Warehouse positioning evolves to cm level accuracy (half-inch accuracy)! Boost operational efficiency with smartphone-linked LRTK

Table of Contents

• The importance of location information for in-warehouse operations

• Conventional indoor positioning technologies and their limitations

• What RTK positioning is, and how it enables centimeter-level accuracy

• Revolutionary indoor positioning enabled by smartphone-linked LRTK

• Use cases that improve warehouse operational efficiency

• Simple surveying made possible by LRTK

• FAQ

The importance of location information for in-warehouse operations

In modern logistics warehouses, the location information of items is directly linked to operational efficiency. When handling vast inventories in a large warehouse, it is important to know precisely “where a package or pallet is.” Unclear location information can lead to longer picking times and unnecessary travel to search for stock. Furthermore, for forklifts and automated guided vehicles (AGVs) to operate safely and efficiently, it is desirable to know positions with centimeter-level accuracy (cm level accuracy (half-inch accuracy)). In recent years, automation and robot implementation in warehouses have progressed, and high-precision location information is indispensable for their control and navigation.

However, accurately positioning in a large indoor space is not easy. Above all, GPS satellite signals rarely reach inside buildings, making it difficult to directly obtain absolute coordinates. Traditionally, visual checks by personnel and paper-based records were the norm, and accurate indoor positioning sometimes relied on specialist surveying teams. For example, when installing new shelving, workers had to measure positions with tapes or laser distance meters, mark them, and then proceed with installation—a time-consuming process. Such tasks not only consume time but also depend on personnel with specialized knowledge, making scheduling and staffing a challenge.

Conventional indoor positioning technologies and their limitations

Various technologies have been used to measure positions indoors. Representative indoor positioning technologies and their accuracy/challenges are as follows.

• Positioning using Wi‑Fi or Bluetooth beacons: This method estimates position by installing many access points or transmitters in the warehouse and using signal strength or time-of-arrival. Dedicated infrastructure is required. Accuracy remains on the order of several meters, and it may misidentify locations by as little as one shelf.

• Positioning using UWB (Ultra-Wideband): Systems using UWB tags and antennas can achieve relatively high accuracy (on the order of several dozen centimeters). However, this also requires deploying tags and a receiver network within the warehouse, leading to high initial costs and operational burden.

• Location management using QR codes or RFID: By attaching QR codes or RFID tags to items or shelves and having workers scan them with handheld terminals, locations can be inferred indirectly. This approach requires scanning work and the location accuracy depends on the scanned point, so it does not provide exact absolute coordinates.

• Surveying instruments such as total stations: Surveyors measure optically using prisms. Accuracy is high, but specialized equipment and expertise are required, and operations need teams and considerable time. In warehouses with poor line of sight, repositioning the equipment can be time-consuming and reduce productivity.

As described above, conventional indoor positioning technologies have limits in accuracy and cost. Errors of several meters are insufficient for tasks that require precise positioning (such as equipment installation locations or storage optimization). Seeking higher accuracy typically requires specialist equipment or infrastructure, making adoption difficult for small- and medium-sized sites.

What RTK positioning is, and how it enables centimeter-level accuracy

RTK positioning technology, cultivated in outdoor surveying, has attracted attention in this context. RTK (Real Time Kinematic) is a positioning method that corrects satellite positioning errors in real time using correction signals from a base station, achieving accuracies on the order of centimeters. Put simply, it is “ultra-high-precision GPS usable on site,” allowing map coordinates and real-world positions to match almost exactly. GPS positioning that once had errors of several meters has been reduced to several centimeters with RTK, dramatically expanding the ways location information can be used on site. For example, guiding the installation point of shelving or equipment specified on a design drawing with an RTK-capable receiver enables far more precise positioning than before.

Traditionally, using RTK required expensive dedicated equipment, base station setup, and communication infrastructure. However, recently in Japan, the introduction of the centimeter-class augmentation service (CLAS) provided by the Quasi-Zenith Satellite System “Michibiki” has made it possible to obtain high-precision correction information directly from satellites without needing an internet connection. This technological innovation brings RTK positioning closer to everyday use, and its application is expected across various tasks that require centimeter-class positioning accuracy both indoors and outdoors.

Revolutionary indoor positioning enabled by smartphone-linked LRTK

A solution that makes the RTK technology above easy to use on site is the smartphone-linked LRTK. LRTK is a groundbreaking device that turns a smartphone into a centimeter-accuracy surveying instrument simply by attaching a small RTK-GNSS receiver to the phone. It weighs only about 150 g and has a thickness of about 1 cm (0.4 in), so it is as portable as a phone case; it also has a built-in battery that allows about 6 hours of continuous positioning on a single charge. Because it can be operated without cables, handling is easy. Even without specialized knowledge, anyone can intuitively operate it using a dedicated app, enabling everyone on site to use one high-precision positioning tool per person.

