Ergonomics, axiomatic design and complexity theory

Ergonomic systems must be designed to be robust and efficient in satisfying their functional requirements (FRs) and constraints. This paper deals with the application of axiomatic design theory and complexity theory to ergonomics. Axiomatic design theory prescribes criteria for the best design and the complexity theory provides means of minimizing the complexity of a system. Axiomatic design divides the design world into four domains and the design activity consists of mapping between the domains. Two axioms - the Independence Axiom and the Information Axiom - must be satisfied during the mapping process. The highest-level FRs and design parameters are decomposed until the details of the design are completely developed. Uncoupled designs and decoupled designs satisfy the Independence Axiom. The complexity theory shows that there are four different types of complexity: time-independent real and imaginary complexity, and time-dependent combinatorial and periodic complexity. To reduce complexity, the real complexity and imaginary complexity must be eliminated and the time-dependent combinatorial complexity should be transformed into a periodic complexity. Uncoupled designs are the best from the ergonomic point of view, since they do not have imaginary complexity and thus eliminate unnecessary work. Decoupled designs can create imaginary complexity and are thus less desirable than uncoupled designs. Functional periodicity can transform a system with combinatorial complexity to a periodic complexity to reduce complexity and provide a long-term stability to an ergonomic system.