Project image
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$3,557
pledged of $15,000pledged of $15,000 goal
24
backers
0seconds to go
Funding Unsuccessful
The project's funding goal was not reached on Thu, June 20 2013 4:03 AM UTC +00:00
Paul SandinBy Paul Sandin
First created
Paul SandinBy Paul Sandin
First created
$3,557
pledged of $15,000pledged of $15,000 goal
24
backers
0seconds to go
Funding Unsuccessful
The project's funding goal was not reached on Thu, June 20 2013 4:03 AM UTC +00:00

About

Introduction

Today, anyone who wants to develop a mobile robot must either design and build their own mobile base, or pay many thousands of dollars for a research robot before they can start working on their robot concept. There are no inexpensive mobile robot bases big enough to hold widgets sized to do real work.

Butler answers that need. Robot designers will no longer have to keep reinventing the wheel(s).

I have been designing and building robots for 20 years at companies such as RedZone Robotics, iRobot, and Harvest Automation. The idea for Butler came about when I noticed that smartphones with their built-in sensors, and ever more powerful micros like Arduino, Raspberry PI, and the Beaglebone Black, were being used for robot brains for much less cost than it takes to design, build, and test a custom electronics board and integrate sensors. This advantage opens the doors for a much larger community of robot developers because it reduces design effort, risk, and cost. What is missing though, is a low cost robot base big enough to hold large contraptions, robot arms, lift-tables, large monitors, follow-me grocery cart, whatever you want to be mobile.

Whether you are a hacker, maker, hobbyist, parent of a budding young roboticist, teacher, professor, researcher, or engineer you will find that it provides a useful tool that will save you money and speed up the development of your robot idea. Butler has simple attachment points and is strong enough to carry anything you want to put on it.

Paraphrasing A Roadmap for U.S. Robotics From Internet to Robotics 2013 Edition: “rapid progress toward the goal of deploying mobile and dexterous robots in human environments to enable coexistence and cooperation will critically depend on the broad availability of adequate research infrastructure, including hardware and software.”

Butler is a major part of that hardware and will make it faster, simpler, and cheaper for robot developers like you to design and test new robotic applications that provide real value in homes, offices, and work sites, so that the robot revolution can finally take off!

Description

Butler is about a 20 inches wide and 8 inches to the top of the platform. It travels at walking speed, and is steered with the now-classic robot steering method called differential steering (also tank steer or skid steer). The back end of the roughly triangular shaped chassis is supported by a low rolling resistance non-marking caster. A bit of trivia: The Butler logo and the shape of the chassis is based on a Reuleaux triangle, a "Curve of Constant Width".

There are brackets under the chassis to hold two 7 amp-hour 12VDC PowerSonic 1270 lead acid AGM batteries. This battery chemistry was chosen because it is low cost, simple to charge, and robust. Batteries are not included because they would cost too much to ship. It is up to you buy, install, and connect the batteries to Butler using the simple spade lugs on the batteries. There is a convenient screw terminal strip to connect the batteries, cliff sensors, and the motor controller to your micro. The strip also has 5VDC, 12VDC, and 24VDC outputs.

The gearmotors are equipped with quadrature encoders that provide about 1/8” position resolution at the ground, and with more than 50 inch-lbs of torque per wheel will easily move heavy loads. Butler has a simple set of mounting holes designed to make it as easy as possible to attach whatever you want, anywhere you want on the chassis.

The chassis has a cliff detector in front of each wheel to prevent driving off steps, and motor current sensors for both motors. Also included is a powerful RoboClaw motor driver that can provide closed loop speed control. Butler can drive anywhere indoors (except stairs), and also outside on pavement, grass, and gravel.

High level control of and communications to your widget is handled by your smartphone, tablet, or laptop, lower level stuff like not driving off a step can be handled by any of the many available microcontrollers (Arduino, Spark Core, Hydra, LPC mbed, Phidget, Propellor, PIC, Raspberry PI, STAMP, Beaglebone, etc.). It is assumed you will write your control code as an app on your smartphone, but nothing prevents you from using a micro by itself, or even a tablet or laptop strapped to the top of Butler that talks directly to whatever you have attached to Butler, and to the RoboClaw motor controller via the screw terminal strip.

