Labor savings through use of position correction information: Smartphone- and small-device-compatible LRTK enables reduced cabling and offline positioning

Table of Contents

• Introduction

• What is position correction information

• Labor savings and efficiency improvements brought by position correction information

• Challenges and evolution of high-precision positioning technologies

• What is LRTK? A new positioning solution for smartphones and small devices

• Reduced cabling and offline positioning enabled by LRTK

• Benefits and use cases of adopting LRTK

• Summary

• FAQ

Introduction

In recent years, high-precision positioning technologies that utilize “position correction information” have been attracting attention across various fields such as construction and civil engineering, agriculture, logistics, and autonomous driving. As needs to address labor shortages and improve work efficiency grow, situations requiring centimeter-level accurate positioning as a means to achieve on-site labor reduction (reduction and automation of manual labor) have increased. Conventional satellite positioning, including GPS, can have errors of several meters, but by using position correction information those errors can be reduced to within a few centimeters. The use of this high-precision positioning enables autonomous operation of drones and construction machinery, autonomous navigation of agricultural machinery, and digitalization of on-site operations, leading to substantial reductions in manpower and labor.

On the other hand, there has been the challenge that applying high-precision positioning on-site requires specialized equipment and expertise. However, recently solutions that enable easy centimeter-level positioning (cm level accuracy (half-inch accuracy)) on smartphones and small devices have begun to appear. This article explains what "position correction information" is and how its use contributes to labor-saving. Furthermore, focusing on the latest high-precision positioning device for smartphones and small devices, LRTK, we introduce the mechanism and benefits of "reduced-wiring, offline positioning" that cuts down on complex cabling and can be used even outside internet coverage.

What is position correction information

First, "position correction information" refers to data used to correct errors in satellite positioning. GNSS (Global Navigation Satellite Systems) such as GPS, which we use in car navigation and smartphone maps, can have positioning errors caused by weather, slight satellite clock offsets, atmospheric effects, and other factors. Typical smartphone GPS can have errors of about 5–10 m (16.4–32.8 ft). To reduce this error to the centimeter level (cm level accuracy, half-inch accuracy), you need to use correction data in addition to standalone GNSS positioning.

A typical example of position correction information is correction data sent from a base station (a fixed receiver) that has a known, accurate position. Because the base station knows its own position, it can calculate in real time how much error is currently present by taking the difference between that known position and the position computed from the received satellite signals. By transmitting that error amount (the correction information) to a moving receiver (a rover), the rover can apply the correction to its own positioning results and cancel out the error. This is the basic principle of the high-precision positioning technique called RTK (Real Time Kinematic). In short, it is a method of “measuring together with a point whose position is known to cancel out errors.”

Traditionally, this correction information has been transmitted and received via radio communications or the Internet. For example, reference-station data can be obtained via base-station radio signals or mobile communication networks. In recent years, national and carrier-operated reference station networks have been established, and services that provide correction information nationwide have appeared. In Japan, the Quasi-Zenith Satellite System "Michibiki" has begun offering a centimeter-level positioning augmentation service (CLAS), making it possible to receive correction signals directly from satellites overhead. By utilizing this position correction information, errors caused by weather and terrain can be greatly reduced, dramatically improving GNSS positioning accuracy.

Labor savings and efficiency improvements brought by position correction information

When high-precision positional information becomes available, effects such as labor savings and improved operational efficiency appear across various sites. Let’s look at a few examples of the specific fields that benefit.

• Construction and civil engineering: High-precision positioning is useful on construction sites for operating heavy equipment and measuring as-built conditions. For GPS-equipped construction machines known as ICT construction machinery, it is possible to automatically control the blade by matching design data with the machine’s real-time position. This allows accurate earthworks and excavation without relying on operator skill, reducing the number of personnel required. Also, if site supervisors can check as-built conditions themselves with high-precision GNSS equipment, there is no need to call surveyors each time, leading to labor savings in construction management.

• Agriculture: The use of high-precision positioning information is advancing in the agricultural sector as well, with autonomous tractors and rice transplanters. Automatic steering based on position correction information enables straight, uniform tillage and planting without human intervention. Because GPS guidance allows accurate work even at night, it helps alleviate labor shortages and shorten working hours.

• Logistics & Transportation: In outdoor logistics centers and ports, autonomous mobile transport vehicles and drones have been demonstrated. With high-precision positioning, forklifts in warehouses and transport vehicles in container yards can be automated, enabling 24-hour operation while reducing human error.

• Infrastructure inspection and disaster prevention: When autonomously flying drones for inspections of infrastructure such as bridges and dams, high-precision position information contributes to stable flight and precise data acquisition. Also, during disasters when operating unmanned aerial vehicles and robots in affected areas, if position correction information more accurate than GPS alone is available, it becomes easier to have machines perform tasks in hazardous areas where people cannot enter.

