On the Silk Road of Robotics
These web-slinging robots mimic spiders to adapt to new environments, crawl across gaps, and even modify their own bodies.
Broadly speaking, there are two primary paths one can take when designing the body of a robot. A robot can be finely-tuned for operation in a specific environment, in which case it may be very effective in that environment, but will struggle the moment that conditions change. Alternatively, it could be designed to be a jack of all trades. Such robots can be expected to have fair performance under a wider range of conditions, but they will not be especially well-suited for handling any one of them.
This situation is in sharp contrast to what is seen in nature where animals tend to be very versatile, showing a great ability to adapt to many different environments. Researchers at the University of Tartu are attempting to bring this sort of adaptability to robots by emulating the way that spiders spin webs.
Unlike traditional robots that rely on fixed mechanical limbs or rigid bodies, the team’s adaptive robots use a system of deployable filaments — similar to a spider’s silk — that can be extended, contracted, and rearranged to form temporary support structures or alternative locomotion methods. This allows them to respond in real-time to changes in their surroundings.
The robots are equipped with micro-extrusion units that function similarly to a 3D printer. They are capable of producing strong but lightweight polymer threads that are something like a synthetic spider silk. These units heat and extrude a specialized polymer that quickly solidifies upon exposure to air, allowing the robot to create structural elements on demand. The polymer composition is designed for both strength and flexibility, ensuring that the produced filaments can support weight while remaining lightweight. These threads can be rapidly deployed to create new support structures, form makeshift limbs, or even act as tethers for controlled movement across challenging terrain.
To enhance adhesion to different surfaces, the robot uses a combination of electrostatic charges, chemical bonding agents, and micro-hooks that mimic the adhesive properties of spider silk. This multi-mode adhesion system enables the robot to anchor itself securely to a variety of materials, from smooth glass to rough concrete, ensuring stability in diverse environments. Additionally, the extrusion system can adjust the filament’s thickness and tensile strength in real time, allowing the robot to optimize its web-like structures for different tasks, such as climbing, bridging gaps, or reinforcing unstable terrain.
The performance of the robotic system was evaluated in a series of experiments by having it traverse a variety of challenging terrains while constructing support structures in real time. The robot successfully navigated uneven rocky surfaces, climbed over obstacles by creating temporary footholds, and even spanned small gaps by extruding polymer bridges. It was also tested on steep inclines, where it adjusted its web-like structures to enhance grip and stability.
The researchers are currently working on improving the speed and efficiency of the self-assembly process. They are also exploring how different materials and reinforcement methods could enhance the strength and durability of the synthetic webbing. With future enhancements, the dream of highly flexible and responsive robots may soon become a reality.