Robust Design is a proven development philosophy focused on achieving target reliability. Approaching this aggressive goal requires that Robust Design principles be an early and integral part of the development cycle. The objective is to make the end-product immune to factors that could adversely affect performance. Robust Design requires that the following four factors be considered in the design process: signal, response, noise, and control.
Noise factors are disturbances that cause the systems response to shift from specification. These factors are likely beyond the designer's control, such as manufacturing tolerances, aging, usage patterns, environmental conditions, etc. Noise factors must be identified and quantified so that accurate choices can be made about which effects require compensation. Control factors are used by the designer to compensate for noise factors that could significantly influence the system away from nominal performance.
Once the critical noise factors are identified and the control factors selected, a Robust Design flow is used to implement and analyze the design to ensure system reliability. The objective of a Robust Design flow is to meet performance requirements with the highest possible system reliability and the most reasonable systems cost.
Adopting Robust Design principles to improve reliability means making system performance immune to variations in design technologies, component parameters, manufacturing processes, and operational conditions. In a Robust Design flow, these variations become the noise factors affecting system performance. The method of control for each variation may be as simple as selecting high precision components or as involved as implementing new control algorithms. The matrix of possible variations and control combinations becomes so complex that the traditional design-prototype-test flow is not practical. Designers must move their design activities to the virtual world, where powerful simulation tools support complete system design and verification using Robust Design techniques outlined in the diagram below.
Implementing an effective and efficient Robust Design process requires simulation tools with specialized capabilities. The key tool requirements are simulation support, model library support, modeling language support, and advanced data analysis. A simulator must have special, built-in capabilities for each of the steps in the Robust Design process.
