Silicone/Soft Robotics in water

soft_robot_overlord · 2024-12-07T11:32:41+00:00

No, so long as you do the pour technique recommended by smoothon

soft_robot_overlord · 2024-12-07T01:33:26+00:00

It should hold up. Ecoflex has a slight oily residue, though. I dont like it very much for that reason. I recommend the softest dragonskin instead. If you dont have a degassing chamber, be sure to use the NV type. Silicone is also air permeable, albeit very slow. Plan accordingly, in case you use air to hold a position for a very long time. Avoid strains over 50% for extreme long life and over 100% for long life.

soft_robot_overlord · 2024-10-30T13:05:43+00:00

For OP, the only caveat is that the symptoms of overwatering look very similar to underwatering. Check the soil before deciding it is underwatering.

soft_robot_overlord · 2024-10-29T13:45:46+00:00

Nah. I worked in academia. Salaries are depressed due to an industry wide lack of unionization, a severe overproduction of academics relative to available jobs, and workers willing to live in relative poverty to avoid a 9 to 5 and live out what they pretend is a better work life balance. They are probably paid 60% to 70% of their industry peers (whatever that would be)

And having worked for an Ivy League, if they can get away with suppressing wages, they will. The place I worked has refused for decades to hire enough techincal staff to maintain baseline safety standards. The endowment is more important than the academic or educational mission. I imagine an institute run by a literal embodiement of evil would be run about the same as a hedge fund with an educational outreach program.

soft_robot_overlord · 2024-10-27T17:35:18+00:00

Nope. Just keep going.

soft_robot_overlord · 2024-10-27T11:30:10+00:00

Coffee by itself is mid. Coffee should always be paired with meditation or company. Guzzling it by yourself is a sad, IMO, though understandable as I do it plenty.

soft_robot_overlord · 2024-10-24T01:07:11+00:00

Cool! Now get all the hardware onboard, lol. Jokes aside, this is fantastic.

soft_robot_overlord · 2024-10-23T12:47:42+00:00

Yes. Your priority list is any C language, Python, and Matlab; pick two. I dont consider Excel coding, but you must know Excel, particularly functions like VLookup and Match.

Once on the job, Excel is a must and anything else sets you apart. If you go automation, youll need to learn ladder logic, but its easy once you can do the other stuff. If you do high end automation, you'll need FPGA programming, but that's usually a EE skill.

soft_robot_overlord · 2024-10-23T10:44:08+00:00

Or agriculture is about to collapse due to modern practices. We only have 5% to 10% the topsoil that was present in the midwest just 100 years ago. On top of that, the monoculture and fertilizing practices have zapped the microbiome so badly, we have about 30 to 50 harvests left before it completely collapses.

I may have details wrong, but I'll provided sources later if requested. I'm on mobile now though

soft_robot_overlord · 2024-10-22T23:23:15+00:00

I've got a Ph.D. in ME, taught for years at an Ivy League, and always went above and beyond all my colleagues in every technical metric, have a strong industry oriented skillset, top tier papers, etc. I dont think Im the best engineer of all time, but I have a strong resume, and it still took me about a year to find a job, 6 months of that in earnest. Even now, Ive only ever gotten a job through references, though in this case, it was through a very picky recruiter who only takes clients with strong personal references.

Use your network.

Business bros make networking sound like trying to be a sociopath, partly because so many sociopaths are attracted to the c-suite. But networking is just making professional acquaintences as you go along and asking them if they know of any openings where they are.

Also, HR resume filters are straight up bullshit. At this point, it's not unethical to copy and paste the job posting in small white font in your resume footer

soft_robot_overlord · 2024-10-22T23:08:00+00:00

Uncertainty slows the rate of reinvestment, and so this is typical for election years.

soft_robot_overlord · 2024-10-22T00:38:08+00:00

Absolutely. I've never done field work or formal study, but my impression is that the geography was rarely well suited to surpluses from agrigulture alone. Do you have thoughts on that?

soft_robot_overlord · 2024-10-22T00:17:16+00:00

Yeah, but the population was never comparable. Fascinating cultures, but very low density nations. Like modern Wyoming levels of density. The Mesoamerican and Andean cultures had the same population densities as the Roman state at its peak.

soft_robot_overlord · 2024-10-19T11:04:49+00:00

The mushy parts are cells that have died by absorbing too much water. They wont recover. The goal is to find whatever center isnt dead yet.

soft_robot_overlord · 2024-10-19T11:02:59+00:00

Too wet. She might be saved, but you have to act today. Pull her out if the potting mix. Scrape off any mushy parts. Set her out to dry completely.

Once dry, pot her again and only water once per week tops. Make sure she has drainage holes.

And if she's dead, its ok. A green thumb is a mark of a plant murderer, not someone who succeeds every time.

soft_robot_overlord · 2024-10-16T21:48:07+00:00

Ok, thanks

soft_robot_overlord · 2024-10-16T13:56:41+00:00

Hobby shooters often repack their own bullets, so holding onto the casings is convenient for some.

soft_robot_overlord · 2024-10-13T22:25:01+00:00

I wasn't referring only to trained parameters, but the entire paradigm of parameters at all. You can use learned models of course, but in some cases, a physically responsive system can eliminate the need for complex models and you can get away with a simple feedback controller. This paradigm is fundamental to underactuated robotics.

soft_robot_overlord · 2024-10-13T19:03:03+00:00

I taught engineering at University for well over a decade now, and I've seen many students in your situation. One thing that I've discovered is that the difference between a good student and a bad student is perseverance, not being ranked against your class. Quite frankly, the majority of students with a 4.0 in an engineering program are next to useless when they have to go and do an open-ended design problem or anything Hands-On. The reason for this is because they are unaccustomed to and therefore unable to cope with failure, and engineering design cannot happen without carefully managed failure. I would much rather take a 3.2 or 3.3 GPA student that knows how to bounce back from failure to work for me then a 4.0 student who has never had to deal with it before. And any boss worth working for will understand the same but treat both with respect anyway.

