- These robots could come in handy in search-and-rescue situations, where they could navigate collapsed buildings to find and assist survivors.
- With slender, flexible bodies, limbless robots could readily move through confined and cluttered spaces such as debris fields, where walking or wheeled robots and human rescuers tend to fail.
- However, even the most advanced limbless robots have not come close to moving with the agility and versatility of worms and snakes in difficult terrain.
Undulators and mechanical intelligence
- Our team wanted to figure out a way to simplify these systems by highlighting mechanically controlled approaches to dealing with obstacles that don’t require sensors or computation.
- Animals don’t rely solely on their neurons – brain cells and peripheral nerves – to control movement.
- While computational systems are governed by the laws of mathematics, mechanical systems are governed by physics.
- To achieve the same task, scientists can either design an algorithm or carefully design a physical system.
- If you compare a diverse set of undulating organisms with the increasingly large zoo of robotic “snakes,” one difference between the robots and biological undulators stands out.
To get to the bottom of this question, our team built a new robot called MILLR, for mechanically intelligent limbless robot, inspired by the two bands of muscle on snakes and worms. MILLR has two independently controlled cables that pull each joint left and right, bilaterally.
We found this method allows the robot to spontaneously move around obstacles without having to sense its surroundings and actively change its body posture to comply to the environment.
Building a mechanically intelligent robot
- This way, it mirrors the muscle activation methods that snakes and nematodes use, where the left and right sides take turns activating.
- This activation mode pulls the body toward one side or another by tightening on one side, while the other side relaxes and is pulled along passively.
- When the robot collides with an obstacle, depending on the cable tension, it selectively maintains its shape or bends under the force of the obstacle.
- If, alternatively, the robot experienced a force that opposed the bend, it would remain rigid and push itself off the obstacle.
Testing MILLR
- We sent MILLR through a similar course and compared the results.
- We noticed that the worms made the same type of body movements when they collided with obstacles as MILLR did.
This work was supported by the National Science Foundation Physics of Living Systems Student Research Network, NSF-Simons Southeast Center for Mathematics and Biology, Army Research Office Grant, and the Dunn Family Professorship.