7.4 mm/s with load mass of 50 g. We considered a method of a cable-free movement of the actuator by using two iron rails and four permanent magnets. The magnetic actuator is able to move stably a ceiling plane and a wall plane. This actuator is able to move on the plane of the magnetic materials only a function generator and a power amplifier.
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