New Part Day: Lynxmotion Smart Servos

May 3, 2019 by Roger Cheng 33 Comments

Anyone who shops for robotics kits would have come across a few designed by Lynxmotion. They’ve been helping people build robots since 1995, from robot arm kits to hexapod chassis and everything in between. We would expect these people know their motors, so when they launched their own line of servo motors called Lynxmotion Smart Servos (LSS), it is worth spending a bit of time to look over what they offer.

While these new devices have a PWM mode compatible with classic remote control servos, unleashing their full power requires bidirectional communication over a serial bus. We’ve previously given an overview of three serial bus servos already on the market for comparison. A quick look at the $68-$100 price tags listed on Lynxmotion’s parent company RobotShop made it clear they do not intend to compete on price, so what interesting features do these new kids on the block have?

Digging into product documentation found some great details. Acceleration and deceleration rates are adjustable, which can help with smoother robot movement. There’s also an adjustable level of “stiffness” that adds some “give” (compliance) so a robot won’t have to be as stiff as… well, a robot!

Mechanically, the most interesting internal component is the magnetic position sensor. They are far more precise than potentiometers, but more importantly, they allow positioning anywhere within full 360 degrees. Many other serial bus servos are constrained to positions within an arc less than 360 degrees leaving a blind spot.

An interesting quirk of the LSS offerings is that the serial communication protocol uses human-readable text characters, so sending a number 255 means transmitting a three byte string ‘2’, ‘5’, and ‘5’ instead of single byte 0xFF. This would make debugging our custom robot code far easier, at the cost of reduced bandwidth efficiency and loss of checksum for detecting communication errors. It’s a trade-off that some robot builders would be happy to make, but others might not.

Externally, these servos have bountiful mounting options including some we didn’t know to ask for. Historically Lynxmotion kits have used a wide variety of servo mounting brackets, so they are motivated to make mechanical integration easy. The most novel offering is the ability to bolt external gears to the servo body. A set of 1:3 gears allow for gearing the servo up or down, or you can use a set of 1:1 gears for a compact gripper.

As you’d expect of servos in this price range, they all have metal gears, but they also have the ability to power the motor directly from a battery pack (a 3 cell lithium polymer is recommended). There are additional features, like an RGB LED for visual feedback, which we didn’t cover here so dig into the documentation for more. We look forward to seeing how these interesting little actuators perform in future robotics projects.

Self-aware Robotic Arm

April 24, 2019 by Pedro Umbelino 16 Comments

If you ever tried to program a robotic arm or almost any robotic mechanism that has more than 3 degrees of freedom, you know that a big part of the programming goes to the programming of the movements themselves. What if you built a robot, regardless of how you connect the motors and joints and, with no knowledge of itself, the robot becomes aware of the way it is physically built?

That is what Columbia Engineering researchers have made by creating a robot arm that learns how it is connected, with zero prior knowledge of physics, geometry, or motor dynamics. At first, the robot has no idea what its shape is, how its motors work and how they affect its movement. After one day of trying out its own outputs in a pretty much random fashion and getting feedback of its actions, the robot creates an accurate internal self-simulation of itself using deep-learning techniques.

The robotic arm used in this study by Lipson and his PhD student Robert Kwiatkowski is a four-degree-of-freedom articulated robotic arm. The first self-models were inaccurate as the robot did not know how its joints were connected. After about 35 hours of training, the self-model became consistent with the physical robot to within four centimeters. The self-model then performed a pick-and-place task that enabled the robot to recalibrate its original position between each step along the trajectory based entirely on the internal self-model.

To test whether the self-model could detect damage to itself, the researchers 3D-printed a deformed part to simulate damage and the robot was able to detect the change and re-train its self-model. The new self-model enabled the robot to resume its pick-and-place tasks with little loss of performance.

Since the internal representation is not static, not only this helps the robot to improve its performance over time but also allows it to adapt to damage and changes in its own structure. This could help robots to continue to function more reliably when there its part start to wear off or, for example, when replacement parts are not exactly the same format or shape.

Of course, it will be long before this arm can get a precision anywhere near Dexter, the 2018 Hackaday Prize winner, but it is still pretty cool to see the video of this research:

RIP Rex Garrod, Creator Extraordinaire

April 22, 2019 by Jenny List 30 Comments

Earlier this month, the youth motocross champion, special effects creator, inventor, TV presenter, and Robot Wars competitor, [Rex Garrod] died at the age of 75 after a long battle with dementia. We do not often carry obituaries here at Hackaday, and it’s possible that if you are not a Brit you may not have heard of [Rex], but his work in the time before YouTube would have made him an international must-watch star had he been operating in the age of on-demand Internet video.

I first became aware of Rex when he appeared as assistant to [Tim Hunkin] on his Secret Life of Machines TV series in the late 1980s. He was the man whose job we all wanted, making the most incredible machines and operating them for our entertainment. Our Hardware heroes tribute to [Tim] has a picture of him operating the needle on a giant mock-up of a sewing machine, but he appeared in many more episodes. Of the many tributes to [Rex] that have appeared over the last few days it is [Tim]’s one that probably says the most about his appeal to our community. His propensity for picking up interesting parts from junkyards strikes a chord, and the tale of hugely overpowering car wiper motors by allowing them to be submerged in water is pure genius.

