Probabilistic Design for Optimization and Robustness for Engineers

6 Desirability

6.1 Introduction

In nearly all product design decision making, designers and managers must consider multiple requirements. Sometimes optimizing these requirements may be done independently, but often they involve trade-offs with other requirements. Consider the case of designing the portable 3D scanning equipment for measuring solid objects shown in Figure 6.1. Customers may desire a large field of vision to reduce the time for data capture. Customers may also want to reduce the size and weight of the equipment and maintain flexibility and portability for measuring objects of varying sizes in different environments.

Figure 6.1 Measuring an object with 3D scanning system.

We use this simple example to highlight challenges with multi-response optimization. For this scanning system, to improve the requirement metric, field of vision, the focal distance between cameras may need to be increased. This, in turn, may require increasing the length of the scanning equipment. If the scanner is too long, this reduces its portability and flexibility for measuring different objects in different usage environments.

To further complicate the design process, some potential customers may place greater importance on increasing field of vision (e.g., an aircraft manufacturer), whereas others may place a greater importance on portability (e.g., a headlamp manufacturer). As such, ...