On page R2 of the 17 October 2011 issue of The Wall Street Journal, in
the midst of WSJ's Innovators' Awards, a purely mechanical innovation
was recognized, the ZeroG arm from Equipois
http://equipoisinc.com/products/.

What it does is to mechanically cancel the weight of a tool, so the
worker can use a very heavy tool as if it were weightless.

The original invention was to stabilize the big video cameras used by TV
stations and the like.

For technical details, see US Patent 7,618,016, available from
www.pat2pdf.org.

There is a series of related inventions by the same person, Garrett W.
Brown, but 7,618,016 explains the problems with each of these prior
approaches.

This is simple enough that a HSM could adapt the idea.

Joe Gwinn