Using LRTK, centimeter-class positioning can be achieved even inside warehouses. The secret is LRTK’s “indoor positioning mode.” For example, after measuring and fixing a reference point at a location where satellite signals can be received such as a warehouse entrance, you can move into parts of the building with poor reception and estimate position using smartphone sensors (inertial measurement units and cameras). This allows continuous tracking of one’s position even in areas where GPS signals drop out, enabling measurement of arbitrary points inside the warehouse in global coordinates. Even deep inside large warehouses where positioning was previously difficult, LRTK can realize indoor positioning at centimeter-level accuracy (cm level accuracy (half-inch accuracy)).

In addition, smartphone-linked LRTK offers many convenient features unique to smartphone integration. For example, the smartphone screen can display the current and target coordinates, and a coordinate navigation function guides you to the target by arrow and distance information. As you approach the destination, it can show messages like “remaining ○ cm,” supporting fine adjustments so even inexperienced workers can reach the specified point accurately. By overlaying AR (augmented reality) guidance on the smartphone camera feed, you can display virtual markers or lines in the real space to assist on-site work. For instance, you can indicate shelf installation points in AR without marking the floor, or visualize hazard zones. The reason AR can be displayed without misalignment is that high-precision positioning minimizes the gap between virtual and real spaces.

LRTK also has functions to upload acquired positioning data and photos to the cloud on the spot. Coordinates of measured points and point cloud data (3D scanned data) can be shared within the company immediately, greatly streamlining warehouse layout planning and recordkeeping. Previously, workers had to measure with tapes, jot measurements on paper, and later transcribe them to drawings; with LRTK, measurements are digitized the moment they are taken, preventing record omissions and transcription errors.

The fact that it provides high precision without infrastructure is another major attraction of LRTK. Without laying a new sensor network in the warehouse or installing expensive equipment, positioning can start immediately with just a smartphone and an LRTK device. Because it supports satellite augmentation service CLAS, stable positioning is possible even at sites without network coverage. It is truly a tool that enables centimeter-level positioning (cm level accuracy (half-inch accuracy)) “anytime, anywhere, by anyone.”

Use cases that improve warehouse operational efficiency

High-precision in-warehouse positioning enabled by smartphone-linked LRTK brings efficiency improvements to various tasks. Here are some specific use cases and their effects.

• Improved inventory management: If items are tagged and their positions recorded with LRTK, the exact location of pick targets can be identified instantly even in a large warehouse. Workers simply follow the smartphone navigation and can approach the target pallet down to a “remaining ○ cm” precision, dramatically reducing search time. As a result, picking and inventory counting speed up and mis-picks due to human error are prevented.

• Faster layout changes and equipment installation: When installing new shelves or equipment, LRTK can immediately mark installation positions according to the coordinates on design drawings. The step of having a surveying team perform floor marking can be omitted, reducing wait times for construction. It is also easy to verify after installation whether positions and leveling match the plan by checking with point cloud scans. Because you can detect deviations down to millimeter levels on the spot, rework is avoided and high-quality installation is achieved.

• Safety management and travel optimization: By recording and analyzing forklift or AGV travel paths with high precision, layouts can be improved to eliminate unnecessary movements and safety measures can be taken by identifying near-miss locations. Visualizing trajectories acquired by LRTK in the cloud allows objective understanding of where stops or congestion frequently occur and where collision risks exist. This provides scientific grounds for layout changes and operational improvements, boosting overall operational efficiency.

• 3D digitalization of warehouse space: With LRTK you can walk through the warehouse while scanning to generate an accurate 3D model (digital twin). Point cloud data that records the structure and equipment shapes to centimeter accuracy (cm level accuracy (half-inch accuracy)) helps staff in the office grasp on-site conditions in virtual space and use it for layout simulations. Previously, specialist contractors’ laser scanners were required, but with LRTK it becomes possible to regularly update a warehouse’s digital twin as part of routine operations.

• Simplified equipment inspection and maintenance: LRTK is also useful for inspecting equipment located at heights or hard-to-reach places in the warehouse. For example, you can measure the positions of overhead crane rails or lighting fixtures from the ground and attach position-tagged photos for records. Inspections that previously required ladders or aerial work platforms can be done safely from the ground with LRTK, reducing work time and risk.

As described, LRTK-based in-warehouse positioning brings effects such as time savings, labor reduction, and improved safety, significantly improving overall operational efficiency. Accurate positioning tasks that formerly required surveying specialists can now be performed immediately by on-site staff, eliminating previous wait time bottlenecks. Accumulating and analyzing the obtained data will also drive future operational improvements.

