On 05/08/2018 01:11 PM, Fons Adriaensen wrote:
On Mon, May 07, 2018 at 07:05:37PM -0700, Fernando Lopez-Lezcano wrote:
So I bought a robotic arm. Len (from Core Sound) asked off-list about it, so
I'm including some information here. I got the WidowXL from Trossen
Robotics. Anything better (as far as I could find, not an expert!) would
have driven the price up exponentially - this one is not cheap anyway. I
just spent two full days assembling it (lots of pieces, lots of screws).
Beware, ask before you buy as to delivery times - mine was delayed several
times and they were not very upfront about it (or just did not know).
One problem you may observe with robotic arms is vibration.
Yes, I did observe that "feature" :-)
It depends
on if the robot has mechanical brakes, or is using the actuator servos
to maintain a static position.
No brakes, just servos (it is a relatively "low cost" arm[*], or an
expensive "toy", depending on how you look at it).
In the latter case there may be some
vibration due to marginally stable control loops. This is usually very
low level but a microphone will be all too happy to pick it up.
I wonder how the WidowXL performs regarding this.
Yes, it does make, sometimes, a tiny quite low level buzzing sound (no
other way to describe it). I would like to imagine that it would not
affect too much the recording of long sine sweeps at relatively high SPL
levels... plus the mic mount attaches with a bit of padding. We'll see
(hear?). See picture of one of my old prototypes taped to the grip (to
test that the arm could actually handle the weight, had the needed
torque, and could contort as needed :-) Not much testing done, just
first impressions.
(busy designing and 3d printing the custom grips and mounts I need for
the mics...)
-- Fernando
[*] at least for what I found online the next step up was about > $5-6k,
for a good one but not industrial you could expect to pay >$20k , and
for the real (industrial) thing maybe about the same but then you have
to spend $$$$ in the environment in which you can run it safely... There
were actually quite a few open source 3d printed arms but I could not
find out that was convincing and already available.
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