Let's Make Robots!

Simple motor control for Mr. Basic

I have seen a few people asking questions about controlling Mr. basics motors. One problem is that they draw more current than an L293D can handle. A L298N will do the job but you will want at leat 6V. Below is a schematic of the simplest way I know of to control your motors. Using a 5V relay you can run from 3.6V to 6V. I suggest a 9V relay if you want to use 7.2V.

Cheap Sonar

One of the most important parts of a robot is it's sensors. If it cannot sense it's surroundings then it cannot respond. Unfortunately good sensors are usually expensive. For this reason I am always experimenting with cheaper home made alternatives such as my light up antenna, conductive foam touch sensor, IR obstacle detector and my not so successful laser range finder.

Robot arm design, my ideas and progress so far.

Armpic2.jpg

Building an arm for your robot can be the hardest part of robot design. There can be many different designs besides a humanoid design. For example you might have a CNC style XYZ axis or even a tentacle design where multiple joints are surrounded by cables. For BoozeBot I've decided to go for a humanoid design because I would like him to be able to pick things up like a person would. Reguardless of your design the first problem you are likely to face is strength vs weight.

And now for something completely different!

** Update **

I delivered the gun to KJ precision engineering for testing. It has been named "Soldestroyer" by my former boss.

 

Building the perfect robot power supply

One thing most robots need is a power supply that can put out a reasonable amount of current for servos and other small motors as well as run a processor and sensors. Probably the best setup is 5x 1.2V NiMh cells to provide 6V for motors and servos with a low dropout regulator providing 5V for the processor and sensors. Unfortunately this isn't always practical. Sometimes you have motors that need higher voltages or maybe the only battery you have lying around is a 7.2V battery from a RC model.

Death of a tripod, a polymorph tragedy :(

This was my camera tripod used for videoing my robots at ground level.

Tripod_with_camera.jpg

After videoing Turbo Trike I left it in the car by mistake. I forgot all about it. After the car being in the hot sun for nearly a week, I found my tripod like this............

Tripod_meltdown__small_.jpg

H bridges and transistors

There have been a lot of questions lately about transistors, NPN vs PNP, Bipolar or BJT vs FET and their use in "H" bridges. I had considered doing a tip/walkthrough on the subject but typing "transistor" into google gave lots of great results. Same happened when I typed in "H bridge design". I realised I would be wasting my time writing a tip/walkthrough on either subject as there is better more detailed explainations already available. So for those who are afraid to google I present these links.

Laser Range Finder MkII

This is my second attempt at a homemade laser range finder now with video. I nearly gave up after hearing about the Sharp IR sensors but I think this has potential as it focuses on an area the size of a laser pointer spot. The other sensors work on a much larger area. After a lot of frustration I've finally got all the circuitry working properly and hope to have a video posted as soon as I work out one last difficulty. Click on the photo for a full sized image. This is a work in progress, not a finished product.

Make a reusable robot base / power suply in 5 easy steps

Every now and then I want to test a circuit or a new sensor or even some new idea for code but I don't have a starter kit or anything. While shopping for some robot parts I had an idea for a simple base that could be my equivalent of a starter kit, a power supply and a small robotic platform. This is what I came up with in 5 easy steps.

 


Step 1:

 

Robot_base_1.jpg

Homemade Laser Rangefinder

My laser range finder got a lot of interest so I thought I'd try to explain it in more detail.

Laser_rangefinder.jpg

It's not finished yet as it still needs to be mounted on it's stepper motor with a home position switch.

The sensor side has been tested on an oscilliscope. When I moved my hand in front of it, the pulse width varied to match.  Below is a diagram showing how the sensor works.