ROBUST DESIGN WITH PREDICTABLE PERFORMANCE: A THREE-LEGGED CHAIR

The performance of a three-legged chair is predictable in the sense that it will never rock, regardless of production tolerances of the legs and the conditions of the surface on which the chair is placed. The three-legged chair is an example of Robust Design. The robustness is due to the fact that the structure is a statically determined system with no over-constraints.