Wheels Or Legs? Why Not Both?

Out of the thousands of constraints and design decisions to consider when building a robot, the way it moves is perhaps one of the most fundamental. The method of movement constrains the design and use case for the robot perhaps more than any other parameter. A team of researchers at Texas A&M led by [Kiju Lee] is trying to have their cake and eat it too by building a robot with wheels that transform into legs, known as a-WaLTR (Adaptable Wheel-and-Leg Transformable Robot).

a-WaLTR was designed to conquer one of wheeled robots’ biggest obstacles: stairs. By adding a bit of smarts to determine whether a given terrain is better handled by wheels or legs, a-WaLTR can convert its segmented wheels into simple legs. Rather than implemented complex and error-prone articulated legs, the team stuck with robust appendages that remind us a little of whegs.

The team will show off their prototype at DARPA OFFSET Sprint-5 in February 2021, which is a program focused on building robots that can form adaptive human-swarm teams.

Thanks to the rise of 3D printers and hobbyist electronics there are more open-source experimental robot designs than ever. We’ve seen smaller versions of the famous Boston Dynamics’ Spot as well as simpler quadruped bots with more servos. a-WaLTR isn’t the first transforming robot we’ve seen, but we’re looking forward to seeing more unique takes on robotic locomotion in the future.

Thanks to [Qes] for sending this one in!

When The Going Gets Tough, These Wheels Transform To Tracks

When we want to build something to go where wheels could not, the typical solution is to use tracks. But the greater mobility comes with trade-offs: one example being tracked vehicles can’t go as fast as a wheeled counterpart. Information released by DARPA’s ground experimental vehicle technology (GXV-T) program showed what might come out of asking “why can’t we switch to tracks just when we need them?”

This ambitious goal to literally reinvent the wheel was tackled by Carnegie Mellon’s National Robotics Engineering Center. They delivered the “Reconfigurable Wheel-Track” (RWT) that can either roll like a wheel or travel on its tracks. A HMMWV serves as an appropriate demonstration chassis, where two or all four of its wheels were replaced by RWTs. In the video (embedded below) it is seen quickly transforming from one mode to another while moving. An obviously desirable feature that looks challenging to implement. This might not be as dramatic of a transformation as a walking robot that can roll up into a wheel but it has the advantage of being more immediately feasible for human-scale vehicles.

The RWT is not the only terrain mobility project in this DARPA announcement but this specific idea is one we would love to see scaled downed to become a 3D-printable robot module. And though our Hackaday Prize Robotics Module Challenge has already concluded, there are more challenges still to come. The other umbrella of GXV-T is “crew augmentation” giving operators better idea of what’s going around them. The projects there might inspire something you can submit to our upcoming Human-Computer Interface Challenge, check them out!

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Reinventing The Wheel Makes For A Better Wheel…

When robots take over the earth, it will be important that they maneuver across various types of terrain quickly and effectively. Bipedal motion is a tricky feat to accomplish for machines, so [Carter Hurd] decided, why not invent a better wheel? Even wheels can be improved, right?

Making excellent use of the prototyping capabilities of a 3D printer, [Carter] designed a set of bulb-shaped mechanisms which act effectively to drive themselves around on a smooth surface. The bulb is split radially into a series of wedge slices which can articulate outward, transforming the robot into something of a spiky razor-beast, able to tear through piles of fall leaves or wakes of loose sand. In order to unfurl itself however, the shaft driving the central mounting plate of the wedges has to fight the robot’s own weight. To solves this, [Carter] modified his design so that the rest of the wedges would unfold around the one supporting the load, the wheels would then rotate to shift the weight, allowing the last piece to extend.

[Carter] shows a proof of concept from earlier this year, explaining his hinge design which stretches a tendon-like connector in order to tension the wedges in one state or the other. Since then it looks like his transforming wheel has evolved a bit. You can get a better view of his robot in action here :

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