Robotic arm in SketchUp 8 & SketchyPhysics

Other Hardware Motors, Mechanics, Power and CNC
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Hello,
Yesterday I stumbled across the pretty neat Google (free) program SketchUp v.8. Decided to 'mess' around a bit and design a robotic arm.
I got the idea for the gripper part of the arm from a page (page 353) in Robot Builders Bonanza...
I had an idea of using 'double-ended' stepper motors for the upper shoulder, elbow and wrist joints.
The arm is probably going to be a bit on the heavy side toward the gripper end, but was thinking of some type of counterweight/springs..? (I also was looking into some type of hydraulic method...)
*Actually may start looking at some hydraulic motors instead...and make it hydraulic :slight_smile:
The last stepper (at bottom right) rotates the gripper.
I was thinking of using a 'gyro' type device found on BMX bikes (used on front brakes to turn handlebars 360deg.+) to actuate the gripper fingers.

Also tried to get the SketchyPhysics plugin to work (to check out the animation), but there seems to be some problem with the latest version (3.2) as it installs as 3.1.... :confused: (seems to be a lot of people experiencing this problem).

Yeah, just messing around/having fun with it, will probably change some things, etc.. Here is a pic of what I have so far:

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Btw, if anyone has any info, websites that deal with hydraulic components (smaller scale) for robotics (hydraulic pistons, motors, actuators, etc..), I would appreciate it :slight_smile:

t

3

thomas3120:
Btw, if anyone has any info, websites that deal with hydraulic components (smaller scale) for robotics (hydraulic pistons, motors, actuators, etc..), I would appreciate it :slight_smile:

t

Hydraulics (water/oil), pneumatics (air), or linear actuators (electricity) - or some hybrid? What I mean by this, is generally someone poses the question "I want to use hydraulics?" - but they don't really understand what they are wanting to use, they just know that it is some kind of linear motion device.

Also - what is "smaller scale" - because that will be relevant to getting you a good answer (you don't tend to see much in the way of real hydraulic or pneumatic cylinders and equipment under a certain size; you should also be aware that a real hydraulic system is not something you play around with inside the house - not to mention how expensive they can be)...

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Thanks for the reply cr0sh.
Well, just thought about this last night. Definitely not on a 'caterpillar' machinary scale hehe.
I was thinking of using possibly 2 hydraulic (oil, not water) pistons to control the upper arm and lower arm portions.
I would need a hydraulic (oil) pump, motor to run the pump, a 'hydraulic line seperator'...to keep the movements independent.
Also(eventually) probably some type of electronic control/microcontroller to control each hydraulic piston.

This part of my project is still a good ways away...no hurry. Just like to start looking at different concepts using oil hydraulics and products. So no rush and any advice is greatly appreciated :slight_smile:

**Also, if I ever get the SketchyPhysics plugin (for SketchUp8) to work, I can see what kind of travel I would need, as well as add the hydr. piston attachment points or 'horns'? to my sketch above and see how it works out.

Thomas

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thomas3120:
Thanks for the reply cr0sh.
Well, just thought about this last night. Definitely not on a 'caterpillar' machinary scale hehe.

Ok - then -what- scale? What would be the smallest minimum and fully extended lengths you are looking for?

thomas3120:
I was thinking of using possibly 2 hydraulic (oil, not water) pistons to control the upper arm and lower arm portions.
I would need a hydraulic (oil) pump, motor to run the pump, a 'hydraulic line seperator'...to keep the movements independent.
Also(eventually) probably some type of electronic control/microcontroller to control each hydraulic piston.

Just be aware of a few things:

  1. This stuff isn't cheap
  2. It is messy and not very easy to assemble (hydraulic oil isn't fun stuff, either)
  3. It typically isn't small
  4. Did I mention it's not cheap?

I've never really shopped around for such components - you'd probably want to look at Grainger or McMaster-Carr, places like that, to get an idea of what you are looking for. Whether they have the sizes you need or not is another question, because they deal mainly with industrial needs. Generally, when you get below a stroke length of about 8 inches or so, you start getting into pneumatics or electro linear acutators, as there isn't typically much call for the capabilities of hydraulics (there's also the possibility of electro-hydraulic actuators - if you have the money).

A hydraulic system, from what I have read about, is a fairly complex and expensive system. It is a system which, if there is a failure of a component, is going to leak hot and potentially caustic fluid under pressure (pressure high enough to penetrate skin or worse). This is not an indoor project.

thomas3120:
This part of my project is still a good ways away...no hurry. Just like to start looking at different concepts using oil hydraulics and products. So no rush and any advice is greatly appreciated :slight_smile:

You might look into other options; I don't know what your minimum sizing is, but some pneumatic cylinders can be run as low-pressure hydraulics with the appropriate fluids (the manufacturer of the cylinders will specify whether they can be used in this manner or not, and what to use). Pneumatic cylinders tend to be smaller, but you can't run -any- such cylinder as a hydraulic; the fluid must be compatible with the seals (o-rings and such), otherwise leaks and failure will occur.

