First interview is a general chat about your CV, skills and expertise. Second interview is technical. You get tested on Maths, OOP, a programming language (C++, Java, it's up to you), MATLAB and Control/DSP/another programming language. Third interview is again technical, but it's more based on applications and slightly tougher than the second one. Basically you have to apply the concepts of the second interview onto practical examples/exercises. So be ready to write some code, solve control problems, model physical systems. It is not extremely difficult, but you need to revise. General/vague concepts are not enough. Fourth interview is with HR. Final interview is with the hiring manager(s). It's a behavioural discussion. All the people involved in the interviews are super nice, helpful, and if you struggle a bit they walk you through the answer. It is important to show how much you care about their company and how passionate you are about the role (if you are).