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Robotic Technology

Menacing mantis

By Nick Wright

Inspired by “Star Wars,” U.K. designer builds 9-ft.-tall, six-legged driveable hexapod

May 2013 - At first glance, the six-legged Mantis robot looks like it just walked off the set of a sci-fi war movie. Step by step, it methodically creeps along and senses the terrain at a constant, calculated clip. It’s a hexapod, borrowing more from a praying mantis’ (or cockroach’s) anatomy than a spider’s, which has eight legs, despite the robot’s resemblance to the former.

By now, if you haven’t seen Matt Denton’s creation, take a look here and here. At 1,900 kg (about 2 tons), and 9 ft. tall, Mantis is the largest robot Denton has built, and according to him, is one of the world’s largest robotic hexapods. 

Denton is the founder of Micromagic Systems, an animatronics and special effects company for film and television, based in Winchester, U.K. Inspired by movies like “Star Wars” and “Labyrinth,” and driven by a background in electronics and computer engineering, Denton has created 15 to 20 tabletop-sized robots, the biggest no more than a foot long.

“I have an office full of them, which is a bit ridiculous,” he laughs. He’s done creature effects for movies including “Lost in Space,” “Prometheus” and the Harry Potter series.

He had been building robots since 2000 as a hobby, but through working on so many FX-based projects, he picked up the skills needed to create something as ambitious as the Mantis. The project took about four years from start to finish, and debuted at the music festival Bestival U.K. in 2012.

Mantis’ muscular metal legs, powered by hydraulic actuators, are fabricated from 3 mm steel for the box sections and 25 mm machine grade aluminum. Each leg weighs about 130 kg (287 lbs.). The steel sections were laser cut and welded, while the aluminum parts were waterjet cut using a dynamic head to keep the cut as true as possible. Then they were brought to Denton’s workshop for post machining, such as boring, tapping and pocketing, using a flatbed Pacer Cadet CNC router and a CNC mill. The chassis, which looks as though laser cannons and missile launchers could unfurl from it at any moment, is a lattice of 30 mm square box section steel 3 mm wall, and 20 mm tube support struts. It looks as though.

“Without the use of custom hydraulic manifolds, the plumbing of the machine was somewhat of a challenge,” Denton says. “So the chassis was kept as open as possible so as to make routing of the pipe work simpler.”

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On the move

As menacing as it looks, most people could probably outrun—or outwalk—the Mantis. Its mechanical gait is most stable around 1 km/h, however Denton says it can reach about 10 times that if needed. With 18 axes, it can be driven with three feet on the ground at all times, creating a walking tripod, or four feet, the most stable option. 

Sensors in each foot determine the terrain’s characteristics (like slope), which Mantis tilts and balances itself accordingly. It’s piloted with two three-axis joysticks (left for walking, right for rotating), and can be Wi-Fi remote controlled—lending itself to private hires and custom commissions.

During the development, Denton says, figuring out the best configuration for the fuel tank made for design revisions. The Perkins 2.2 l turbo diesel engine originally had a 30 l tank, but had to share space with the hydraulic tank.

“It seems strange, but there’s not much space left on the machine to put anything,” he adds. The original hydraulic tank’s shape kept the pump from getting good suction. That, and a “diesel tank disaster” that dumped 30 l of fuel all over the machine and shop floor one day.

“It doesn’t evaporate easily, so it was a big cleanup. At that point I decided to change things, so I made the hydraulic tank taller and thinner so there’s more oil above the suction point. I also moved the fuel tank and redesigned it from scratch from aluminum.” Mantis now holds 20 l of fuel. Its legs retract and fold up so it fits nicely on a trailer bed for transportation. 

Denton had help from a mechanical engineer and software developer for periods during the development, but he mainly worked solo. “I would say the biggest challenge of the project was staying motivated when much of the time I was working alone,” he says, noting he had issues outsourcing cut parts and, if he had the capabilities, would have done everything in-house.

But motivation paid off. “There has been a great response from the media, and it seems to fire the imaginations amongst the young engineers, so that’s a win,” he says. 

Dentons Mantis currently is billed as a creative prototype, but that doesn’t rule out its potential for useful applications. FFJ

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Sources

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AIR FILTRATION

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Camfil APC - Equipment Beckwood Press Co. Metamation Inc. Admiral Steel
Camfil APC - Replacement Filters Triform

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Alliance Steel
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Messer Cutting Systems Inc.

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AMADA AMERICA, INC.

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Mate Precision Tooling AIDA-America Corp.
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Burghardt + Schmidt Group

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Alliance Steel
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Red Bud Industries UFP Industrial Automec Inc. BLM Group
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MC Machinery Systems Inc. Prudential Stainless & Alloys

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Advanced Gauging Technologies SafanDarley

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Mayfran International

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Barton International

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Cincinnati Inc. Hougen Manufacturing Flow International Corporation
ATI Industrial Automation LVD Strippit

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Jet Edge Waterjet Systems
Lissmac Corp. Scotchman Industries Inc. Behringer Saws Inc.

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Osborn Trilogy Machinery Inc. DoALL Sawing American Weldquip
SuperMax Tools

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HE&M Saw Strong Hand Tools
Timesavers FAGOR Arrasate USA Inc. Savage Saws T. J. Snow Company

 

MetalForming Inc.

 

 

 

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Titan Tool Supply Inc.

 

 


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