As described above, centimeter-level positioning that leverages position correction information is important not only because it "makes positions more accurate" but also as a foundational technology that supports task automation and real-time processing. By enabling machines and systems to accurately perform tasks that humans used to do manually, it can reduce the required manpower while increasing the speed of operations.

Challenges and Evolution of High-Precision Positioning Technologies

However, when attempting to apply high-precision positioning in the field, there used to be various hurdles. Centimeter-level positioning using the RTK method is extremely accurate, but its operation requires specialized knowledge and equipment, and it was not a technology that anyone could easily handle. Here we summarize the main challenges of using conventional high-precision GNSS equipment.

• Extensive equipment and wiring: In conventional RTK positioning, in addition to high-performance GNSS receivers and antennas, it was necessary to bring many devices to the site, such as a tripod for the base station, external batteries, radios, and communication modems. The rover-side receiver and controller had to be connected by cable, and communication equipment had to be wired to receive data from the base station, so setup and takedown were time-consuming. These cumbersome wiring tasks were a major burden when handling equipment on site.

• Securing reference stations and dependence on communications：To obtain highly accurate correction information, connection to nearby electronic reference points or reference-station services is indispensable. If you set up your own reference station, you need to mount the antenna on a precisely known control point, and securing the installation site and arranging permissions and land rights are also challenges. You can use public or private reference-station networks (e.g., the Geospatial Information Authority of Japan's electronic reference station network or telecom carriers' VRS services), but in that case stable internet connectivity at the site is a prerequisite. In mountainous areas or regions outside coverage, correction information via the network cannot be obtained, making high-precision positioning impossible.

• Cost and expertise: High-precision GNSS receivers and RTK systems were expensive and required a substantial investment to introduce. In addition, equipment setup and management of positioning modes required specialized knowledge, so they were not something field staff could use easily. As a result, surveys were often carried out by contracting specialists or surveyors each time, which increased labor costs and the number of days required.

The latest high-precision positioning solution that has emerged to address these challenges is LRTK. In the next chapter, we will look at the all-in-one RTK device LRTK that can be used with smartphones and small devices, and examine its features and the mechanism of "reduced wiring and offline positioning."

What is LRTK? A new positioning solution for smartphones and small devices

LRTK (L-R-T-K) is a next-generation GNSS receiver that integrates into a compact device the RTK positioning equipment that was previously separate. Developed by Refixia Co., Ltd., it has attracted attention as an innovative solution that eliminates the complexity of conventional high-precision positioning systems. It houses all components required for RTK—antenna, receiver, battery, and communications module—and is condensed into a palm-sized form factor.

In particular, the smartphone-compatible model called LRTK Phone turns your handheld smartphone into a surveying instrument with centimeter-level accuracy (cm level accuracy (half-inch accuracy)) simply by attaching a slim receiver weighing only about 150 g to the phone. It operates in conjunction with a dedicated app, allowing you to intuitively start/stop positioning and save data from the smartphone screen. Because it communicates with the smartphone via Bluetooth or Wi-Fi, there's no need to connect cables, making it easy to handle. With the "all you need is your smartphone" simplicity, you can minimize the equipment you bring to the field.

There is no need to separately prepare base station equipment or a special controller terminal as before. With an LRTK device and a smartphone, RTK positioning can be completed with that combination alone. You are freed from complicated wiring and power cables, and the initial positioning setup can be completed with a single touch. As a result, even without a specialist technician, you can quickly start high-precision positioning on site.

Wiring reduction and offline positioning enabled by LRTK

One major advantage of LRTK is "reduced wiring." As mentioned above, because LRTK has a built-in antenna and power supply and can link wirelessly with a smartphone, the positioning system as a whole requires almost no cable connections. For example, whereas traditional setups needed cables connecting the GNSS receiver to a controller and power cables to an external battery, LRTK eliminates those wiring needs. This dramatically simplifies on-site setup and removes the stress of cables getting tangled when handling equipment. Even at heights or on unstable footing, cordless, compact positioning devices allow work to be carried out safely and smoothly.

Another key point is support for 「offline positioning」. LRTK is a multi-band (multiple-frequency) GNSS receiver equipped with the capability to directly receive CLAS (centimeter-level augmentation information) provided by Japan's Quasi-Zenith Satellite System Michibiki. This allows it to obtain position correction information from satellites overhead and continue high-precision positioning even in environments such as mountainous areas and remote islands where mobile phone signals do not reach. Traditionally, real-time corrections were difficult without a network connection, but with LRTK, which can obtain correction signals directly from satellites, completely offline centimeter-level positioning is possible.

Furthermore, Michibiki (QZSS) follows an orbit such that at least one satellite is always present over Japan, which gives it the advantage of being able to acquire satellite signals relatively easily even in locations prone to shading from mountain terrain or tall buildings. There are also reports that, in situations where other GPS devices would experience errors of several meters, LRTK was able to perform positioning by using satellite augmentation information.

As described above, LRTK is highly suited as a precision positioning tool for on-site use because it eliminates the hassle of wiring while maintaining high accuracy even in offline environments.

