The collective behaviors of ants, honeybees, and birds to solve problems and overcome obstacles is something researchers have developed in aerial and underwater robotics. Developing small-scale swarm robots with the capability to traverse complex terrain, however, comes with a unique set of challenges. Researchers have built multi-legged robots capable of maneuvering in challenging environments and accomplishing difficult tasks collectively, mimicking their natural-world counterparts.
Legged robots can navigate challenging environments, such as rough terrain and tight spaces, and the use of limbs offers effective body support, enables rapid maneuverability, and facilitates obstacle crossing. However, legged robots face unique mobility challenges in terrestrial environments, which results in reduced locomotor performance.
The researchers hypothesized that a physical connection between individual robots could enhance the mobility of a terrestrial legged collective system. Individual robots performed simple or small tasks such as moving over a smooth surface or carrying a light object but if the task was beyond the capability of the single unit, the robots physically connected to each other to form a larger multi-legged system and collectively overcome issues.
Using a 3D printer, the team built four-legged robots measuring roughly 6 to 8 inches in length. Each was equipped with a lithium polymer battery, microcontroller, and three sensors — a light sensor at the front and two magnetic touch sensors at the front and back, allowing the robots to connect to one another. Four flexible legs reduced the need for additional sensors and parts and gave the robots a level of mechanical intelligence that helped when interacting with rough or uneven terrain.
After printing each robot, they were built and tested over grass, mulch, leaves, and acorns. Flat-ground experiments were conducted over particle board, and stairs were built using insulation foam. The robots were also tested over shag carpeting and rectangular wooden blocks were glued to particle board to serve as rough terrain. When an individual unit became stuck, a signal was sent to additional robots that linked together to provide support to successfully traverse obstacles while working collectively.
The work will inform the design of low-cost legged swarms that can adapt to unforeseen situations and perform real-world cooperative tasks such as search-and-rescue operations, collective object transport, space exploration, and environmental monitoring. The research will focus on improving the control, sensing, and power capabilities of the system, which are essential for real-world locomotion and problem-solving.
For functional swarm systems, the battery technology needs to be improved. Small batteries are needed that can provide more power, ideally lasting more than 10 hours. Otherwise, using this type of system in the real world isn’t sustainable. Additional limitations include the need for more sensors and more powerful motors while keeping the size of the robots small.