Most controllers are either defined based on a control law which is either linear or non-linear, how can we add an attribute for novelty with controller design.
It depends on how far your system robustness against variation and how fast to respond that variations. But almost the world is become going towards the nonlinear controller rather than linear controller due to developing of real time simulator such as OPAL-RT etc…
I believe that if a control law is so obvious that control practitioners in the field would develop it without much effort, then the publishers may find the research findings unworthy of publication on the basis of lacking originality and significance.
Every engineering problem contains at least one contradiction and you can attribute this to the improvements or enhancements offered by your proposed control scheme. You can also use the CO-STAR criteria (a mnemonic acronym that I use in my lecture) as a guide in setting the goals for your research project.
It is on the basis of the effective realization of the controller and according to a specification (type of model, performance criterion, computes parameters of the controller in real time, ...) whose requirements are increasingly strong. Filling and satisfying its conditions can only be done by such advanced control, intelligent controllers robust and inexpensive (MPC, ANFIS, NNPC, ...). Also the implementation aspect is taken into consideration by a judicious choice oriented towards the light processors.
If it involves new parameter update equation(s), or new framework in which control can be applied or Lyapunov based stability is proved of the developed control law equation.
With the growing global demand for smart automation and mechatronics, the control design specifications and requirements get stricter (as mentioned by Prof. Lafifi), and it is not easy to come up with a novel controller. The key is to search for significance.
Now, drawing insights from your project goals, here are some thought-provoking ideas for the design and development of an advanced controller with novelty values for
sextuple (or higher) inverted pendulum system,
multiple inverted pendulum system of different fixed lengths (static),
multiple inverted pendulum system of time-varying lengths (dynamic), and
stair-climbing biped locomotion which applies gravity-compensated inverted pendulum mode.