199,759 research outputs found

    Ground-Challenge: A Multi-sensor SLAM Dataset Focusing on Corner Cases for Ground Robots

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    High-quality datasets can speed up breakthroughs and reveal potential developing directions in SLAM research. To support the research on corner cases of visual SLAM systems, this paper presents Ground-Challenge: a challenging dataset comprising 36 trajectories with diverse corner cases such as aggressive motion, severe occlusion, changing illumination, few textures, pure rotation, motion blur, wheel suspension, etc. The dataset was collected by a ground robot with multiple sensors including an RGB-D camera, an inertial measurement unit (IMU), a wheel odometer and a 3D LiDAR. All of these sensors were well-calibrated and synchronized, and their data were recorded simultaneously. To evaluate the performance of cutting-edge SLAM systems, we tested them on our dataset and demonstrated that these systems are prone to drift and fail on specific sequences. We will release the full dataset and relevant materials upon paper publication to benefit the research community. For more information, visit our project website at https://github.com/sjtuyinjie/Ground-Challenge

    Design and Implementation of 2×4 Truncated Corner Patch Microstrip Array Antenna with U-Slot at 2.4 GHz Frequency for Wi-Fi Applications

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    Antennas are an important component in wireless communication systems that continue to grow in the use of the 2.4 GHz frequency for 4G/LTE applications. Technology in the field of telecommunications has developed very rapidly using wireless communication, which is easily accessible by various devices, for example, Wi-Fi or Wireless Fidelity. Microstrip antenna is one type of antenna that has a narrow bandwidth, small gain. This research aims to widen the bandwidth by designing and manufacturing a truncated corner microstrip patch antenna with a 2x4 array at a frequency of 2.4 GHz with a U-slot. The truncated corner method is used to obtain circular polarization. The truncated corner microstrip antenna is designed by cutting corners. The array method is used to obtain the maximum gain value, while the addition of U-slot aims to reduce the return loss and Voltage Standing Wave Ratio (VSWR) values

    Toolpath dependent stability lobes for the milling of thin-walled parts

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    The milling of thin-walled parts can become a seriously complex problem because the parts have variable dynamics. Firstly, the dynamics evolution of the part has been calculated through Finite Element Method (FEM) analysis. Then, the 3D stability lobes have been calculated for the thin walls and the thin floor. Finally, several milling tests have been performed in order to validate the predictions made by the model

    Planar graphs as L-intersection or L-contact graphs

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    The L-intersection graphs are the graphs that have a representation as intersection graphs of axis parallel shapes in the plane. A subfamily of these graphs are {L, |, --}-contact graphs which are the contact graphs of axis parallel L, |, and -- shapes in the plane. We prove here two results that were conjectured by Chaplick and Ueckerdt in 2013. We show that planar graphs are L-intersection graphs, and that triangle-free planar graphs are {L, |, --}-contact graphs. These results are obtained by a new and simple decomposition technique for 4-connected triangulations. Our results also provide a much simpler proof of the known fact that planar graphs are segment intersection graphs
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