gyenesvi

Exactly, as I understand, the reason why hydraulics works better than pneumatics is because liquids are much less compressible than air, so you can adjust things more precisely. However, pressurized air is also less compressible than normal air, so it could have the same effect to some degree. I also realized that there would be no need for switches for pressurization, a simple regular valve (that lets air flow only in one direction) would do, then it would be possible to pressurize multiple circles with a single pump at the same time. If this would work, the whole peristaltic pump could be made as a single lego part, with two (plastic) air outlets where pneumatic hoses can be attached (like on the cylinders), and the inner part of the hose could be preinstalled and could be made from some more flexible / durable material to withstand constant pumping. The whole piece could also include the simple valve for pressurizing (a third air inlet). That would be an amazing extension part for the pneumatic system, no liquids required, and RC ready! Each model would only require one manual pump for pressurizing the system from time to time when it gets jerky (which could also be detached from the model after pressurization).

Ok, I get what you mean, but where would to connect the booster? Into one of the PU ports? Then you'd end up using up one, so you'd have 5 in the end. Also, how can the software tell the difference between the data coming from the two booster ports, when they are connected to the same port on the hub? Even if the FW would handle this by some kind of multiplexing, what would happen if you plug a booster into a booster? Or do you mean that the booster could have some dedicated connection port? Then it's the same as having more than 4 ports on the hub. So it's not clear to me how this could actually work.

What do you mean by simple hub? The one that has the two switches? I don't think many people own that. Plus it does not make use of advantages of the PU system. I guess the most widely available hub is the 4-port Technic Hub (if we are talking about PU). Then what makes sense is the restriction of 4 motors max (of any kind, and also allow the 6-port Mindstorms hub as well to be used in an RC setup). With model size constraints, it could be interesting.

Well the concept is worked out already, just need to see if/how it actually works in real life. There are some tight spaces, the steering linkage is close both to the drive motor and to the axle's gearing (there's an 8:24 down-gearing in the axle), but it might just fly. Also, the right speed/torque ratio is a question for a single L motor, but that is somewhat adjustable by using old/new differential. Unfortunately I won't have any time to build it at least for a week (or more)..

If you are only looking at the functions and build techniques then yes, I agree with you that there's not that much difference, and that could work in case of a jury vote, but as @Seasider notes, on a public vote, the RC one will likely get more votes just for being cooler. Also, the play experience is very different for the two, and voters may relate to that as well. Another thing to consider is that if space (scale) is constrained then motorized models are a much bigger challenge than manual ones, simply because you need to place all the electronics in a small space, and that just got more difficult with PU, as components got more bulky. Also, often motorized builds need better framing and more sturdy building techniques in order not to fall apart under torque. So I think the challenges and building techniques required are different, and that could be the focus of a competition.

Exactly, great, thanks!

Not sure I understand the booster idea, could you guys elaborate? What electronics would be in the hub, and what in the booster? And through what cable would the booster connect to the hub? I guess the same PU wire does not suffice, because then the data of multiple ports need to flow through 1 cable at some point (not impossible, but more cumbersome to implement and potentially slower). As for the electronics, I guess there is need for a generic processor for running the FW processing the inputs and generating the control signals, and there is a need for a BT receiver and some motor controllers somewhere. In the PF system, there was no generic processor for running any FW, that is why it was probably easier to make a separation. A possible way of separation could be duplicating all the electronics into the receiver unit (processor, BT receiver, motor controller) and the hub would contain just a battery, as for PF. But that would probably be the same price as the current hub, and even its size could become considerably bigger than that of a PF receiver due to the processor included, and the remote controller would need to connect to two processors (like two hubs now), which would make configuration even more complicated. I don't think it would be easy to keep the processor in the hub while separating out the BT receiver and the motor controller into a booster unit, because the data flow between them would need more bandwidth than a single cable can allow. I think a good compromise could be a hub that has 6 ports but at the size of roughly 9x5x4 studs (length x width x height) with a rechargeable 2s LiPo battery. But that's probably never going to be included in regular Technic sets due to more complicated distribution regulations for rechargeable batteries. Also another big problem is that often motors need to be stacked / coupled for driving larger models, and that uses up multiple ports. That is why motors with larger power would be very much needed. I'd already be happy with a system that allows some basic configuration using the buttons of the remote (and some lights on the remote as feedback), and advanced configuration using a smart device (but then the smart device would not be required for playing). And I think that would be possible with existing BLE compatible gamepad controllers and an appropriate FW.

That's what I fear too.. so an RC contest sounds more promising. That might make some happy, but in my opinion comparing / judging manual models vs motorized models is hard and often meaningless, unless it's another "recreate an existing model's functionalities" contest, because then the criteria is to compare each to the original, not to each other. In a dedicated electronics contest, the RC capabilities of models can be compared. That coupled with a scale constraint can make the competition interesting and the comparison easy / meaningful.

Hmm, that is true. It could be done with valves though, and one valve could be used for pressurizing two separate circles, son only half the amount of valves needed. Or a small pump for each circle could also do. @2GodBDGlory, since you are already experimenting with it, could you try how a single circle works with pressurized air vs non-pressurized air?

