PNT (positioning, navigation, and timing) is the core functional part of kinds of wireless sensor network, which can provide high-precision timing and positioning services for cooperative work systems. Unfortunately, the mature wireless PNT schemes are generally based on GNSS and other auxiliary sources to complete the high accuracy synchronization process, which cannot be applied to GNSS degraded and denied environments such as mines, underground application. In order to solve the application problem of high-precision wireless PNT, Hybsync—a novel non-GNSS-aided wireless PNT architecture, is proposed in this paper, which integrates the information from the UWB communication, inertial sensor, and camera to achieve great PNT performance. Hybsync improves the accuracy of time deviation measurement by collecting and recording timestamps in hardware layer, and with the coarse/fine synchronization two-phase calibration, Hybsync greatly improves the accuracy of time deviation adjustment, thus providing accurate time information for the whole system. Besides, Hybsync uses the VINS framework to further integrate the real-time information of IMU and camera to complete the multinode positioning service. Under the premise that the cost is much lower than existing solutions, Hybsync can provide nanosecond-level clock synchronization and centimeter-level positioning. Experiments prove that Hybsync supports high-precision clock synchronization and positioning of more than 10 nodes; the maximum clock synchronization error is 3 ns, and the positioning error is 7 cm. It can provide accurate time and position services for cooperative work systems under complex and GNSS-denied conditions.
Visual language support for planning and coordination in cooperative work systems