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ROFI bipedal robot

by jdow, published

ROFI bipedal robot by jdow Oct 22, 2012

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Description

ROFI is the fifth prototype from Project Biped. It is a self-contained, bipedal robot that uses accelerometer feedback to balance. It has 12 DOF (degrees of freedom) and can walk around while avoiding obstacles using an ultrasonic range sensor. A small on board Android tablet provides the brains and an Arduino mega board provides the hardware interface. All of the designs, source code, and parts lists are free and open source. Detailed step-by-step animated assembly instructions are provided to allow anyone with a low cost 3D printer and an interest in learning about robotics to build ROFI.


A full overview (with source Blender files) can be found at the Project Biped ROFI website:

projectbiped.com/prototypes/rofi

walking info:
projectbiped.com/prototypes/rofi/walking-analysis

video of the robot:
projectbiped.com/prototypes/rofi/video

Recent Comments

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I'm having an issue with the body_strut_v3.stl myself. It's strangely incomplete. Does anyone have a better copy?
Has anyone tried to making a ROFI with Cube 2 Printer?When I build in software, these files doesnt compile.body_strut_v3.stl
foot_NH_v3.stl
heel_left_v2.stl
heel_right_v2.stl
servo_bracket_left_NH_v5.stl
servo_bracket_right_NH_v5.stl
servo_wrap_lower_right_v2.stl
servo_wrap_upper_right.stlWhats going wrong?
Has anyone tried to making a ROFI with android 4.1 or upper?I'm thinking to make an ROFI using an updated android phone with the same weight of Archos 28 (68g) and size (100 x 54 x 9 mm).
or I'm thinking try to making and parametric ROFI that accept some Androids phones like mine (113.2 x 61.6 x 11.6mm 120.6g).Has anyone tried something like that?

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Instructions

Step by step animated assembly instructions:
projectbiped.com/prototypes/rofi/instructions

printed part diagrams:
projectbiped.com/prototypes/rofi/printed-parts

non-printed parts list (vender and cost):
docs.google.com/spreadsheet/ccc?key=0Ai_h1KTMNaWNdHktUVZlT3RZaGdzZm1tSXFrSm QzTmc#gid=0

UPDATE 11-05-2012

Thanks to the CSULB EE class (building the first ROFI clone) for pointing out that some of the parts designed to work with the new MG966R horn style were too thick. Affected parts are:

- Center Bracket
- Foot
- Body Riser
- Servo Bracket Left
- Servo Bracket Right

The new parts have been fixed and the zip and STL files have been updated.

UPDATE 11-28-2012

A few parts weren't slicable with Slic3r because they had problems with their meshes. Interestingly they all sliced fine with ReplicatorG, so I didn't catch the problems with the parts when I printed them. Thanks to 3daybreaker and Architect for pointing this out! Affected parts are :

- body strut.stl
- center bracket NH v2.stl
- heel left.stl
- heel right.stl
- servo bracket left NH v4.stl
- servo bracket right NH v4.stl
- servo wrap lower left.stl
- servo wrap lower right.stl
- side knee bracket.stl

The new parts have been posted along with a new zip file for the entire set of ROFI parts.

UPDATE 11-30-2012

Thanks to wildseyed for pointing out that the foot was missing part of the bracing on the rear riser! This was causing the feet to be much weaker than they should be. The bracing has been added back in and the file "foot NH v3" has been posted. Also the zip file has been updated.

