Видео

Would a larger softer hand like a pouch work better?

i have a brilliant idea for the "eyes" of it.. first, make the hand weigh the balls in real time. then make a program that calculates physics, calculate the balls trajectory in real time. that way the robot "knows" where the balls are. only downside is if someone interrupts the balls or there a wind heavy enough to move the balls enough to mess up the calculations(the wind one can be "fixed" with a simple wind sensor and feeding it to the calculations)

I feel like you should add an Estop for faster shutdowns

tienes que usar cuerda estática de escalada, pero no se si la hay de ese diametro.

I thought of a way to use two pulies in like less then a second you can even get away with one pulley if you change the route the string takes up.

Commenting so that I can come back to this later.... this is a great paradigm to work with.

Love what you are doing! Subscribed ! This is gonna look so amazing with led glow balls when you get it working 😜

Dyneema checks off all what you need.

getting state machine pilled is probably similar to being ros2 or canbus pilled. you won't regret using them i reckon

Would it be beyond the scope of the project to have some sort of feedback from the hand (load cells, IMUs etc) to detect subtle catching and launching errors to incorporate in the ball trajectory prediction to avoid small inaccuracies adding up over time, adjusting the throws and catches accordingly to bring it back to a more stable state and keep things on track for longer?

You talk about needing extremely accurate 3D prints... while also building an extremely accurate 6D + 1D arm robot... that could easily convert to perform 3D printing or etching. The Hand should be changed to a 3D printer head.

Absurdly cool! Very glad this popped up on my recommended; you've earnt yourself a new sub!

Google "Further progress in robot juggling: the spatial two-juggle", Koditschek 1993. They make use of multiple cameras. They paint the robot and background black, and juggle ping pong balls. I, and perhaps you, can juggle 3 balls blindfolded for a couple minutes. I've never seen anyone do 4 for more than a couple seconds. Whereas people using their eyes can juggle 10+ balls these days. This is all to say, you should be using cameras.

If you use fixed programmed trajectories. I think you need to make sure that the ball lays at a well defined rest position before the launch. An the the launch is very smooth. I think i would try a Tennisball. Maybe a not fuzzy one. and also kind of an physical damper mechanism. Just a 3 mm foam layer inside the hand. I recon trying different balls and hands could do big improvements. But really great engineering. Seriously impressed:) I always love to see if someone does fine stuff like that :)

The nodes on the bus go . . .

I know I’m really late in the game, but to terminate that synchromesh cable you could use soldered tubular cable lugs. Just a thought.

I used some thin UHMWPE (more commonly called Dyneema or Amsteel) cord about 1/8 inch for a project a while back. It was ridiculous, unbelievable how much force it took to break when I finally got it spliced it (close to) properly. I know it doesn't stretch much. Could be a consideration? Edit: I went and watched your latest video and the actuators are running on dyneema.

Beware sunk cost fallacy

Keep in mind that the bigger you make the hand, the longer the ball will take to potentially settle for accurate throws and fast patterns might lose accuracy if the ball doesn’t land perfectly and bounces or rolls a bit in the hand. Making the hand as small as possible is more challenging but probably better in the long run because you want to eventually toss and catch faster and faster. I’d stick with the small hand for now and just experiment with shape and do some high speed footage to see if/how it bounces or moves during a catch. Good luck!

your issue with the center rods on the linear actuators having wobble that you mentioned in your video a year ago could be fixed with 3 bearings, each one going to a rod. just like your top bearings keeping the actuating rod in place

The engineering corner of RUclips is definitely my favorite corner.

Awesome work. Very impressive. Have you looked at Molex micro-fit3 connectors? Thats what we use in 3D printers on a print head that has lots of accel..so that might work good here.

More n more we move closer to the future of that terrifying ride from spykids where it juggles you becomes a reality

Since you are already using ROS, there is ros2_control, which should allow to control all the joints and ensure they operate in sync. That would be the Joint trajectory controller, but not sure. I've used that also with more traditional robot arms, which have the same need for synchronisation

Love this series Thank you for the great update!! 💪

Hey Harrison I was extremely impressed with this project BEDORE you casually mentioned that you’re not using CV and the whole juggling operation is basically open loop…. then I nearly fell out of my chair. It’s a testament to the incredible mechanical precision that you’ve engineered from cheap 3D printed parts. Unbelievable work. I’m working on a project that could really benefit from that kind of precision. I would really greatly appreciate an opportunity to talk through it with you and any guidance you could offer me. Please drop me a reply if we can make a short call or email happen!

