Introduction: How to Make an OAWR (Obstacle Avoiding Walking Robot)

Picture of How to Make an OAWR (Obstacle Avoiding Walking Robot)
This Instructable shows how to make a little walking robot which avoids obstacles (much like many commercially available options). But what's the fun in buying a toy when you can instead start with a motor, sheet of plastic and pile of bolts and proceed to build your own. Well I hope you share this attitude and please enjoy.

update - coming soon, lovely prepackaged kits from oomlout


--No difficult to source parts (no switches, relays, or IC's (everything but the motor is available at Home Depot).
--No soldering.
--Has a Mechano for grown-ups feel.
--Choice of options for cutting out pieces (scroll saw & drill, access to a laser cutter, purchasing online from Ponoko).

A quick video of the finished product walking through frame:

( A longer video of it navigating between obstacles can be found on step 7 )


(If you would like any of the files in an editable format they can be found on a parallel Instructable here )

(Coming Soon, an Instructable on how to use a microcontroller (Arduino) to control the robot)

(I have used metric units and components in this Instructable. However those more familiar with imperial units do not despair, replacing the metric component with their nearest imperial counterpart should work (although I have yet to test this)) .

Step 1: Parts & Tools

Picture of Parts & Tools
All parts, with the exception of the motor, can be found at any Home Depot. The motor can be ordered from a number of online stores for about $10.

(there is also a pdf version of the parts list attached to this step '21-(OAWR)-Parts List.pdf')

Parts List:

Nuts and Bolts: (~$10)
  • 3mm x 15mm Bolt (x20)
  • 3mm x 20mm Bolt (x2)
  • 3mm x 30mm Bolt (x9)
  • 3mm Washer (x48)
  • 3mm Nut (x45)
  • 4mm Nut (x26)
  • 5mm Washer (12mm OD) (x2)

  • Various Colours of Electrical Wire (~$5)
  • Crimp Wire Terminals (red 5mm ring) (x18) (~$2)
  • 2 AA Battery Box (x2) (~$2)
  • Motor (Tamiya twin motor gearbox (#70097) (available from many online sources) ( on froogle ) ( manufacturers site ) ( sparkfun ) (~$10)
  • Crank Set (Tamiya 3 mm Diameter Shaft Set) etamiya ) (<$10)

  • Acrylic (150mm x 300mm x 3mm thick) (~$6)
  • Whisker Wire (260mm x 1.6mm)(or two large paper clips) (~$1)
  • Elastic Band

Tool List:

  • Printer
  • 5.5mm Wrench (x2)
  • Screwdriver
  • Pliers
  • Crimp Terminal Crimpers
  • Hot Glue Gun

Additional Tools Depending on Choice of Sourcing Acrylic Parts

Option 1 (Scrollsaw & Drill)
  • Glue Stick
  • Scroll saw
  • Drill
  • Drill Bits (3.2mm, 12.5mm, 16mm)
(I was going to use this option however I snagged a free shipping coupon from Ponoko so instead had my pieces laser cut)

Option 2 (Ponoko)
  • A Ponoko account
(option I used)

Option 3 (Access to a Laser Cutter)
  • Access to a laser cutter

Step 2: Cutting Pieces

Picture of Cutting Pieces
Please chose which steps to follow based on the cutting option you have chosen.

Option 1 (Scroll saw and Drill)

  • Download and print the pdf pattern (please choose the file corresponding to your paper size) -A4 size paper ( '31A-(OAWR)-Scrollsaw Pattern(A4).pdf' )-Letter size paper ( '31B-(OAWR)-Scrollsaw Pattern(Letter).pdf' )(it is important to not scale the drawing while printing)
  • Measure the ruler on the printout against a ruler you trust, if they do not match the pattern has been scaled and you need to look at your printer settings before reprinting. If they do match up, onwards.
  • Glue the pattern to the acrylic sheet.
  • Drill holes
  • Cut out pieces using a scroll saw

Option 2 (Online Digital Manufacturing; Ponoko)(this is the option I used)

  • Get a Ponoko account ( Ponoko )
  • Order the pieces here . (they are priced at cost ($11.47 Cutting cost + $8.28 material cost = $19.75 + Shipping (a warning Ponoko is currently only shipping from New Zealand so shipping is quite costly))

Option 3 (Access to a Laser Cutter)

  • Download the laser cutter optimized pattern (pieces are placed side by side and duplicate lines are removed)-( '32-(OAWR)-Laser Cutter Outline.eps' ) (.eps format)
  • Cut the file on your laser cutter.

