How to Build a Mobile Robot OR, Better Still: How NOT to Build a Mobile Robot

Tom CarrollRobot Builder’s TYPICAL QUESTIONS

* Wheeled or Tracks?R/C or Autonomous?

Large or Small Robot?* Nuts & Bolts or Welded?

* Mounting Wheels to Robot?* 2, 3, 4 or 6 or more Wheels?First Timer or Experienced?

Wood, Plastic, Aluminum or Steel?* Keeping Wheels Contacting Ground?

* Mounting Wheels to Gearmotor / Servo Types of Arms & Mass Compensation?

* Gas Spring & Infinity Cable?* Types of Steering?

Easy or Complex?Using Gears?

April 1984 Popular MechanicsCharlie by Jim Hill

Made by using only Hand Tools

Jim was a auto dealership

Parts Manager and the

only power tool that he

used was a power drill

Boy’s Life- magazine for Boy Scouts

I was a scoutmaster at the time that I wrote this article and my twin sons, scouts, help me design a robot that could be built for under $50 from a trashcan, two surplus dual motors and Radio Shack items

Gismo-2-BL was

made from a

trashcan and

simple parts

available at Radio

Shack with the two

dual motors (for

Wheels and Arms)

obtained from

Surplus ‘Big Track’

motors

Fellow SRS member,

Pete Miles and I wrote

this book on Building

Your Own Combat

Robot

We’re still getting a few pennies tossed our way from McGraw Hill

I mentored Ridgefield Middle School Students in a Robotics Club

They had used LEGO Mind storms in the past and wanted to design and build their own robots

We used VEX and ServoCity parts

Stars ‘Build’ Robot for:

Living in Southern California, 20th Century Fox had heard of me and asked me to build 4 ‘action prop’ robots for a new film. I gave them a quote but they hesitated, and suddenly said ‘go for it’ and tossed any amount of money that I asked for to complete the robots.

First, a foam board mockup for dimensions, then go for the mechanics- base structure, wheel chair motors, driver electronics, large Gel-cells, terminal strips & wiring harnesses.

Dail DeVilleneuve of Vantec

supplied the modified 18-channel

R/C system and the electronic

speed controls. (note- the 12 key

keypad on the transmitter and

the KeyKoder in his other hand)

I had worked with Dail in the past

on many promotional and movie

robots. His Vantec systems hold

up better than most other

systems, especially when set

decorators and prop operators

are using the systems.

One of the completed Revenge of the Nerds Robots.

Two ‘action prop’ robots (full

electronics and motorized wheel)

and two ‘non-action’ props that

looked identical were built.

The ‘jocks’ in one scene wrecked one of the action props when they sacked the house of the nerds.

I’ll discuss the arm mechanisms later.

Beverly Hills children’s dentist, David Powell asked me to build an action robot for his office.

I used similar control systems that I used on the Revenge of the Nerds robots, but this robot was taller and bent at the waist.

Unlike a movie prop, this robot had to withstand years of use by his office staff entertaining children in his waiting room.

Yellow Arrow Points to Spring-Loaded Wheel Caster to prevent ‘High-Siding’ of Robot’s Wheels on Uneven Ground.

We’ll Look at Another Design Later

The DCP2000 robot, as it was called,

bent at the waist, its arms and head

moved and it had a moving LED sign

display in its chest. The arms did

not bend at the elbows as did the

Revenge ‘bots.

I hired two out of work friends to

work out of my garage (I had my job

at Rockwell) and we had to form two

different Fiberglas shells in case he

wanted to change the robot’s

‘clothes.’

TV Journalist interviews David Hanson’s Philip K. Dick Humanoid

Ken Maxon and one of his amazing robots

Beautifully machined wheel hubs and mounts

More Machine Work

Ken’s new CNC Mill

Dave Shinsel

introduces his

robot, Loki to the

Portland Robotics

group about 5 years

ago

Dave scrounged

parts from all sorts

of places, such as

Campbell Soup

cans for the eyes

Mark Curry

and his SRS

RoboMagellan

Robot, Nomad

Seattle

Robotics’

RoboMagellan

contest at the

Seattle

Center on a

sunny day!

Carol Hazlet & a few of her Friends

Unique Robot

construction

Welded rebar

and ServoCity

Actobotics

structural

channels

Tetrix Channel

ServoCity Channel

Aluminum Tile Transition metal Strip

Basic Parallax

Propeller-Bas

ed ActivityBot

Parallax

Propeller-Ba

sed

ActivityBot

With many

add-ons

Mars 2020 Rover

Note: 6-wheel Rocker Bogie Arrangement &Differential Bar at top of robot

Rocker Bogie

Mobile Robot

with Differential

Bar

Students Trying different Wheel Assembly Designs for their Robot

Final Designs

for the Wheel

Assemblies

Four of the

Wheels Steer

and two center

ones are fixed

in fore-aft

positions

Motor Mounted to a

Wheel

Motor

Mounted to

a Wheel

Parallax Heavy-Duty

Motorized Wheels:

Pneumatic Tires,

Machined Hubs, wheel

Encoders

Originally Designed for the Eddie Robot and now used on the Arlo Platform

VEX Clawbot using a Beam Structure

Note the mounting of the four Wheels and the Interconnecting Gear

Beam

Structure

Robot

Platform

Offers

Flexibility and

Simplicity

Parallax Heavy-Duty Motorized Wheels

Another

Simple

Welded

Platform

Using a Belt-Driven

System to Drive Wheels

Uses

Differential

Steering as

Wheels

don’t Steer

BUT

Heavy-Duty Robot Chassis with Chain Drive & Differential Steering

Inflexible Wheel Mountingnot Good

Differential Drive with Caster

Well - Designed

Shock-Loaded Wheels Will Traverse Uneven Ground Easily

Six-Wheeled Robot Must use Differential Steering (and Skid in Turns) BUT

Closer Look at Shock System and Center Channel Structure

Another Shock System and 3DP Mounts- Still Requires Skids on a Turn

Spring Loading Casters in Differential Drive Robots to Keep Drive Wheels on Ground

Remember Yellow Arrow in Dentist’s Robot Pointing at Metal Spring?

Tank Treads may look Cool and can climb Stairs and Such But they Eat Up Battery Life with Friction

Think About It

More Tank Treads

Looks Great!

Remember to Have at

Least One Caster

Spring-Loaded

Simple Differential

Steering using a Fore

and Aft Caster

Ackermann (car-type)Steering

Not Popular for Robots but Used on Model Car Racing

Note Angles of Steering Connections to Wheels and Point that they meet at Center of Back Axel

Curiosity’s

Avoid Trying to Use Gears to change Motor Speeds Use a Gearmotor or Chain / Belt Drives

Compound Gears Change SpeedsNote Middle Gear has two Sizes and number of Teeth

OWI Robotic Arm Edge $45

Using a single Motor Per Robot Arm to Raise Armin a Natural Motion

This is the Same Pulley - Cable Arrangement as Used on the Revenge of the Nerds Robot

Parallax Eddie Robot

Questions ??