Need some mechanical engineering help(hydraulics)

Discuss life, the universe, and everything with other members of this site. Get to know your fellow polywell enthusiasts.

Moderators: tonybarry, MSimon

[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable
kunkmiester
Posts: 876
Joined: Thu Mar 12, 2009 3:51 pm
Contact:

Need some mechanical engineering help(hydraulics)

Postby kunkmiester » Fri Aug 21, 2015 3:48 am

It's not one of my crazier ideas. It involves master/slave controlled robot arms though, and it would be nice to get it all hydraulic.

The larger system arm would follow the movements of a linkage strapped to the operator's arm. Two ways to do it--have a hydraulic system that amplifies the master cylinders into the much larger cylinders on the arm, or have the master system all electronic, and encoders to help control the large arms.

To use electronics is a pain. Sure, industrial grade everything is available, but it'd have to be programmed and troubleshot, etc. Etc.

To do it purely hydraulically I'm quite sure can be done, but my Google fu is being weak. Master and slave bring up things like clutches and brake systems, and papers that seem peripherally related. The help I need is to find the terms so I can find and price the components. With that done I can actally think about telling people what this would cost.

Any help?
Evil is evil, no matter how small

hanelyp
Posts: 2255
Joined: Fri Oct 26, 2007 8:50 pm
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby hanelyp » Fri Aug 21, 2015 4:28 am

Operator moves the small arm, the large arm moves proportionately. Since you're unlikely to want force delivered by the large arm reduced in proportion to scale a direct hydraulic linkage between hydraulic cylinders wouldn't be satisfactory. So some kind of servomechanism is needed. These can be done with mechanically actuated valves. A differential gear set could serve to compare position readings on master and slave.

A nifty additional feature would be force on the large arm being reflected on the small arm. This might be had by a smaller hydraulic actuator on the master arm on the same output line driving the slave.
The daylight is uncomfortably bright for eyes so long in the dark.

ladajo
Posts: 6204
Joined: Thu Sep 17, 2009 11:18 pm
Location: North East Coast
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby ladajo » Fri Aug 21, 2015 12:44 pm

How much range of motion do you need on the wearer's arm, and what is the relevant motion compared to the hydraulic arm?
Are you integrated within the working arm? or is this a remote application?
Are you intending amplification of force, and how do you envision feedback?

For google: try hydraulic haptic interface or haptic hydraulic interface.
I have not searched it, but that should give you some sort of useful results.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

krenshala
Posts: 914
Joined: Wed Jul 16, 2008 4:20 pm
Location: Austin, TX, NorAm, Sol III
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby krenshala » Fri Aug 21, 2015 1:17 pm

Just because its interesting to me, I searched on "haptic interface hydraulic" and the first result seems relevant, if not exactly what you are looking for:

Diogenes
Posts: 6958
Joined: Mon Jun 15, 2009 3:33 pm
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby Diogenes » Fri Aug 21, 2015 2:06 pm





Not quite the same thing, but these guys have done something similar.


Image



http://time.com/4003407/giant-robot-fig ... ots-japan/
‘What all the wise men promised has not happened, and what all the damned fools said would happen has come to pass.’
— Lord Melbourne —

kunkmiester
Posts: 876
Joined: Thu Mar 12, 2009 3:51 pm
Contact:

Re: Need some mechanical engineering help(hydraulics)

Postby kunkmiester » Fri Aug 21, 2015 2:22 pm

This was somewhat inspired by them, though I'm looking at a much smaller machine based on a skid steer. I'm seeing industrial applications too. A straight hydraulic system I'm guessing would be more familiar for troubleshooting.

The slave arm is on the same platform, and would be much larger. I'm guessing the master system would drive some sort of boost mechanism to get the power needed and you do want feedback.

That paper is quite relevant, I will have to peruse it later.
Evil is evil, no matter how small

krenshala
Posts: 914
Joined: Wed Jul 16, 2008 4:20 pm
Location: Austin, TX, NorAm, Sol III
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby krenshala » Fri Aug 21, 2015 4:03 pm


DeltaV
Posts: 2245
Joined: Mon Oct 12, 2009 5:05 am
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby DeltaV » Fri Aug 21, 2015 5:04 pm


hanelyp
Posts: 2255
Joined: Fri Oct 26, 2007 8:50 pm
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Re: Need some mechanical engineering help(hydraulics)

Postby hanelyp » Fri Aug 21, 2015 8:34 pm

I was making a simplifying assumption of master and slave being geometrically similar, allowing each input on the master to directly control a single actuator on the slave. Without that you get some complicated kinematic calculations to translate between motion spaces.
The daylight is uncomfortably bright for eyes so long in the dark.

Tom Ligon
Posts: 1871
Joined: Wed Aug 22, 2007 1:23 am
Location: Northern Virginia
Contact:

Re: Need some mechanical engineering help(hydraulics)

Postby Tom Ligon » Wed Aug 26, 2015 6:40 pm

I used to operate and maintain an MTS servohydraulic fatigue machine. The servovalve on the main cylinder was electro-hydraulic but the basic mechanism could easily be all hydraulic. The bandwidth on this system was phenomenal. Small signal frequency response under precision control was something above 30 Hz (faster than most electric servos used in UAVs and model aircraft). The machine could operate precisely in stroke, strain, or load control, with movement limited primarily by the hydraulic pump capacity.

The servovalve had a small electric solenoid, essentially a meter movement, that drove a tiny lever in the valve. That lever, in turn, operated a small pilot valve system. Oil passed by the pilot valve operated a small piston that operated the larger valve. You could substitute a direct mechanical actuation of the tiny lever if you wished.

The key is that the servovalve needs to be controlled by a differential between your master and slave system, which should be straightforward enough to design.

Me, I'd go electronic control unless there was some compelling reason, like EMP tolerance, for the all-hydraulic. This allows feedback from multiple sensor types, such as load cells in a manipulator. The electronics really are not that daunting, and all the parts are available off the shelf.


[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable
[phpBB Debug] PHP Warning: in file [ROOT]/vendor/twig/twig/lib/Twig/Extension/Core.php on line 1236: count(): Parameter must be an array or an object that implements Countable

Return to “General”

Who is online

Users browsing this forum: No registered users and 4 guests