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Comment by acbart | Hacker News Reader

Looking over the robots they support, low cost means about "thousands of dollars" in this context, right?

Yeah, it's currently ~5k USD for a (pre-assembled) robot arm that is marginally "useful" (and there are several brands/makers at that price point). I've heard of some that are trying to push towards the ~3k price point, with somewhat poorer tolerances.

I'm excited for the time in the near future when a useful robot arm costs roughly as much as a good laptop i.e. ~1k USD.

At that point, it'll become feasible for hobbyists to get one each and start playing around. Which will lead to an explosion in the variety of things tried, and will positively feed back into creating a healthy community, tons of software which makes it easier for the next set of people to get involved, etc. Much like the PC revolution in the 80s/90s.

At the moment, they're kinda like overpriced toys (for a home user / enthusiast point of view) without a killer app.

> I'm excited for the time in the near future when a useful robot arm costs roughly as much as a good laptop i.e. ~1k USD.

I feel like people have been saying this is the "near future" for 20 years now.

We need a breakthrough in low-speed, high torque, lightweight motors and geardowns. Basically if we can get economies of scale up on BLDC motors with higher numbers of poles (think hoverboard motors but lighter), and figure out how to mass manufacture harmonic drives, that'll open up the door to all kinds of low cost robotics.

Odriverobotics already has brought down the barrier to BLDC servomotor control.

Or this thing: https://ieeexplore.ieee.org/document/8613852

Two thoughts: 1) I haven't seen any clear literature on efficiency of affordable servos. It seems like existing technology must be very efficient, given the pretty uniform torque/power ratio I've seen across the servo market.

2) One of the biggest financial roadblocks I've run across in robotics isn't about the torque available in affordable servos, it's about the ability to get force feedback. Servos/motors are useless for the large set of tasks requiring force feedback, without the additional complexity of building a current sensor and calibrating it. We need a cheap servo with integrated force feedback and an easy means of autocalibration (from a quick search, seems like this feature usually doubles or tripples the cost of an identical servo).

Torque/efficiency is still a big issue. A coworker and I put together all the math and specs for a robot which could "cook breakfast", just to see what a PoC would take. For anything approaching human arm levels of strength, in that form factor, you are looking at SWG servos. These are nominally 70-80% efficient, but that drops after a few thousand cycles, if you operate in higher loading regimes [1]. so cooling/maintenance is super important. Planetary gears are also not great efficiency-wise and are heavier.

Force feedback is also super important and challenging.

We just need like, synthetic actin :) Disney is actually working on that [2]. yeah it looks super inefficient but so were vacuum tubes before transistors.

1] https://eeepitnl.tksc.jaxa.jp/mews/EN/19th/text/206.pdf&ved=...

2] https://studios.disneyresearch.com/wp-content/uploads/2019/0...

Interesting! Thank you for all the great information. I'm opening those links from a mobile app, and both ended up as not found (not 404, but as the sites internal unrecognized URL page). Are they live for you?

That progression mirrors many others - but more recently, it makes me think of 3D printing and related making technologies like laser cutters and CNC mills.

Good 3D printers can now be had for under 1k USD – and if you can tolerate some tinkering and modifications $300-$500 can get you decent results as well.

There's a version of the TurtleBot kit with an arm for under $3k

https://www.trossenrobotics.com/interbotix-turtlebot-2i-mobi...

The arms themselves appears to be in the 400-600 range

Is there any use to servo based arms other than to let students discover the word “IK”

The expensive bits are mainly the arms. Strictly speaking there is nothing stopping you from running it on one of those sub-hundred bots from AliExpress.

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