Walker moves by inching himself along on his arms - or legs. Each one is a little more than long enough to reach to the floor as it rotates around to the vertical. This slightly raises his torso and pivots it a bit forward. Then the arm on the opposite side comes around and does the same. And thus he sashays along.
One leg was purposely made longer than the other to constrain Walker's excursions to a small circle in one corner of the living room. That way we know more or less where to look out for him when we are walking around.
There is a short video showing him in on one of his afternoon waddles.
Step 1: CSS555 Solar Engine
Step 2: Walker's Motor Unit
Step 3: Walker's Base
Step 4: Lower Assembly
The solar engine circuit board is held in place by wood screws into the base block.
Step 5: Construction Details
The solar cell is an RU6730 which has an advertised rating of 6.7V and 35mA. These outputs are in full sun - output is less of course in the lighting conditions to be typically found indoors. Now the solar engine with which Walker is equipped turns on when the voltage in his storage capacitor reaches about 3.5V. The solar cell unit easily supplies this voltage throughout the day just from the incident light that enters through our windows. Even on quite overcast days, Walker goes for his strolls - it just takes him longer to recharge between walks when it is cloudy. If he happens to stop in a rather heavily shaded area, he will usually still eventually become active (in fact the CSS555 Solar Engine is particularly adept at dealing with low light situations). During his saunters, Walker slows down little by little as the voltage in his capacitor runs down. It turns off at around 1.9V bringing Walker to a sharp halt.
Walkers arms are lengths of 1/4" square wood drilled to be a tight push fit on the gear shaft. The arms are about 3" apart. The "cut and try" method determined the best lengths for the arms. The longest one protrudes about 3/8" below the base. The other arm is cut shorter to give the size of the circle in which Walker is desired to promenade - which in our case is about 15". Our Walker marches on a hard floor, but he also works on carpet if we let him. If we had thicker softer carpet, his arms would probably have to be longer. The arms are set at about 90 degrees to each other for a waddling gait, but setting them in line gives an amusing hobbling gait.
The capacitor shown in the photographs here and in the video is 0.22F which allows almost a full circle of travel in each waddle. He goes around several times when equipped with a 1F cap, but of course it takes correspondingly longer to charge up between jaunts.
Step 6: Walker Senior
That wasn't his only trip to the robot hospital. Parked somewhere on the floor during the evening hours, he got accidentally kicked every now and then. For a while, a blinking red LED was mounted on his breastplate so we would know where he stopped after his last tramp of the day (the flasher circuit described in the Electronic Paperweight Instructable is ideal for this warning beacon). It was removed during one of his repair operations and never replaced for no good reason. Because of all the injuries and repairs, Walker Sr. was showing his age, so it was decided recently to make the new more colorful Walker Jr. Now we have the two of them moving around on the floor!
Both creatures have the same muscle unit, but Walker Sr. is set to a lower gear ratio, namely 76:1, so the older guy moves a bit slower. This suits him just fine because his solar engine works in a lower voltage range. He has an Easter Solar Engine set to turn on at 2.6V and off at 1.5V. The lower voltage makes it possible to use a simpler storage capacitor. He now has a single 1.5F capacitor rated for operation up to 2.75V which keeps him going for a good long time - once he does get going!