I guess it would be okay to allow all available hubs/HW elements to be used to enable as many participants as possible, however I think it would be important to differentiate a contest that is about programming/robotics/automation (i.e. Mindstorms) with PU stuff from a contest that is about RC models (i.e. Technic), in order to be able to properly compare entries. Both sound interesting, but they sound quite different to me. So which of the two are you guys thinking about? I would personally be interested in both, have hardware for both. I have never really used my Mindstorms set for good, a competition would be a nice excuse. However, I suspect more people have PU HW for RC stuff.

That's a possibility, but updating the first post can make things hard to understand for those who come late and want to read through the WIP topic.. Sure, I get that, WIP thread is for documenting and discussing the build process, and that's great. But I guess many people are not interested in the details of the WIP (or just don't have time to read it all), especially if they are late to the party and the model has already been finalized long ago. Then they may prefer to have a clean summary of the final result instead of looking at a long discussion thread and finding the post where the final model actually came together. I believe a forum where WIP threads are abundant could have some dedicated machinery for such build threads. I am thinking of something like an easy to view opening page where the finalized model is summarized if it's already done, that is separated from the WIP discussion. Also, a WIP topic could be marked by hte author at some point as 'finalized', which would make it pop out somehow for the moderators to consider frontpaging, and also for others for visiting again. What I see some people do know to indicate this is they rename the thread to mark that it is finalized. I meant for WIP topics in general for builds outside of a competition.

It's literally two lines above your question.. Welcome

I know this is not the right place to discuss this, just wanted to note that I agree with you, also thought about this 'incompatibility' of WIP threads and frontpaging. I guess that is why some people make a new thread for the finalized model, where all the half baked images and discussions are not distracting the viewers. Though this is not really done with competition entries (only the entry thread itself, but that's not frontpaged).

That pump is ingenious indeed! Very smooth operation in a quite compact package, given it's RC with all 6 functions. As for lubrication, I saw somewhere that water with some edible oil added was proposed as the best alternative for cost / ease of use / safety reasons. Thinking of things like what happens when a child happens to get some of it in his mouth, or when you spill some on the carpet accidentally.. The video shows that it works somewhat with air too, I wonder how well it could function with compressed air in a closed loop? Would it be possible to design such a system? Would it be enough to add a pump that connects to all the circles of the cylinders through a T splitter and one could manually compress the air in the circles after assembly? If that would work, then that would simplify the setup and solve all the issues with water.

I actually like the idea to popularize Powered Up stuff (I guess that's what you meant), and because it is rather challenging to build smaller models with Powered Up.. It could be interesting with a size restriction. That sounds like a reasonable restriction as well. What was the judging criteria on the PF contest? Did the functions need to be showcased in a video? I can see that that indeed may be the case unfortunately..

Damn, you were fast, I had the same idea to build as an alternate. Nice build! Did you couple the two motors for the drive?

I can only joint all those who say this has been an awesome contest, glad it did not get cancelled. I really enjoyed both taking part in it, and also watching other entries develop. Building smaller models is always more challenging on building techniques, and makes results more interesting. I do think there are tons of very good models out there, so it's going to be a tough decision for the jury.

Thanks for explanation, that makes sense. Found some, thanks :) I know, I have a bunch already :)

Thanks for the explanation, I get it all now! Nice construction. One more question, what is the advantage of the axle based solution for you? From the model itself, as originally built with the old wheel hubs, it seems that the same RC tire (is it the same?) can be used with the 43mm Arocs wheels (as your video shows on RB). Furthermore, to work with the new CV joints, this whole custom made hub could just be replaced with the new non-planetary wheel hubs from the Audi, right? BTW, I like the tires you are using. Do they fit the Arocs wheels well? What is their diameter/width? Do you have a link to them?

Thanks for the video link. I think I roughly get it's construction now. So the bush is inside the hub behind the black disk? What is holding the CV joint/axle and the black disk from sliding outwards together with the whole wheel? Is there a disk inside as well, or just outside of the hub's rim? Furthermore, on your image above, I can see some kind of a spacer on the red 2L axle that comes out of the CV joint's male part. What/why is that? If the CV joint's head is in the same position as in the original planetary hub, than that no spacer would be required there (assuming the rest of the construction is normally positioned parallel with the A-arms).

This sounds interesting, but I don't quite understand what is happening here. I understand that the goal is to use the hub with an axle, instead of a 3 pin wheel mount. But do you keep the planetary reduction or do you throw that away? Does the pivot point of the CV joint fall exactly where it is on the original hub? What is the purpose of that cut bush? Also, in the video in the RB model, you seem to be using it with a 3-pin connected wheel hub, instead of what is shown here..

The finished model looks easily recognisable! Interesting choice of the transparent pneumatic tubes, is that intentional? Did you try it with black ones as well? Did you choose the transparent one so that it does not clutter the whole arm's looks?

I see you finished close to last minute as well :) Nevertheless, it's a nice little tractor, I actually like the way the fenders and solid roof are done, looks more finished than the original!

Thank you guys! Indeed, the half would have looked odd.. Instructions are finished, published on Rebrickable for free: https://rebrickable.com/mocs/MOC-156786/gyenesvi/shrunken-41999-4x4-crawler Now the only thing remains is a motorization. I already have a possible plan for it.. but will have to see if it actually flies..

Model is finalized, video is ready. Building instructions are also ready, will be posted soon on Rebrickable for free.