What the funding will pay for

You can be part of this revolution! Any amount pledged to this campaign is gratefully appreciated, not only by me, but by those who will use Butler. The funds I make from this campaign will pay for parts and materials for at least 15 Butlers in various versions. This quantity will reduce cost due to volume discounts. I will make every effort to minimize the cost of Butler and build as many as I can from whatever funds are raised.

Non-financial help will be welcomed when Butler goes into production, but it takes money to get to that point! Thanks in advance. If you can’t contribute, that doesn't mean you can’t help. Please share this campaign with your friends on Facebook and twitter, and with your contacts who you think might be interested in this project.

Here is a high level breakdown of what the money will pay for.

  • Chassis parts and materials for 15 Butlers, plus spares.

  • Sheet metal fabrication and 3D grown parts

  • Storage racks to hold all those parts

  • Assembly and test Labor

  • Packaging

  • Shipping

Several versions of Butler will be made. The Basic version is just the chassis with wheels, gearmotors, and encoders. The fully equipped Butler has 6 sensors, the screw terminal strip, and the motor controller. If we make a stretch goal of $45,000 I will add a Spark Core version of Butler and hire someone to write robot behaviors for the Arduino in the CoreA larger version of Butler with bigger wheels and more powerful motors is also planned.

Status, When, and Where

Butler is loosely based on early prototypes of Harvest Automation’s HV-100 robot, all of which I designed and built, but is far simpler. I was part of the effort to turn the HV-100 prototypes into product and then shipping them, so I have experience with that part of the process also.

The picture below shows the prototype I built to confirm that critical features were properly sized. Things like caster and drive wheel(s) diameter and width (a compromise of rolling resistance, overall width, mobility, weight, cost, torque loads); and platform height, length, and width (again a compromise: the goal was to be as big as possible but still easily fit thru interior doorways, be easy to carry preferably with one hand, not so tall that it tips over, etc.) were evaluated.

The prototype was lighter than the sheet metal production version will be, so I added weight to it for mobility testing.The small caster turned out to cause mobility issues on some surfaces and terrains, hence the larger caster on the production version. The prototype had a simpler motor driver which mounted was on top as shown, but to leave the top clean, I mounted the RoboClaw motor driver underneath.

Butler carrying the first version of Roomba!
Butler carrying the first version of Roomba!

I am finishing up the details of the production version of Butler in my home office in Brookline, NH. I plan to build and test Butler here also, saving the cost of renting a space. I will work nearly full time on Butler once funding has been received, and expect to have the production version running around by late summer time, then ready to be shipped by fall.

Risks and challenges

I have been designing mobile robots of about the size of Butler for 20 years. This, in combination with the fact that Butler is designed to be simple and robust, reduces mechanical design risks to a minimum.

The electrical layout is really simple, basically just wiring, but if problems arise I have the help of two electrical engineers with many years experience, to whom this design will not be much of a challenge.

Sheet metal fabrication will be done in New Hampshire by a well-known short-run manufacturing company located just a short drive from my office.

Assembly will happen in-house, literally. I have a large basement and barn that will be set up to handle assembly, testing, and shipping. Butler's simple design and relatively few parts simplifies and minimizes risks during the production process. Simplicity is in fact one of the main goals of the design for just this reason!

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    Pledge $10 or more About $10

    A big "Thank You", and recognition on the blog and website as a supporter!

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    A foam promo robot with the Butler logo!

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    All promo items!

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    Early bird special! Get a Basic Butler: heavy-duty sheet metal chassis, wheels, motors with encoders, and chain drive!

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    Basic Butler: chassis, wheels, motors with encoders, and chain drive

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    Butler B2: Basic plus dual motor driver (not wired)

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    Butler B3: B2 plus fenders/chain guard, cliff sensors (not wired)

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    Butler: B3 plus obstruction sensors, motor current sensors, cabling, and screw terminal block (wired)

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Funding period

- (30 days)