GOFIRST regularly has engineers or other professionals come in and speak to our group for our general meetings, and today we had an engineer from Boston Scientific who gave an excellent presentation focusing on this exactly (his day job is designing pacemakers and other implanted medical devices). He had a few things which I think are particularly applicable to competitive robots:
1: Understand when reliability is needed, and what the acceptable threshold for reliability is.
He related this back to developing consumer versus “mission critical” equipment, but I think it’s particularly relevant in the context of robotics where 100% often isn’t actually feasible for a variety of reasons. If failure isn’t a huge time sink, designing something that can do the thing multiple times very quickly might actually be a better option than trying to design something that is 100% reliable (and inevitably failing).
2: Fundamental simplicity is better than any level of complexity.
His example for this was a manufacturer who had a laser device for which the lens changed its focal length between operating temperatures (-20 to 100 degrees celsius). The solution that worked best wasn’t adding thermal sensors and a control loop, but making the stand out of a material with similar thermal expansion properties as the lens, which automatically kept it at the right length. On robots, this is sometimes more difficult to catch, but think of some of the most famous/well designed robots out there-- like 1114’s Simbot SS, which have a fundamental simplicity and functionality to them.
3: Understand modes of failure and alleviate or plan for them.
Often in FRC this means building a part more robustly or more intelligently, or bringing back ups. It also might mean using COTS parts and building in the design to easily remove and replace critical subsystems. I believe Nemesis (2590) has designed robots for which the drive rails are replaceable, which may be an example of this.
There’s my small digression, but next up is my personal opinion from someone who has only designed one subsystem that I consider to have been 100% reliable during competition (2220’s 2014 drive train). So take it with a grain of salt since I am definitely not the most qualified person on here to be speaking on this subject.
I think Tom hit on the core of it with his last point: consistency is about planning. Not just planning in the general sense, but knowing what can and should be planned for. Sure, a complete failure to plan can ruin your day, but so can putting too much time and effort into planning/designing for things to go wrong when the most effective solution might be to cut your time and make an extra plate or part. And ultimately that knowledge comes from being willing to learn from your experiences.