Simple surveying made possible by LRTK

LRTK, which improves positioning accuracy and efficiency in warehouses, heralds an era of “simple surveying.” Without relying on expensive dedicated equipment or complicated procedures, anyone with a smartphone can perform accurate measurements when needed, greatly enhancing on-site agility. The ability to complete tasks that previously depended on surveying experts directly on site is a major benefit for companies. This simplification of centimeter-level positioning (cm level accuracy (half-inch accuracy)) is a technological innovation that will also push forward DX (digital transformation) across the construction and surveying industries.

Additionally, the introduction cost of LRTK is much lower compared to traditional surveying equipment, making it realistic to equip one device per person. If on-site staff carry their own positioning tools and can make decisions and perform work on the spot, workflows accelerate dramatically. For example, losses caused by work being paused while “waiting for surveying” disappear, contributing to improved overall productivity.

In this way, smartphone-linked LRTK is a versatile positioning platform applicable not only to warehouses but also to civil engineering, construction sites, infrastructure inspections, and disaster surveys. Wherever high-precision positioning is required, the range of applications is virtually unlimited. If you are considering “making it easier to use accurate location information” in warehouse operations or surveying work, consider simple surveying with LRTK. Centimeter-level positioning (cm level accuracy (half-inch accuracy)) will surely open new doors for operational improvements.

FAQ

Q: Can you really achieve centimeter-level positioning indoors? A: Yes, it is possible. LRTK’s indoor positioning mode enables high-precision positioning even inside warehouses where satellite signals do not reach. By first obtaining a reference position at a location where signals can be received and then estimating position using the smartphone’s inertial sensors, positioning can be maintained with errors on the order of a few centimeters for short movements indoors. This is a solution that answers the previously difficult demand of “indoor positioning at cm level accuracy (half-inch accuracy).”

Q: What kind of positioning accuracy can actually be obtained? A: It depends on the environment, but you can obtain horizontal accuracy of about 1–2 cm and vertical accuracy of several centimeters. Satellite reception conditions and measurement time affect errors, but using the averaging function of the LRTK app can improve accuracy to the millimeter level. Compared with conventional GPS positioning with errors on the order of meters, this is orders of magnitude more precise and comparable to dedicated surveying instruments. This level of accuracy is sufficient for normal surveying tasks.

Q: Do you need special skills or qualifications to operate LRTK? A: No, specialized qualifications or advanced skills are not required. LRTK is designed for anyone to use, and positioning is performed by following guidance in the dedicated smartphone app. The current and target locations are displayed visually on the screen, making it intuitive to use; even those without surveying experience can operate it after a short training session.

Q: Which types of smartphones are supported? A: Currently, it mainly supports iOS devices such as iPhone and iPad. The LRTK unit is attached to the smartphone with a one-touch mount, and launching the dedicated app (iOS) starts positioning. Because the system applies RTK corrections while coordinating with the phone’s GPS functions, you can obtain high-precision results on hand. Expansion of supported devices is expected in the future.

Q: Does centimeter-class positioning require a base station or internet connection? A: In Japan, you can use it without preparing a special base station. LRTK can receive the centimeter-class augmentation service (CLAS) provided by the Quasi-Zenith Satellite “Michibiki,” so it can obtain correction information and perform high-precision positioning even at sites without network coverage. Of course, if mobile networks are available, correction information from GNSS reference stations such as those of the Geospatial Information Authority of Japan can also be used to ensure stable accuracy both outdoors and indoors.

Q: How can positioning and point cloud data be shared and utilized? A: Data acquired with LRTK can be easily shared and used via the cloud. Positioning results are plotted on a cloud-based map in real time and can be shared immediately with office staff. Point cloud data and photos are also saved with location information, allowing detailed analysis on a PC later or use in reports. Information sharing between departments and history management can be done smoothly.

Q: Isn’t the introduction cost high? A: Compared to conventional high-precision positioning equipment, it is surprisingly affordable. Considering the cost of dedicated surveying instruments and large systems, LRTK operates with a small device and a smartphone, greatly reducing initial investment. Running costs are also low, and deploying multiple units on site is not burdensome. As a result, small- and medium-sized companies and sites can more readily adopt high-precision positioning.

Q: Can it be used for outdoor surveying as well? A: Of course, it is also effective outdoors. LRTK was originally developed as a high-precision GNSS positioning device, and it achieves its highest accuracy in open outdoor areas by performing RTK positioning directly from satellites. It is also possible to measure reference points outdoors and then seamlessly transition to surveying indoor areas. Because it provides consistent accuracy both indoors and outdoors, it is an effective tool for managing positions across an entire site.