{'fraction_non_alphanumeric': 0.02100271002710027, 'fraction_numerical': 0.0027100271002710027, 'mean_word_length': 4.792156862745098, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Wheel & Track hybrid robot platform for optimal navigation in an urban environment

Various robot platforms are used for tasks in a variety of disaster fields. For public safety in some urban environments, a novel wheel and track hybrid robot platform which is able to perform fast navigation in flatland and stairs is developed. For its applicability on various environments, we devised a transformable track structure which can climb stairs and navigate the flat floor rapidly. The transformable track can transfer the power with three actuators. Track arms installed in front, rear, and side are used for mode change between floor-navigation and stair-climbing. When the robot navigates on a flatland, tracks on its left and right side are down-folded and kept up folded posture in which four wheels are exposed to the outside of tracks. In this floor-navigation mode, the robot fast navigates flat floors without contact between tracks and the floor. When the robot ascends stairs, the robot spreads tracks until they enclose four wheels. In the stair-climbing mode, two tracks are working. The wheel and track hybrid robot platform was verified by real-navigation experiments in some indoor test-bed environments. The experimental result shows that the developed robot platform has good performance in climbing stair with two tracks and navigating flatland. The platform's maximum speed on flatland is 7.2 km/h and its maximum slope to climbing is an angle of 45 degrees.