Step 3: Whiskers

Picture of Whiskers

The last step before we start putting it all together.

Bending the whiskers is quite straightforward. Use pliers and a 130mm length of 1.6mm wire (actually a large paper clip will also work), using the pattern in the attached PDF ( '41-(OAWR)-Whisker Bending Guide.pdf' ).

(note: while initially designing this robot I experimented with many different shapes of whiskers. The pattern below is the one I found to work best, however it is quite interesting to experiment with different shapes. I was surprised how even small changes could drastically alter the navigational behavior of the robot)

Step 4: Assembling

Picture of Assembling
I tried to make assembling all the pieces together as straight forward as possible. To this end I have included a Lego style assembly guide ( '51-(OAWR)-Assembly Guide.pdf' ).

A step before you begin:

  • assemble the motor gearbox (I used the 58:1 ratio with output shaft exiting at hole 'A' however battery life on this setting is not great, mounting holes have been included to allow for using the 203:1 ratio with output shaft exiting at hole 'C'. If you prefer a slower longer lived version)

A step after you finish:

  • add shoes to the feet of your robot (the rounded acrylic feet don't grip surfaces well). I applied a bead of hot glue to the bottom edge of each leg and performance was greatly enhanced. (But if you have access to six miniature sized running shoes that would be a much better option)

(To inspire you to assemble yours here is a 'video' of me assembling mine in about thirty seconds :) )

Step 5: Wiring

Picture of Wiring
With the big pieces all together and it beginning to look pretty, the time has come to add the copper veins which will give it life. A first look at the wiring diagram ( '61-(OAWR)-Wiring Diagram.pdf' ) can be scary however if you tackle each wire individually it is quite straight forward.

Also if you are wondering how the robot operates please refer to the second image below which shows it in each of its four operating states.

Four Notes to Help You Out:

  • Each wire end which connects to a connection point should have a crimp wire terminal (red 4mm ring) affixed to it (there are 18 of these points).
  • The exploded view linked to each connection point illustrates whether the wire is meant to attach above or below the acrylic sheet.
  • Any connection point that does not already have a bolt in it uses a 3mm x 15mm bolt and a matching 3mm nut.
  • Most of all don't worry the next step is fully devoted to trouble shooting so have a go and if it's not working properly chances are you'll find your answer there.

A note of encouragement:

  • You can do it.

Step 6: Troubleshooting

Picture of Troubleshooting

If you've made it this far and your robot is walking and avoiding obstacles then you may skip right over this step. However if it isn't quite working or is not working at all hopefully you'll be able to find the solution to your problem here.

(If you have a problem not addressed mention it in the comments and I'll try to help (or if you have a problem that's addressed here and have a better way to deal with it please also comment))

(I'm afraid I haven't figured out how to do tables on Instructables so this section will be formated)

Cause 1
Solution 1
Cause 2
Solution 2

Troubleshooting list:

Left legs walk backwards when they should be walking forward.
The left motor is connected backwards.
Reverse the wires from the left motor connected to connection point 'G' and connection point 'H' (ie. G<-->H & H<-->G).

Right legs walk backwards when they should be walking forward.'
The right motor is connected backwards'.'
Reverse the wires from the right motor connected to connection point 'H' and connection point 'J' (ie. H<-->J & J<-->H).

When whisker is pressed relevant leg continues walking forward.
The Reverse Battery is wired backwards.
Switch the wires from the Reverse Battery holder connected to connection point 'A' and connection point 'I' (ie. A<-->I & I<-->A).
The elastic band is too tight and not letting the switch arm swing.
Use a larger or less powerful elastic band.
The bolt holding the switch arm in place is too tight.
Loosen the bolt holding the switch arm.

In the off state when one whisker is pressed the legs begin walking.
This is unfortunately a flaw in the wiring design.
If you wish to fix this add a switch on one or both of the battery boxes or remove the batteries when not in use.

After hitting an obstacle one side continues walking in reverse after the obstacle has been cleared.
The Elastic band is not powerful enough to return the switch arm to its forward position.
Use a stronger elastic band
The bolt holding the switch arm in place is too tight.
Loosen the bolt holding the switch arm.

