My interest in robots goes back over thirty years. During that time I have built a few mostly not very successfully. I gave up when my eye sight started giving me too much trouble and I found it too difficult to make reliable solder joints. At that time I would build them from scratch starting out in my garage building the mechanical parts then inside to design and build the electronics. I still have many of these lying around in boxes some place if they survived and not been scrapped for parts and rebuilt into the next project.
Recently I discovered Lego not the blocks you may have played with as child but the technic series with its stud less construction and mindstorm programmable controllers. In particularly MINDSTORMS NXT set. There are several advantages with using Lego technics like the speed of construction, no need to spend days machining up parts out in the shed. A wide variety of gears, beams and wheels available etc. Unfortunately I soon discovered one big disadvantage with using Lego to start a new project I would have to dismantle my last. Even though I have now got a large collection of technic parts and two NXT Bricks.
Due to the short life span of my Lego projects I have built I have documented some of my more interesting robots. Hopefully this will give me the chance to rebuild them at a later date and help to inspire others to create even better robots.
Like all good Lego NXT owners this was one of my first designed and built robots. It worked well with front wheel steering and two back wheel drive motors. Programming the steering was tricky as there was no feed back as to where it was pointing. I over
came this by turning to a hard lock and then coming back a known distance to centre.
I have always wanted to build a tracked vehicle so soon after getting my NXT I purchased another Lego set with four rubber tracks. This was my first project using these like above
its a simple rover type bot. Although it worked well it had very little ground clearance and not very strong.
Following on from the tracked vehicle I rebuilt it strengthening it as I went and adding the claw to the back. Placing the light and ultrasonic sensor just behind the claw. I then programmed it to search for the Lego ball, grab it and return back to start point.
From this project I discovered the US sensor was very short sighted and could only see the ball some 400 mm away at best.
After the two previous projects I decided to have one more go at a tracked vehicle. The objective was to see how small I could make one as well as getting better speed and ground clearance. It ended up so small that the only place for the NXT brick was on top.
The other objectives were successful.
Car with Suspension
This was one of my less successful projects. It grew too heavy for the Lego motors to propel it along even with two drive motors. It was therefore abandoned before completing the remaining car structure. Even so it did fill my design brief in that it
had full four wheel suspension with rear wheel drive and front wheel steering.
This was my first attempt at making a 6 legged walker. The design was not mine. I copied it from a picture on the net. Unfortunately I have now lost the link to the original. Although it worked it was very slow and not very efficient at walking.
This project was based on the Landmaster truck in the 1979 move Damnation Alley. The Tri-star wheeled machine has been my largest project so far. It took a lot of rebuilds to get the gearing system to work. Then to track down enough parts to build four sets.
Getting it to track in a straight line and turn was fun. If anything went wrong it would spit out broken gears.
Another small rover type vehicle this time with four wheel drive and full suspension this
used skid steering. I was surprised that the chain drive used to drive the rear wheels worked so well Was expecting the chain to brake under load.
I have never liked the way the NXT brick always looks like it has been stuck onto a project as if it was an after thought. Its large size and need to asses the battery's and control buttons is the reason for this. My farm truck was an attempt to integrate it more into the build. To add a little more interest I also gave this truck four wheel steering.
Weight once again became a problem thank goodnes we now have the power function XL motors.