File Name

Downloads

Size

Has anyone tried to making a ROFI with Cube 2 Printer?When I build in software, these files doesnt compile.body_strut_v3.stl
foot_NH_v3.stl
heel_left_v2.stl
heel_right_v2.stl
servo_bracket_left_NH_v5.stl
servo_bracket_right_NH_v5.stl
servo_wrap_lower_right_v2.stl
servo_wrap_upper_right.stlWhats going wrong?
I'm having an issue with the body_strut_v3.stl myself. It's strangely incomplete. Does anyone have a better copy?
Has anyone tried to making a ROFI with android 4.1 or upper?I'm thinking to make an ROFI using an updated android phone with the same weight of Archos 28 (68g) and size (100 x 54 x 9 mm).
or I'm thinking try to making and parametric ROFI that accept some Androids phones like mine (113.2 x 61.6 x 11.6mm 120.6g).Has anyone tried something like that?
That very tablet, unless you are willing to cut holes for something a little bigger, or can find one with the same dimensions. It is surprisingly small. If you need one, I still have one here that I'm not using.
I just ordered one from Amazon, but I can get my hands on any of a variety of these things. But I seem to have read that the software is specifically geared for this particular tablet. Have you tried any other? I can easily modify the head to carry a different tablet, that's not an issue, but I'd hate to be tied to something that's largely dead technologically that can't be replaced. What do you want for the one you are not using?
Did anyone try something other than the Archos tablet or must it be that very tablet?
To a certain degree i hate you - some parts really have some issues printing, especially the feet (tried 5 different layer infills/stuff, every single one broke) but since it's a PrintJob i just can't say no :) Especially the Top Part with the pieces printed in the air is not a nice thing to do.
I had similar problems as you when I printed my parts, particularly with the heels. I am using a Solidoodle. To get around this, I imported the parts into TinkerCAD and then exported them back out, creating a plate for parts to do a bunch at once and that worked. I'm guessing TinkerCAD cleans up some of the points in the process.
Hi, do you sell the package of printed parts?
ROFI LIPO's

I could not locate the prescrybed SKY lipo's, but after some intense googling I found these for replacement at Honny King (NL Warehouse)

T1300.2S.20/35821 Turnigy 1300mAh 2S 20C Lipo Pack

You can see the ftting on my blog 3daybreaker.blogspot.com

or here: 2.bp.blogspot.com/-6CwzvoY8HZU/UUNKt0qgwhI/AAAAAAAAAb0/w1FK7cuD6_0/s320/LYPO1.JPG

Thomas
To all ROFI builders:

The horns that Architect has developed fit perfect into the ROFI parts, but mine will not slide over the servo. I have reworked them with a hot 5mm hex-wrench after which I pressed them onto the servo to have it cool down together. After that the fitting is good: Heat the hex, push the horn onto it, rotate it 2x 360 degrees and push it onto the servo.

Pictures on my blog 3daybreaker.blogspot.com

or: 4.bp.blogspot.com/-qi5G7EwgvHM/UUNFmpSJMGI/AAAAAAAAAbk/dNSgICFElYs/s200/ays1.JPG

and: 1.bp.blogspot.com/-nScDOGUuq6M/UUNFmlC5Z4I/AAAAAAAAAbo/VoY3WCKmRec/s200/ays2.JPG

and: 3.bp.blogspot.com/-2a0c1d3obE8/UUNFmDVFVPI/AAAAAAAAAbY/-5TIy0wmCc0/s200/ays3.JPG

Thomas
ROFI IS great.
ROFI is tough to build until he (or Her?) really "static" walks. Really tough..
You get so addicted, that you are willing to spend lots of money (Euros in my cas) and time.
The hardes things are printing the parts with a (wooden !!!) Replicator and cabling all those parts and wires.
I use ABS on my (wooden..) dual replicator, lots of capton tape and many days of trial and error. Then I reworked all Parts with acethone to get as much strength out of it. I filled the bores which act as nuts with dissolved ABS to get screws to hold.
To "train" ROFI, build some Stand as you can see in my 1st picture to give full freedom of movement.
Headaches (some more) are caused by too much play in construction and especially gear-play inside the servos. Watch out: even a well (poser-) trained ROFI will do funny things when falling over his legs...
Thanks Jonathan for that mountain of (fun!-) work
Peter,

Thanks for all of your great feedback, and also let me apologize for your time and money ;-) Be warned that building robots is contagious ... once you make the first one it is hard to stop. In the future I'll be careful to record all of my printer settings because it sounds like you've been working too hard to get your plastic parts strong enough (my ROFI has face planted so many times during development that if he wasn't rock solid he'd be in pieces by now). I'll be releasing an update to the Robot Poser application soon with your suggestions incorporated. I'm also trying to get Google to undepricate gifs in their new version of presentations so I can finish the calibration presentation.
HA! just received mine. they say "TowardPro" on the same looking sticker as the towerpro. Haven't tested yet. :-/ i'm sure I can use them somewhere if they don't workout.
TowardPro is normal. Both the good and fake has TowardPro. TowerPro website even shows it
So it does. :-)
danka
Hello Jdow,

