| 3D environment sensing has already become the foundation of applications like mobile robot, which is the key technology of pattern recognition, obstacle avoidance, mapping and localization. Currently, there exit a number of sensors and techniques for acquiring 3D data, such as radar, ultrasonic, video or laser, many of which have particular utility for various robotic tasks.3D laser scanning system has been considered as an optimization for its advantages of long range, high accuracy, low cost and non-contract, however, most of the 3D laser scanning system domestic and overseas are on-site product which need to set up based on a pre-known reference point or similar point can be calculated by surveying, and capture the point cloud of visible zone. As for the large-scale scene, in order to complete a 3D laser survey, a multi-station stitching technology is demanded to form a global registration from different sites of view. All the procedure seems to be high cost, low efficiency and much too complicated. Meanwhile, another technology called airborne laser radar is able to complete the continuous laser scanning, but it’s expensive, complicate and huge, not suitable for the daily building survey, road survey, obstacle avoidance and outdoor mapping. Nowadays, the portable 3D laser scanning system is highly demanded.We introduce a new design for a 3D laser sensing system, constructed from a 2D range scanner and an inertial measurement unit, which are coupled with a passive linkage mechanism, such as a spring. By mounting the other end of the spring to a vehicle or a pedestrian, disturbances resulting from vibrations of the vehicle or body propel the 2D range scanner in an irregular way, thereby extending the device’s field of view outside of its standard scanning plane.Meanwhile, we developed a special method for point cloud processing, simultaneously localization and mapping and global registration algorithm for the 3D laser sensing system, ensure it can be calculated during each neighboring samples.In order to verify the accuracy, reliability and efficiency of this system, we produce a model system and carry out a series of experiments. First, we perform an indoor test especially in our lab stuffed with desk, chairs and furniture. After that, we extend the test to a forest with a close-loop country road.For verification of the performance of the demo system, a spinning laser ranger based on SICK and an ART online motion tracing system are adapted to measure the same scene and the reference point cloud and reference trajectory are used as a comparison to the output of 3D laser sensing system.The results demonstrate that the 6D0F trajectory of a passive spring-mounted range sensor can be accurately estimated from laser range data and industrial-grade inert ial measurements in real time and that a quality 3D point cloud map can be generated concurrently using the same data. This 3D laser sensing system is advantageous due to its mechanical simplicity, mobility, low weight, and relatively low cost, which has bright future for its technical advantage and marking value. |
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