News – Page 4 – Marginally Clever Robots

News

Friday Facts 9: Daisy Stepper Driver 1.0

2021-12-03 Dan

Daisy Stepper Driver is a closed-loop stepper controller that can be daisy-chained.

A stepper controller is a dual h-bridge circuit for controlling a stepper motor. You may be familiar with the A4988 stepper driver common in 2020s 3D printers. This board includes a more advanced model of the same. It can drive any one stepper motor at 24V up to 2A.

Closed-loop means that the board has a brain chip (MCU) that can read the motor position as well as direct. This way it can tell if it missed a step, bumped into something, is being driven, etc.

Daisy-chained means that they can be hooked sequentially. Sequential wires are much shorter. Shorter wires make for easier construction and repair. They are designed for up to 6 Daisies in a row. The Daisies talk to each other via the CANopen protocol.

The MCU is an STM32F103. In speaks CANopen natively while driving the stepper and listening to the sensor.

DaisyStepperDriver-1.0-Schematic Download

The CANopen master at the base of the robot can be any MCU that speaks CANopen. It synchronizes each motor and provides a single USB or bluetooth serial connection to the world.

What does this have to do with robots?

This board is designed to fit inside each gearbox of the Sixi 3 robot arm.

The old way a wire from every part had to run all the way through the arm and out the base. To replace the second joint from the bottom you would have to dismantle the entire arm. In the daisy chain model you only need to remove the elbow and disconnect the two cables to the next link in the chain.

Here’s a video of the arm moving IRL. Note the large cable hanging off the side – this version does not have the board in yet. It is the “outside” version of the wiring. I live in constant anxiety that they will get caught on something while moving.

Editor’s note – in this video one motor misbehaves. It was later found that the motor was negative 400-steps per turn instead of the expected 200-steps-per-turn.

Why isn’t the board in already?!

To test the board I have to be able to program it. To program the STM32F103 MCU I need to flash it with a bootloader via the programming pin J6. I have an STLINK V3 MINI to flash the bootloader BUT the MINI has male pins at 1.25mm pitch and my board’s J6 is 2.5mm pitch.

Editor’s note – I believe the larger connector is also a reversible connector.

Do you want to see this board get done? Say something nice on Discord.

What comes next?

Assuming this board is good and can be programmed… the next tasks are:

mount the board in the actuator
attach the disc to the output of the gearbox
run wires from one to the next and test the daisy chain
get an appropriate brain board and drive everything synchronously
make more boards

At the last stage it will be time to go to Kickstarter to scale production and bring the price down.

Did you design this board yourself?

No, and I’m proud of it! I have played with KiCAD in the past and done a few but this was beyond my skill. I found a great EE on Fiverr, gave him my specs, and he routed everything in a couple of days. Truly blown away by his skill. He even had a PDF step-by-step guide for ordering from PCBWay so I didn’t have to assemble the board or nothing.

Sadly, he closed his account and I have no way to reach him any more. Electroniikka! If you’re out there, know that I want to work with you again. I love working with talented people, it’s fun, easy, and it helps me scale up to the speed I long for.

News

Friday Facts 8: Plotting large sewing patterns

2021-11-12 Dan

Here’s a use for Makelangelo plotters that I never considered, offered up by Discord member Jolo: Sewing patterns for home sewing, cosplay and costume design!

It turns out that there’s many free pattern sites. Here’s just one example of a hoodie.

I used Freesewing.org to get a pattern for a hoodie and then chose export pattern > SVG and saved to my desktop.

In Inkscape I opened the file, set the document size to A2 and used that as a guide to split up the file into sections that fit on the paper for the Makelangelo. Just to be cautious I used Object > Ungroup and Path > Object to Path to prevent any import questions. These might not be necessary, but I do them with my laser cutter and it’s a habit now.

I had to delete everything except the part on the paper for each export. Then I used Save As > DXF R14. Makelangelo also understands SVGs – another habit from my laser cutting work. (this post was not paid for by Big Laser – Ed)

Then I loaded it into Makelangelo software and drew it just like any other drawing.

Final thoughts

The HUGE extension for Makelangelo draws up to A0 (841 x 1188 mm aka 33-1/8 x 46-13/16 in)

Do you have other great uses for a large plotter? Share with us and we’ll share it with the world!

You might also get a kick out of open source, parametric pattern design app called Seamly.

News

Friday Facts 7: A 2D physics engine in Processing (Java) and the Sunk Cost Fallacy

2021-11-05 Dan

I have a robot dog being operated on by the Students at Alpha Secondary school in Burnaby, BC, as part of a work experience program. The goal is to make the dog walk as good or better than Spot Micro. Obviously this is not done in a weekend. How do you eat an elephant? One piece at a time. The current plan is to tackle things in order:

get it to turn on (done!)
move each motor individually (done!)
move them together (done!)
make it stand up and sit down (working on it!)
teach it to roll over and recover from a fall
teach it to walk

In a sense I’ve delegated all these steps to the students. Which frees me to do the part that needs experience – making tools that will empower them to do the hard steps at the end.

I don’t want to break the robot because it’s expensive to fix. Therefore I don’t want anyone to drop the robot hundreds of times while testing it. Given the tools I have, what can I do to test the robot without dropping the robot? The same thing I’ve done with all my robots – simulate them! But I’ve never used a phsyics system in Robot Overlord before.