Other possible options (again, depending on needs and scale) would be to homebrew your own cylinders, etc - and/or use syringes (you see this occasionally on small-scale model hydraulic systems).

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Some videos from youtube.

http://www.youtube.com/results?search_query=hydraulic+arm+syringe&oq=hydraulic+a&aq=1&aqi=g10&aql=&gs_l=youtube.1.1.0l10.7358.17267.0.21601.11.8.0.3.3.0.167.1221.0j8.8.0...0.0.lMYW6uMqrmw

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cr0sh:
Ok - then -what- scale? What would be the smallest minimum and fully extended lengths you are looking for?

Just be aware of a few things:

  1. This stuff isn't cheap
  2. It is messy and not very easy to assemble (hydraulic oil isn't fun stuff, either)
  3. It typically isn't small
  4. Did I mention it's not cheap?

I've never really shopped around for such components - you'd probably want to look at Grainger or McMaster-Carr, places like that, to get an idea of what you are looking for. Whether they have the sizes you need or not is another question, because they deal mainly with industrial needs. Generally, when you get below a stroke length of about 8 inches or so, you start getting into pneumatics or electro linear acutators, as there isn't typically much call for the capabilities of hydraulics (there's also the possibility of electro-hydraulic actuators - if you have the money).

A hydraulic system, from what I have read about, is a fairly complex and expensive system. It is a system which, if there is a failure of a component, is going to leak hot and potentially caustic fluid under pressure (pressure high enough to penetrate skin or worse). This is not an indoor project.

You might look into other options; I don't know what your minimum sizing is, but some pneumatic cylinders can be run as low-pressure hydraulics with the appropriate fluids (the manufacturer of the cylinders will specify whether they can be used in this manner or not, and what to use). Pneumatic cylinders tend to be smaller, but you can't run -any- such cylinder as a hydraulic; the fluid must be compatible with the seals (o-rings and such), otherwise leaks and failure will occur.

Other possible options (again, depending on needs and scale) would be to homebrew your own cylinders, etc - and/or use syringes (you see this occasionally on small-scale model hydraulic systems).

The lengths of the upper and lower arms in the sketch I did are 10", the wrist is 6", so total length not including the gripper is 26".
I may try/play around with a previous version of SketchyPhysics to try and animate the model to see what lengths I can get (or give me a better idea).

Yeah lol :slight_smile: I've seen some of the prices of some of the components :confused:
Also read a story where a hydraulic system failed and sprayed nice hot oil over everyone.

Again, still 'getting my feet wet' at the idea or open to other options.

I may look at a pneumatic system again, so things are still up in the air...

@ zoomkat Thanks for the link to the videos :slight_smile: I've watched several but wasn't too impressed (at least) by the syringe method.
But will definitely go through the list and see if something catches my eye.

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@ zoomkat Thanks for the link to the videos I've watched several but wasn't too impressed (at least) by the syringe method. But will definitely go through the list and see if something catches my eye.

If you do a google search you should find the model hydraulic setups. Thye are complex and $$$. Syringes can be operated via servos to provide hydraulic pressure (similar to below link). Tap water and aquarium valves might provide another source of hydraulic pressure. Simple low pressure hydraulic cylinders can be made from such as plastic toy air pumps and bicycle tire pumps. Linear actuators might be an alternative like the mini excivator model in the bottom link.

http://www.lynxmotion.com/p-788-vacuum-gripper-kit.aspx

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thomas3120:
The lengths of the upper and lower arms in the sketch I did are 10", the wrist is 6", so total length not including the gripper is 26".
I may try/play around with a previous version of SketchyPhysics to try and animate the model to see what lengths I can get (or give me a better idea).

Yeah lol :slight_smile: I've seen some of the prices of some of the components :confused:
Also read a story where a hydraulic system failed and sprayed nice hot oil over everyone.

Again, still 'getting my feet wet' at the idea or open to other options.

I may look at a pneumatic system again, so things are still up in the air...

Even pneumatics can be fairly expensive for all the parts and such needed (especially if buying new); compressor, valves, manifolds, hoses, air dryers (and sometimes oilers), cylinders, etc - it can get expensive really fast. I suggest shopping surplus for as much as possible; sometimes you can find surplus but worn cylinders, and depending on their construction (and whether the manufacturer is still around) you can get rebuild kits to bring them back up to spec (kits contain o-rings and other parts).

You might also look into homebrew pneumatic cylinder building - do some googling on "darkhouse", "props", "effects", etc - along with "homemade pneumatic" and such; a lot of people into haunted house building tend to build their own cylinders due to the cost of actual cylinders (especially long travel).

Alternatively - try to find a surplus shop in your area, or find an online surplus supplier of such parts (they do exist - but like I said, while cheaper than new, even surplus can be a bit expensive).

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I may look at a pneumatic system again, so things are still up in the air...

I doubt you want a pneumatic setup for your arm project.

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thomas3120:
I was thinking of using a 'gyro' type device found on BMX bikes (used on front brakes to turn handlebars 360deg.+) to actuate the gripper fingers.

Might this help?