DARPA Challenge Autonomous Robot Teams To Navigate Unfinished Nuclear Power Plant

March 6, 2020 by Roger Cheng 4 Comments

Robots might be finding their footing above ground, but today’s autonomous robots have a difficult time operating underground. DARPA wanted to give the state of the art a push forward, so they are running a Subterranean (SubT) Challenge which just wrapped up its latest round. A great review of this Urban Circuit competition (and some of the teams participating in it) has been published by IEEE Spectrum. This is the second of three underground problem subdomains presented to the participants, six months apart, preparing them for the final event which will combine all three types.

If you missed the livestream or prefer edited highlight videos, they’re all part of DARPAtv’s Subterranean Challenge playlist. Today it starts with a compilation of Urban Circuit highlights and continues to other videos. Including team profiles, video walkthrough of competition courses, actual competition footage, edited recap videos, and the awards ceremony. Half of the playlist are video from the Tunnels Circuit six months ago, so we can compare to see how teams performed and what they’ve learned along the way. Many more lessons were learned in the just-completed Urban Circuit and teams will spend the next six months improving their robots. By then we’ll have the Caves Circuit competition with teams ready to learn new lessons about operating robots underground.

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ESP32 Rover With PCB Chassis Is Ready To Roll

March 2, 2020 by Tom Nardi 12 Comments

The microcontrollers are cheap, the sensors are cheap, even the motors are cheap. So why are all the good wheeled robotics platforms so expensive? [Dimitris Platis] wanted to develop an affordable platform for experimenting with rovers, but the cheap plastic chassis he was using gave him all sorts of problems. So he did what any good hacker would do, and built a better version himself.

Interestingly, [Dimitris] decided to go with a chassis made from two PCB panels. The motors, mounted to small angled brackets, bolt directly to the lower PCB. These aren’t your standard $2 DC cans either. Each JGB37-520 gearhead motor comes complete with an encoder that allows your software to determine speed, distance, and direction. The upper PCB connects to the lower with several rows of pin headers, and plays host to whatever electronics payload you might be experimenting with at the time.

For the controller, [Dimitris] says the ESP32 is hard to beat by pretty much any metric you want to use. With integrated wireless and considerable computational power, there’s plenty of options for controlling your little rover either remotely or autonomously. But he also says that every effort has been made to ensure that you could switch out the microcontroller with something else should you want to spin up a customized version.

The whole idea reminds us a bit of quadcopters we’ve seen in the past, where the PCB wasn’t just being used structurally as a place to bolt the motors and hardware to, but actually contained functional traces and components that reduced how much wiring you needed to do. Naturally, this means that any damage to the chassis might cripple the electronics, but presumably, that’s what the big foam bumpers are there for.

[Dimitris] designed this project for educational use, so he assumes you’ll want to build 10 or 12 of these for your whole classroom. In those quantities, he says each bot will cost around $60. If you wanted to reduce the price a bit more, he says swapping the motors would be your best bet as they’re the single most expensive component of the design. That said, $60 for a quality open source rover platform sounds pretty fair to us.

Still too much? You could check out one of the 3D printable rover designs we’ve covered over the years. Or see if you can get lucky and pick up a cheap robot from the clearance rack and hack it.

Gripper Uses Belts To Pinch And Grasp

February 27, 2020 by Danie Conradie 6 Comments

For all the work done since the dawn of robotics, there is still no match for the human hand in terms of its dexterity and adaptability. Researchers of the IRIM Lab at Koreatech is a step closer with their ingenious BLT gripper, which can pinch with precision or grasp a larger object with evenly distributed force. (Video embedded below.)

The three fingered gripper is technically called a “belt and link actuated transformable adaptive gripper with active transition capability”. Each finger is a interesting combination of a rigid “fingertip” and actuation link, and a belt as a grasping surface. The actuation link has a small gearbox at it’s base to open and close the hand, and the hinge with the “fingertip” is spring-loaded to the open position. A flexible belt stretches between the finger tip and the base of the gripper, which can be tensioned to actuate the fingertip for pinching, or provide even force across the inside of the gripper for grasping. Two of the fingers can also rotate at the base to give various gripper configurations. This allows the gripper to be used in various ways, including smoothly shifting between pinching and grasping without dropping a object.

We love the relative simplicity of the mechanism, and can see it being used for general robotics and prosthetic hands, especially if force sensing is integrated. The mechanism should be fairly easy to replicate using 3D printed components, a piece of toothed belt, and two cheap servos, so get cracking! Continue reading “Gripper Uses Belts To Pinch And Grasp” →

Sonic The Self-Balancing Robot: Face-Plants And The Challenges Of Sensor Integration

February 26, 2020 by Danie Conradie 2 Comments

Watching a child learn to run is a joyous, but sometimes painful experience. It seems the same is true for [James Bruton]’s impressive Sonic the Self-Balancing robot, even with bendable knees and force sensitive legs.

