The high-precision positioning and anti-collision issues you raised for ports/container yards are core technological challenges in current smart port construction. In open-air, large-area, and multi-vehicle operating environments, high-precision positioning technologies such as UWB (Ultra-Wideband) and RTK (Real-Time Kinematic) are crucial cornerstones for achieving area speed limits, electronic fences, and collision avoidance warnings.

I will analyze in detail how these two technologies work together and build a complete positioning and anti-collision solution.

Core Technology: Collaborative Application of UWB and RTK
In port container yards, a single positioning technology often cannot meet all accuracy and coverage requirements, so UWB and RTK need to complement each other.
1. RTK-GNSS (Global Navigation Satellite System Real-Time Kinematic)
RTK is based on satellite signals such as GPS/Beidou, combined with ground base stations (reference stations) for real-time differential correction, providing absolute coordinates with meter to centimeter accuracy.
Principle: GNSS base stations are set up in the container yard or port area. GNSS receivers (mobile stations) are installed on operating vehicles (such as container stackers, reach stackers). The base station sends differential correction data to the mobile station, which then calculates high-precision WGS-84 absolute coordinates in real time.
Applicable Scenarios:
Large-area coverage: Suitable for wide-area positioning of the entire open-air container yard and dock.
Absolute coordinates: Provides vehicles with precise positions in the Earth's coordinate system, which is the basis for electronic fences and area division.
Limitations: Satellite signals are easily blocked by stacked containers (high-rise container areas), leading to reduced accuracy or signal loss in local areas.
2. UWB (Ultra-Wideband Positioning)
UWB is a short-range wireless communication technology that achieves high-precision positioning by measuring signal transmission time (ToF), performing excellently in obstructed or indoor environments.

Principle: UWB base stations (Anchors) are deployed in the container yard area, and UWB tags are installed on the vehicles. The tags measure distances to multiple base stations, and a triangulation algorithm is used to calculate the tag's position in the UWB system coordinate system, with centimeter-level accuracy.

Applicable Scenarios:
Local high precision: Suitable for areas with poor GNSS signals, such as stacked container areas and under loading bridges, as a supplement to RTK. Close-range Collision Avoidance: UWB's high ranging accuracy and fast response make it an ideal choice for achieving close-range collision avoidance between vehicles and between vehicles and obstacles.

Limitations: Coverage is limited by the number and density of base stations, and coordinate transformation with the port's GIS map is required.

Implementation Schemes for Three Major Application Functions

Using the above positioning data, three core safety management functions for port operations can be realized:

1. Zoning Speed Limit
Implementation Mechanism:
Zone Division: On the port's GIS map, different electronic zones are divided according to safety requirements (e.g., main roads, container stacking areas, maintenance areas, office areas).
Speed Threshold Setting: A specific maximum safe speed is set for each zone (e.g., 40 km/h for main roads, 15 km/h for container stacking areas).
Real-time Comparison and Control: The vehicle's on-board unit (OBU) obtains high-precision RTK/UWB positioning in real time. The system compares the vehicle's position with the preset electronic zones and speed thresholds.

Forced Intervention: Once the vehicle enters a speed limit zone and its real-time speed exceeds the limit, the OBU immediately sends a command to the vehicle controller to trigger an audible and visual alarm or forced deceleration/speed limit.

2. Geo-fencing
Geo-fencing is used to define the operating range and restricted areas for vehicles (e.g., dock edges, hazardous chemical areas, maintenance area entrances).
Implementation Mechanism:
Fence Definition: On the GIS map, polygons or circular restricted areas are defined using high-precision RTK coordinates.
Intrusion Monitoring: The vehicle's OBU continuously monitors its RTK/UWB position.
Warning/Braking:
When the vehicle's position approaches the fence (e.g., within 5 meters), a first-level warning is triggered.

When the vehicle's position enters the fence, a second-level advanced alarm is triggered, and can be combined with the vehicle control system for remote or forced stopping.

3. Collision Avoidance Warning
Collision avoidance is the most critical aspect of port safety management, requiring both vehicle-to-vehicle and vehicle-to-object collision avoidance.
Implementation Mechanism:
Long-range Collision Avoidance (based on RTK):
All operating vehicles share their respective RTK absolute coordinates.
The central system or on-board OBU calculates the Euclidean distance between two vehicles in real time. When the distance is less than the safety threshold (e.g., 30 meters), a warning is triggered.
Close-range collision avoidance (based on UWB):
UWB devices are installed on vehicles and critical fixed obstacles (such as gantry crane columns and yard corners).
UWB's high-precision ranging provides fast and accurate distance data within a range of several meters.
When the distance between two vehicles or between a vehicle and an object is less than the safe braking distance (considering speed and load), the system immediately triggers an alarm and performs emergency braking.

Sensor fusion: Millimeter-wave radar or LiDAR is used as a supplementary sensor. These sensors provide information about obstacles within the field of view, especially when UWB/RTK signals are interfered with or when obstacles without UWB tags need to be identified, providing final confirmation.

System Architecture and Challenges

System Architecture

Components	Function	Technical Requirements
High-Precision Positioning Layer	Provides real-time, centimeter-level vehicle positioning.	(RTK base station, UWB Anchor, on-board GNSS receiver/UWB Tag)
On-board unit (OBU)	Collects location, speed, and status; receives commands; performs control functions	Features a high-performance chip, multi-sensor fusion interface, and CAN bus communication capability.
Communication Network	Transmits differential data, location data, and control commands	5G/LTE-V or Wi-Fi coverage; low latency is crucial
Central Management Platform	GIS map, area/geofencing/speed limit policy configuration, data analysis, unified scheduling	Powerful geographic information processing and real-time data computing capabilities

Main Challenges:
Multipath effects and obstruction: The metal structures of containers in the yard severely affect the accuracy and stability of GNSS and UWB signals, requiring multi-sensor fusion algorithms to smooth and correct the data.
Coordinate system unification: Ensuring accurate and seamless conversion between the RTK absolute coordinate system (WGS-84), the UWB local coordinate system, and the port's GIS/TOS system coordinate system.
System latency: The entire link latency, from position acquisition to issuing a forced braking command, must be controlled to the millisecond level to ensure the real-time performance of collision avoidance.

Next Steps/Recommendations:
To further optimize safety and efficiency in the port yard, you may consider testing and deploying RTK-UWB fusion algorithms. Would you like to learn more about specific multi-sensor data fusion algorithms (such as UWB+RTK+IMU) or standard safety distance settings for port collision avoidance systems?