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Ocean Secrets hydraulics gripper proyect

Hi everyone,

I leave you a link to the video with the first tests of a gripper built with hydraulics.

It works quite well and it has a lot of strength, I am still with the initial tests but it looks promising.

I like this system because the electronics and motor will go inside the watertight compartments. The hydraulic system being pressurized in principle does not present problems with depth, at least up to 20 bar, which is the pressure of the hydraulic circuit.

Regards

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That is very cool. Nice work.

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Impressive Work! Well done.

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I applaud your building skills and effort, but that is noisy, inefficient, and weak.

With a simple DIY acme thread linear actuator driven by a small brushless motor with planetary gear, you could exert enough force to crush those objects (if you wanted). It would also be nice to have a reconfigurable grip, from linear to centric, with a small mineral-oil-filled servo, a few linkages, and another finger. That would allow you to change your grip style when picking up differently-shaped objects. Magnetic encoders could provide force feedback so you could ‘feel’ how much force was being applied.
The recent pandemic has actually freed up my time, and i will be building a 9-dof manipulator arm soon. With no desire to market my design, i will document the build and post it here for others to use.

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Hi Darrel, thanks for your comment and contributions.

As I mentioned in the post, this is the first test with the hydraulic system. This gripper is made with cheap and small RC hydraulic pump with light duty brushless motor, there are much more powerful hydraulic motor pumps if you want more strength. On the other hand, the hydraulic bottle is also one of the smallest, with pipes and fittings of 1.8 mm internal diameter, there are larger diameter bottles with 2.5 mm internal pipes that provide more speed and force.


Regarding noise, by introducing the motor inside the watertight tube it is minimized, and if you want less noise you can epoxy seal the stator and put the motor in the water like the ROV propellers or use the M100 or M200 to obtain a noise similar to propellers, which is muffled by water.

The motor gear system that you tell us about, if I am not mistaken, is very similar to the newton gripper, of course I am referring only to the gripper system, not to the multi-movement servo system that is already more complex. I have chosen another path because it has been very difficult to find a commercial arm in Europe and more with the COVID 19. The newton gripper is discontinued because I suppose that the guys from bluerobotics are trying to improve the system, I am sure that they will soon release a new version improved and more durable, as they do with everything that gives little errors.

My intention was to open an alternative way of working that was very simple and that despite not being perfect, was cheap, functional and durable. With this system you only have to buy the hydraulic bottle, the pump with motor, an ESC, print the parts of the gripper (I used the 3D designs of the newton gripper, light modified), use a penetrator to epoxy seal the pipes and connect the esc using a pixhawk light output or any other auxiliary servos. In this way, no electrical part will be in the water and no component will have to be sealed with epoxy except for the penetrator, nor will it be necessary to build a specific watertight compartment to encapsulate, the brushless motor, the gear motor, the electronics for its operation and the DYI acme linar actuator. So anyone, who has a specific need, as it happens to me, can have a gripper easily for less than € 100.

This system also allows multiple movements to be used with a different-way valve actuated by servos, being able to build a much more complex system.


In any case, thanks again for your contribution, since it makes us think of everyone and provides new ways of development. I am waiting impatiently to see your 9 dof project running, I am sure you are making an amazing system.

regards

Hi Andres,
How did you manage to fix the jaws on the hydraulic cylinder?
Can you share your 3D Model?
Regards

Andres, i didn’t fully comprehend this part of your last post, prolly lack of sleep…

In this way, no electrical part will be in the water and no component will have to be sealed with epoxy except for the penetrator, nor will it be necessary to build a specific watertight compartment to encapsulate, the brushless motor, the gear motor, the electronics for its operation and the DYI acme linar actuator.

Being notified of a response to this thread, and re-reading it, i noticed your above reference to a ‘watertight compartment’.

I don’t put my gripper parts in any watertight compartment, as a brushless motor, planetary gear reduction, and acme threaded rod/ linear actuator/servo can be exposed to water just fine. Yes, the ESC’s for the brushless motors will need to be sealed with epoxy for shallow-depth ROV’s, or inside a pressure-rated WTC for deep-dive ROV’s, but everything else handles immersion just fine.

Of course i seal my brushless motor stators with thinned epoxy resin, and replace the bearings with ceramic ones, and even then rinse after every dive with fresh clean water.

How about something like this?

Hi @achat

I attach the modifications in .stl and solidworks:

Clamp 1 (central part).SLDPRT (331.9 KB) Clamp 1 (central part).STL (72.3 KB) Clamp 1 (side parts).SLDPRT (326.8 KB) Clamp 1 (side parts).STL (128.1 KB) Clamp 2 (central part).SLDPRT (381.9 KB) Clamp 2 (central part).STL (132.7 KB) Clamp 2 (side parts).SLDPRT (381.1 KB) Clamp 2 (side parts).STL (84.8 KB) Hydraulic clamp support.SLDPRT (285.6 KB) Hydraulic clamp support.STL (212.8 KB) Hydraulic shaft coupling.SLDPRT (190.7 KB) Hydraulic shaft coupling.STL (51.4 KB)

Regards

Hi Darrell,

Excuse me, I probably expressed myself badly because my English is not grammatically correct.

When I say that no electrical part will be in the water, I mean the hydraulic design that I shared in my post. Both brushless motors and ESCs, etc. will go inside a watertight compartment, the same as the battery.

I understand that your design is totally submerged.

Regards