Benefits and Use Cases of Introducing LRTK

What concrete benefits can be gained by introducing LRTK on-site? Finally, we will summarize the effects LRTK brings and the expected use cases.

• High-precision positioning usable even by beginners: LRTK is a device designed to enable "anyone, anywhere, easily" to handle centimeter (cm) level positioning (half-inch accuracy). Even without specialist surveyors, on-site workers and technicians can use it with the ease of a smartphone. The dedicated app’s easy-to-understand UI and one-touch start for positioning minimize training costs. For example, if a junior field staff member can immediately perform a suddenly required survey by themselves, it reduces waiting time for tasks and leads to improved on-site productivity.

• ・Equipment reduction and improved mobility: In the past, transporting tripods and large batteries was a major hassle, but with LRTK you only need a pocket-sized receiver. The significant reduction in equipment is particularly effective in confined sites and for high-altitude work. Because you no longer need to lift heavy equipment or assign people to wiring during surveys at height, safety is also improved. Increased mobility makes it easy to acquire data in locations that were previously difficult to measure and to carry out flexible additional measurements of inspection points.

• Real-time sharing and promoting DX: Because LRTK integrates with smartphones, it also offers the advantage that acquired coordinate data and point cloud data can be easily uploaded to the cloud or shared on the spot. Since drawings can be updated immediately based on positioning data and results can be shared with stakeholders, tasks that were traditionally taken back to the office for processing can be performed in real time. This is also an important step in advancing on-site DX (digital transformation).

• Cost reduction: By bringing high-precision positioning in-house, you can reduce the frequency of relying on external surveying contractors. Once LRTK is introduced, it can be used repeatedly across multiple sites, leading to long-term reductions in surveying costs. Additionally, improved operational efficiency can be expected to lower labor costs and shorten project schedules.

Thus, LRTK is not merely a miniaturization of positioning equipment but a solution capable of transforming on-site workflows and the division of responsibilities. In actual deployment sites, there have been reports that "tasks that previously required waiting for surveyors could be completed on the spot by site supervisors themselves," and it is being regarded as a tool that overturns conventional wisdom.

Summary

High-precision positioning using correction data is becoming a key to labor savings and efficiency improvements across various industries. If centimeter-level accurate position information can be obtained, a wide range of applications becomes possible, from automatic control of machinery to the simplification of on-site work. Positioning technology that was once the domain of specialists is also becoming more accessible thanks to devices compatible with smartphones and small equipment, such as LRTK.

With LRTK, anyone can perform high-precision positioning on-site immediately, without the need for complex wiring or bulky equipment. Because it can receive correction information directly from satellites even in locations without an internet connection, it will prove powerful in situations that were previously difficult, such as surveying in mountainous areas and investigations during disasters.

Making highly accurate location information your ally will further accelerate on-site DX and labor-saving. If you feel there are hurdles to adopting high-precision positioning, why not start with simple surveying using LRTK that can be easily used on a smartphone? You'll surely be surprised by its ease and usefulness.

FAQ

Q: What is position correction information? A: Position correction information is data used to correct errors that occur in satellite positioning such as GPS. It refers to the error values calculated by a reference station (a receiver whose position is accurately known) and to augmentation signals broadcast from quasi-zenith satellites (such as CLAS). By using this information, satellite positioning accuracy can be improved from several meters to several centimeters.

Q: Do you need any special qualifications or knowledge to use LRTK? A: No. LRTK is designed to be usable even if you are not a professional surveyor. By following the dedicated app’s guidance, you can achieve centimeter-level positioning without detailed GNSS knowledge. However, using survey results for official purposes may require supervision by a licensed surveyor, so you should consider the intended use.

Q: What environments can LRTK be used in? A: LRTK features a dustproof and waterproof design and can operate in harsh outdoor environments. Even in mountainous areas and remote locations without internet access, it can directly receive the CLAS signal from Michibiki (QZSS) to perform high-precision positioning, so it can be used where cellular signals do not reach. On the other hand, in countries or regions that do not support CLAS, it may be necessary to use it in combination with conventional network RTK services.

Q: Which smartphone models are supported? A: LRTK's smartphone-compatible models (LRTK Phone) include types that can be attached to iOS devices such as iPhone and iPad, and types compatible with Android devices. Detailed supported models depend on the product specifications, but most modern smartphones can be connected via Bluetooth or Wi-Fi. By installing a dedicated app on the smartphone, positioning data can be displayed, saved, and shared.

Q: What specific effects can be expected from introducing LRTK? A: Introducing LRTK dramatically improves the efficiency of on-site surveying work. For example, site supervisors can take as-built measurements themselves and verify them immediately, eliminating the need to wait for an external surveying team. This can shorten construction schedules and reduce labor costs, and allows flexible responses to sudden measurement needs. Also, because data can be shared digitally and instantly, the effort required to prepare reports is reduced, contributing to the project's overall digital transformation (DX).