High-Precision Positioning and Navigation Technology for Overhead Cranes: Integrated Positioning Solutions Combining LiDAR, Barcode Strips, Encoders, and UWB
The crane positioning system serves as the foundation for position sensing in automated cranes, enabling fully automatic lifting, intelligent anti-sway control, and unmanned dispatch. The positioning accuracy directly impacts the efficiency of lifting device alignment and the degree of automation. The industrial-grade overhead crane positioning solution integrates four technologies: incremental encoders (economical, relative positioning), laser rangefinders (SICK DL100-21, ±1 mm accuracy), barcode tape systems (PSA series, ±0.5 mm repeatability), and UWB indoor positioning (±10 cm). Configurations are available in four tiers ranging from ±50 mm to ±1 mm, depending on control accuracy requirements.
I. Comparison of Technical Specifications for Four Positioning Technologies
| Positioning Technology | How It Works | Absolute/Relative | Typical accuracy | Maximum distance | Communication Interface | Cost per axis | Applicable Scenarios |
|---|---|---|---|---|---|---|---|
| Incremental encoder | Optical/Magnetic Pulse Counting | relatively | ±1–5 mm (cumulative error must be reset to zero) | No restrictions | HTL/TTL/SSI | 低 | Manual/Semi-automatic overhead crane |
| Laser Distance Measurement (SICK DL100-21) | Time of Flight (TOF) | Absolutely | ±1 mm | ≤100 m | SSI/RS-422/Profinet | 中 | Automated Overhead Crane (Standard Configuration) |
| Barcode Ribbons (PSA/BPS) | Optical barcode reading position | Absolutely | ±0.5 mm repeatability | ≤10 km (can be spliced) | SSI/EtherCAT/Profinet | Upper-middle | High-Precision Fully Automatic Overhead Crane |
| UWB Positioning | Ultra-wideband Pulse TOA/TDOA | Absolutely | ±10 cm | ≤50 m | TCP/UDP/Modbus | High (requires a base station) | Multi-vehicle coordination at the workshop level |
For standard semi-automatic overhead cranes, an incremental encoder combined with an end-of-travel stop is sufficient to achieve ±10 mm repeatability at the lowest cost. Fully automatic overhead cranes come standard with one laser distance sensor each for the main and auxiliary hoists; when used in conjunction with an AI anti-sway system, the positioning accuracy of the lifting device can reach ±5 mm. Overhead cranesAI-Powered Unmanned Crane Dispatch System(For more details, seeMulti-Vehicle Coordinated Dispatch Solution) relies on UWB workshop-level positioning to enable multi-vehicle collision avoidance and path planning.
II. Key Considerations for Selecting and Installing Laser Rangefinders
| Model | Measurement Range (m) | Accuracy (mm) | Repeatability (mm) | Measurement Frequency (Hz) | Laser Class | Operating temperature (°C) | Protection Rating |
|---|---|---|---|---|---|---|---|
| SICK DL100-21AA2116 | 0.15~100 | ±1 | ±0.5 | 12~100 | Level 1 (Safety) | -40~65 | IP65 |
| SICK DL100-21AA2115 | 0.15~100 | ±1 | ±0.5 | 12~100 | Level 1 | -40~65 | IP65 |
| Leuze AMS 304i | 0.2~300 | ±1.5 | ±0.5 | 50~250 | Level 1 | -35~60 | IP67 |
| Pepperl+Fuchs OMT300 | 0.5~300 | ±2 | ±1 | 20~50 | Level 2 | -40~60 | IP65 |
Install a reflector at the end of the track for the laser rangefinder; the measurement spot must be aligned with the center of the reflector (deviation ≤ ±5 mm). For gantry cranes, use dual reflectors to eliminate the effects of lateral offset. The cleanliness of the reflector surface directly affects measurement stability—inspect once per shift; when dust coverage exceeds 30%, the deviation can reach ±5 mm. The mounting bracket design must account for the impact of camber changes on the main girder of the gantry on the optical path, allowing for an adjustment margin of ±20 mm.
