Original Source: Forschungsverbund Berlin e.V. (FVB)

Night-time collisions with robotic lawnmowers are a significant animal welfare and conservation problem for hedgehogs as they often suffer serious or even fatal injuries. In order to make the operation of robotic lawnmowers hedgehog-safe, the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), the specialist crash test company CTS and the computer magazine c’t are developing special hedgehog dummies and standardized tests to prevent fatal collisions.

National and international experts will be discussing the latest developments in this project and many other topics related to hedgehog research, animal welfare and conservation at two conferences organized by the Leibniz-IZW in Berlin from January 16 to 19, 2025.

In October 2024, Leibniz-IZW, CTS and c’t carried out tests on prototypes of hedgehog dummies to assess their similarity to real hedgehogs. These dummies should not necessarily look like real hedgehogs to the human eye, but should “behave” identically when a robotic lawnmower approaches and collides with them, so that realistic and standardized safety tests for the mowers can be carried out.

In the test series, the team compared a prototype developed by CTS with real, already deceased hedgehogs collected at the Leibniz-IZW. The dummies have a 3D-printed internal skeleton, can be heated to hedgehog body temperature, have different sizes and shapes (curled and uncurled) and resemble hedgehogs as closely as possible in appearance, weight-to-size ratio, mobility and flexibility—so that in the future they can be used in tests on all robotic mower models regardless of their object detection sensor technology (laser, ultrasound, optical, thermal imaging or contacts in the bumper) to assess the extent to which these models can recognize hedgehogs.

Accurate design, correct weight and stability are essential, especially for mechanical detection with impact sensors. In addition to testing the detection of hedgehogs, the injuries of the hedgehog carcasses and the dummies in the event of identical (forced) robotic mower accidents were analyzed.

“The tests revealed a close resemblance between the injuries of the hedgehog carcasses and the dummies during the forced collisions,” says hedgehog expert Dr. Anne Berger from the Leibniz-IZW. “However, the dummies are still a little too heavy and inflexible compared to real hedgehogs and will still undergo some improvements in the coming months. The team will carry out final tests again in spring 2025 and finalize the dummies.”

Berger and her colleagues at CTS and c’t are working towards the introduction of an SI-DIN standard in Germany, which would make standardized crash tests for robotic lawnmowers with these dummies mandatory for all brands and models on the market. The tests will demonstrate the extent to which each robot mower model is able to reliably detect hedgehogs and initiate evasive maneuvers or emergency braking.

In the past, Berger and her colleagues have conducted extensive empirical investigations on hedgehog cuts caused by robotic lawnmowers. For example, they analyzed 370 cases of cut injuries reported throughout Germany and found that their occurrence was evenly distributed across the days of the week.

“This is a clear indication that robotic lawn mowers are often the cause of these injuries, as these devices are the only ones that can legally be used on a Sunday,” says Berger. Almost half of the animals found and reported (at 47%) did not survive the injury.

Hedgehog rescue centers also report a steady increase in the number of cases of injured hedgehogs, which indicates a growing conservation problem in the context of declining hedgehog populations in Germany. “We furthermore suspect that a high number of cases of injured or deceased hedgehogs are not even found or reported,” says Berger.