Thesis project outside of advisor's expertise

I'm working on a project outside of my advisor's experise. He doesn't have background in this area (he's not familiar with both the big picture nor the basic detail). For example, it's a machine learning project, and while the first critical thing is training data, he told me to focus on finding features. Also he's not consistent with the design of solution: sometimes he want it to be unsupervised, and when I mention training data he switched to supervised system.

I managed to do the work on my own, but without the advisor's guidance I couldn't go further. I can only go to the point of reimplemeting state of the art papers and add small modification to them. Whenever I present a new idea/working solution, he couldn't criticize it since he's not familiar with the field.

How should I resolve this situation ( ask for a coadvisor etc)? I absolutely love this project and am capable of working out the solution, just need better guidance from professor.

P/S: This project is one of the main project of my advisor since he gets funding from that.