How Does That Grab Ya?

Ever tried one of those mechanical cranes where you try to pick up a teddy bear? They look easy but theyre next to impossible because mechanical manipulators are so awkward at handling irregular objects. But this week in New Scientist I report on a new DARPA development which will make robots a lot more dextrous.

DARPAs OCTOR (sOft robotiC manipulaTORs) program is building a new type of robot limb patterned after an elephants trunk or octopus arm. Its flexible, fast, and can handle fragile objects and reach into narrow spaces, as well as coping with a range of different sizes, as this 55 Mb video shows The current Octarms use an industrial Pentium processor board and a 24-volt electro-pneumatic pressure system. They are mainly built with off-the-shelf components, with much of the work going into modelling the behaviour of the system and designing software for kinematics (movement control), and the operator interface.
The strength of the arm is governed by actuator pressure and diameter. The current Octarm is pneumatic and works at 60 psi, but in principle a 2000 psi hydraulic system would be possible which would be far more powerful. The design is scaleable; small six-inch Octarms have been built, and a 20-foot tentacle is certainly possible - all it would take is funding. A vehicle-mounted Octarm capable of tearing down walls or shifting rubble would be worth seeing
A team including Bill Kier from the University of North Carolina and Roger Hanlon from the Marine Biological Laboratory provided the biological research behind the Octarm. They found that octopus arms in nature have transverse and longitudinal muscles as well as two sets of helically-wound muscles which spiral around the arm, giving the ability to shorten, lengthen, rotate or bend at nearly any angle.
The taper also borrowed from the octopus - means it can reach into narrow spaces, and helps with handling objects of many sizes. Small objects can be grasped with the thin end section of the Octarm, with larger and heavier objects the thicker and more powerful base sections come into play. Existing manipulators tend to me limited in the range of sizes they can deal with because their grippers can only open to a certain width.
Hanlon and colleagues are working on further improvements to the Octarm, using a range of biological models for inspiration, so later versions may take advantage of refinements observed in animal systems.

The latest demonstration featured an Octarm mounted on a Talon robot carrying out a variety of tasks, including retrieving a dummy and working underwater. Military applications may include reconnaissance (theres a camera at the end of the Octarm) and IED disposal, but there are host of civil applications where Octarms should be able to outperform existing designs.
The Octarm project is another one of DARPAs Biodynotics biologically-inspired robotics programs, and its interesting to see how leveraging techniques perfected in nature brings rapid improvements in robotics. Its also interesting to see how much of this is led by the military. This follows the same path as early computing described in my book Weapons Grade, which shows how the military were responsible for introducing major innovations in both hardware and software including digital electronic computing and the silicon chip.
Octarm joins other well-publicized creations like the BigDog prototype for a robotic mule , Carnegie Mellons snakebot and DARPAs robot flying insects and RoboLobster - and I can guarantee more some even more surprising innovations where these came from. Stay tuned!
-- David Hambling.