TECHNOFILE

The lat­est ro­botic tech­nol­ogy tack­les the sur­pris­ingly dif­fi­cult task of mim­ick­ing hu­man gait, writes CATHAL O’CON­NELL.

Cosmos - - Contents -

— Walk­ing with ex­oskele­tons

THE OPEN­ING KICK of the 2014 FIFA World Cup was not taken by a pro­fes­sional foot­baller; it was taken by a para­plegic. Ju­liano Pinto, paral­ysed from the waist down, took the kick us­ing a ro­botic ‘ex­oskele­ton’ to power his legs. The suit was ex­per­i­men­tal, but com­mer­cial ex­oskel­tons are be­gin­ning to en­ter the mar­ketplace, giv­ing para­plegic pa­tients who can af­ford the price tag the power to walk again.

Though we rarely give it a con­scious thought, walk­ing is de­cep­tively com­plex move­ment; a kind of con­tin­ual fall­ing for­ward in­volv­ing tens of mus­cles op­er­at­ing in smooth syn­chronic­ity to ‘catch’ the body at each step. Walk­ing has been in­cred­i­bly dif­fi­cult to re­pro­duce in ma­chines. Most ro­bots, and ro­botic ex­oskele­tons, still ‘shuf­fle’ slowly and steadily from one foot to the other.

The A$130,000 Re­walk Per­sonal 6.0, from Ger­man firm Re­walk Ro­bot­ics, is one of a new gen­er­a­tion of ex­oskele­tons that more nat­u­rally mim­ics hu­man gait. When the user tilts for­ward, Re­walk’s gy­ro­scope senses the mo­tion and takes a step. Keep re­peat­ing the move­ment and Re­walk can reach about 2.5 km/h, the fastest on the mar­ket. Even pa­tients with com­plete paral­y­sis of the legs can stand up, walk, turn, and climb stairs, though with the help of crutches for bal­ance.

The Phoenix Ex­oskele­ton, by Suitx, a new spin-out from the Univer­sity of Cal­i­for­nia at Berke­ley, is more of a bud­get model. At about half the cost of Re­walk, the Phoenix lacks the auto-step func­tion. In­stead the user con­trols it by tap­ping but­tons on a pair of crutches. Top speed de­pends on the user, but can reach up to 1.7 km/h.

It’s been a long and tor­tu­ous path to reach this mile­stone in ex­oskele­ton de­vel­op­ment. As long ago as the 1960s, Gen­eral Elec­tric teamed up with the US armed forces to build the Hardi­man, a bulky metal suit de­signed to am­plify a sol­dier’s strength 25-fold. But the tech­no­log­i­cal lim­i­ta­tions of the age made the de­vice so er­ratic and dan­ger­ous, it was never tested with a per­son in­side.

More re­cent ef­forts at build­ing su­per­suits have fared only a lit­tle bet­ter. Lock­heed Martin spent more than a decade de­vel­op­ing their Hu­man Uni­ver­sal Load Car­rier (HULC) for the US mil­i­tary. HULC was sup­posed to al­low US sol­diers carry 91kg back­packs for hours with­out tir­ing. But the project was shelved in 2012 as the strap-on metal frame forced wear­ers into a sightly un­nat­u­ral gait that ac­tu­ally in­creased fa­tigue on some mus­cles.

But the lat­est ex­oskele­tons are fi­nally man­ag­ing to work in lock­step with nat­u­ral biome­chan­ics of walk­ing. Har­vard’s Biode­sign lab threw out the clunky metal com­po­nents and are build­ing soft ex­oskele­tons in­stead, us­ing reg­u­lar cloth­ing fabric. Their de­vice, funded by the De­fense Ad­vanced Re­search Projects Agency (DARPA), looks a bit like a pair of span­dex pants strapped to a climb­ing har­ness. Ca­bles snake from a mo­torised belt down the user’s legs, fol­low­ing the curve of the user’s mus­cles. Take a step, and the ma­chine works in har­mony with the wearer’s calf mus­cles to drive the body for­ward. Coun­ter­in­tu­itive as it sounds, the soft ex­o­suit re­duces the en­ergy ex­pended through walk­ing by about 23%.

While soft ex­o­suits might en­hance the nat­u­ral mus­cle mo­tion of able bod­ied users, para­plegic pa­tients re­quire sup­port sim­ply to stand. But the lat­est hard ex­oskele­tons are also mak­ing head­way. For these users, a 100 kilo­me­tre route march isn’t the tar­get, a sim­ple stroll to the lo­cal shops would be life-chang­ing. At the cur­rent price it could be a while be­fore ex­oskele­tons be­come a com­mon sight on our foot­paths, given that mo­torised wheel­chairs are avail­able for a few thou­sand dol­lars, around one fifti­eth the price of a Re­walk. Costs need to come down, and more ev­i­dence shown for their ef­fec­tive­ness, says An­drew Mc­daid, a bio­med­i­cal en­gi­neer at the Univer­sity of Auck­land. “Then there will be a huge rush in adop­tion of this tech­nol­ogy.”

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