Analysis showed that the 8 bar walking mechanism was the most viable solution. A prototype of such an 8 bar mechanism was developed to demonstrate its resultant walking gaits. The prototype contains vertical and horizontal slots in the baseplate's mounting location for one of the grounded rotary joints. This allows the position of the joint to be adjustable relative to the other grounded joints. Scaled index marks on the baseplate allow for precise placement of the adjustable joint. The prototype is a scaled up model of the 8 bar mechanism to be used in the final design. The increased scale makes differences in the gait more obvious. The prototype 's baseplate has an attachment area for trace paper under the travel of the "foot". A marker will be fixed to the foot, tracing the path of the walking gait.
The images below below show the fabrication of the prototype in process. All parts were laser cut. A Test Strip of 20 holes ranging in size by increments of 0.001" diameter was made to find the best diameter for a good joint fit. This determined a dimension for the holes that prevented excessive play, but allowed the joint to move without binding due to friction. The joints in this prototype are 1/4-20 bolts, with washers between each moving part, and a locknut. The locknut was not tightened to the point of clamping the parts together in order to maintain their freedom of movement.
In addition to the laser cut links, a few 3D printed spacers were used where necessary to achieve the required clearances between legs. A CAD model of the complete prototype is shown below.
