Miniature Hydraulic

[loosewire]

WE seem to have some members that are knowledgeable
on hydraulics take police robots,tell us how the small valves work
doing muliple task just talk about hydraulics not there
police duty, like other things like hands and knees.

[rjenkins]

I've seen lots of miniature pneumatic gear used in industry & handling equipment etc., but never any truly miniature hydraulics.

Due to the typical pressures involved, hydraulics needs thicker wall pipes and larger couplings. Pneumatic cylinders operate at around 80 - 100 PSI, hydraulics often work in the 1000 - 2000 PSI range. Miniaturising is difficult.

I suspect anything really small and running from batteries will be using electric motor driven actuators of some sort.

I'm not saying such things don't exist, just that it's likely to be a last resort if no other type of actuator can be used.


You can get some info on the type of small tracked robot used for bomb disposal etc. here:
http://www.irobot.com/filelibrary/pd...Bot510_EOD.pdf

[loosewire]

What do they use for movable fingers.

[retched]

The robot hand I've worked with used pneumatic actuators in the wrist with a tendon(wire and pulley) system the the finger joints.

[VoodooMojo]

Originally Posted by loosewire

What do they use for movable fingers.

http://www.shadowrobot.com/hand/overview.shtml

pneumatics is a very efficient way.
A hydraulid circuit would involve actuators, pumps, valves (also relief valves as oil is not compressable). A hydraulic hand without relief valves would be a scarey thing!
Every component that oil has to run through costs energy.

The efficiency is lost with turning voltage and current into psi and gpm.
An electric motor turning a hydraulic pump to produce flow going through electric valves to a hydraulic actuator is costly.
Electric actuators are costly also.
Pneumatic hands sometimes just use the flexing of hoses to accomplish movement, pulleys and strings to accomplish grip..
It takes comparably less energy to pump air than to do it another way.

[rjenkins]

You could use model servos in the arm and 'snake' cables to the finger joints.

Snake cables are like push-pull bowden cables, one form of link between servos & rudder / elevator in a model aircraft.
Example:
http://www.mugi.co.uk/shop_product.php?id=74

There is a load of other servo linkage stuff on he left of that page.