Robot navigates like desert ant without using GPS
French scientists at a university in Marseille have developed a six-legged robot that can navigate without using a positioning system such as GPS. The robot imitates desert ants by orienting, just like the insects, based on polarized light.
Like the ants, the robot uses strips of polarized light from the sun. Unlike ants, humans cannot perceive this. To be able to observe this, the robot, called AntBot, is equipped with two optical sensors that consist of fourteen pixels. With two pixels of this, a kind of star compass was formed that is sensitive to ultraviolet light. In combination with two rotating polarizing filters, the compass is comparable to two expensive installations consisting of 374 photo sensors, according to the scientists. This allows the robot to determine in which direction it is moving.
In addition to this optical capacity, AntBot also needs a second source of data for precise navigation. To this end, the robot is equipped with a sensor that maps the optical flow field. This sensor, made up of the remaining twelve pixels, actually registers how fast the ground moves under the eye. This can be compared to the method used by desert ants: they track their steps and watch how quickly the ground moves past their eyes.
In this way, thus mapping orientation and distance, desert ants are able to navigate very precisely. That is not a superfluous luxury in the desert, where pheromones are destroyed immediately by the high temperatures and are therefore not usable as a means of navigation. In addition, there is always the risk that the ants will burn alive if they travel for too long, which could happen if they do not exactly find their way back to their burrow after foraging.
AntBot turned out not to be quite as good as the ants, but still performed quite well. The researchers had the robot travel multiple, randomly shaped trajectories in different weather conditions, somewhat mimicking the zigzagging of the foraging ants. The distances to be covered varied from 4.7 to 10.2 meters. Then the question was whether the robot could find its way back to the starting point in a straight line. During the test in which the robot performed best, the deviation was only 6.47 cm.
According to the scientists, this navigation method can be used for all kinds of applications, such as exploring unknown areas or navigating after natural disasters. The range and reliability of GPS are not always guaranteed. The same sometimes applies in cities, where tall buildings can limit the efficiency of GPS. For example, adding the ants’ navigation method to self-driving cars can provide additional reliable information for the car’s brain. Another option is automatic navigation for inspecting crops or allowing ships to navigate autonomously.
The six-legged robot has a diameter of 45 centimeters, weighs 2.3 kg including the batteries and reaches a top speed of 3.2 km/h. The batteries give the robot enough energy to walk around for half an hour.