III. Multi-Sensor Fusion Localization Algorithms
The high-reliability crane positioning system employs a multi-sensor fusion strategy: an incremental encoder provides high-frequency position signals (sampling period of 10 ms), laser ranging provides low-frequency absolute calibration (sampling period of 50 ms), and a barcode strip provides an absolute position reference (read once per barcode strip pass). The fusion algorithm employs a Kalman filter, with the state vector consisting of position p and velocity v, and the measurement vector comprising encoder pulse position and laser absolute position. When the laser signal is obstructed (e.g., by a suspended load passing through the optical path), the system automatically switches back to pure encoder estimation mode and reconverges once the obstruction is removed. Position sensor fault diagnosis logic and overhead craneSecurity Monitoring and Management System(For more details, seeSecurity Surveillance System Solution) If the positioning fails for more than 500 ms, a deceleration alarm is triggered.
In practical engineering applications, encoder pulse loss (due to signal interference or broken wires) often leads to position drift. Redundancy solutions employ dual encoders (one on the mechanical end and one on the motor end) for cross-verification; when the deviation exceeds a preset threshold, the system automatically switches to using laser distance measurement values. Slippage of the encoder roller on the gantry side is another common source of error—the probability of slippage is approximately 51% when acceleration exceeds 0.3 m/s². The solution is to install a pressure roller or switch to a rack-and-pinion drive. Field test data for the integrated positioning system on a crane with a 28.5-meter span: after 8 hours of continuous operation, the maximum positional deviation was 1.8 mm (Kalman filter) compared to 28 mm for the pure encoder system.
IV. Key Points for Deploying Barcode Ribbon Systems
The barcode tape positioning system uses high-precision barcodes affixed to the side walls of the crane rails (PSA series, containing 1,000 code blocks per meter, with absolute position encoding and no cumulative error). The barcode reader is mounted on the side of the crane end beam, 15–25 mm away from the barcode strip, with a reading speed of ≥50 m/s. The advantage of the barcode tape is that it is completely unaffected by dust, oil, and light; its reliability in high-dust crane environments (such as foundries and metallurgical workshops) is superior to that of laser ranging. The disadvantage is the high requirement for initial installation accuracy—deviations in the barcode tape’s straightness directly affect reading accuracy; an installation tolerance of ±0.5 mm/10 m is recommended.
V. Advantages of the Krud Heavy Industry Crane Positioning System Solution
Krud Heavy Industry offers positioning solutions tailored to the automation level of overhead cranes: L1 Manual Overhead Crane (incremental encoder, ±50 mm, cost: 3,000 RMB/axis), L2 Semi-automatic (laser ranging, ±5 mm, cost: 15,000 RMB/axis), L3 Fully automatic (laser + encoder fusion, ±1 mm, cost: 28,000 RMB/axis), L4 Unmanned (laser + barcode strip + UWB triple fusion, ±0.5 mm, cost: 50,000 RMB/axis). All solutions support direct Profinet/EtherCAT integration with Siemens/Beckhoff PLCs, offering plug-and-play functionality. Krud Heavy Industry provides free on-site accuracy testing and solution design for crane positioning system retrofits.
Frequently Asked Questions
问：天车激光雷达定位和UWB定位各有什么优缺点？
A：激光雷达精度高（±2~5mm）但受粉尘影响大、成本较高；UWB抗干扰强、成本低但精度较低（±10~30cm）。工业场景常采用激光雷达+UWB融合方案，粉尘环境用UWB+编码器组合。
问：天车自动导航需要哪些基础条件？
A：需要：精准定位传感器、变频调速驱动、PLC控制系统、无线通信（5G/WiFi6）、安全防护系统（激光雷达避障+安全触边）。自动化程度越高，传感器冗余要求越高。
问：定位系统执行哪些标准？
A：参考GB/T 3811和GB/T 28264，工业通信参考GB/T 38869，无线频谱符合工信部无线电管理规定。
