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@nico71 thanks for the explanation :). It's great to see ideas 'outside of the box' like this!

Beautiful. Some interesting functions while still looking nice. Could you explain this a bit more please? I would think that the distance of the wheels to the centre of turning is irrelevant, as long as their axes pass through it? Does this type of steering exist on any real world vehicles?

Yesss. Great news! This should make controlling many motors much easier than with the Powered Up remote. Also the proportional control looks really nice.

Simply plotted some 10*10mm squares and measured them. Backlash is approximately how far undersized the squares are.

Hi, I am working on a classic XY Plotter that is controlled by the new Mindstorms hub. It's a work in progress and hopefully I can show some improvements here over time. I made it with the Robot Inventor Hub instead of the Technic Hub simply because I wanted to try programming with the bundled Mindstorms MicroPython software. I was unable to achieve some crucial things with this software (most importantly a simple way to run multiple motors in parallel?) so I switched to Pybricks but kept the Mindstorms Hub. The code was adapted from my Cartesian Parallel Robot - easy! Features: Lightweight XY carriage with all motors mounted off the moving parts Pen raising and lowering Programmed to 0.1mm accuracy Programmed with backlash compensation (0.9mm in X, 0.5mm in Y) I hope to reduce the mechanical backlash some more. For the moment though, programming it out seems to help. Also, I have implemented the method described by Didumos69 here to maintain tension in 'loops' going through the chains and remove backlash in them (I found this to be a better solution than tensioning the chains with springs). In this video the hub's display shows when backlash is compensated for in each axis: Plot #1: File: Gaudi's Honeycomb (SVG) Paper: A5 200gsm Speed: 20mm/s Plot time: ~30min Pen: Rotring 0.5mm graphic pen I found a good website with some free SVG files to start with (link above). This particular file required around 4000 lines of Pybricks code to plot. I'm approaching the point where files are too big for the Inventor Hub (and its ~252KB of available RAM). Perhaps someone could tell me if there's some way to load larger files onto the hub using Pybricks or is this something that's only possible with the Mindstorms software or am I stuck with splitting larger files into multiple plots? I'm reasonably happy with the result. There are some obvious defects though and I would like to make it faster. Here's a short real-time video. What's next? I have a bricklink order on the way with parts to increase the plotting area to A4. I think this is the maximum size that this design can be, given the 32L axles along the Y-axis and for the pen raising/lowering. Aside from that, I will try to further reduce the backlash and increase the speed. Mostly though, I just want to plot some different things (which I will post here). Thank you for reading. More to come soon...

88010 remote control connected directly to the hub with the program loaded on it gives no noticeable lag for me.

Nice! I originally planned to build a CoreXY style plotter but figured out other ways to mount the motors remotely, so went with that. Hopefully we can see yours in action soon.

I agree, a pleasure to watch!

It's just made of liftarms connected together. In order for the cracks to not show up on the plot I used thicker than usual paper - 200gsm seemed to work well.

It also appears that YouTube promotes content with catchy thumbnails and that viewers are unlikely to skip through - both of which might be seen unfavourably by the algorithm for Sariel. It's unfortunate because he has some quality content, and I often refer to his reviews for technical details of sets/pieces.

Has anyone built such a thing? All pressure switch designs I can find online are similar to this one by @mocbuild101 and use the old PF polarity switch, which hasn't been produced for 10 years now: I have been thinking that maybe a switch built using the current system could use a variable sensor and be fine-tuned, turning the pump on/off at whatever pressures are desired. Here's a quick proof of concept I made. I don't have a manometer or storage tank to properly test it but if somebody else did that would be great. It uses the pump speed itself to detect when the pressure has risen and turn off, then every 5 seconds does a short pump to check if the pressure has since dropped. Maybe this is too ambitious and something else should be used as the sensor... If anyone has designed something similar using current parts I would be interested to see it! Alternatively, feel free to improve on my concept or use this as a discussion topic.

