Harmonious Radar for Intralogistics - SHIELD

The SHIELD research project is developing a harmonic radar in the ISM radio band at 61 and 122 GHz for millimeter-precise localization in intralogistics. Seven partners from research, industry and implementation are investigating how accuracy, reliability and cost-effectiveness can be combined for the first time in a single sensor system. The solution is based on active, frequency-doubling tags whose echo signals stand out clearly from ambient reflections. This allows autonomous guided vehicles (AGVs) and small load carriers (SLCs) to be precisely located even in metal-rich, dynamic warehouse environments.

SHIELD is researching a novel localization system based on harmonic radar technology in the 61 to 122 GHz radar frequency range. The goal: to create a foundation for products that combine millimeter-precise positioning with high reliability - while remaining cost-effective.

The field of intralogistics faces concrete challenges. Dynamic warehouse environments constantly change due to shifting rack positions, moving robots and human workers. Existing technologies present trade-offs: Simultaneous Localization and Mapping (SLAM) methods offer limited reliability; radio frequency RF-based systems such as ultra-wideband (UWB) achieve limited accuracy; and optical systems such as motion capture demand high investment along with daily calibration.

The SHIELD project addresses this trilemma. By using active tags with nonlinear components, the system generates response signals at twice the transmission frequency. These harmonic echoes stand out clearly from ambient reflections - a physical property that ensures immunity to interference at the system level.

Further details on the SHIELD research project are available upon request.

Services Offered:

• Requirements analysis for highly dynamic intralogistics localization
• Development of compact radar sensors and tags operating at 61 or 122 GHz
• System architecture with comprehensive interfaces (REST, WebSocket and MQTT)
• Validation in real production environments at industrial partners
• Software-based localization calculation with data analysis tools

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“The key challenge is to transfer the accuracy of the harmonic ISM radar as demonstrated in the laboratory, to industrial environments - which involve metallic interference sources, multipath propagation, and dynamic changes. Harmonic radar solves this problem at the physical level by ensuring that the response signals from the tags differ in frequency from all ambient echoes.”
Sönke Kauffmann M. Sc. conducts research on harmonic radars at the Fraunhofer IML

The SHIELD system uses the Frequency-Modulated Continuous Wave (FMCW) radar principle in the license-free ISM bands at 61 and 122 GHz. Active tags - consisting of antennas with nonlinear components - receive the transmission signal at 61 gigahertz and respond at 122 gigahertz. This frequency jump separates the useful signal from interference reflections.

The core methodological approaches:

• Multilateration using a network of distributed sensors enables three-dimensional localization
• MIMO radar approaches increase the spatial resolution in tag localization
• Joint Communication and Sensing (JCS) combines communication with positioning
• Sensor fusion with an IMU, UWB or GPS increases robustness in scenarios where line  of sight is not available
• Built-in self-tests ensure continuous self-monitoring during operation

An application-specific address encoding method distinguishes between multiple tags within the same sensor field. The software processes raw data, calculates positions using a multilateration algorithm and provides results via Representational State Transfer (REST), WebSocket or Message Queuing Telemetry Transport (MQTT).

Further information about collaboration opportunities or the industry committee supporting the project is available.

• Inquiry regarding project collaboration with the SHIELD Consortium
• Information on the project advisory committee
• Access to scientific publications from the project

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In intralogistics, small load carriers (SLCs) are difficult to track. Sorting bin racks - such as those used for assembly work - are returned to incorrect locations or become misplaced within complex shelving systems. Manual searches require time, cause production pauses and disrupt the flow of materials.

The SHIELD system solves this problem. Each small load carrier is marked with a compact harmonic tag. A network of radar sensors continuously locates these tags - even when they are stored on metal shelves. Frequency doubling to 122 GHz reliably separates the tag signal from reflections from the metal surroundings.

Project Procedure:

• Marking selected KLTs with harmonic tags
• Installation of the sensor network in test environments (PACE Lab, SDFS Würth)
• Repeated localization to track container movements
• Comparative measurements with the motion-capture reference system

Validation takes place in stages: from the laboratory test field through the SDFS real-world lab to the production environment at Würth Industrie Service. There, real Kanban systems serve as the application context.

The LoadRunner® developed by Fraunhofer IML reaches speeds exceeding 10 meters per second. When operating in a swarm, the speed is reduced because existing localization technologies are still developing the accuracy required for collision-free navigation. Higher update rates are therefore desirable.

In the second use case, ISM radar serves as a real-time logistics solution for the navigation of mobile robots. The approach inverts the measurement principle: A radar sensor is mounted on the AGV, while tags are distributed throughout the space as fixed reference points. The vehicle determines its position relative to these nodes - in real time, with millimeter precision.

Key aspects of this scenario:

• A radar sensor on the LoadRunner® measures distances to distributed tags
• The multilateration principle calculates the 3D position from multiple distance measurements
• High update rates support dynamic swarm coordination
• The tags’ communication channel enables additional data transmission

The real-time localization system enhances the dynamics of swarm-based robot fleets, improves safety by enabling precise separation and increases throughput in the warehouse.

The SHIELD consortium brings together complementary expertise across the entire value chain: from integrated circuit design (RUB, Fraunhofer FHR) to system integration (Localino), logistics application research (Fraunhofer IML, TU Dortmund University FLW), and industrial validation (SDFS, Würth).

The advantages of harmonic radar over existing solutions:

• Millimeter-level accuracy thanks to the broadband FMCW principle in the ISM band
• Immunity to interference due to the physical separation of useful and interference signals
• Compact design thanks to short wavelengths at 61 to 122 GHz
• The system enables minimally invasive installation and requires only simple infrastructure.
• Wireless operation with minimal calibration
• Scalability thanks to integrated chip technology with decreasing unit costs

The localization system is suitable for applications beyond intralogistics, including autonomous swarm robotics, indoor drone navigation, joint angle measurement in rehabilitation and position-based control in the creative industries. Joint Communication and Sensing is also a key concept for the next generation of mobile communications, 6G.

As the world’s largest research institute for logistics applications, the Fraunhofer Institute for Material Flow and Logistics IML contributes comprehensive expertise in automation technologies. In the project, Fraunhofer IML is responsible for key tasks in localization and application testing, software design and evaluation under real-world conditions.

The PACE Lab (Positioning Accuracy Communication Evaluation) provides a test infrastructure that is unique worldwide. Two test halls covering approximately 1,500 square meters offer space for various scenarios. A motion-capture system localizes objects with sub-millimeter accuracy as a reference. In addition, a cable-guided robot enables three-dimensional measurements.

The institute develops swarm-based AGV systems such as the LoadRunner® - a system that directly benefits from SHIELD technology. Existing experience with laser- and camera-based SLAM, feature-based ground camera localization and DGNSS evaluation is incorporated into the assessment of the harmonic radar. Together with the FLW at TU Dortmund, our institute is responsible for translating basic research into system solutions that can be used in industry.

European Regional Development Fund (ERDF)

Just Transition Fund (JTF)