Sorry no photos yet. I had my to take my ROFI apart to replace the counterfeit Towerpro servos which also explains why the horn/arms were a different sizes. New/real ones might not make it this year. Value Hobby is stocking the MG996R state side for $11.99. Watch out for Ebay. Hard to believe the Chinese are now coping/counterfeiting their own cheap products.

The BOM could reflect 12 bearings instead of 10. I'm also using some 20 mm long bolts on the knee frame which is giving me 3-4 mm of threads engagement.

Thanks for the updated instructions

Notes to others about the real Towerpro servos. My fake servo were glossy not matte/flat black, did not have the "do not throw in trash" symbol on the bottom, The CE symbol was at the cord end, bottoms screw were black. The real Towerpro servo are very responsive and smooth when turning by hand. Huge difference in performance.
Bummer ... I've added a warning in the BOM about the fake servos (I'll update it if you give me any additional info about the seller). I also modified the number of bearings in the BOM, thanks for posting!
Hmm, that's a bummer. I am expecting my servos from china this week. can you explain a little more what the problem was with yours?
Cheap, crappy. sorry but blunt

When ROFI was assembled the fake servos had backlash and much resistance when moving the joints. The real servos, with no electrical power applied, can be manually re-positioned with a constant smooth sound and feel. The fake would sometimes feel like you were going to break them to get them moving.
Mine are sitting at my doorstep waiting for me to get home after the new year. I will be checking as soon as I get to them thanks for the heads up. Just so anyone else knows these are not the ones in the BOM Jdow put together.. :-)
Jdow,
Me too, I now have finished printing all parts.
Peliminary fitting parts on my old servo"s is going well.

(progress and parts on 3daybreaker.blogspot.com)

As referenced, I also added some support on the foot inside the front riser.

I see your point around slippingbhorns and printer resolution. This might be an issue,mhowever, if that does notnwork I might be forced to design a converter between my horns and your spaces for them.

One more issue: if I include your .stl in Openscad and add some stuff to it, new heels will generate new .stl. Old heels did not. Current feed do not either. Do you have some parameters that orevent openscad to regenerate on your parts?

Thomas
 Nice blog posts!  With my R2 printer I've started printing in PLA and I've suspected that my white PLA is stronger than my clear and orange PLA although I've never quantified that. One trick that some people have done with FOBO when they had the wrong horns is they just super glued the horns into place. It isn't the ideal solution, but it gets the job done and you can still change out the servo if one burns out.  I'm not sure I understand your last question about Openscad.
Openscad allows you to import someone elses .stl. You can than add or boolean your own code to it and generate new .stl from the total of all.

Some of your .stl will do that,mothers won"t as the feet. Funny enough, the previous heeld did not, but the last heels do generate new .stl

So the question is.... What is the difference?
 I'm not sure what the difference is.  All of the parts are manifold now, so no holes in the meshes.  You could try flipping the normals on the parts that are giving you problems.  You could also use blender to manipulate the stl files and then export a new stl file.  Let me know if you find something strange and I'll fix the other parts with the same issue.
Love it Jdow,
Everything is on order today. Had to juggle a few things around due to some items out of stock. Thanks you for the detailed BOM (saved me hours) and instructions. Will post photos from the Christmas build with the kidsDo you mind adding what your replicator settings were at. My TOM been dormant for a few months and needs tweaked  Not sure upgrading to rev40 was a good idea. Never the less your input could save me a few more hours trying to get a clean print again.Many thanks
jdow - in reply to burkeam
The TOM settings that I used to print ROFI :
  Layer height 270 microns
  ABS
  exterior walls 3
  (think this was with Skienforge 37)

Favorite R2 settings so far :
  PLA
  use the finest quality setting from makerware 1.02
  Layer height 200 microns
  infill 25%
  exterior walls 5

I tried 1.03 because it is supposed to fix some issues, but the prints came out a lot worse for me.
 
burkeam - in reply to jdow
Thanks Jdow,
 
I want to clarify the size of servo horn you are using? The ones I got with the servos are multi sided and need to be trimmed. Much smaller than the pocket inside servo brackets. My arms are only 18 mm long from centerline to tip.
 
