Positioning and telemetry from ROV survey ARTofMELT2023/1_20-3 on 2023-05-20, survey 2

The horizontal position of the remotely operated vehicle (ROV) during the ARTofMELT2023 expedition in May and June 2023 was measured using an acoustic Long Base Line (LBL) positioning system (LinkQuest Pinpoint) with an operating frequency of 26.77-44.62kHz. It consists of a transceiver onboard the ROV and 3 transponders which were deployed on 5 m long chains through the drifting ice cover at different horizontal distances from the ROV ice access hole. Due to the high latitude and glitches in the Pinpoint software's coordinate conversions, the surveys were virtually moved and 'fake' geographic positions centered around 1°N/1°E were used. The survey track was smoothed using a Kalman filter from initial acoustic fixes and cleaned for most obvious outliers. This calibration result in a floe-fixed, relative coordinate system (distance, relative, X and distance, relative, Y) with the origin (X=0 m, Y=0 m) at the ROV hole. The final position was recorded in the SPOT.ON survey systems software (OceanModulesTM). A quality flag for the position is introduced based on the time to the closest fix with \"1\" indicating good positon (fix reached <= 3s), \"2\" medium position (fix reached > 3s & <= 5s), and \"3\" bad position (fix reached > 5s). Depending on the scientific aim, a position with quality flag \"3\" can still be useful. The ROV depth was measured by an integrated pressure sensor (Keller A-21Y, Keller AG) included in the main electronics housing of the ROV and calibrated to 0 during pre-survey procedures, when the top side of the ROV was at the same level as the water surface. The accuracy of the sensor is 0.10 m. ROV attitude (roll, pitch, heading) was measured with an onboard inertial measuring unit (Microstrain) with three axis accelerometer, magnetometer, and gyroscope.

2023年5月至6月的ARTofMELT2023科考航次中，遥控水下机器人（Remotely Operated Vehicle, ROV）的水平位置采用声学长基线（Long Base Line, LBL）定位系统（LinkQuest Pinpoint）进行测量，该系统工作频率为26.77~44.62kHz。该系统包含ROV搭载的收发器与3台应答器；3台应答器通过长度为5米的锚链部署于浮冰覆盖区域，与ROV冰上出入孔的水平距离各不相同。受高纬度环境影响，且Pinpoint软件的坐标转换功能存在故障，本次勘测的原始数据被平移处理，最终采用以1°N/1°E为中心的“虚拟”地理坐标。勘测轨迹通过卡尔曼滤波（Kalman filter）对初始声学定位点进行平滑处理，并剔除了绝大多数明显的异常值。本次校准最终建立了以ROV冰上出入孔为原点（X=0 m, Y=0 m）的浮冰固定相对坐标系（相对距离、相对X轴、相对Y轴）。最终位置数据记录于SPOT.ON测量系统软件（OceanModules™）中。研究引入了位置质量标记体系，基于距最近定位点的响应时长进行分级：标记“1”表示位置质量良好（定位响应时长≤3s），标记“2”表示位置质量中等（3s < 定位响应时长≤5s），标记“3”表示位置质量较差（定位响应时长>5s）；根据具体科学研究目标的差异，标记为“3”的位置数据仍可具备使用价值。ROV的深度由集成于其主电子舱的压力传感器（Keller A-21Y, Keller AG）测得，该传感器在预调查流程中已完成零点校准，校准时机为ROV顶部与水面齐平时刻，传感器测量精度为0.10 m。ROV的姿态参数（横滚、俯仰、航向）由搭载的惯性测量单元（inertial measuring unit, Microstrain）测得，该单元集成了三轴加速度计、磁强计与陀螺仪。