Batteries are in but the robot does not move.
Washer is not contacting the powered bolt.
Because the 5mm washer has a hole bigger than the 3mm bolt we use, you must center it and then tighten the screw to hold it in place. If it gets pushed off center the acrylic switch arm may be contacting the bolt in its place. To fix this loosen the whisker screw and re-center the 5mm washer.
Motors are being powered by both battery packs simultaneously resulting in a net zero voltage.
The washers on the switch arm are too big, look for washers that seem a little smaller or bend the contact bolts outwards a little.
There is too much friction in the arm links causing the motor to stall.
Loosen some of of the tighter bolts holding your legs and push arms in place.

Step 7: Finished

Picture of Finished

I hope you have reached this point without too much frustration and you are happy with the results.

If you have any tips or suggestions on how the design or Instructable could be improved I'd love to hear them.

Also if you have finished it would be lovely if you could add a photo to the comments section or perhaps send me one so it can be added to this stage.

A video of the finished OAWR in action:

(A couple of issues still to be resolved when the legs get synced in a particular way they push against one another and almost stop the robot (thats what I was reaching in to fix), and it is still not corner proof but I'm working on it)


JamesX1 (author)2015-01-18

cool, a little to complicate

xzolian (author)2008-03-08

I'm in the process of building one of these guys but unfortunately my Tamiya Twin motor gear box didn't come with any cranks. Was it supposed to? Where can I buy some extra cranks from?

sbouse (author)xzolian2011-10-20

did you check out Pronoko?If that dosent work try mano factors site

clement.fletcher (author)xzolian2008-08-19

Hey; Oh that's not good news, It sounds like there may be a few versions of the Tamiya Gearbox to be purchased. Not sure the exact part number of the one which comes with the cranks. In a push remote control servo horns will work (it takes a little super glue to hold them in place). Regards Clement

erreur401 (author)2008-01-26

hi ;
i make one in a bigger size ; it 'll be manage by an arduino to be atonomous

here is the link to the video

i 'll make an instructable when the project will be finish

thanks you


sbouse (author)erreur4012011-10-20

why not add a cover so its not showing wires?Yo can have bronze, silver or gold i picked bronze it has pointy feet like spikes but how does it start?Is there like a button or something?

Hey; Wow it looks great, I like the look of the red acrylic and the prospects of what can be done giving it's Arduino brain. Regards Clement

101nemesis (author)2011-02-11

i got all the parts ready..
just gona start assembling it..
was wondering ..
it doesnt use any sensors how does it work..?

penester (author)2009-12-23

 This is very cool.

regipalka (author)2009-07-14

Not to be mean but in the video I'm really sure i saw that walk into the wall at the end

robbotica (author)regipalka2009-10-16

 it seems like that it's recorded by a camcorder has wide-angle lens.. so it made some illusion.. 

genesplicer (author)2009-06-23

I have a question. The motor kit did not have a crank (mentioned in step 5 of the assembly guide. Can anybody suggest a good substitute? Or, can you give me some dimensions that would work for making a substitute crank? Thanks!

jmontaa (author)2009-06-20

What is you add a pin on the front that goes in and out so that it can push the robot out of the corner? The pin could go in and out in slightly different directions. About the legs getting stuck. Looser joints may help. Maybe mount the legs on rubber bases so they wiggle a bit. That may also help with obstacles.

crohnsninja (author)2009-06-15

Im making the oawr and I went to a Home Depot in California and I was only able to get 3 items needed. Also...Where can I get the bolts. I cant find that small of bolts anywhere. Please reply I need help fast!!

oomlout (author)crohnsninja2009-06-16

Hi crohsninja;

Goodness me that is a bit of a surprise.

A fall back is all the a parts nuts bolts wires, battery boxes etc. can be bought online at McMaster Carr

crohnsninja (author)oomlout2009-06-16

I also cant find a motor that comes with the two cranks. Were you able to find one with cranks? If so, where did you get it? Thanks a million!

maurice1993 (author)2009-05-16

hey, this give me a nyce idea to a robot, but this run off a little to the rule of K.I.S.S, either that, I'll buid and post here how I made mine. you're robot it's a very well job, realy goob enginering on it. five stars!

kl1nt_1994 (author)2009-04-19

how do you connect the wires to the motor

Madrias357 (author)2009-04-10

Had a design once with 4 wheels instead of legs. Problem with it was it was too bloody fast. Sold it to a friend a few years ago, though, and he thought it was funny.

robomaniac (author)2009-02-27

Very nice robot. I see that is use the same circuit has the beetle robot.