To a slightly younger generation he is best known for his appearances in the British Robot Wars series‘ with his Cassius series of fighting robots. He created one of the first really potent flipper robots in UK robotic combat, and incidentally the first effective self-righting mechanism. As one of the many members of the SMIDSY team that didn’t appear on the recorded TV series’ I encountered him only peripherally, but I remember his work being a major influence on SMIDSY’s run-any-way-up design. Meanwhile for a younger generation still he created the models for the popular children’s TV character Brum, an anthropomorphised scale-model Austin 7 car.

We’ll leave you with a couple of videos featuring [Rex]. The first is from The Secret Life of Machines, in which along with [Tim] he helps explain electronics from first principles, while the second is a fan-created medley of his Robot Wars appearances. Rest in peace [Rex], and thank you.

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Watch These Two Robots Cooperate On A 3D Print

April 20, 2019 by Donald Papp 16 Comments

Putting a 3D printer on a mobile robotic platform is one thing, but two robots co-cooperatively printing a large object together is even more impressive. AMBOTS posted the video on Twitter and we’ve embedded it below.

The robots sport omnidirectional wheels and SCARA format arms, and appear to interact with some kind of active tabletop to aid positioning. The AMBOTS website suggests that the same ideas could be used for other tasks such as pick and place style assembly work, and the video below of co-operative 3D printing is certainly a neat proof of concept.

As a side note: most omni wheels we see (such as the ones on these robots) are of the Mecanum design but there are other designs out there you may not have heard of, such as the Liddiard omnidirectional wheel.

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3D Printed Tank Track Pops Together With Plastic BB For Hinge

April 20, 2019 by Donald Papp 20 Comments

3D printing is well-suited to cranking out tank tread designs, because the numerous and identical segments required are a great fit for 3D printing’s strengths. The only hitch is the need for fasteners between each of those segments, but [AlwynxJones] has a clever solution that uses plentiful hard plastic spheres (in the form of 6 mm airsoft BBs) as both a fastener and a hinge between each of the 3D printed track segments.

Each segment has hollows made to snugly fit 6 mm BBs (shown as green in the image here) which serve both as fasteners and bearing surfaces. Assembly requires a bit of force to snap everything together, but [AlwynxJones] judges the result worth not having to bother with bolts, wires, or other makeshift fasteners.

Bolts or screws are one option for connecting segments, but those are heavy and can get expensive. Segments of printer filament have been successfully used in other tread designs, though that method requires added work in the form of either pins, or heat deforming the filament ends to form a kind of rivet. This design may be a work in progress, but it seems like a promising and clever approach.

[via Reddit]

The Drones And Robots That Helped Save Notre Dame

April 17, 2019 by Tom Nardi 61 Comments

In the era of social media, events such as the fire at Notre Dame cathedral are experienced by a global audience in real-time. From New York to Tokyo, millions of people were glued to their smartphones and computers, waiting for the latest update from media outlets and even individuals who were on the ground documenting the fearsome blaze. For twelve grueling hours, the fate of the 850 year old Parisian icon hung in the balance, and for a time it looked like the worst was inevitable.

The fires have been fully extinguished, the smoke has cleared, and in the light of day we now know that the heroic acts of the emergency response teams managed to avert complete disaster. While the damage to the cathedral is severe, the structure itself and much of the priceless art inside still remain. It’s far too early to know for sure how much the cleanup and repair of the cathedral will cost, but even the most optimistic of estimates are already in the hundreds of millions of dollars. With a structure this old, it’s likely that reconstruction will be slowed by the fact that construction techniques which have become antiquated in the intervening centuries will need to be revisited by conservators. But the people of France will not be deterred, and President Emmanuel Macron has already vowed his country will rebuild the cathedral within five years.

It’s impossible to overstate the importance of the men and women who risked their lives to save one of France’s most beloved monuments. They deserve all the praise from a grateful nation, and indeed, world. But fighting side by side with them were cutting-edge pieces of technology, some of which were pushed into service at a moments notice. These machines helped guide the firefighters in their battle with the inferno, and stood in when the risk to human life was too great. At the end of the day, it was man and not machine that triumphed over nature’s fury; but without the help of modern technology the toll could have been far higher.

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This Bot Might Be The Way To Save Recycling

April 13, 2019 by Lewin Day 24 Comments

Recycling is on paper at least, a wonderful thing. Taking waste and converting it into new usable material is generally more efficient than digging up more raw materials. Unfortunately though, sorting this waste material is a labor-intensive process. With China implementing bans on waste imports, suddenly the world is finding it difficult to find anywhere to accept its waste for reprocessing. In an attempt to help solve this problem, MIT’s CSAIL group have developed a recycling robot.

The robot aims to reduce the reliance on human sorters and thus improve the viability of recycling operations. This is achieved through a novel approach of using special actuators that sort by material stiffness and conductivity. The actuators are known as handed shearing auxetics – a type of actuator that expands in width when stretched. By having two of these oppose each other, they can grip a variety of objects without having to worry about orientation or grip strength like conventional rigid grippers. With pressure sensors to determine how much a material squishes, and a capacitive sensor to determine conductivity, it’s possible to sort materials into paper, plastic, and metal bins.

The research paper outlines the development of the gripper in detail. Care was taken to build something that is robust enough to deal with the recycling environment, as well as capable of handling the sorting tasks. There’s a long way to go to take this proof of concept to the commercially viable stage, but it’s a promising start to a difficult resource problem.

MIT’s CSAIL is a hotbed of interesting projects, developing everything from visual microphones to camoflauge for image recognition systems. Video after the break.

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