Bloody fantastic, and a very smooth video! Nice one Harrison

Absolutely amazing! The weight of your middle cable and the fact that it is moving like a pendulum, will dampen the side to side movement of the Jugglebot. It will act like a mass damper similar to the big ball in the skyscraper in Taiwan the Taipei 101. See what I mean in this video: ruclips.net/user/shortsk7993zeNxoY I don't know if this is good or bad...just an observation. Cheers, John

What do I have to study in college to make cool stuff like this?

I think it is really satisfying to see the robot do this without any cameras tracking. If one uses tracking, in any project, i always think it is constraining the environment it will work in so much. Wouldnt it be cool, to just take it somewhere and have to care just about the robot and its brain only, not the + / - 10 cameras and and and

Very cool project! I would suggest a microfit 3 or similar molex connector for the CANBUS connection. I use those for my CANBUS system on my 3D printers and they hold up to extreme speeds and shaking very well.

I think a limited jerk could help to reduce the vibrations and long settling time. If I understood correctly you are using trapezoidal velocity trajectories so you are only limiting the acceleration. There are also trapezoidal acceleration trajectories which limit the jerk and therefore reduce vibrations when reaching a target position. Furthermore, input shaping could help but is a bit more complex to implement.

This is the second video that I have seen on your Channel. Great work and I look forward to viewing the rest of your content. Subscribed. 🔔

Amazing video, Love your content from Sri Lanka. 😄

spacex needs a big modded one of these to catch their spacetoobs

For the CAN connections, you could try MOLEX

Check out industrial M8 / M12 connectors. There are various configurations (pin counts, key position, ...) and they are designed to by used on industrial robots - preferably with robotic cables. You can start by looking at SICK or Phoenix contact. Also, those green phoenix connectors you use are also made with locks, so they doesn't fall out so easily. We are using them without problems, lock-less versions always had to be glued in place to be secure.

The amount of progress you've made in the past couple months is incredible, I havent kept up with the livestreams, but WOW! And I concur that a state machine would be a good plan - implemented one for one of my recent projects and it the feeling of switching everything over from nested if statements was wild.I could feel the code becoming easier to reason about and also more flexible as I wrote the new version

If Jugglebot ever gets eyes and computer vision, you couldn't just make it throw balls at you or see the balls it threw itself, you could also make it catch balls you throw at it.

Hardwire in an endstop buttons if it over-extends. Then it cant destroy itself.

What an exciting project. Have you considered mounting an IMU to the top of your juggler for the option to run active vibration control/compensation to reduce the ringing? Basically use the IMU data to calibrate and counteract vibrations.. Maybe people with more experience in this field can give constructive suggestions on how to implement this code. Love the project!

Soft stops

Could you explain a bit more what exactly did you do with the jacobian? I am working on a stuart platform for uni, would be super nice as I am trying to some kinematic optimization

Fantastic project! In addition to the great result, for me this is also a great example of how much physical stress is placed on the joints and connections even on such small machines with fast movements. I am really looking forward for the further development with ‘two hands’ and ‘eyes’ - thanks for sharing and good luck with the further development.

You could use a pneumatic soft robot hand to grab the ball and let it go.

Excellent work

🤫🧏‍♂️

your CAN bus can include periodic watchdog messages and your teensy on the other end can reply to them and from your controlling side, if you don't get the reply it means communication is not working and you just cut the power to the motors or something like that. awesome job btw.

Awesome! All I could think while watching is that you need motion capture! An optitrack / vicon rig would directly tell you the position of all joint and the ball with sub millimeter accuracy @ 100s of Hz. This would make debugging a lot easier since you can play back all the actual motions and zero in on what’s contributing to errors. It would also let you generate a calibration to null out the Stewart platform errors. Also if you wanted to be fancy, you could close the loop on the ball position fairly trivially. Univerities often have rigs in the robotics / sports / bio labs. Your project is interesting enough that I bet you could get access if you found the right interested researcher…

this is so beautiful