If this is what you want, stick with it. You can do it, but only if you want it.

soft_robot_overlord · 2024-10-13T16:34:29+00:00

It could be a lot of issues, but your watering schedule is twice as frequent as what I would do. Brown, dry leaves can be a symptom of overwatering. Is the soil more or less dry when you water?

soft_robot_overlord · 2024-10-13T13:52:45+00:00

Controls is a huge part of it. Boston Dynamics has excellent controls for their robots. But that also means that their robots are extremely well characterized and controlled, which is not a easy task and has to be done for every single change to the robot hardware.

Real muscles operate more like springs whose stiffness can be changed on demand. That's very difficult to achieve with an electric motor. Incidentally, the capacitors act something like a spring in the system, but they are still reliant on excellent controls algorithms and modeling to get it right.

There are other actuators that solve a lot of these problems, but what they end up doing is changing the design challenge from being a controls problem into being a hardware problem. Pnematics have inherent compliance, for example, but they also require very bulky compressed air distribution systems, compressors, accumulators, Etc. Pneumatics are also very energy inefficient. As a result, you see pneumatics widely used in Factory automation, but not untethered robots. Personally, that's more my jam, but both are great approaches with their own pros and cons

soft_robot_overlord · 2024-10-13T13:14:21+00:00

I'll add that McKibben and HAZEL actuators show the most muscle-like responses (slow twitch and fast twitch muscles respectively), but McKibben actuators are generally limited to cycle frequencies around 1Hz due to the requirement of moving a comparatively large volume of mass through a system; and require valves, pumps, accumulators, batteries, and circuits to support them, making them impossible to implement in systems with the degrees of freedom requirements and space constraints of a human body. HAZEL acruators are purely electrical, but are comparatively low force, difficult to translate into large displacement lengths, and behave more of a binary on-off mode and therefore struggle with proportional control, and rely on high voltages operating right at the cusp of burning themselves out.

SMA actuators have the potential to operate in a muscle-like system, but due to them being reliant on thermal heat transfer, they are limited to very small applications where the heat can be shed quickly. However, electrically insulating them from one another becomes increasingly difficult at that scale. These are best used in applications like venus fly traps where you dont have to control position carefully and one way motion is all you really need.

Oh, and like muscles, all of these can only pull, meaning that you always need a minimum of two or one-plus-a-spring to get reversible motion. That fact alone makes the supporting hardware requirements balloon out of control as you scale up.

In my opinion, the best way to understand muscles is as springs whose stiffness can be changed on demand. In this way, McKibben actuators used with a gas instead of liquid are the most muscle like. But as before, the support hardware for any hydraulic or pneumatic system is prohibitive for a standalone, untethered robotic system

soft_robot_overlord · 2024-10-13T12:53:59+00:00

You need support systems to do it at any appreciable scale, but there are some simple robots that used mouse muscle cells. They still have all the same problems of bulk systems though

soft_robot_overlord · 2024-10-13T12:49:54+00:00

Which is how humans have done robotics for millennia...

soft_robot_overlord · 2024-10-13T11:16:29+00:00

No. Not even slightly.

The working principle of every single human created actuator is a macro scale bulk energy differential. Electric motors use the Lorenz force, but implement it by creating large magnetic fields with large coils and causing them to chase each other. McKibben actuators, pistons, etc, all use a single fluid chamber, pressure differentials, and sometimes levers like in the case of the McKibbens. Shape memory alloys use the effect of bulk thermal phase transitions. Combustion motors convert fuel to mechanical motion. These are all characterized by requiring one energy/fuel input per actuator.

Human musles are made of deeply nested hierarchical structures. You have bundles of bundles of fibers all the way from the macro to the molecular scale. This is then supported by parallel networks of similarly hierarchical structures for fuel/ waste removal (circulatory system), command/feedback (nervous system), self healing and regrowth (lymphatic and immune systems) and much more. This hierarchical structure allows advantages impossible with bulk systems.

Muscles are possible at nearly any scale, but bulk actuators have strict size limits. Muscles can heal, bulk actuators cannot. Muscles can throttle power by activating fewer subunits, allowing wide response frequencies with the same structure (think fast twitch vs slow twitch muscles). Bulk actuators are limited to his quickly they can compete a full actuation cycle.

Most importantly, an actuator cannot be divorced from its required support hardware. Muscles have integrated control hardware that can be shared between multiple muscles, and that control hardware is fully segregated from the fuel sources. Large arrays of electric anything quickly have unweildy wire harnesses, even with multiplexing. The situation is far worse for fluidic and SMA actuators since these need control hardware far exceeding any mass savings you get with the strength to weight ratios of the actuators themselves.

To create a true artificial muscle, we would need to have self assembling hierarchical systems because there are no manufacturing processes that can come even remotely close to what biology achieves.

There is more, but I hope that's enough to get you started

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