Several infrastructures, such as bridges and tunnels, require periodic inspection and repair to prevent collapse. There is a strong demand for practical bridge inspection robots to reduce the cost and time associated with the inspection of bridges by an inspector. Bridge inspection robots are expected to pass through obstacles such as bolted splice part and right-angled routes. The aim of this study involved developing a bridge inspection robot that can travel on a right-angle path as well as splicing parts. A two-wheel-drive robot was developed and equipped with two rimless wheels as driving wheels. A neodymium magnet was provided at the tip of each spoke. Non-driving wheels were attached at the rear as a rotatable caster. The robot can turn on the spot to avoid the bolt on the splicing part. Experiments were conducted to check the performance of the robot. The results confirmed that the robot passed through the internal right-angle paths in a laboratory and in an actual environment that corresponds to a box girder of a bridge. It is extremely difficult to manually control a robot on the splicing part. Therefore, a camera and an LED (light emitting diode) were attached to autonomously control the robot. The results indicate that the newly developed robot could run through the splicing part without hitting the nuts.
Terrestrial hermit crabs which are a type of hermit crabs live on land, whereas typical hermit crabs inhabit the sea. They have an ability of climbing a tree vertically. Their claws allow them to hang on the tree. In this study, an outer-pipe inspection robot was developed. Its locomotion mechanism was developed in imitation of the terrestrial hermit crab’s claws. It is equipped with two rimless wheels. Each of the spokes is tipped with a neodymium magnet, which allows the robot to remain attached to even a vertical steel pipe. Moreover, the robot has a mechanism for adjusting the camber angle of the right and left wheels, allowing it to tightly grip pipes with different diameters. Experiments were conducted to check the performance of the robot using steel pipes with different diameters, placed horizontally, vertically, or obliquely. The robot attempted to move a certain distance along a pipe, and its success rate was measured. It was found that the robot could successfully travel along pipes with vertical orientations, although it sometimes fell from oblique or horizontal pipes. The most likely reason for this is identified and discussed. Certain results were obtained in laboratory. Further experiments in actual environment are required.
Many infrastructures such as bridges and tunnels had been constructed in various parts of Japan during the high economic growth period. They need periodic inspection because they are aging. Inspecting them by inspector is both costly and time-consuming. There is a strong demand for practical bridge inspection robots to reduce the costs and times. The inspection robot running autonomously on the bridge needs to determine moving route and to estimate self-position. The robot must have a three dimensional map of the bridge to take these actions. This paper proposes a method of making a three-dimensional occupancy grid map of the large scale infrastructure where the inspector cannot go easily such as an underside of the bridge. A bridge inspection robot equipped with magnets had been developed in present study. We attached a measuring device which consists of a small 2D laser range finder and a servo motor. Experiments were conducted to make the 3D map by using the robot. The robot climbed to target position on the wall without falling although it was equipped with the measuring device which is heavy. Moreover, the robot can make the 3D occupancy grid map and the map can be useful to inspect bridges.
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