v1.0
flickr:3951203382

This is the first in a series of PC based robots I built with the name Lazlo. I worked on him around 2000-2001 time frame. I never fully completed him, but did get far enough to run autonomously with simple object avoidance. I bought a house and didn't work on him for a long time. When I got back into robots, I had smaller & faster PCs, better sensors, way better motor controllers, etc to play with at the time and rather than modify v1.0, I thought I would use my new shop at my house and build v2.0 from scratch using an all aluminum frame. Looking back, I should have just stuck with v1.0. :)

Chassis

Probably one of the most complex designs I've attempted at the time, I designed him with stacked hexagonal plates with an enclosed electronics box in the center. The box was vented and had a fan for air flow. The large (car battery sized) battery sat on the lowest platform, to keep center of gravity low, in-between the drive motors. The top platform was going to house some kind of head with additional sensors, cameras, antennas, etc.

I also had a channel cut out of the front where an arm would be mounted on a linear slide so the base of the arm could travel up and down the height of his chassis. The arm could also fold itself into the chassis so not to be sticking out when not in use.

The main components of the frame were made from plastic that I glued together with a strong etching glue. In addition, there were 4 threaded rods that 'clamped' everything together. To provide additional strength for the heavy battery and locomotion motors, I built an aluminum frame on the bottom plate to take the load.

Locomotion

I used a differential drive system mounted in the center line of the robot so he could spin in his own space. There was a caster wheel on the front and the back, one of them on a crude spring suspension mechanism to allow him to travel over uneven terrain without high centering one of his wheels.

The motors were very nice swiss motors I found that where surplus (supposedly used in hospital beds). They didn't turn very fast, but with 8 inch wheels, they were fast enough. I really liked these motors. Only downside may have been their size in some applications. But I liked them for many reasons…

  • They were energy effcient…
    • 200ma no load.
    • 400ma moving Lazlo over carpet.
    • Stalled around 3 amps (which was almost impossible as they were extremely powerful).
  • Worm gear driven so they locked when no power was applied.
  • Practically no slop. At 4 inch radius I got maybe .5mm free-play.
  • Extremely silent, even under heavy load.
  • Output shaft mounted on ball bearings making it suitable for load bearing.
  • Extremely powerful. I once put 100 pounds of weight on him and could not find a surface (even rough concrete) that could generate enough traction to stall the motors. In one test the motors rotated the metal sub-frame and snapped the plastic of the lower plate rather than stall or spin the wheel, and they only hit 2 amps during this!

Electronics

I've long since lost track of many of the hardware specs. But he ran an Intel PIII motherboard powered off an AT power supply I found that ran off 12v DC. There were two large relay boards for powering the motors (just had on and off) that were connected to a very simplistic motor controller board that interfaced to the PC.

The battery was a large sealed lead-acid 38Ah battery that was the size of a car battery. The PC drew about 4 amps so in total I could get about 6-7 hours of runtime depending on use.

I had a 6 amp battery tender mounted to the chassis and hard wired to the battery. It supplied enough power to be able to run the PC and still charge the battery (of course slower than when PC was off). The battery tender is electronically controller so you could leave it plugged as much as you wanted without worry of damaging the battery.

Video

This is the only video I have of Lazlo. It's of him running around my old apartment with a simple wired controller I had made for him so that I could manually move him without the PC running (he was very heavy) and was testing it out when I made the video. The video has no sound and shows him performing turns, driving over objects, and even pushing heavy items around.


You can also download the original WMV file. It's a little over 6MB. Download

Photos

(click photo to see larger version and description)

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