Snake robots are always incredible to watch, and CMUs modular snake robots are no exception. They are incredibly versatile – being able to crawl, climb, swim and scale flights of stars. The video shows all — and I was really impressed when it crawled up and down the leg of one of its creator … fast!



Creators and Project Origins

The snakes are a project of CMUs Biorobotics lab, named Modular Snake Robots (or Modsnake for short). See also the list of project members.

Snake robots can use their many internal degrees of freedom to thread through tightly packed volumes and access locations that people and machinery otherwise cannot. These highly articulated devices can coordinate their internal degrees of freedom to perform a variety of locomotive gaits that go beyond the capabilities of conventional wheeled and legged robots. The true power of these devices is their versatility; they can crawl, climb, swim, and scale flights of stairs. [Official description from CMU]

Project Goals and Design

The issues tackled in the project are twofold, according to the information provided on the project’s site. The first is to achieve snake-like locomotion and the second is to have the artificial being’s design modular. The robots are a chain of modules, each of which have one degree of freedom. They’re powered by low-cost hobby servos (named SuperServos by CMU, or more recently SuperServo2), and an encapsulating mechanism designed to optimize efficiency and robustness.

Each robot is currently controlled by a tethered cable and are embedded with a camera on the snakes’ edge module.



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Speed of Locomotion in Complex Environments

I’m very impressed by the speed of the robots, and you can see that CMUs team is proud as well, sporting the “real time” tag in the video. Lack of speed is one of the things I’ve touched on regarding modern robotics. It’s hard to deal with complexities of normal, or even catastrophic environments (for rescue-type, or military robots). If a robot moves fast its intelligence must be capable of making good judgement calls in real time, fast and efficiently.

Our (humanity’s) physical machinery is advancing rapidly and hopefully these superb platforms will help us excel development of systems that endow them with higher intelligence.

Related AI Projects & Commentary

From what I gathered on CMUs information I believe an emphasis is currently being put on engineering and physical versatility. But there are of course several projects focused on AI, specifically regarding path planning and the snakes’ ability to coordinate each of its joints by itself. As noted on the CMUs Snake Motion Planning Page (see also more of the snakes’ Control Theory projects):

Snake robots have many applications, but are hard to control. A person cannot simply operate each joint of a snake individually because there are too many. These robots require a motion planning algorithm. Motion planning for snake robots is difficult because the robots have many internal degrees of freedom that have to be coordinated to achieve purposeful motion. In motion planning jargon, this means the snake robots exist in large dimensional configuration spaces. Our work will make it possible for the robots to operate in several different modes from fully autonomous to human-guided. The robot will be able to optimize its own path based on a range of cost functions from power consumption to safety or even stealth. [...] We are working on two approaches for snake motion planning right now. The first introduces a new topological decomposition of space called WAFT (WAve Front Topology) This decomposition is well suited to tethered robots, like a snake that is fixed to the ground at one end. This decomposition of space allows for path planning that is path-dependent, meaning that veering left around the first obstacle encountered will change the options that are available in the future as compared to the options had the path to the right of the first obstacle been chosen. This WAFT planner can be implemented in a sensor based way and can be used to guarantee complete coverage of the work space. This is important for exploring unknown spaces when searching for survivors in collapsed building or when doing surveillance operations.





Very interesting and impressive work and I personally look forward to seeing how the projects progress.

Links & References

The video and images are Copyright 2008 Biorobotics Lab, Carnegie Mellon University. All Rights Reserved.

See the list and specifications of the Modsnake robots that have been created

See links to the BioRobotics lab, Modsnakes and relevant AI projects in the article

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