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Low Cost Robot Arm

github.com

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Re: Low Cost Robot Arm

#251

Post by Climato »

GabeIsko wrote: post #243
Climato wrote: post #223

Earlier quoted context omitted.

I meant to control single segments to compensate for build quality. 1 AI model per motor

But motor and motion control isn't exactly so mysterious that we need AI for it. Inductance in electric motors can have some odd effects in the acceleration domain, but it generally boils down to a second to third order differential formula. Even when linking multiple together in a serial manipulator, the math is really well understood for modeling the motion output. Maybe there are some outputs to be gained implemen…

The problem this ml should solve is pricing: get cheaper components and compensate with ml.

Basically increasing the precision of the arm by controlling the voltage much more precisely

Re: Low Cost Robot Arm

#252

Post by regularfry »

FrojoS wrote: post #141
regularfry wrote: post #71

Earlier quoted context omitted.

There have been a few around, but the limiting factor (as you can see from the BOM in the link) is the cost of the actuators. They get expensive fast.

Sensors too. E.g. force sensors are important for dexterous manipulation and safety. But they are all expensive, bulky, imprecise, or require constant recalibration, or all of the former. Our robotics Prof used to quote his industry peers: "The best sensor is no sensor."

That's presumably one reason why everyone's so keen on doing all the force sensing from the motor current.

Re: Low Cost Robot Arm

#253

Post by mapt »

mglz wrote: post #149
mtreis86 wrote: post #134

I started working on a similarly sized arm. I've got a use-case, long time friends with a glass blower. I was thinking of using it to make faceted glass pendants. They've got a faceting machine but it is manually operated. The hard part is repeatability. You need tight tolerances and each joint in the arm adds inaccuracy the further you get from the base. If the base has 1mm of wiggle, the 20cm arm has 4mm wiggle at…

One thing that is amazing about industrial robots is how rigid they are when at standstill. Breaking systems start to be a challenge too at high speeds and loads. And once you manage to get the hardware working, getting a kinematic solver to really work is a massive challenge. Tons of edge cases, real-time feedback to handle and the need to balance usability with reliability. That's where robot companies charge a lot…

Why aren't all these applications that have only recently been examined for automation absolutely flush with cheaper lower axis count robotics, like SCARA or parallel manipulators?

Re: Low Cost Robot Arm

#254

Post by fasa99 »

As a level 12 necromancer, I myself am a fan of necrobiotics: https://onlinelibrary.wiley.com/doi/10.1002/advs.202201174

Spiders move not through direct-muscle limb manipulation as we do, but something more akin to hydraulic pressure moving a joint. Thus they become self-building hydraulic soft actuators with a very simple i/o interface(psi in the necrospider)

Re: Low Cost Robot Arm

#255

Post by zingelshuher »

regularfry wrote: post #71
7373737373 wrote: post #69

I'm surprised (or perhaps very unaware) that there doesn't seem to exist a company yet that mass produces cheap, high quality, reasonably standardized robot arms. So many things like 3D printers or CNC machines have entered the consumer/amateur level price realm, but this seems to be something still largely unexplored. Seems to have Arduino/Raspberry Pi scale potential, but I haven't heard of a name/ecosystem that po…

There have been a few around, but the limiting factor (as you can see from the BOM in the link) is the cost of the actuators. They get expensive fast.

Have to disagree with this. The major limiting factor is the software and lack of applications. If there was a killer application it would be much easier to sell. Then the numbers would drive the prices down.

Re: Low Cost Robot Arm

#256

Post by gertlex »

ozten wrote: post #179
gertlex wrote: post #177

Earlier quoted context omitted.

Hah! Not actually a robot... but I half suspect I could convince the that wife a fold-out arm with a modest clamp (that could rotate a bit if needed) at the end would be worth mounting to a wall along the kitchen counters for holding/draining various containers like your first two use-cases.

Julia Child's kitchen was famously functional with a peg board wall for quick access to hanging supplies. I could see her doing that!

Nice idea for helping convince! I too am for the functional stuff; I use a tension rod (like used for shower curtains sometimes) between cupboards, over the kitchen sink to hang S hooks off, and let a significant number of pots and pans hang to dry after washing.

Re: Low Cost Robot Arm

#257

Post by GabeIsko »

Climato wrote: post #251
GabeIsko wrote: post #243

Earlier quoted context omitted.

But motor and motion control isn't exactly so mysterious that we need AI for it. Inductance in electric motors can have some odd effects in the acceleration domain, but it generally boils down to a second to third order differential formula. Even when linking multiple together in a serial manipulator, the math is really well understood for modeling the motion output. Maybe there are some outputs to be gained implemen…

The problem this ml should solve is pricing: get cheaper components and compensate with ml. Basically increasing the precision of the arm by controlling the voltage much more precisely

Well, that doesn't really work. There is only so much electrical efficiency you can crank out of these motor. Essentially, there is a relationship between the current you pump through them, which is limited by their thermal characteristics, and the inductance of them. So you are trading off building more inductive motors that are more powerful but less reactive, and current draw which you can increase by putting more material in the motor and making it dispose heat much better but also bulkier. There are diminishing returns in many places in this process, and at a certain point you have to consider switching to hydraulics if you more force at a high reactivity, under essentially much less energy efficient conditions.

Maybe you could make a model that sizes motors correctly per application? But you are still much better hiring an engineer that knows what they are doing that can explain what is going on and trouble shoot things when they go wrong. At a certain point you are trying to figure out how to completely replace an engineer with a machine learning model, which I would like to think is a bad idea.

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