We covered the mechanical side of the project recently, and now [James] has added the electronics to turn it into a truly impressive working robot (videos after the break). Getting it to this point was not without challenges, but fortunately he is sharing the experience with us, wipe-outs and all. The knees of this robot are actuated using a pair of motors with ball screws, which are not back drivable. This means that external sensors are needed to allow the motors to actively respond to inputs, which in this case are load cells in the legs and an MPU6050 IMU for balancing. The main control board is a Teensy 3.6, with an NRF24 module providing remote control.

[James] wanted the robot to be able to lean into turns and handle uneven surfaces (small ramps) without tipping or falling over. The leaning part was fairly simple (for him), but the sensor integration for uneven surfaces turned out to be a real challenge, and required multiple iterations to get working. The first approach was to move the robot in the direction of the tipping motion to absorb it, and then return to level. However, this could cause it to tip over slightly larger ramps. When trying to keep the robot level while going over a ramp with one leg, it would go into wild side-to-side oscillations as it drops back to level ground. This was corrected by using the load cells to dampen the motion.

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DARPA Subterranean Challenge Urban Circuit Now Livestreaming

February 20, 2020 by Roger Cheng 1 Comment

Currently underway is the DARPA Subterranean Challenge (SubT) systems competition for urban circuits streamed live on YouTube now through Wednesday, February 26th.

The DARPA Grand Challenge of 2004 kicked research and development of autonomous vehicles into high gear. Many components on today’s self-driving vehicles can be traced back to systems developed for that competition. Hoping to spur further development, DARPA has since held several more challenges focused moving the state of the art in autonomous robotics ahead.

To succeed in this challenge, robots must handle terrain that would confuse today’s self-driving cars. Cluttered environments, uneven surfaces of different materials, even the occasional flooded section are fair game. These robots also lose access to some of the tools previously available, such as GPS. The “systems track” denotes teams building physical robot systems versus a separate “virtual track” for simulation robots. “Urban circuit” is the second of four phases in this competition, environments of this phase are focused on man-made underground structures. (Think subway station.) For more details on this competition as well as description of various phases, see our introductory post or the competition site.

Those who rather not watch robots tentatively exploring unknown territory (and occasionally failing) may choose to wait for summaries published after competition rounds are complete. The first phase (tunnel circuit) from August-October 2019 was summarized by IEEE Spectrum here. Or you can go straight to DARPA for details on the systems track and virtual track with overall results posted on the competition site.

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Lil’ ESP32 Bot Does Remote Surveillance, And It’s Easy

February 19, 2020 by Lewin Day 7 Comments

Digital cameras have been around for a long time, as have small remote control robotics platforms. However, combining the two has really only come into its own in the last decade or so, as more bandwidth has become available to the home tinkerer. This ESP32-CAM surveillance bot is a great example of what was once hard becoming trivially easy.

It’s a case of standing on the shoulders of giants. The ESP32-CAM is a device that allows one to stream live video images over a network using existing example code. In this case, it’s combined with an L298N DC motor driver which allows the Adafruit robot platform to be steered like a tank via its two wheels. A pair of SG90 servos then serve as a pan/tilt mechanism to further improve the robot’s field of view.

If you aimed to attempt this back in 2010, you’d have spent six months figuring out how to get a microcontroller to talk to a small camera module. Only then could you consider solving the multitude of other problems presented by getting the video feed off the bot to somewhere useful. These days, you can order a bunch of parts online and have it up and running in a couple hours. This project from 2013 serves as an example of how much things have changed in the intervening years. Video after the break.

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Simple 3D Printed Robotic Arm Uses Compliant Mechanism

February 9, 2020 by Danie Conradie 5 Comments

Learning through play is effective for humans of all ages, and since 2016 [slantconcepts] has been designing STEM kits that help teach kids to build their future overlords. They are launching version 3 of their LittleArm robotic arm, and the progression from version 1 is an interesting study in simplification and parts count reduction without sacrificing functionality.

In all of the LittleArm versions the main mechanical components are 3D printed, and driven by 3 servos for motion plus one additional servo to run the gripper. These kits are specifically intended to be built and disassembled repeatedly, and classrooms are a great place for small screws to easily disappear, so reducing the number of screws was a big goal for v3. The gripper/forearm shows the most dramatic improvement from the previous versions, being simplified from 8 separate components to a single 3D printed part by using a compliant mechanism — that squiggly pattern that allows the gripper to flex into place. The gripper tips also feature a simple “cutout” that allow it more easily grasp horizontal objects.

An Arduino Nano based expansion board is used to control the arm, with a HC-06 Bluetooth module to allow it to be controlled via a smart phone app. Various sensors can also be added to expand the kit’s capabilities. Unfortunately the mechanical design is not open source, but it can still be a source of inspiration for your own design projects.

Hopefully this kit will inspire some future hackers to build a more advanced 3D printed version, or even a giant hydraulic powered arm.