My latest "aha moment" related to product development came during a recent training class on Customer Requirements. The familiar model for medical device development dictates that we start with customer (user) requirements, translate them into design inputs, design the product, develop design outputs, and then build the device. In the end, we try to get them all to line up so that we can perform verification and validation per FDA requirements. Often, there is some other requirement that isn't really a customer requirement—be it an internal business requirement or desired product feature—that we must try to fit it into this model. In my experience, it often feels awkward labeling these requirements that don't necessarily come from the customer, but still must be included in the device design. My "aha" came when the instructor put a name to these nebulous requirements: "design constraints." Of course they are! I knew what design constraints were, but had never used that terminology in conjunction with the FDA model. For example, a surgical instrument may require a size restriction to fit in the instrument case. This size restriction is not necessarily a user need, but really a design constraint that will limit the final design of the instrument to that size or smaller. Or perhaps the device maker wants to use a particular technology for product. Alternative technologies may solve the problem; however the solution is limited to the technology of choice—i.e. it is simply a design constraint. 

While as innovators and problem solvers we generally do not like to think of "constraining" the design process, design constraints are perfectly fine to include in requirements for a new product. It is the simple fact of specifying them as design constraints upfront instead of trying to fit them into the traditional model that has opened my eyes and eased my mind. They should be called out as such and communicated to all what is really going on. They are really limiting our potential solutions. Communicating this clearly will facilitate an open discussion on the impact on the project.