PROJECTS:
Dexter Companion Robot
My Monkey
Companion Bot
Written by Jorvon Moss
78 make.co
Build a fun robot
monkey you
can customize,
wear with you on
adventures, or
use as an avatar
JORVON “ODD JAYY” MOSS
is a tinkerer, creator, designer,
and maker of gadgets and robots
in Compton, California. He’s
also a big fan of steampunk and
cyberpunk. @Odd_Jayy
TIME REQUIRED:
2 Weekends
DIFFICULTY:
Intermediate
COST:
$60–$80
MATERIALS
» Chemion customizable LED glasses Amazon
#B01B41PHJM
» Micro servomotors, SG90 (5)
» Ar du i n o -c o m pa t i b l e m i c r o c o n t r o l l e r , 5 V, 16M Hz
I used the Adafruit Pro Trinket 5V, Adafruit #2000,
but you can use the newer ItsyBitsy or other small
Arduinos.
» Bo o s t c o n v e r t e r , 3.7V t o 5 .2V D C Adafruit
PowerBoost 1000C, Adafruit #1944
» Ba t t e r y, L i Po , 3.7V, 20 0 0 m Ah
» Ba t t e r y c h a r g i n g /m a n a g e m e n t b o a r d such as
the Adafruit LiIon/LiPoly Backpack, #2124
» M i c r o s wi t c h e s ( 2–4) Right now I’m using one
for servos and one for lights. There’s room for 2
more, to toggle whichever systems you add.
» 3D pr i n t e d b o dy pa r t s Download the free files
for printing at makezine.com/go/dexter.
» S c r e ws ( m a n y)
» Ac r yl i c s h e e t , ⁄" t h i c k, a b o u t 4"×8" ( o pt i o n a l )
to make the eye covers
» L E D s ( o pt i o n a l ) I used Adafruit NeoPixel rings.
» C o ppe r t a pe ( o pt i o n a l ) I used it as a touch sensor.
TOOLS
» C o m pu t e r wi t h Ar du i n o ID E s o ft wa r e free at
arduino.cc/downloads
» Ho t g l u e g u n
» D r i l l
» S c r e wdr i v e r s
» S o l de r i n g i r o n a n d s o l de r
» S o l de r s u c ke r o r de s o l de r i n g b r a i d to remove
the Chemion LCD display
» 3D pr i n t e r ( o pt i o n a l ) You can print the files
yourself, or send them to a printing service.
Allow me to tell you the tale of my robot
monkey. Last year was a big year for me and my
companion bots, entering the eye of the maker
world: I even got invited to talk at Hackaday
Superconference. Thanks to that event, and me
being told about it three months prior, I began
working on my robot monkey companion, Dexter.
What’s a companion robot? To me, it’s a robot
you can take with you on any type of adventure,
the way R2-D2 rolls next to Luke Skywalker. I
started making them in 2018 and couldn’t stop.
When adults see me with a companion bot they
might think it’s weird or ask me a polite question,
but kids get so excited: “OMG, it’s a robot!” They
know where it’s at.
Dexter was a 4-month journey of failure. Dexter
V1 was fragile like a baby; I took him out one day
and he snapped in half, wires everywhere. Dexter
V2 was much sturdier, and I added fingers and
constantly kept upgrading him; a lot of things
worked, and did not work. I even upgraded
him to V3 at the Hackaday event, inspired by
some amazing makers there: I gave him his
new custom eyes, improved his movements by
changing up some screws and adding a power
booster, and reprinted a new face for him. Then
Early sketches of Dexter’s design.
Tiffany Chien – bytiffanychien.com, Jorvon Moss
79
makeprojects.com
PROJECTS:
Dexter Companion Robot
I showed him off at Maker Faires in Los Angeles
and the Bay Area.
What I’m sharing with you is Dexter V4, the
most upgraded version yet. I used Fusion 360,
and a bit of SolidWorks, to design him. His eyes
are a hacked pair of LED glasses, and I made him
with the intention and ability to be upgraded and
customized depending on the person making
him. He’s still not perfect — I drilled my own
holes to add screws, and hot-glued a lot of him
—but I hope you like him.
ASSEMBLY
I recommend starting with the head, which is
made of three parts: the front (face), the back,
and the middle plate. I would print these first,
then the neck gear and the ribcage. Use these to
assemble the head to the neck; that way you’ll
quickly have a piece of him built.
Next, the servo gears. Print these at high
quality; they should fit any micro servo but I
know they tend to warp if the quality is low. Add
one gear to the neck servo and fit the servo into
its place in the rib cage. I recommend you run a
servo test and see how the gears mesh and move
the neck. I used the Arduino example code at
FileàExamplesàServoàSweep.
