## Sensitivity

No matter what kind of engineer you are, or what systems you are working on, your projects will have sensitivities. In simplistic terms, sensitivity is a measure of how much changing an input will vary the output. From a mathematical point of view, you can assign coefficients to describe how important each input is, and generate a model of your process. From a practical point of view, this means it’s important to understand which factors in the project you are working on are the critical factors. For instance, let’s take making biscuits as an engineering project. Making basic biscuits is a fairly simple, well-known process. There are only a few ingredients, it only takes one bowl, and cooking only involves popping them in the oven. So what parameters do we have in our process? For the purposes of the example, let’s make a short list (although there can be many more):…

## Flexure Design

I talked a couple weeks ago about how you can design fixtures and constraints for holding pieces in precise alignment. But not always do you want machine pieces to hold still – sometimes you want them to move. If you want pieces to move a long way (also called “large range of motion”), you can use things like bearings, slides, and gears. But because I work in the precision world, often I want things to move only a small amount – a millimeter or less. (This is much the same as you would use bolts or clamps for fixturing a non-precise machine, but I need to use kinematic couplings for micrometer precision). So I thought today I would talk about designing flexures. And because I came down a little harder than I intended on theoretical engineers last week, I’ll show the modeling I use to design a flexure. (I do…

## Courage & Conclusions

There’s been an interesting back and forth on here where Miss Outlier discussed the conflicts of the theoretical versus the experimental in the week where we discussed interdisciplinary engineering and our struggles therein. Miss Outlier expressed her own point of view in working with theoreticians. Cherish then responded with her post the model engineer a sort of defense of simulations. This was on my mind lately as I had a few separate pieces of analyses that I had to complete this week. Last month I asked the question of whether a design can be too robust. I talked about the issues inherent where an engineer is expected to make predictions on the future. Sometimes predictions that have critical safety connotations. These can be terrifying, especially to an early career engineer. In my experience I’ve been asked to do analyses that fall into two separate categories. The first is a theoretical prediction…