Dear Biomch-L readers,

The following Usenet posting seems interesting from a gait control point of
view, one of the references quoted in the mentioned report. Interestingly,
this posting refers to cost compensation in a university setting. Of course,
it stands to reason that a large number of "orders" to the Computer Science
Department at Bloomington may facilitate subsequent commercialization of this
interesting device.

Stiquito: A Small, Simple, Inexpensive Hexapod Robot
Part 1. Locomotion and Hard-Wired Control

Jonathan W. Mills
Computer Science Department, Indiana University
Bloomington, IN 47405, U.S.A.

ABSTRACT: 80 figures illustrate the construction of a six-legged robot
that walks up to 10 cm/min and carries up to 50 grams. Ninetol actu-
ator wires drive the robot's legs. Power and control are supplied
through a tether or with on-board batteries and electronics. The robot
provides an inexpensive platform to study computational sensors, sub-
sumption architectures, neural gait control, behavior of social insects,
and machine vision. A single robot costs between $ 10 and $ 30. The
pro-rated cost of material to construct robots in volume (200 or more)
is less than $ 3. The design can be replicated to build complex arthro-
pods, or colonies containing hundreds of insectoid robots.

In a number of follow-up postings on Usenet, the pro's and con's of this
device have been discussed. Furthermore, the non-profit nature of this
service was re-emphasised (the author does not receive any royalties), and
the impossibility to process purchase orders and credit cards was mentioned.
For ordering through official channels, it was suggested that institutional
purchasing departments prepare a check to be sent to Bloomington. I imagine
that International Money Orders will be acceptable, while checks drawn on
non-US banks may not be acceptable due to high banking charges; sending cash
was discouraged.


Ref.: R. Beers, An artificial insect. American Scientist, Sep/Oct 1991,


Article 7073 in
From: (Jonathan Mills)
Subject: Stiquito, A Small Nitinol-Propelled Robot
Summary: An inexpensive legged robot for research & education
Keywords: Nitinol, Flexinol(tm), legged, robot
Date: 24 Sep 92 16:36:12 GMT (corrected -- HJW)
Organization: Indiana University, Bloomington

Stiquito: A Small Nitinol-Propelled Hexapod Robot

The Computer Science Department's Robotics Laboratory at Indiana
University (Bloomington) has designed, built, and tested "Stiquito",
a six-legged robot that you customize by adding sensors, controllers,
power sources, etc. The robot provides an inexpensive platform to
study computational sensors, subsumption architectures, neural gait
control, emergent cooperative behavior, and machine vision. It is
currently being used for research at IU, and, at a ratio of one robot
per student, in "VLSI for Robotics" and "Machine Learning" classes.

Stiquito is small (3cm H x 7cm W x 6cm L) and simple (32 parts)
because its legs are propelled by nitinol actuator wires. Each
leg has one degree of freedom. The robot walks up to 10 cm per
minute and can carry a 9-volt cell, a MOSIS "tiny chip" and power
transistors to drive the nitinol actuator wires.
Alternatively, power and control can be supplied through a tether.

A single robot costs between $10 and $30. The pro-rated cost of
materials to construct robots in volume (200 or more) is less than
$3. The design can be replicated to build complex arthropods, or
colonies containing hundreds of insectoid robots.

IUCS Technical Report 363a, "Stiquito: A Small, Simple,
Inexpensive Hexapod Robot -- Part 1. Locomotion and Hard-Wired
Control" contains detailed instructions to build the robot and a
hard-wired, manually-operated controller. The instructions are
illustrated with 80 life-sized figures that include dimensions and
enlarged details. Materials, tools, and vendors are listed.
Special sections include construction skills for novice users, how
to fix mistakes, and troubleshooting problems found in real-world
experience with the robot.

Stiquito and its manual controller are assembled by crimping and
press-fitting parts. No soldering is necessary. The resulting
robot is very reliable. A tethered Stiquito walked for over 100
hours. During the test each leg made 300,000+ 2-3mm strokes. The
leg movement was reduced because power was supplied during the
test by a 6v AC/DC adapter. With a 6v "J" battery typical leg
movement is 3-7mm. Battery-powered leg movement was unchanged
after the test.

Anyone may build and use Stiquitos in any quantity for educational
or research purposes, but Indiana University reserves all rights
to commercial applications. Part 1 of the technical report is now
available and can be obtained in two ways:


Use anonymous ftp to obtain the technical report free. IU's
ftp site is: (

Log in as "anonymous" with username@host or "guest" as a

I've split and compressed the PostScript & raw Word 4 files, and will
do the same for the .hqx version if necessary. If you have problems
with timeouts, our net guru, Bruce Sheu, has kindly offered to help.
Send him mail at

The reports are in /pub. Set the ftp mode to binary to access the Post-
Script and raw Word 4 files: (restore with uncompress, cat)

stiquito.w4.aa.Z (restore with uncompress, cat, uudecode
stiquito.w4.ab.Z to get a MacBinary Word 4 document)

stiquito.hqx (stuffed, binhexed Microsoft Word 4 for Mac)

Unfortunately, some of the illustrations in the PostScript
file print with minor errors (patterns missing, and some
polygons deformed), but they are still understandable.

2. BY MAIL (with options for a kit and a videotape)

Send your request for the report with payment to:

Computer Science Department
215 Lindley Hall
Indiana University
Bloomington, Indiana, 47405, U.S.A.

To receive the technical report only send $5 US PRE-PAID and
add the following line to the address:

ATTN: TR 363a

To receive the technical report and a kit containing all
materials needed to construct Stiquito and its manual
controller send $15 US PRE-PAID. Add the following line to
the address:

ATTN: TR 363a Stiquito Kit

The kit alone is available for $10 US PRE-PAID. Add the
following line to the address:

ATTN: Stiquito Kit

The charges cover materials, a kitting fee, the technical
report, and mailing. The kit is provided as a non-profit
service by Indiana University. The author receives no fee or
reimbursement from the sale of the kit.

The CS department has also videotaped the assembly of a
Stiquito (including the author making some mildly
embarrassing mistakes during construction! :-). It is
available separately for an additional $10 US PRE-PAID.
Just add VIDEO to the attention line.

For example, if you purchased the TR, kit, and video then
$25 US would be enclosed and the following line would be
added to the address:

ATTN: TR 363a Stiquito Kit VIDEO

Part 2 of the technical report, "Sensors and Controllers," is in
preparation. It describes analog and digital controllers, legged
Braitenburg vehicles, and sensor and communicatons interfaces to
Stiquito. Part 3 of the technical report, "Experiments with
Arthrobots," will describe a variety of arthropod robots and
report on experiments in emergent cooperative behavior using a
colony of Stiquitos.

Questions about Stiquito should be sent to

There are many different ways to design smaller, larger, or
multiple-degree-of-freedom nitinol-propelled robots, legs,
tentacles, grippers, etc. Some we've tried, most we haven't. We
hope you will be encouraged to use Stiquito as a stepping-stone to
better and more effective miniaturized robots.


This research was funded in part by NSF Grant MIP-9010878
"Lukasiewicz Logic Arrays" awarded to J.W. Mills, and NSF Grant
CDA-8852304 "Incubator Laboratory Development" awarded to D.
Gannon, G. Rawlins, and J. Smith. NSF's support is gratefully
acknowledged. Standard disclaimer for opinions, etc. expressed in
this posting.
- J. W. Mills "Sic ago!"