Writing better software is a good start. Recognizing the difference between regulation and tracking For linear control systems, regulation and tracking are essentially identical. For nonlinear systems, and particularly motion control systems , the problem of tracking is significantly different and considerably harder. The role of trajectory generation is very important in nonlinear problems and is the motivation for much of our work in differential flatness . Exploiting special structure to analyze and design controllers You can't build a theory for nonlinear control that works for everything.
Nonlinear systems are a lot more complicated than that.
Concentrating on special classes of systems, like mechanical systems and propulsion systems , is the most likely way make significant progress in synthesizing nonlinear controllers. Integrating good linear techniques into nonlinear methodologies People who work in nonlinear control need to figure out how to make use of all of the latest advances in linear control techniques when they apply. This is what we are trying to do on the ducted fan and is the basic idea underlying two degree of freedom design 5. Recognizing the difference between performance and operability One of the things that nonlinear control can do is increase the range over which a system can run without catastrophic failure. This is different than providing good performance and is a particularly hard problem because you have to know about the global behavior of the system in order to define something like operability.