4WD: my base for development

Let's Make Robots Robots
1

Hello fellow LMRians!

This robot is in progress but I hope that it will be driving by Christmas - but that may just be wishful thinking. 4WD (pronounced Forward) will become a moving base for other projects, and will constantly be having upgrades; however the basic sensors when I get it moving will be 5 ultrasonics.


Right now it's just an over-ambitious box.

The box
The box4000×3000

 

The body is made from soffit board - very versitile stuff, I highly recommend it for any kind of build! It's very strong, but also flexible, it's waterproof and shiny, and best of all - cheap!

 4WD has motors (that's about 100 dollars of the total cost already!) bolted under the body, hidden inside piping.

Piping
Piping800×600

 

 

 


To attach the motors to the body I had to drill holes in the 'runners' to fit the motors through, and then bolt the motors onto disks of metal, and then screw the disks of metal onto the body.

[picture of the fitted motors]

The wheels (old rc rock crawler wheels & tyres) are bolted onto disks of soffit board that fit in the inside rim of each wheel, then the disks in turn are bolted to meccano pulleys. (this is because the pulleys accept the same 4mm shaft as is the output of the motors)

[picture of the wheel attached] [picture of the wheel's connection design]

This may be a weak spot - there is only a small grub screw holding the wheels to the body. Also, because the grub screw is on one side a wobble in the wheel's rotation may develop as the pulley is pushed to one side of the motor's shaft slightly. We shall have to see.

One of the aspects of this 'bot that I am keeping at a maximum is strong, rugged design. I want it to be able to drive outside over stuff without cowering as soon as it sees a rock!

A display, 5x ultrasounds and 2x motor drivers are in the post, I will update this page when they arrive and I start playing with them.

Senses with ultrasound, 4 powerful motors to give it 4wd

  • Actuators / output devices: Wild Thumper 75:1 motors and gearboxes
  • CPU: Arduino Uno Rev3
  • Programming language: C++ for Arduino
  • Sensors / input devices: HC-SR04 Ultrasound
  • Target environment: Indoor/Outdoor
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/4wd-my-base-for-development
2

No offense but

No offense but if you’re new to robot building (you did say your first attempt didn’t work) then why re-invent the wheel by writing your own library for the ultrasonics? If you go with tried and tested code you’ll have a better chance of having the finished project actually work.

3

Well, just today I got the

Well, just today I got the code for the us library working! I might look into other libraries.

4

do you know what is the

do you know what is the brand and model of your soffit borad ?

where did you buy it ?

 

you said you going to have 4 motors for a 4WD robot, do you expect to control the speed of each motor ?

 

5

Soffit

I bought it at the local builder’s merchant. It is just soffit, bog standard soffit! You can buy it almost anywhere. It is actually designed for protecting the walls of houses just under the roof. That’s what I like about it - it’s designed for very large scale length, so for the robot builder’s needs it is quite cheap. Here’s an example source:

www.pvccladding.com

6

The motors

I will use some basic h-bridges from eBay. I won’t have motor speed control. This is just because I do not want to spend very much money. I may upgrade to proper speed control at a later date. Thanks for your interest.