A research team of physicists, engineers and mathematicians from the Georgia Institute of Technology have developed a multi-legged motion model that controls the locomotion of multi-limbed robots. They can move better in difficult terrain with their redundant legs.
“When you see a scurrying millipede, you’re essentially looking at an animal living in a world that’s very different from our world of movement,” says Daniel Goldman, a professor in the School of Physics. Human movement is largely dominated by inertia. A person swings his leg, placing one foot at a time, thereby moving forward. Millipedes move forward by wiggling their body parts and limbs. As soon as they stop, they stop.
The research team wanted to find out whether this type of locomotion could also be used to advantage in the robotic world. They summarized the results in the studies “Multilegged matter transport: A framework for locomotion on noisy landscapes” and “Self-Propulsion via Slipping: Frictional Swimming in Multilegged Locomotors”, which were published in Science and Proceedings of the National Academy of Sciences respectively .
The team theorized that adding pairs of legs increases a robot’s ability to move robustly over rough terrain. The researchers call the concept “spatial redundancy”. She is responsible for allowing robot legs to move successfully on their own without the need for sensors to sense their surroundings. If one leg fails, the other legs keep the robot moving. This turns the robot into a reliably functioning system that can transport itself and loads in blocked terrain.
More legs, no sensors
The scientists write that a modern two-legged robot normally requires a large number of sensors for this. “However, in applications such as search and rescue, exploration of Mars, or even microrobots, there is a need to control a robot with limited sensor capabilities. There are many reasons for such a sensorless initiative. The sensors can be expensive and sensitive, or the The environment can change so quickly that the response time of the sensor and controller is insufficient,” says Baxi Chon, a physics postdoctoral researcher.
In a “non-uniform natural environment” the researchers tested a robot in the laboratory. They gave him six to 16 legs one after the other – each one raised by a pair of legs. With an increasing number of legs, the robot moved more nimbly through the terrain without sensors, thus confirming the theory of “spatial redundancy”. The robot also showed the same success in natural terrain in field tests. “Whereas two-legged and four-legged robots rely heavily on sensors to traverse complex terrain, our multi-legged robot takes advantage of leg redundancy and can handle similar open-loop tasks,” the scientists say.
The scientists now want to further develop the robot. You know why the “centipede” robot works, but you haven’t figured out the optimal number of legs yet. However, it is largely responsible for achieving cost-efficient locomotion without sensors. To do this, however, the scientists must first understand the trade-offs between energy, speed, performance and robustness.
Goldman then plans to use this robot on agricultural fields. To do this, he founded a company that wants to use the robots for ecologically correct weed control – at least where weed killers are ineffective.