Curious Aardvark wrote on Apr 19
th, 2018 at 6:27am:
Quote:It’s probably better to buy a $20k industrial arm
that confirms it - you are made of money
At the end of the day it does depend what you actually want to test.
With a treb you can only really test forces at release, and effect of release points and methods.
pretty limited.
Don't see the problem with a robotic arm, plus it would be way more fun to build
Ha! Not quite made of money. If I were, I wouldn’t need to be resourceful

It might be fun to build one, but it would not satisfy the current project. My point is that industrial arms are so hard to build from scratch that drumming up $20k would probably be easier. That definitely doesn’t mean it’s easy to just buy a robot (unless Morphy has a few gold plated emerald encrusted parangs to sell too).
Any robot arm that stands a chance at the performance we would need would at least cost thousands in parts cost alone. You can buy some robotic arms in the $10-20k range that would perform better and wouldn’t take years to finish building. Even those are not likely to give the performance we would want.
The other problem with electric motors is that they perform best under one specific load. That’s why you need to change gears to get a wider range of performance from a motor, but I’ve never seen a robotic arm with variable transmissions at the joints. Electric motors are a terrible surrogate for a human arm which can activate more or fewer muscle fibers at any time and transition smoothly between high strength and high speed motions while maintaining precision control the whole time.
I would love to be proven wrong. It may be possible to get the performance we want on a budget, but I am not qualified to do that myself... at least not by building a robotic arm.
On a related note, Boston Dynamics did some impressive throwing experiments with an arm on a 4-legged robot, but it was using its whole body for the throw and the robot cost millions of dollars:
https://m.youtube.com/watch?v=-q7RsdxE76k