A snake-arm robot is a slender hyper-redundant manipulator. The high number of degrees of freedom allows the arm to “snake

Snake

Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...

” along a path or around an obstacle – hence the name “snake-arm”.

Definition

Snake-arm robots are also described as continuum robots and elephant’s trunk robots although these descriptions are restrictive in their definitions and cannot be applied to all snake-arm robots.

• A continuum robot is a continuously curving manipulator, much like the arm of an octopus.
• An elephant’s trunk robot is a good descriptor of a continuum robot. This has generally been associated with whole arm manipulation – where the entire arm is used to grasp and manipulate objects, in the same way that an elephant would pick up a ball.

This is an emerging field and as such there is no agreement on the best term for this class of robot.

Snake-arm robots are often used in association with another device. The function of the other device is to *introduce the snake-arm into the confined space

Confined space

Confined space is a term from labor-safety regulations that refers to an area whose enclosed conditions and limited access make it dangerous.- Description :...

. Examples of possible introduction axes include mounting a snake-arm on a remote controlled vehicle

Remote control vehicle

A remote control vehicle is defined as any mobile device that is controlled by a means that does not restrict its motion with an origin external to the device. This is often a radio control device, cable between control and vehicle, or an infrared controller...

 or an industrial robot or designing a bespoke a linear actuator

Linear actuator

A linear actuator is an actuator that creates linear motion .Mechanical and hydraulic actuation are the most common methods of achieving the linear motion...

. In this case the shape of the arm is coordinated with the linear movement of the introduction axis enabling the arm to follow a path into confined spaces.

Other features which are usually (but not always) associated with snake-arm robots:

• Continuous diameter along the length of the arm
• Self-supporting
• Either tendon-driven or pneumatically controlled
  Pneumatics
  Pneumatics is a branch of technology, which deals with the study and application of use of pressurized gas to effect mechanical motion.Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or compressed inert gases...
  
   in most cases.

A snake-arm robot is not to be confused with a snakebot

Snakebot

A snakebot is a biomorphic hyper-redundant robot that resembles a snake.Snake robots come in all shapes and sizes, from the three meters long, fire fighting snakebot developed by SINTEF, to a medical snakebot developed at Carnegie Mellon University that is thin enough to maneuver around organs...

 which mimics the biomorphic motion of a snake in order to slither along the ground.

Applications

The ability to reach into confined spaces lends itself to many applications involving access problems. The list below is not intended to be an exhaustive list of possibilities but merely an indication of where these robots are being used or developed for use.

Industry

• Nuclear
  Nuclear power
  Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
  
  
  • Decommissioning
  • Repair and maintenance

• Aerospace
  Aerospace
  Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...
  
  
  • Manufacture and assembly: inside wing boxes, jet engines and ducts.
  • Surface Preparation: wielding pneumatic sanders for all stages of surface finishing prior to final paint application.
  • Maintenance, Repair and Overhaul

• Automotive
  • Manufacture: Snake-arm robots allow structures to be assembled in a different way.

Security and defence

• Bomb disposal
  Bomb disposal
  Bomb disposal is the process by which hazardous explosive devices are rendered safe. Bomb disposal is an all encompassing term to describe the separate, but interrelated functions in the following fields:*Military:...
  
   and counter terrorism
• Search and rescue
  Search and rescue
  Search and rescue is the search for and provision of aid to people who are in distress or imminent danger.The general field of search and rescue includes many specialty sub-fields, mostly based upon terrain considerations...
  
  

Robotic surgery

• Endoscopy
  Endoscopy
  Endoscopy means looking inside and typically refers to looking inside the body for medical reasons using an endoscope , an instrument used to examine the interior of a hollow organ or cavity of the body. Unlike most other medical imaging devices, endoscopes are inserted directly into the organ...
  
  
• Colonoscopy
  Colonoscopy
  Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...
  
  
• Neurosurgery
  Neurosurgery
  Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spine, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.-In the United States:In...
  
  

History of Snake-arm robots

• Tensor arm manipulator, invented in 1968 by V.C. Anderson, commonly called the Scripps Tensor Arm, is a spine-like elephant trunk arm. Control is via a large number nylon microfilaments.

• ANAT (Articulated Nimble Adaptable Trunk) AMI-100, invented in 1997 by Charles Khairallah, is a modular hyper-redundant snake-like industrial robot
  Industrial robot
  An industrial robot is defined by ISO as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes...
  
  arm.

External links

Snake-arm robots are currently being researched by several major universities:

• Cornell University: Student Project team with goal to design and fabricate a class of robotic arms that best resemble the strength, fluidity, precision, and dexterity of a snake
• Carnegie Mellon: Research into various hyper-redundant robots including snake-arms
• Clemson: Research into elephant’s trunk robots
• Mississippi State University: Research into designing, analyzing, and building continuum robots.

Snake-arm robots are being made commercially by:

• OC Robotics: manufacturing for the aerospace sector (automated assembly of aircraft), security (robotics for counter-terrorism), nuclear (decommissioning and asset management), and other industries (inspection and maintenance).