Unmanned watercraft autonomously scans bodies of water

06 Jul 2023

Fraunhofer IOSB development uses laser scanning, cameras, and sonar to map above and below waterline.

Surveying bodies of water precisely is a challenging task. Authorities and port operators need to provide up-to-date maps of riverbeds and port facilities. Until now, this has required the costly use of special mapping vessels and significant effort. This limits the frequency and precision that will be required for future applications, such as autonomous shipping.

Now, a team of researchers at the Fraunhofer Institute of Optronics, System Technologies and Image Exploitation (IOSB) has developed an easy-to-operate, unmanned watercraft that autonomously surveys bodies of water both above and below the surface, generating 3D maps.

The IOSB researchers say it is far less expensive to carry out underwater and surface mapping using autonomous watercraft. They developed such a system as part of the TAPS project (German-language acronym for “semi-automatic navigation system for rivers and lakes”) based on a commercial unmanned surface vessel (USV).

Connected only to a central workstation or control station on land, the survey vessel maps all types of inland waters and their surroundings, surveying both above and below the water surface. Coastal applications are also feasible, since in its current form, the system can map depths of up to 100 meters.

High-precision 3D models

Using its GPS, acceleration and angular rate sensors, and a doppler velocity log sensor that enables the boat to incrementally feel its way along the bottom of the body of water, the vessel is able to move autonomously.

The data from the various sensors are merged to guide the semi-automatic navigation system. For mapping above water, laser scanners and cameras are used in combination with mapping software developed at Fraunhofer IOSB, enabling the devices to reconstruct high-precision 3D models of the surroundings.

The underwater mapping, in turn, is carried out with the help of a multi-beam sonar, which is integrated into the sensor system and creates a complete 3D model of the bed.

Dr. Janko Petereit, a scientist at Fraunhofer IOSB, explained, “Our navigation system is semi-automatic in that the user only needs to specify the area to be mapped. The surveying process itself is fully automatic, and data evaluation is carried out with just a few clicks of the mouse. We developed the software modules required for the mapping and autonomous piloting.”

The first step is to specify the area to be surveyed. The software then uses this information to calculate the route. Next, the USV, which measures 2 m x 1.5 m x 1 m and weighs 64 kg, scans the target area. Whilst fulfilling its task, it autonomously evades obstacles detected by the laser scanner and sonar.

During the journey, a quick 3D model is generated in real time for navigation purposes, including dynamic objects such as moving vessels. A second high-precision 3D model is computed by the software after data evaluation, capturing both the floor of the body of water and the scene above the water surface, whilst also hiding moving objects.

Green-focused Fraunhofer ISE restructures

As the largest solar research institute in Europe, the Fraunhofer Institute for Solar Energy Systems (ISE) has been developing solutions for a sustainable and climate-neutral energy supply for over 40 years. This week, the ISE has announced that it is reorganizing its competencies in the areas of energy provision, energy distribution, energy storage and energy utilization.

With the reorganization, Fraunhofer ISE's numerous research fields which contribute to providing the necessary know-how for the energy transition will work in a more interdisciplinary and cooperative manner on solutions for a sustainable and climate-neutral energy supply. As of July 1, 2023, the Institute will have a new organizational structure as follows:

• Photovoltaics under the direction of Prof. Dr. Stefan Glunz and PD Dr. Ralf Preu.
• Power Solutions under the direction of Dr. Harry Wirth.
• Heat and Buildings under the direction of Dr. Peter Schossig.
• Hydrogen Technologiesunder the direction of Prof. Dr. Christopher Hebling.