Enhancing the vertical mobility of six-legged robot RHex

Enhancing the vertical mobility of six-leggedrobot RHex using microspines27 June 2019, by Ingrid Fadelli

Credit: Adam Zeloof.

A team of researchers at Carnegie MellonUniversity has recently proposed a method toimprove the vertical mobility of a renownedhexapod robot. Their approach, presented in apaper pre-published on arXiv, entails the additionof microspines to RHex, an existing cockroach-inspired robotic platform designed to navigateunstructured environments at relatively high speed.

While rare, microspines have been previouslystudied by researchers at other institutions andorganizations. In their work, the team at CarnagieMellon drew inspiration from the work of otherteams at Stanford's Biomimetics and DexterousManipulation Lab and NASA-JPL's ExtremeEnvironment Robotics group.

"This work started as a semester long project forProfessor Aaron Johnson's Robot Design andExperimentation class at CMU," Matt Martone, oneof the researchers who carried out the study, toldTechXplore. "Many of the team members haveworked in the Robomechanics Lab with X-RHex, asimple but rugged robot that can traverse almost

any rough terrain. However, X-RHex is stymied bysteep slopes and vertical walls, so our teamdecided to improve it's climbing ability by addingmicrospine feet and designing a lighter body."

The new version of RHex proposed by Martone andhis colleagues, called T-RHex, is augmented withmicrospine feet that make it ideal for climbingnatural surfaces. These microspine feet use dozensof tiny hooks to catch onto millimeter-scale surfaceirregularities on walls, adhering and allowing therobot to climb a variety of surfaces. Thesemicrospines work really well on rough rockysurfaces, concrete and brick surfaces, as well assofter surfaces, such as wood, as all of these haveplenty of 'catch-points' typically referred to asasperities.

"Other climbing approaches such as geckoadhesive and suction cups are better for glass orpolished metal, but would fail on natural surfaces,which are more realistic for the use case of ourrobot," Martone explained. "By adding microspinesto the back of the robot's feet, we leave its forwardwalking motion on the ground unaffected, using aspecially-designed backward motion to climb."

The researchers evaluated their upgraded RHexplatform in a series of experiments on three surfacetypes: cork, brick and plywood. They found that T-RHex was able to statically hang on slopes up to135° from horizontal (45° overhang) and ascendslopes up to 55° without any loss in its groundmobility.

"Our team was really excited by the ability to clingonto overhangs of up to 45°, but practically themost important result is the steep slope ascent,"Martone said. "Our work in designing these feetand the climbing footfall pattern is directlyapplicable to other RHex-type robots, which willexpand the types of terrain they would be able toconquer."

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T-RHex. Credit: Adam Zeloof.

Credit: Adam Zeloof.

Credit: Adam Zeloof.

Credit: Adam Zeloof.

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T-RHex hanging from a tree. Credit: Adam Zeloof.

Over the past two decades, studies carried out atdifferent universities worldwide have significantlyenhanced the RHex platform, enabling capabilitiessuch as running, jumping, and stair climbing. Intheir recent study, Martone and his colleaguesadded to this pool of research by enhancing therobot's vertical mobility and thus its climbingcapabilities. According to the researchers, RHexmight soon overcome even greater obstacles andthis could allow its deployment as areconnaissance robot, payload delivery system, oreven a wildlife observer.

"We are now focusing on improving the motion T-RHex uses to climb to finally achieve a fully verticalascent," Martone said. "We also want to iteratefurther on the leg design to be more flexible anddurable to enable ground sprinting."

More information: Matt Martone, et al.Enhancing the vertical mobility of a robot hexapodusing microspines. arXiv:1906.04811 [cs.RO]. arxiv.org/abs/1906.04811

© 2019 Science X NetworkAPA citation: Enhancing the vertical mobility of six-legged robot RHex using microspines (2019, June 27)retrieved 27 November 2021 from https://techxplore.com/news/2019-06-vertical-mobility-six-legged-robot-rhex.html

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