"Long before it's in the papers"
January 28, 2015


Robot walks and swims

March 8, 2007
Special to World Science  

Eu­ro­pe­an re­search­ers have de­vel­oped a sal­a­man­der-like ro­bot that can walk or swim, and switches be­tween dif­fer­ent speeds and gaits on com­mand.

The sal­a­man­der ro­bot walks down to take a dip in Lake Ge­ne­va, Switz­er­land. (Cour­te­sy EFPL)

The sci­en­tists say the de­vice, a string of con­nec­ted boxes with four ap­pendages for limbs, pro­vides in­sights in­to the cir­cuit­ry of the spi­nal cord. Such stud­ies could help im­prove treat­ments for spi­nal in­ju­ries, they add.

“Salamandra Robotica” has a con­trol sys­tem that mim­ics the am­phib­i­an spi­nal cord. 

The device, and a math­e­ma­t­i­cal mod­el on which it’s based, may al­so help re­search­ers un­der­stand how an­i­mals evolved walk­ing abil­i­ties as they moved on­to land mil­lions of years ago, the de­vel­op­ers said. 

The com­pu­ter system that drives its mo­tion is based on the nerv­ous sys­tem of the lam­p­rey, a fish that swims in a style si­mi­lar to the sa­la­man­der. Sala­man­ders, whose swim­ming and walk­ing gaits are quite dif­fer­ent from each oth­er, are thought to re­sem­ble the first land-dwel­ling an­i­mals fair­ly close­ly. 

Jan Auke Ijspeert of the Fed­er­al Pol­y­tech­nic School of Lau­sanne, Switz­er­land and col­leagues de­vel­oped a math­e­ma­ti­cal mod­el to show how lam­p­rey nerve cir­cuit­ry could be mod­i­fied to drive walk­ing in a sal­a­man­der-like an­i­mal. It would al­so let the crea­ture switch to swim­ming.

To check the mod­el, the team built the ro­bot, which can switch among swim­ming, snake-like crawl­ing and walk­ing gaits. Sim­ple com­mands sent wire­less­ly from a lap­top com­put­er mod­u­late its speed, di­rec­tion and gait, anal­o­gous to the sig­nals com­ing from the brain, they said. The team de­tailed the work in the March 9 is­sue of the re­search jour­nal Sci­ence.

“Na­ture found a nice way of mak­ing a so­phis­ti­cat­ed cir­cuit in the spi­nal cord and then con­trol­ling the mus­cles from there,” Ijspeert said. The work, he added, viv­idly dem­on­strates that robots can serve to test and ver­i­fy bi­o­log­i­cal con­cepts—and that of­ten na­ture her­self of­fers ide­al so­lu­tions for ro­bot de­sign.

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European researchers have developed a robot, based on the salamander spinal cord, that can walk or swim, and switches between different speeds and gaits on command. The scientists say the device, a string of linked-up boxes with four appendages for limbs, provides insights into the circuitry of the spinal cord. Such studies could help improve treatments for spinal cord injuries, they say. The robot has a control system that mimics the amphibian spinal cord. It, and a computer model it’s based on, may also help researchers understand how animals evolved walking abilities as they moved onto land millions of years ago, the developers said. Salamanders, whose swimming and walking gaits are quite different from each other, are thought to resemble the first land-dwelling animals fairly closely. Jan Auke Ijspeert of the Federal Polytechnic School of Lausanne, Switzerland and colleagues developed a theoretical model to show that the nerve circuitry of a primitive fish could be modified so that it would drive walking motion in a salamander-like animal. It would also allow the animal to switch between swimming and walking. To check the model, the team built the robot, which can switch among swimming, snake-like crawling and walking gaits. Simple commands sent wirelessly from a laptop computer modulate its speed, direction and gait, analogous to the signals coming from the brain, they said. The team detailed the work in the March 9 issue of the research journal Science.