The Evolution of Salvius - Summery until January 2012

I have been a bit busy lately but I have some very exciting improvements that I will be making on the robot sometime in the next few weeks. While going through some old photos of the robot I was surprised to see how much the robot has changed since I first started building it. Probably the most noticeable changes have occurred in the design of the robot's face. The first face I built in 2007 and it had very little mobility and contained very few sensors. In fact the only sensor it had was a single inferred motion sensor that I had removed from a toy security alarm.

Evolution of the Salvius Robot head design (1: oldest, 4: newest).
The first head design (1) was extremely simple. The dome-shaped head housed only a motion sensor alarm and had a large speaker that could be plugged into a computer to make the robot speak. That first version was radio-controlled but the receiver had to be removed as soon as the robot got more motors than the receiver could control. While researching what the best way to control the robot was a second head was being prototyped.

The second head (2) was a cardboard cutout that could be easily modified and fitted with all sorts of sensors to test them out. Two speakers were added to this head along with a webcam that could be used to see what the robot was observing. The cardboard head fixed a lot of the problems that the first head had. The first head had lacked sufficient flat surface area to mount sensors and despite its appearance it lacked the volume to contain sophisticated circuitry.

After the cardboard head was thoroughly tested a few modifications were made and it was cut apart to be used as a template to cut sheet metal pieces to make a metal version (3) that would be much sturdier. The black painted metal housing of an old cassette player became the robot's new face. Only two things were changed from the original cardboard template. The first change was that the upper portion of the head was re-measured to provide a rounder top of the head so that the head could have more horizontal interior space. The second change was that the sharp point at the bottom of the chin was completely eliminated. This allowed the head to lean further forward to look at the ground in front of it.

The third head was nearly perfect although it had a few problems with stability due to the fact that the sheet metal was somewhat flimsy and there was no real secure way to mount it on the robot's body. Because of this fact a fourth head was designed. This head (4) had a thick metal plate for the front of the face that had to be meticulously rounded out by hand in order to make it the correct shape. The ears from the previous two versions of the head were enlarged and recessed into the sides of the head to protect them and a plexiglass face plate was cut out. The face plate could easily have holes drilled in it for sensors and many more could be made to replace it. Many of the previously used sensors were moved to the face plate and securely mounted on or behind the protective layer of the plexiglass. The final thing was to create a cranium that had enough volume to hold many electronics. To do so the original plastic domes used on the first version of the robot became re-recycled by putting them together to form the curvature of the head's cranium.

The fourth head is the strongest most versatile head yet built. It incorporates all of the best features of the previous versions that were created during the robot's evolution. I found that the most important features were flat surface area for mounting sensors and lights, volume for containing electronics, and structural integrity but along with these features there was one more aspect that I was looking to accomplish more in the fourth head than in any other version. I wanted the head to look friendly. I wanted to make the robot have a face that didn't necessarily replicate the features of a human face but would still be identifiable as a head which arguably was a major flaw of the first model of the head that was built.