andres36 (author)2008-12-18

I think this excellent manual is very detailed and very help full Loes the link attached to the center of robotics and vision of ESPOL place where many of these projects [http:// (ESPOL)]]Center for Vision & Robotics (ESPOL)]

codongolev (author)2008-08-31

I made something that turns around when it hits obstacles. it consists of two big wheels and a pivot rod. when it hits a wall, the pivot rod is thrust beneath the wheels , and it rotates. that means that for the second that the robot is supported by the rod, it turns about 90 degrees. when it goes back down, the rod flips back around and the robot continues. his name is earl g. (electronic always relocating little guy.)

mojoatomic (author)2008-07-09

Here it is with a picaxe 28x1, ping sonar and motors -

Hey it looks rather brilliant, I do like how much more bug like it looks with the sonar on the front. Regards Clement

emilk (author)2008-03-19

you used some kind of cad software to make those blueprints for the parts ? this looks quite interesting I think for my next robot project. I figured i want to build a robot that can lift the legs independently back and forth up and down. with servo motors or something.

clement.fletcher (author)emilk2008-08-19

Hey; Well not so much CAD software I'm a bit of a Luddite and actually use Corel Draw for the design. Then for the three-D model I used Google's Sketchup. Strange you mention a more dexterous walker I actually have a six legged 12 servo version in the works which I will post here when completed. Regards Clement

mojoatomic (author)2008-06-08

Well, I cut the chassis last night on my Epilog laser. Made a few revision changes to fit the acrylic thickness from Home Depot (in Florida) and resized the holes to fit 4-40 screws available at Home Depot here in the states. Good easy project for those wanting to give it a try. For the fellow who asked about the Tamiya crank arms not coming with the motor - make sure to order Tamiya part# 70105 as it comes with 2 crank arms (among other things).

fidgety2 (author)2008-05-20

hey i am really looking into building this and can i get reallyreally detailed instructions for this i know i am asking alot but i really want to build this if you can get me the instructions please e-mail me


colt45 (author)2008-01-24

what kind of motor do you use.

parwana90 (author)2008-01-19

cool Thanks

cotton (author)2008-01-11

its silly

brainspater (author)2007-12-20

that is very nice idea that you came up with, you should put a patent on it if there is no patents on your idea.

dickda (author)2007-12-19

Ah yes, very nice work - please do add the Arduino.

GorillazMiko (author)2007-12-17

looks really cool, all gadgetish looking :-)

MadMechanicMike (author)2007-12-17

i like how it looks

Dorkfish92 (author)2007-12-10

Very cool! I'll make one of these of christmas break. The only thing I noticed wrong is that you say it is "Obstacle Avoiding" but it doesn't really avoid obstacles, it just goes around them and isn't stoped by them. +1!!!

JROdden (author)Dorkfish922007-12-12

Dorkfish is right, it's not an OAWR, it just an obstacle detecting walking robot... Avoidance require vision (IR sensor, sonar++) and some level of AI. This one just boldly walks ahead until it hits something (read: the whiskers hit something). Seems like a good project for beginners though. But I like 6 independent legs with at least 2 DOF (degrees of freedom) for my walkers.

I hope you give it a go. On the name front too true it is more of a Bump And Go Around Walking Robot but the acronym BAGAWR didn't seem quite as friendly. Regards: Clement

ha ha. very true, cool robot though! I think this is a good way project to help give people that aren't good with soldering and complex electronics the chance to make a small robot.

cotton (author)2007-12-11

ok thx want to be frieds? and i love the funny robot

zjharva (author)2007-12-10

this is a great instructable. you should add it to the homemade holidays contest too! woot! :P

clement.fletcher (author)zjharva2007-12-10

:) Thank You. I hope you enjoy Regards Clement

cotton (author)2007-12-10

on the last vid why did it keep on walking into the wall?

clement.fletcher (author)cotton2007-12-10

:) I like to think it's because it has developed a liking for that corner but the sad truth is I have some tuning to do in whisker shape and switch tension and the like before it is able to navigate perfectly. It's not quite perfect I'm afraid. Regards Clement

danemery (author)2007-12-10

This is very cool.

fredgilman (author)2007-12-10

Very nice! I might just have to try this out!

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More by clement.fletcher:How to Make an OAWR (Obstacle Avoiding Walking Robot)(Source Files For) How to Make an OAWR (Obstacle Avoiding Walking Robot)Hot-Wire Foamcutter (Battery Powered)
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