Project: ULTRABOT

ULTRABOT - Multi-frequency, ultrasound-based safety system for safe human-robot collaboration

Project duration: 07/2025 - 06/2028

The ULTRABOT project helps ensure that people and robots can work together safely.

Our vision: Industrial robots and humans share the same workspace - safely, without protective fencing, and without obstructed visibility.

The ULTRABOT research project makes this possible: Miniaturized, multi-frequency MEMS ultrasonic sensors are mounted directly on the robot’s surface and ensure seamless 360° environmental detection with dynamic safety zone monitoring in accordance with ISO/TS 15066.

The Challenge – Safety in Human-Robot Collaboration

There is a great need within industry as well as the medical and healthcare sectors for collaborative robot systems that share the workspace with humans and perform tasks together. The goal of this human-robot collaboration (HRC) is to combine humans’ cognitive, highly flexible, and sensitive abilities with the strengths of robots, such as precision, high payload capacity, and continuous operation.

Conventional safety solutions, however, reach their limits in this context:

TechnologY	LIMIT
Safety fences	Inflexible; do not allow for a shared workspace
Camera systems	Light-dependent, susceptible to obstruction, smoke, and dust
Capacitive sensors	Detection range only 10–20 cm, so the robot can only work very slowly
Bulk piezo ultrasonic sensors	Fixed transmission frequency, no position determination, RoHS compliance issues (contain lead)

The Solution – ULTRABOT: Intelligent Ultrasonic Skin for Robots

© Fraunhofer IPMS, Fraunhofer IFF
Messsystem mit elektronischer Ansteuerung und zugehörender Software. Links: Modellaufbau am Fraunhofer IPMS / Rechts: Testaufbau am Fraunhofer IFF

The ULTRABOT project is developing a flexible ultrasonic sensor skin that is mounted directly on the surface of robotic arms. This enables robots to continuously monitor their surroundings and detect people or obstacles early on. At the heart of the sensor skin is the LCMUT (Lateral Capacitive Micromachined Ultrasonic Transducer) technology patented by Fraunhofer IPMS - a miniaturizable ultrasonic transducer made entirely of silicon that is particularly well-suited for compact and robust sensor systems.

Unlike conventional ultrasonic sensors, the new technology not only measures the distance to objects but also determines their exact position and detects whether and how fast they are moving. This is made possible by the simultaneous use of multiple ultrasonic frequencies as well as highly sensitive microphones, which enable a larger detection range and significantly higher measurement accuracy. Specially developed electronics and intelligent signal processing analyze the measurement data in real time and provide reliable information about the robot’s surroundings.

This enables the robot to detect people and obstacles earlier, take their direction of movement and approach speed into account, and react accordingly. This increases safety in human-robot collaboration while also allowing for smaller safety distances without compromising reliability. As a result, robots can be deployed more flexibly, efficiently, and safely in production and work environments.

An Overview of Unique Technological Features and Their Resulting Benefits:

Multi-frequency, time-synchronized acoustic emission (30 kHz – 100 kHz)	Faster and more precise detection of people and objects without any time loss due to sequential measurement cycles. The system responds in ≤ 100 ms, enabling higher robot speeds while ensuring maximum safety.
Bio-inspired measurement principle (similar to a bat's echolocation): low frequencies for long-range detection, high frequencies for precise close-range detection	The system “thinks for itself”: The closer a person gets, the more accurately they are detected (±10 mm at < 1 m). Unnecessary robot stops caused by false alarms are minimized - the robot continues to operate normally at a safe distance and brakes only when absolutely necessary.
Simultaneous Distance and Velocity Measurement Using Frequency-Modulated Chirp Signals	Conventional systems only know where someone is - ULTRABOT also knows how fast someone is approaching. The dynamic safety distance is therefore calculated with even greater precision. The robot can respond in a correspondingly nuanced manner and avoid unnecessary production interruptions.
No infrastructure required in the surrounding area - fully robot-based	The system is ready for immediate use - without the need for costly modifications to the production facility. This is particularly valuable for autonomous mobile robots (AMRs) and flexible production lines that change locations: The safety system simply moves with them. Installation and commissioning costs are drastically reduced.
Redundant Sensor Configuration for Functional Safety (Diverse Redundancy)	Diverse redundancy is a core requirement of ISO 13849-1 for safety-critical control systems. The system thus meets the normative requirements for use as a certifiable safety device, without the need for additional external backup systems.

How does ULTRABOT work?

1. Sensor detection: Multiple LCMUT transmitters simultaneously emit signals at different frequencies. Broadband MEMS microphones receive the reflected signals.

2. Signal processing: A modular electronics system processes the measurement data in a time-synchronized manner and determines the distance, position, and approach speed of people or objects in real time.

3. Dynamic safety zone determination: Based on the distance formula from ISO/TS 15066, a dynamic safety distance is continuously calculated and monitored depending on the robot’s speed, joint position, and payload.

4. Safety response: If the safety distance is not maintained, the system reacts within ≤ 100 ms - the robot slows down or stops.

Which areas of application stand to benefit from the new technology?

© edited using magnific AI
ULTRABOT helps ensure safe operation in production and manufacturing environments.

© edited using magnific AI
ULTRABOT supports the safe use of robots in the medical and healthcare sectors.

Industrial Production & Manufacturing

The demand for maximum flexibility in the production process (product and variant diversity with batch size 1), as well as the existing and growing shortage of skilled workers and labor, are driving a high demand for robot-assisted systems in industry. ULTRABOT is designed to ensure the safety of stationary industrial robots and contributes to their safe operation in production and manufacturing environments.

Healthcare and Nursing Sector

The high demands placed on human workers in the healthcare and nursing sector, as well as the shortage of skilled workers fueled by demographic change, are challenges that offer great potential for innovative solutions using robots. The advantages of robots lie in their high precision, load-bearing capacity, and ability to operate continuously, which relieve humans of mentally and physically strenuous, non-ergonomic, or monotonous tasks. Since people who are unfamiliar with robots (e.g., patients) are often present in the vicinity of robots, ULTRABOT supports the safe deployment of robots.

Mobile & Location-Flexible Robotics (AMR)

The technology is also suitable for autonomous mobile robot platforms (AMR) as well as collaborative, location-flexible industrial robots, thereby expanding the range of applications beyond stationary robots.

Consortium

The ULTRABOT project is a joint research project between Fraunhofer IPMS and Fraunhofer IFF:

Fraunhofer Institute for Photonic Microsystems IPMS, Dresden: Development of LCMUT ultrasonic sensors, electronics, signal processing, and multi-frequency measurement methods. Fraunhofer IPMS possesses patented NED/LCMUT technology and many years of experience in MEMS-based ultrasonic applications.
Fraunhofer Institute for Factory Operation and Automation IFF, Magdeburg: Safety concept, safe zone procedures, regulatory requirements, and demonstrator integration. Fraunhofer IFF possesses patented technologies for tactile sensing and camera-based distance monitoring, as well as close collaborations with certification bodies (IFA of the DGUV).