I already have all my code and development tools in Java, so my first instinct is to continue in that direction. I didn’t find any up-to-date physics engines that work in Java. JBullet hasn’t been updated since 2016. Other engines I found were Java ports of C libraries. I don’t have links to them any more but those I found were stale and had no “contact us” system. Two solutions present themselves:

Write my own physics system in Robot Overlord from scratch
Install Gazebo on a linux system, ?, profit.

For your consideration, this is my attempt at number 1.

2D physics with circles and boxes in Processing

This is the first time I’ve had to simulate things with physics in Java.

This is a 2D physics engine written in Processing 4.0b. At tag 1.0, it looks like this:

Much help and inspiration was obtained by reading the code for Impulse Engine by Randy Gaul. Do your homework!

It took a day to write the drawing of shapes and 13 more to debug the physics up to this point. Here’s what it looked like at the half-way point:

The hope is to extend this into 3D, add constraints (think bones connected by joints), add friction, and then make physically approximate ragdoll models of the Spot Mini. They can be dropped, kicked, drop kicked, and beat up over and over until the simulated walking gets them up and balanced. Then the simulation can be tied to the real machine and our goal should be within sight if not in reach.

The sunk cost fallacy

Initially I didn’t even consider option no 2. The cost of setting up a linux box or partition, learning Gazebo, installing the robot model, unknown further mysteries tbd… I choose the devil I know over the devil I don’t!

Discord user M2710 DM’d me to ask “why don’t you just [gazebo]?” and made a compelling case that it might be easier than running my own physics engine. I couldn’t immediately prove the idea wrong so I have to consider it might be right. I’ve booked a day in the near future to try Gazebo and Webots. Look for that in an upcoming FF.

Hiring

If you have experience with Gazebo or Webots, share your story with us on the Discord channel. we really want to ~~eat your juicy brains~~ know what you know.

If you have java/physics skills and you think you can get the Robot Overlord features (3D, constraints, friction, physically approximate ragdoll models of the Spot Mini) working, DM me! I want to help you help me. Make me an offer, I’m eager. I only have so many hours in the day and I need your help.

Makelangelo News

Friday Facts 6: Makelangelo software 7.28.2

2021-10-22 Dan

Today I’m pleased to announce the stable release of Makelangelo software 7.28.2. I’d like to thank everyone in the community for your support, especially the Discord users working to find and report bugs.

Goodbye, Makelangelo Firmware

The big news is that Marginally Clever is no longer maintaining Makelangelo-firmware. It was too much esoteric work taking up all my time. Instead I teamed up with the good people that make Marlin 3D printer firmware. Together we’ve added polargraph robot support. Check out FF4 if you want the open source code or to make your custom machine tweaks.

New plotter controls separate making art from driving robot.

Get Makelangelo Software

The newest makelangelo software is available in our store, by donation. You can also get releases from our open source github repository.

In order to make it run you will need to install Java JDK 17 or later.

Use Makelangelo Software

Video time!

video late because editor is AFK. one more pandemic shortage!

Contribute

We’d love more people translating the app and sharing ideas about how to make it better. Join us on Discord or submit a ticket to github today.

News

Friday Facts 5: How (and why) be a Makelangelo Tester

2021-10-15 Dan

To describe the mood here this week in a word it would be “challenged”. My productivity is greatly affected by the all-grey of Vancouver winters – I can’t work if I’m not happy and it takes a lot more time to find my happy place each day in the winter.

How (and why) be a Makelangelo Tester

Not too long ago, with the help of the Marlin 3D printer firmware team, I managed to switch to Marlin. This was a huge time savings for me as I can now focus on making the software better. To make it great – for me, for you, for everyone – as fast as possible I need to shorten the cycle time – the time it takes to check a new feature works right.

Maybe you’ve noticed the app is missing something you need. Maybe you found a bug. Now for a lot of programs out there the way to tell them about a bug is not obvious, hard to achieve, and the turnaround time is … who knows.

I want to make a great app and put new issues to bed quick-fast. To me, the report-fix-test loop should be as short and fast as can be. I hope you agree! That is why I’m asking you to help me help you. Become a tester: to shorten the loop.

Report

With our without being a tester, the process starts by going to the Makelangelo code project and filing a good bug report. The bug report comes with a template to fill out that should make writing your report painless.

Fix

Then I or some other brave soul will (maybe) ask follow up question and (definitely) work to make the thing happen. Some are easier than others in surprising ways.

Test

Now this is the sticky part of the loop. When I write code I bang away in the magic language of the drow elves, cursed to roam the underdark. When the machine says I have atoned enough, it produces a jar file. This is then packaged with other essentials like the README file and somehow delivered to you to give it a little run-see, a little double sanity check, a thumbs up or down.

The packaging and delivery process is slow. So slow. In a more perfect world you should be able to say “get me the latest update from Dan!” and moments later be able to run it. Two clicks, right? Well friends, read on.

Thank you

Making it easy to make you happy is … it’s the greatest gift. A win/win. Thank you. It’s very easy to get lost in the weeds with code, and your input gives me clear focus and direction.

Special shout out to CaptFuture, Headly, and OopsHeIsDead for being awesome contributors this week.

Final thoughts

Here’s a gallery of recent Makelangelo Software updates to the app. Many of these changes were brought about by you and yours. I’ll continue to write, you continue to stay awesome. Until next week, be well!