Indeed, it's a pretty nice sensor! I had initially thought it was just a touch sensor. I wonder what other novel uses it may have... 🤔

Apologies for the late reply. I don't think so. I think a spring just creates a constant opposing force that does nothing to change the friction that must be overcome. The internal friction of the cylinder is what I think is the problem. True, I have changed to a large cylinder (levered onto the force sensor) and it seems slightly better. Still, there is a large drop in pressure before a change is detected. This is the best I could come up with: Interesting, thanks for sharing!

Hm, it looks awfully similar to my plotter design: This is basically how I did it @Knight3, except with a Robot Inventor hub rather than EV3. There is a lot of detail in the WIP thread here (including the python program I wrote in pybricks): I highly recommend the command-line tool "vpype" and a plugin for it called "vpype-gcode". They are purpose built for plotter vector graphics, and with them you can convert any .svg file into gcode, which you then just paste into a program and run it (feel free to use/copy mine).

Wow, so good! Love the camera angle looking at the side of the loop.

Sadly, things are not this simple. I believe the internal friction of Lego cylinders prevents accurate readings, at least in both directions. With this setup, while increasing the pressure, I could obtain fairly accurate readings. However, once I then decreased the pressure, it would take a drop of about 0.8 bar before any change was detected by the force sensor. I think this is simply due to the static pressure (EDIT: static friction) that has to be overcome to move the cylinder. I also tried using a battery box to gauge the pressure. It works, in an on-off fashion, but needs a similar drop in pressure before it falls back down (which isn't necessarily a bad thing for a simple compressor). My hopes of building a fine-tunable compressor are dashed. I probably won't revisit the OP concept, as I don't like the idea of constantly having to run a motor to check the pressure. At least, the SPIKE force sensor can be used as an on-off pressure switch (with on and off points ~0.8bar apart), so this is what I'll use going forward.

Thanks for sharing. It's a smart solution you have come up with to operate many cylinders with just 2 motors. Someone has used the battery weight mechanically with the old switch: https://rebrickable.com/mocs/MOC-113088/olivierz/pneumatic-pressure-controller/#details I don't think it's crazy to use the gyro. In fact, I think it could give accurate readings. The downside I think is that it would always have to be on a flat surface (due to gravity), whereas a force sensor could be put anywhere.

@Mr Jos nice! I did skim through your GBC videos to look for a compressor but I didn't notice it. Good to hear that it's reliable and working in (what seems like) a good pressure range. I think I will give this a try.

That could work... From the Lego website: The LEGO® Technic™ Force Sensor measures pressures of up to 10 Newtons (~1kg) for accurate, repeatable results. From what I've seen, a maximum pressure of 2 bars seems adequate for a Lego compressor, so, if using a small cylinder to actuate the sensor, the maximum force it would exert would be: 2 bars * area of cylinder = 0.2N/mm² * pi*3mm² (assuming piston diameter of 6mm) = 5.65N On paper then, this is within the realm of possibility, and could be as simple as connecting a cylinder directly to a force sensor and getting accurate pressure readings! If anyone has the necessary parts to try this out that would be great. Otherwise, I think I'll be ordering a manometer, a small cylinder, and a force sensor :).

@jamesaguilar there's definitely a sweet spot with the duty limit - for me 30 has worked (with speed 100). Putting it much higher has me worried too about damaging pieces. Of course, a well-built end-stop goes a long way :).

Enjoy! Many useful and interesting parts have been released in the past 20 years in the Technic theme. That would be great if you could make this work - it could open the door for (inverse kinematics for) 7dof robots the likes of which I haven't seen before in Lego...

Nice work fitting those functions in at such a small scale! This link just takes me back to this page...

Cool! What an epic and ambitious project. This could end up as the most advanced GBC ever . Thanks for sharing the updates.

Interesting... the new worm gear can be used as a helical gear, as demonstrated by Yoshihito Isogawa:

I think you are so close to making it work, and it would be so cool if you did. If you do decide to revisit it, I strongly suggest you watch this video (from 6:37 particularly). The principle shown in this video is almost fundamental to many of my creations now. If you built such axles into the main drivetrain of your machine, I think you'd be halfway to making it work. Then maybe some better pen holding method would be the finishing touch. If you leave it be, that's understandable. Either way, thank you for sharing such an interesting project despite it not being finished.