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by Joel_Mckay 479 days ago
"closed-loop means open-loop repeatability is not critical"

Hobby servos have limited repeatability especially as they wear, and when swinging an arm with shifting center of mass the errors will be quite obvious.

One may want to look at the UR5 platform design before wasting time and money. Best of luck =3
1 comments
quanto 479 days ago
> Hobby servos have limited repeatability especially as they wear, and when swinging an arm with shifting center of mass the errors will be quite obvious.

Your statement is correct by itself, but it is not completely applicable to what the GP comment (not my comment) said. Aloha uses optical encoders (which themselves are far better than hobby-grade potentiometer servo encoders) and in fact also compensates for inaccuracies in the optical encoder.

I have no experience with UR5 but looks interesting. Any reason why you recommend this?

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Joel_Mckay 479 days ago
"Any reason why you recommend this?"

Pre-built 3D simulation models for easier software development, official ROS support from the company, and better physical safety with advanced force-sensing motion systems.

"optical encoders" have their own set of issues... usually require quadrature encoder tracking FPGA or dedicated ASIC features in the mcu. i.e. you now have 2 problems to solve, and higher costs.

Best of luck, =3

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Xmd5a 479 days ago
Related optical encoder project I found a while back that used to rely on an FPGA but doesn't anymore:

https://github.com/JamesNewton/HybridDiskEncoder

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