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A Proposal of Method for Position Measurement of Active Landmark Using Image Processing and Ultrasonic Sensor

In recent years, the proportion of Japanese children has been decreasing and that of elderly people has been increasing. Because of them, the working population has been decreasing. We sometimes use a robot to help them. In this situation, the research on autonomous mobile robots is progressing to do more advanced tasks. An autonomous mobile robot is actually working to transport luggage in a warehouse]. Line-trace robots are well used in the room. This type of robot moves along a magnetic tape or white line in a floor. It can move with high precision. This is because that it is easy to recognize white line and magnetic tape. On the other hand, a robot, which scans a room with a laser to create the spatial map and moves based on the map, is often used. This kind of robot can also move with high precision. Robots used for industrial factories are required to move with high accuracy without malfunction. So the above mentioned robots are very useful, but have some problems. Line trace type robot needs to paint the line again to change the route. It takes cost and time. Laser scanning robot needs to scan the entire room again. This takes a lot of time. As the other method, mobile robots using drones have recently been researched. In order for the drones to move autonomously, GPS is generally used. However, we cannot often use GPS. For the reason, it is difficult for the drone to move in a room with high accuracy. Thus, we propose a method using active landmark as a new method that can accurately acquire the position even in an environment where GPS cannot be used. An active landmark means a landmark that can transmit and receive signals by itself. However, with a conventional landmark, although the direction to the landmark can be obtained, the distance from the device to the landmark cannot be obtained. In this study, we propose a method that can measure the direction and distance simultaneously. An active landmark that emits ultrasonic wave and a coded light is proposed in this study. The device was actually developed and the experiment was practiced. As a result, the direction to the landmark was correctly detected from the camera image which is attached on the device, and the distance between the device and the landmark was correctly measured using ultrasonic wave. As a result, the three-dimensional position between the landmark and the device can be accurately gotten. For the use of this, a drone will be able to move while always recognizing the 3D position in a room correctly.