If it works well
(or good enough for your specific uses), continue.
The ribcage has two more of the same servo
placements, one in each side; add servos there
to move the arms, and test those too. In the end
I used ball joints to make Dexter’s arms because
they can be moved in more directions and adapt
to his riding position when he’s on my back.
I recommend printing the belly next. It’s pretty
big and will be used to hold most of the circuit
inside it. It’s got two block-like platforms; use these
to attach it to the ribcage using screws or glue.
SERVO CIRCUIT
Now prepare your circuit. Dexter is cool because
he can be customized: I made him so that you
can edit his systems and make and put your own
circuits in him. For his servos I used an Adafruit
Trinket Pro microcontroller driven by a single
LiPo and an Adafruit voltage booster board
(Figure
A
). With this setup I can move as many
as 6 servos at random intervals, so Dexter is
always doing something.
An early Fusion 360 STL.
Head/neck test movement, V1.
Dexter’s arm with ball joints
Dexter V3 at Downtown L.A. Maker Faire, 2019.
Jacques Alexander Katzoff, Jorvon Moss
80 make.co
Next the ears. These are pretty simple. Attach a
simple micro servo to the back of the inner skull
piece as in Figure
B
.
Attach the servo arms to the ears in such a way
that they’ll push and pull the ears up and down,
then attach each ear with a single screw to the
top part of the inner skull, so it can pivot. This
gives Dexter his moving ear look (Figure
C
).
CHEMION EYES
The eyes are next. Dexter V4’s “emote” eyes are
actually hacked Chemion LED glasses. There are
multiple tutorials online on how to hack these
and rewire them; my favorite is youtube.com/
watch?v=xBOrmM351pg. The eye covers are just
laser-cut acrylic and they’re hot-glued to the face
(Figure
D
). I control the eyes from the Chemion
phone app; previous Dexters had LED matrix eyes
controlled by a microcontroller.
Next I recommend printing out the other parts:
the butt plate, legs, hands, and feet. It’s easy to
assemble Dexter, but the print time does take a
while. I designed the back of the head plate with
four slots for switches, so you can wire up the
servos, LEDs, etc., separately with the ability to
turn them on and off. I usually put the circuit in
Dexter’s stomach, so some of the wires show
through his neck (Figure
E
); I usually hide these
with a scarf.
Oh, also his tail. Almost forgot, I used these
modular cable covers I found on Thingiverse
(Figure
F
) designed by Greg “sirmakesalot”
McRoberts in Toronto (thingiverse.com/
thing:25872) to make his tail, and used armature
wire as a base so you can bend his tail where you
want it, and you
won’t have to
worry too much
about his tail
hitting people.
A B
C
D
E
81
makeprojects.com
F
PROJECTS:
Dexter Companion Robot
Now for Some
Monkey Business
MONKEY ON YOUR BACK
To wear Dexter, I use a GoPro mount to attach his
chest plate to a backpack strap, so his center of
gravity stays low, behind my shoulder. An earlier
version sat up high on my shoulder but that was
too tippy (Figure
G
).
YOUR BASIC RANDOM MOVEMENT
SERVO CODE
This Arduino code moves the servos 0°–180° in
random intervals; in my opinion, this just helps
simulate life. You can rewrite or replace it with
your own Arduino code to make Dexter move
however you want. There are 5 servos in Dexter
currently but the code provides for 7 because I
wanted Dexter to have the ability to be hacked or
updated later, by me or other people. You can find
the code on my Dexter project page at hackster.
io/Odd_Jayy.
EXPANDABLE AND UPGRADABLE
Lastly I wanted to add what’s special about
Dexter. The reason there are 4 switch holes in the
back of the head design is so you can add other
circuits to him (Figure
H
).
In different versions of Dexter I have added
an LED circuit to glow inside (NeoPixel rings)
and a touch sensor to make him do high fives,
hahaha (copper tape on his forehead, connected
to an Adafruit Circuit Playground microcontroller
inside, Figure
I
). There’s room for whatever
sensors, brains, and behaviors you want to add.
THE FUTURE
I have other, crazier ideas for companions, like a
dragon with a real flamethrower — not sure I’ll be
able to bring that one to work — a fairy robot, and
a fox I’ve already started sketching. Right now I’m
working on a smaller dragon that blows smoke
from a vape pen (see sidebar). I’ll still work on
a bigger dragon one day, but I want to continue
upgrading Dexter and coming up with more ways
to make more fun bots.Star Wars doesn’t have to
have all the cool droids, we can make some cool
ones too!
G
82 make.co
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