ShaynaSo we'll get rolling a couple of minutes after the hour, just to give folks some time to gather
Feel free to start submitting questions if you got 'em! https://hackaday.io/event/156850-building-robotics-hack-chat-with-mearm
In the meantime, would you like to introduce yourself @ben.phenoptix ?? :)
Hi everybody, I'm Ben from MeArm. MeArm is a project that got started some years back now when I lusted after an open source robot arm project. Since then we've built quite a few and there are many many more out in the world thanks to folk like Scott on here who have been sharing the project
The first good version of the MeArm owed a heck of a lot to a chap called Jack Howard, and the latest one a chap called Ben Pirt. It's always been a collaborative project
: Oh yeah doormouse here doing the Drink Crow Badge this year for DC26. Glad to finally make it in time for this weeks chat and touch bases with everyone.
Thanks for joining us for Hack Chat today!
Ready for some questions?
Yup!
Fabulous
First up from @Elecia White :
"Have you looked at how difficult it would be to integrate the MeArm into ROS? I tried to make a URDF so the MeArm could work in the Gazebo simulator but couldn't get the shoulder right."
(Hey, other people should ask questions too! I have a monopoly over at https://hackaday.io/event/156850-building-robotics-hack-chat-with-mearm and, unless stopped, I will keep adding more until @ben.phenoptix redesigns my whole mearm-based project for me.)
Ah Elecia! there's an email I need to respond to! Unfortunately I haven't, most of my time this last year has been sucked up by the day to day running of the business so I haven't had the time to look into the ROS side of things, or listen to your pod cast. That last part I can remedy sooner than the first!
Just chuckling to myself that this is going to turn into all of the emails that are starred but not responed to in my gmail account!
hehe
folks are usually a little shy to start out but we'll get more ;)
But @Elecia White asked the first few so here goes the next one up: "How are other people doing feedback to get real position of the gripper? "
ROS (Robot Operating System) is used a lot in academic life, I'd love to see mearm added, not just selfishly but also because the on-line modelling means less breakage of the arm as I play with reinforcement learning or motion planning.
Hmmm, I've seen hacked servos used for feedback, like in the UArm. Feedback is something that the MeArm lacks, and it would be good to solve that, but I've always struggled with keeping the MeArm to a price point.
It would be great to have it set up properly in ROS, I'm hoping to have some more time this next 12 months to work on fun stuff with Robotics myself and be freed somewhat from the day to day of running a company.
Adding anything to the capability of the MeArm in terms of feedback just seems to add so much to the cost. I'd be really happy to see of hear of anything cost effective we could do, or even be pointed towards projects that use feedback
Totally understand not wanting to burden the mearm itself, just wondered if you have heard of other people doing common things...
I think the _cheapest_ way to do it would be to take apart the micro servos and tap the potentiometer wiper into a high impedance ADC. Would require a bit of modification but I'm guessing you could pull that data into an Arduino with minimal added analog bits.
also thanks for the awesome product Ben! MeArm is awesome.
awesome @ben.phenoptix. Just watching your project. Some encoders or resolvers?
And also from @Elecia White "Other than occasionally tightening things when they get loose, is there maintenance I can do to make my mearm last longer?"
Cheers zakqwy! Elecia, it is a bit Ikea in that you need to tighten things when they get a little loose! I've added some lubricant to the joints for our MakerFaire models in the past, also making sure that you have sensible time outs for the servos in you code makes the servos last way way longer
I use current feedback for the servos so they'll likely be ok.
:D
I tend to put them into "fairground" mode for events were they time out just before someone has finished stacking blocks, like those grabber things where you don't win toys
Got one from @Martin Esser : "I have a feel that robots are divided along the lines of either being cheap and inaccurate or using harmonic drives or similar that make them very expensive. Where is the goldilocks zone of cheap but still accurate enough"
I think that the goldilocks zone depends on your application, the MeArm was designed to be something that would be cheap and just about good enough to get you playing in the field of robotics. Accuracy has never been too much of a concern (as some will testify to!).
Bringing high accuracy at low cost is probably the biggest challenge faced in robotics today. Anyone can make a cheap robot, anyone can build an accurate robot, but nobody has yet made a cheap accurate robot.
Where in the world is everybody from btw?
Idaho, USA
I'm right outside New York City :)
Germany
Whereabouts in German WooDWorkeR?
Tarragona (Catalonia)
Berlin, Germany
Los Angeles
Also from @Martin Esser : "Does a gripper interface standard exist mechanically, electrically and software-wise in the industrial world that makers can aim for to implement to solve that gripper design problem ?"
Zürich
so cool!
I know where you are Scott, who could forget a name like Fruitland!? Shayna, I'm hoping to get to NY Maker Faire this year.
Wow, its amazing to be connecting with everyone here across the planet! Nice work Hackaday!!
Ah, excellent! I will definitely be there
Berlin is has also been recommended as an excellent Maker Faire to attend. Sorry I'll get back to the questions!
speaking of which if anyone need a LiPo mule for DEFCON shoot me a message. My room is a 10 minute walk from ceaser's.
lol, I know....there used to be a ton of orchards here...
enough to fill a whole land with fruit?
So the legend goes! lol
Regarding the gripper design standard, I don't know. Elecia is this something that you might know more about? Lol Scott.
