This paper proposes the design of a 360° map establishment and real-time simultaneous localization and mapping (SLAM) algorithm based on equirectangular projection. All equirectangular projection images with an aspect ratio of 2:1 are supported for input image types of the proposed system, allowing an unlimited number and arrangement of cameras. Firstly, the proposed system uses dual back-to-back fisheye cameras to capture 360° images, followed by the adoption of the perspective transformation with any yaw degree given to shrink the feature extraction area in order to reduce the computational time, as well as retain the 360° field of view. Secondly, the oriented fast and rotated brief (ORB) feature points extracted from perspective images with a GPU acceleration are used for tracking, mapping, and camera pose estimation in the system. The 360° binary map supports the functions of saving, loading, and online updating to enhance the flexibility, convenience, and stability of the 360° system. The proposed system is also implemented on an nVidia Jetson TX2 embedded platform with 1% accumulated RMS error of 250 m. The average performance of the proposed system achieves 20 frames per second (FPS) in the case with a single-fisheye camera of resolution 1024 × 768, and the system performs panoramic stitching and blending under 1416 × 708 resolution from a dual-fisheye camera at the same time.
A walking machine is equipped with leg mechanisms so that it can move across uneven ground. In this study, feasible leg mechanisms for walking machines are generated through the Creative Mechanism Design Methodology, including the steps of existing designs analysis, generalization, specialization, and particularization. One design of a linkage mechanism with eight links and ten joints is selected at the first step. Then, according to the concepts of generalization and specialization, one of the kinematic generalized chains with the same number of links and joints is chosen, and five feasible specialized chains are generated by assigning the frame, thigh link, calf link, and the crank, sequentially. Moreover, by applying feature encoding, two of the feasible designs are obtained by removing the results that cannot fit the motion characteristics, and the corresponding mechanism sketches are presented through particularization. One of the innovation designs is selected, and the dimensional synthesis is made through the techniques in geometric constraint programming. Finally, the motion characteristics are determined to verify its feasibility through theorical determination and computer simulation. The analysis results can be used to explore kinetics and mechanism advantage.
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