Having breakage issues with the foot along the top edge of the battery box. Using ABS/acetone glue to repair. Will see if this hold before re-tweaking skinfordge
 
Thanks agin for sharing such a cool project.
never mind on the horn, read the other threads below.
It seems the foot also lacks support at front side for strength. I broke one foot already at that point. Inadded somemsupport myself, just as you did at the backside.

One thing puzzles me though: my servo control horns are way smaller than the spaces in the brackets. Did you specify bigger horns? I have Hitec HS 300 servos from flying.

Maybe have a printable horn that fits?

A printable horn is a good idea!  My only concern is that if the horn started slipping it could cause some strange issues. Perhaps with a high resolution printer you could make the teeth mesh well enough to avoid any slippage.
the Servos I ordered ended up not coming with Horns at all. so I've been thinking about printing some. was considering heating  the gear and mashing it into a printed hole o make the fitting.gonna look today here for some advice. otherwise i will need to order horns from somewhere, So far all the new Files seem to be printing well. gonna need to reprint the feet though with the new file. Is the Front support needed? 
Architect: One foot slipped out of my hand and fell (only 30 cm) and broke at the point where front riser starts from the body. So that is a weak place.

However, my infill is only 10%.
I added support like JDOW did at the back. Seems much stronger now.
thanks 3day, i've been printing at 40% infill with slic3r, which also has a setting of 100% infill if volume is less then 80mm squared. So The front of the one foot I have seems pretty strong. 
jdow,
any idea if these are the correct horns? 
http://www.hobbypartz.com/mg996-servoarm.html
appreciate the input before I buy as I need to get 4 of them 
 The picture is of the original horns that came with the MG996R prior to March 2012 ... but they might ship you the newer horns (either one should be fine).  The ROFI parts for the older horn style can be found at
https://www.projectbiped.com/prototypes/rofi/printed-parts/old-servo-horn-parts
cool, thanks again. almost done printing. 
O.K. I'm taking the plunge.  If anyone is bored, they can watch the printing at wildseyed.com:9090/

@jdow: The feet need some work, to make them stronger 
 The feet turned out plenty strong on my TOM ... but maybe your ROFI is going to do some serious stomping?  Definitely send me/ post your mods!  If you're going to make the feet bigger/stronger I'd avoid going too far inward so that the feed won't rub when it walks.  This might mean that you'll have to make too separate models (mirrored) for the feet.  I'll check out the video feed later if it is still up!
 Ah ha!  I see what happened.  Take a look at the STL uploaded here, and you will see that the inside support on the back of the foot is missing.  It shows up in the blender files though.
I think you're talking about the heels?  They are separate parts and are printed separately ... otherwise it would be really hard to get the batteries in there ;-)  3daybreaker had similar issues getting the foot to print and fixed it by adding some removable support struts (see comments below).  You might also try lowering the extruder temperature a bit to reduce sagging.  By the way I checked out your camera feed, cool 3D printer!
Sweet! Just in time for me getting in some more servo's .
Every Time I review this project, I just can't get out of my head the days of playing Mech Warrior 4...  I soooo want a minuature Mech to do battle with!! lol, baby steps here, baby steps.
 I'm sure there is enough extra carrying capacity for a gatling gun (or at least a nurf rocket launcher ;-).
So gonna happen one of these days...
Great, thanks for the rework.
I wiil give the new parts a go this weekend.

Congrats for being featured too :-)

Thomas

3daybreaker.blogspot.com
Can't reply below anymore.

Slic3r v97 does slice the bracket indeed.
I am gonna try and print them today.

However, the heels still are not manifold.

rgrds Thomas 
I printed 2 feet,

I was surprised by the bridging demand, which turned out not to be very nice in my Orca. (Never bridget that much before),

o for conveiniace, I added 3 support shields to the 2nd foot, which turned out to be better after that.

