hydraulic motor-pump?
its being a while and no luck with the search of finding a hydraulic pump or motor that are small enough to fit in a robotic arm but in the same time have high pressure.
found some motors but after posting them here i got really sad because people said that they worth only to empty toilets... (not actually a high pressure)
however i am still searching to find onne (make it 5). is there anyone that actually knows, used or anything with any hydraulic high pressure motors?
what i want to achieve is to make a robotic arm lift weight far more than the servos now it has. i have modifieded the arm and have already installed syringes, but htey are used manually and once a small load is on the arm they start decompressing.
looking forward to your replies thank you very much
found some motors but after posting them here i got really sad because people said that they worth only to empty toilets... (not actually a high pressure)
however i am still searching to find onne (make it 5). is there anyone that actually knows, used or anything with any hydraulic high pressure motors?
what i want to achieve is to make a robotic arm lift weight far more than the servos now it has. i have modifieded the arm and have already installed syringes, but htey are used manually and once a small load is on the arm they start decompressing.
looking forward to your replies thank you very much
Comments
The motor could either be a stepper motor or a DC motor. If you use a DC motor, I think it would be a good idea to use one with a quadrature encoder so you could monitor the speed and position of the motor.
I'm not sure if Parallax's 30:1 gear motors would work well to drive a syringe but I'm inclined to think they would.
I see you previously had asked about controlling DC motors. Not too long ago I made a video as part of my attempt to explain how to use a h-bridge with a microcontroller. Hopefully the video and forum thread will help if you're still not sure how to do this.
There are small pistons available for industrial use bit they are pretty expensive. Not aware of much in the way of hobby hydraulics.
I kind of think "hobby hydraulics" is a bit of an oxymoron. Not quite as extreme as "hobby brain surgery" but I understand most hydraulic equipment is very expensive.
@John, Have you considered pneumatics? Several years ago there was an interesting article (I believe in Nuts & Volts) about hobby pneumatics. I purchased a few parts myself but have yet to put them to use.
I think pneumatics is a lot easy to get into than hydraulics. An air compressor is a useful tool to have around and much easier to acquire than a hydraulic pump.
If you do pursue the hydraulic project, I hope you keep us posted on your progress.
Also good points, but pnematic actuators are very difficult to position accurately. Not a problem if you want to move from position a to position b and have mechanical stops at both positions, but stopping at some arbitrary point is very difficult.
@johnproko
I don't know how practical it would be for your project but you might want to look at schedule 40 or 80 PVC pipe to make the actuators. It can handle enough pressure to be used for something like this.
saw pneumatics and think they might actually work.
still i have some questions you might be able to answer. the arm is the picture provided.
i need 4 at the bottom to stabilize the weight, one on the platform to keep the vertical part from moving. 2 for lifting (except from the servo there i have added on more that pulls the arm with rope (not as efficient as you expect because it needs adjustment every once and a while) and probably 2 more (thinking of where they should go) the actuators are the red lines. you can see the syrigne i have previously used and really works great with a lot of lifting capacity but its manually control that there is no fun in that!
the lifting capacity right now is about 300-400gr which is pretty good but still i want to be able to lift its own weight aprox 1 kilo (1000gr). will the pneumatics work with these loads? and what about accuracy? servos can be controlled with pings of 20ms are there any pumps that allow the actuators to fill with air the quantity i want? the other solution is to place servos to the valves and measure the time to inflate. last but not least can air have the same lifting capability of fluids?
dont mind the bs2 in the photo, the arm is controlled by a propeller in c.
@kwinn what is 40 or 80 PVC pipe???
the arm is just for spare time fun although i intend to use it as an assistant when i paint plastic models. probably if i achieve this i will make iron man :-P
thank you very much!!!
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The difficulty with using pneumatics is that air is compressible. Lets say you want to move the piston 2 inches so you pump air into a cylinder at 100psi and it moves 2 inches so you stop the air flow. The piston will continue to move until the air pressure drops to the point where the force on the piston equals the force needed to lift the arm. Makes precise positioning difficult.
With a liquid that is not a problem. Stop the flow into the cylinder and the piston stops.
Schedule 40 PVC pipe is used for plumbing and is available at most building sypply and home improvement locations. Schedule 80 is higher pressure piping mainly carried by industrial and commercial suppliers so not as easy to find.
BTW the link you posted is not working. Try re-posting the picture.
hi again.
i have seen pneumatic muscles as well and trying to figure out how i could use them.
BTW, I'd suggest getting 24V values. The industrial world runs on 24V and I think you'll be better off if you start out using 24V equipment.
I just found a video by the Nut's & Volts magazine author.
I agree with Duane
It would be very much worth your time to read up on how pneumatic \ hydraulic circuits work before doing hands on experiments.
From your photo in post 8, it looks like you want to elevate the entire arm structure.
Hydraulics would work pretty good for that.
Also, its possible that using something like an automotive window motor or seat adjusting mechanism may work for you.
Here's something to keep in mind when building hydraulic/pneumatic things.
Hydraulics can make LOTS of pressure. Depending on your design, you could very well damage yourself.
Pneumatics also can make LOTS of pressure, and again depending on your design, you could very well damage yourself.
In a previous life, I have designed and fabricated both hydraulic and pneumatic simple systems.
The video in post 11 is pretty good at demonstrating what I know as a Meter Out system.
I've done this type of thing.
The meter out pneumatic systems work pretty good as long as there is no mechanical binding of all of the linked together parts.
If for example the pincher in the video were starting to close and for some reason, the mechanism were to bind.
The air pressure on the exhaust side of the pneumatic cylinder would drop and speed control would be lost.
When the pressure on the exhaust side drops low enough and the binding was overcome by the actuating pressure, the
pincher would slam shut with great speed and lots of power.
The video does not show that fact. That was not the purpose of the video.
As far as valves and other components for pneumatic and hydraulic systems go;
SMC is a very good manufacturer and so is Parker.
I guess what I'm trying to say here is:
Learn about pneumatic/hydraulic systems and circuits.
Always use caution when operating things that you build.
It looks like you have a pretty good start with your prototype arm.
Robotics in any form is always an adventure!
Garyg
Jim
Vern is a member of these forums.
I thought his name looked familiar. IIRC he does a lot of cool biology experiments with test equipment he builds himself.
i am trying to figure out how i can make all this information into actuall work.
however all of the suppliers propossed are too much industrial and far from my little arm (although i thank you for your time in helping me).
has anyone tryied something else? more hobby style, compact and not worth a small fortune :-P
either way as soon as i calculate and do some diagrams i will keep you posted for my progress!
thank you!
Pneumatic/hydraulic pistons and cylinders can be made from plastic pipe and sheets with simple power tools and a few diy fixtures. O rings work well as seals, and if you want to use liquids instead of air you can use water, mineral oil, or vegetable oil as the hydraulic fluid. A small hobby metal lathe is an ideal tool for this, but a drill and small router would also work.