Scott is one of my Open Source is Awesome stories, Scott built an amazing walking robot from the MeArm and when I came to the States for the Bay Area Maker Faire he helped on the stand, hired a car with me and we ate meatballs in a furniture store.
No, sorry. I know for some of the larger arms, there is some pressure to make grippers interchangeable but for the mearm? No.
Very cool, Scott!
The uArm abandoned a gripper in favour of a suction cup, I wonder if it's because it's mechanically a bit tricky and a little heavy right there on the end?
Another Q from @Martin Esser , when you're ready: "What would you do if you discover your project for sale by a chinese company?"
haha
hehe
should be happen
There are three pages of them! It's a sign of success and I feel really amazed that I've been part of something that's good enough to rip off
is part of the game and development
Scott this one is yours! https://www.aliexpress.com/item/DIY-meArm-Max-Bigger-Badder-Robot-Arm-mechanical-acrylic-plate-kit-set-3mm-laser-cut-acrylic/32829109310.html
highest form of flattery, etc
cool the arm is also avaiable on top of a panzer chassi :D
Early days I did email a few of them, and since I wasn't asking for money or for them to stop selling them they did actually add a link for me in their descriptions.
WooDWorkeR - it's cool that they're actually innovating too.
On google trends the term MeArm is most popular geographicall in Taiwan, and that's all down to a cloner (and innovator) called Lien Ted
Next up from @anfractuosity : "I'm just wondering how you position the arms hands in 3D space, does it use something like inverse kinematics or..? (are there even other approaches?)"
Sorry, I went AFK for a few. It was a HUGE opportunity to do the Bay Area Maker Faire with Ben and the meArm is what jump started and inspired me into building the mePed robot! Thanks Ben!
You can use inverse kinematics, it's pretty simple as you only have to do 2D trigonometry and then use cylindrical polar coordinates for placement in 3d space
ah neat, so IK would be the main way of doing it?
you can go Cartesian too with a bit of extra code
Looking back I've just found this Hackaday prize branded arm with IK
@anfractuosity: I didn't find it trivial. The wiki (https://en.m.wikipedia.org/wiki/Inverse_kinematics) and another post (http://www.learnaboutrobots.com/inverseKinematics.htm) helped. But really, it was getting the mearm code working and trying things out that made the most sense. Also, trig is your friend.
cheers!
will have a look at those
This is a nice write up http://bitofahack.com/post/1433701488
The code: https://github.com/RorschachUK/meArmPi
ah sweet, will checkout the code
Bob Stone's code there, he's a legend!
Anyone mind some easy queries regarding ATtinys? Specifically ATtiny85. I wanted some input on power and regulation, led drivers, and general suggestions. Looking for gaps in my understanding and design theory before I finalize my BOM. Basically the design goal is a ATtiny85 development board/badge with integrated 17x7 charlieplexed surface mount LED matrix for transformations and animated text scrolling.
@Elecia White , if you don't mind, may I save your next question for after @Martin Esser ? I think it's a nice forward-looking note to end with :)
No problem at all!
I don't mind
Fab, thank you! Penultimate Q from @Martin Esser : "how do you compensate for accuracy when the robot arm is mechanically bending under load ? The type that cannot be detected by encoders."
I did a tiny charlieplexed larson scanner on the attiny85. https://www.thingiverse.com/thing:22142
@thedoormouse I'm far from an expert but I tend to use the ATtiny85s a lot for projects, so I'm curious - not sure if I could actually help.
@ben.phenoptix thank you for the reference!
Martin, it's not something we've compensated for. Partly as we've never been able to go for much accuracy with the MeArm and the cheap servo motors we use. I wouldn't know how to go about that, but again it's a really interesting question. I suspect the super rigid mechanicals of professional robots are to combat this. We'd have to start to use more rigid materials!
This is new to me and I think that its a work of art.
@Todd I will put up the schematics I have tonight along with the silkscreen work for the badge etc so you can get an idea of what im trying to do. Might be something you want to get in on if your going to defcon this year . I need someone who is a tad more knowledgeable than myself for some of the programming.
Spoiler i work at a robotics company and this is a really hard problem i was just asking if you found some cheap way to do it.
because even mass produced robots at any company are all unique.
It would have been patented by the morning i suspect!
Lastly from @Elecia White , when you're ready: "Where do you see MeArm going from here? Bigger arms? More control? Different materials? Easier builds?"
@thedoormouse cool. I'll take a look. DefCon's probably not in the cards for me this year sadly....
I've always wanted to do a bigger arm. I think we've recently achieved easier builds, but they're not as open, in that they're more complex to source and manufacture. I'd like to spend some time making the controls easier and opening up basic inverse kinematics in our interface. If I could afford to do it, injection molded parts would be great, more robust for education environments, possibly make the construction easier and smarter.
Right now I'm trying to simplify my life and business, to make more time for the stuff that I actually enjoy about the project. There were so many great questions today that I would have loved to explore, but I spend most of my time now managing money, people and materials.
@ben.phenoptix Thank you so much for joining us today! And thanks to everyone who asked questions.
It's been an absolute pleasure, thanks very much for having me. I'm blown away that people would come along to ask questions. Huge thanks to @Shayna for hosting and the Hackaday team for asking me to attend!
Any links and such you might want to share before you go, @ben.phenoptix ?
Here's MeArm's project page on Hackaday.io: https://hackaday.io/project/181-mearm-your-robot
for all your MeArm needs! :D
awesome, thanks again!
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