(Images on my latest blog: 3daybreaker.blogspot.nl/ )
Nice idea with the support!  I was actually very surprised that my TOM handled the cavity in the feet so well ... didn't have any sagging issues except for the first layer of the roof ( which I just cleaned up with a razor).  Maybe printing at a lower temperature would also help?
The Servo Bracket files give 'not manifold' warnings before and 'no layer detected' warnings after slicing (Slic3r)

Any Clue ?

Thomas
Run the stl's through netfabb cloud first!
Unfortunately servo bracket left NH v4 will not fix with netfabb. 
So.... What 's left for me to fix it? Other repair options?
 Looks like the mesh had some issues, sorry about that.  I've fixed the servo brackets and uploaded new versions.  I printed the old version out with ReplicatorG ... it must be more forgiving than netfabb?
jdow - in reply to jdow
 Sorry for the slow response.  I fixed all of the mesh issues in the files listed and reposted them.  Let me know if Slic3r has any problems with them.
jdow - in reply to jdow
I downloaded the x64 bit version of Slic3r 0.9.7 and  successfully used it to generate gcode for servo_bracket_right_NH_v5 without any errors.  Can you guys try this version and let me know if it gives you any problems? Thanks 
here is a list of files that slic3r gave issues to. 
body strut.stl
center bracket NH v2.stl
heel left.stl
heel right.stl
servo bracket left NH v4.stl
servo bracket right NH v4.stl
servo wrap lower left.stl
servo wrap lower right.stl
side knee bracket.stla couple of them i was able to fix with netfabb not most will not be repaired. I was able to successfully slice these all with skeinforge. 
Hi Johnatan,
the new servo brackets v5 still give "No Layers' error after Slic3r.  (The not manifold has gone)

Thomas
jdow - in reply to jdow
Yes, please post the list of parts that aren't working with slic3r and I'll fix them.  Thanks!
Appreciate that, all these files will slice with skeinforge (repG) My Printer doesn't get the same quality with replicatorG as I do with slic3r and I would like to be able to layout multiple items in OpenSCAD which I believe uses the same engine as slic3r. I have a list of these parts at home which fail in slic3r, perhaps I can post that up for you tomorrow and you might have the time to look at them? 
Hi Jonathan,

great thing you have established over time.

I am starting this ROFI project, however I only print PLA.
Would that be a problem ?  weight-wise for balance I mean ?

Thomas

3daybreaker.blogspot.com
 Thomas,
  I would think that PLA should be fine. Have you had any particular issues with PLA in the past?  I recently got an R2, so I'm going to be using a lot more PLA in the future ;-) If there are any issues, the walking cycles can always be reworked using the Robot Poser application (to be released within a couple of weeks). 
very very cool, made me smile
for weight reason, what infill are they printed at?
The parts were all printed in ABS with 10% infill and a single shell.
Apologies to anyone who already finished printing ROFI, I just updated a few of the parts that are designed for the newer MG966R horn style (see UPDATE 11-05-2012).  The original ROFI has the old horn style, so I didn't notice the issue until the CSLUB EE class building the robot pointed it out.  Thanks guys!
I love the way it walks - looks like Jackie Chan in Drunken Master :D
 Haha ... I'd have to agree! Sadly I just replaced the static walking cycle (a.k.a. drunken master style) with a dynamic walking cycle that looks much more natural. Check out the new video and let me know what you think.  I still have a link to the old video at the bottom of the video ( I renamed it "drunken master" in your honor).
That is some damn fine work there, congratulations!
Very cool. Is it possible to use any other Android devices? It would be nice to recycle an older Android phone. 
jdow - in reply to AUGuru
 Other Android devices should interface properly with the robot.  Some redesign would be necessary for the body enclosure and the walking cycle would need to be reworked to accommodate a heavier phone.  The main motivations for using the Archos28 (the Android tablet in the design) are that it is really light, small, and inexpensive.
Really sensational project !!!
Grande congratulations!!!
This project has come a long way!  So exciting!
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