Antbot: the first walking robot to move without GPS
Updated: Jun 3, 2020
Published today in Science Robotics: A new six-legged robot takes inspiration from the navigation abilities of the desert ant – the first walking robot to move without GPS. Researchers at CNRS and Aix-Marseille University, in the Institut des Sciences du Mouvement – Étienne Jules Marey (ISM), have developed Antbot, equipped with a “celestial compass” that is sensitive to the sky’s polarised light.
The desert ant uses a unique navigational behavior to orient itself in space. In the midday sun of the Sahara, the Cataglyphis desert ant zig-zags from its underground nest to find insects that haven’t survived the relentless heat, and then, rather than re-tracing its steps, it runs directly back to the nest in a straight line. In this perilous environment, following a scent trail back to the nest would put the desert ant at risk of heat stress, and the pheromones typically used to leave a trail would burn up anyway. Instead, it navigates using polarized light and UV radiation from the sky, which is known as its “celestial compass”. Combined with the tracking of the distance travelled, this information allows the desert ants to return to the nest as quickly as possible.
Researchers from the CNRS and Aix-Marseille University at the Institut des Sciences du Mouvement (ISM) have taken inspiration from the desert ant’s extraordinary navigation abilities. The new robot, Antbot, is equipped with an optical compass used to determine its heading by means of polarized light, and by an optical movement sensor directed to the sun to measure the distance covered. “There is a long history of bio-inspiration and biomimetics, and many examples of sensing devices, systems, and robots have been developed based on animals or plants,” said PhD student Julien Dupeyroux. Technological advances in robotics frequently refer to the animal kingdom to unveil new possibilities, including articifical compound eyes, event-based cameras, and cockroach-inspired locomotion.
Much like the desert ant, AntBot can explore its environment randomly and return independently to base with a precision of up to 1 cm after having covered 14 meters. It’s also light (2.3 kg), and has six feet . “Having a legged robot offers far more applications than wheeled ones, as they can climb obstacles”, said Mr Dupeyroux. Indeed, the mobility offered by six feet would allow Antbot to navigate more complex environments, such as disaster areas and rugged terrain. Antbot’s “celestial compass” is an optical compass that is sensitive to the sky’s polarized ultraviolet radiation, which allows it to navigate with a 0.4° precision in both clear and cloudy weather.
How Antbot might deal with distances further than 14 m remains to be seen. This doesn’t detract from the fact that this is the first autonomous bot of its kind. “Such systems are really meaningful for autonomous vehicles development, but also for autonomous robots and drones for exploration, urban infrastructures inspection, long-range transportation – particularly by container ships – and so on.” And then there’s the fact that it relies on the sun – the photodiodes are not sensitive enough to perform at night. “However, we know that the moon reproduces the same kind of polarization pattern as the sun does, but with highly reduced intensity”, said Mr Dupeyroux. With a sensor that is precise and sensitive enough, it’s possible that Antbot could also function at night.