PHASED-CONTROLLED ACTUATOR SYSTEM CAPABLE OF VISUAL INSPECTION INSIDE IRON STRUCTURES

Abstract

In Japan, the percentage of bridges over 50 years old is rapidly increasing. Some bridges are restricted to vehicular traffic due to damage and deterioration caused by aging. However, bridge inspection is extremely difficult due to the location of some sites. Although many types of inspection robots have been developed to ensure worker safety, inspection techniques for bridges have not been fully established. In this study, a phase-controlled electromagnetic vibration actuator with four orthogonally arranged vibration components is proposed for moving on complex iron structures such as bridges. A prototype actuator system, in which two sets of actuators are mounted for inspection and connected in parallel to control the direction of movement and improve propulsion characteristics, is developed. Tests confirm that two receivers, a video capture device, and a personal computer can be used to perform visual inspections inside an iron structure. The actuator system has a maximum traction force of 1.1 N. It can transmit inspection images wirelessly, allowing inspection inside structures over long distances. The actuator system can move in any direction by combining rotational and translational reciprocating movements. The operation of an industrially useful inspection device is thus established. The actuator system is capable of visual inspection of iron structures on flat surfaces but not on stepped surfaces. Furthermore, heavy objects, such as an automatic percussion device with a mass of 260 g, cannot be mounted on the actuator system. By improving the magnetic circuit of the vibration component, the movement characteristics of the actuator system can be improved.