Department of Engineering Cybernetics, Centre for Autonomous Marine Operations and Systems, Norwegian University of Science and Technology (NTNU-AMOS), O.S. Bragstads plass 2D, 7034 Trondheim, Norway.
Sensors (Basel). 2018 Jul 30;18(8):2468. doi: 10.3390/s18082468.
As the use of unmanned aerial vehicles (UAVs) for industrial use increases, so are the demands for highly accurate navigation solutions, and with the high dynamics that UAVs offer, the accuracy of a measurement does not only depend on the value of the measurement, but also the accuracy of the associated timestamp. Sensor timing using dedicated hardware is the de-facto method to achieve optimal sensor performance, but the solutions available today have limited flexibility and requires much effort when changing sensors. This article presents requirements and suggestions for a highly accurate, reconfigurable sensor timing system that simplifies integration of sensor systems and navigation systems for UAVs. Both typical avionics sensors, like GNSS receivers and IMUs, and more complex sensors, such as cameras, are supported. To verify the design, an implementation named the SenTiBoard was created, along with a software support package and a baseline sensor-suite. With the solution presented in this paper we get a measurement resolution of 10 nanoseconds and we can transfer up to 7.6 megabytes per second. If the sensor suite includes a GNSS receiver with a pulse-per-second (PPS) reference, the sensor measurements can be related to an absolute time reference (UTC) with a clock drift of 1.9 microseconds per second RMS. An experiment was carried out, using a Mini Cruiser fixed-wing UAV, where errors in georeferencing infrared images were reduced with a factor of 4 when compared to a software synchronization method.
随着无人机 (UAV) 在工业领域的应用日益广泛，对高精度导航解决方案的需求也与日俱增。由于 UAV 具有较高的动态性，测量的准确性不仅取决于测量值的大小，还取决于相关时间戳的精度。使用专用硬件进行传感器定时是实现最佳传感器性能的事实标准，但目前可用的解决方案灵活性有限，在更换传感器时需要付出大量努力。本文提出了对高精度、可重构传感器定时系统的要求和建议，该系统简化了无人机的传感器系统和导航系统的集成。本文不仅支持典型的航空电子传感器，如 GNSS 接收器和 IMU，还支持更复杂的传感器，如相机。为了验证设计，创建了一个名为 SenTiBoard 的实现，以及一个软件支持包和一个基线传感器套件。通过本文提出的解决方案，我们可以实现 10 纳秒的测量分辨率，并且可以每秒传输高达 7.6 兆字节。如果传感器套件包括具有脉冲每秒 (PPS) 参考的 GNSS 接收器，则可以使用时钟漂移为 1.9 微秒/秒 RMS 的绝对时间参考 (UTC) 来关联传感器测量值。进行了一项实验，使用 Mini Cruiser 固定翼 UAV，与软件同步方法相比，红外图像的地理参考误差减少了 4 倍。
