The beams that the US sensor uses to measure from Right:
US sensor mounting
this controls the adjacent motor changing its speed depending on the distance between
each section. Thus keeping two section in line and moving in a strait line. Left:
The fixed hinge between sections this allowed it to turn but kept the two section level
yet gave it the ability to twist and flex enough to allow it to limb. Right:
Tri-star stepping up and over a set of steps.