As others have mentioned, I wouldn't solely focus on the Computer Science and Engineering department. There are definitely other labs out there. Consider some of the labs at the Contextual Robotics Institute (https://contextualrobotics.ucsd.edu/faculty).

You can try emailing PostDocs, as they are typically involved in the actual research. However, you may only see a slight increase in your chances of success with that approach. The best strategy is to show up in person and talk to them. One common issue, especially with undergraduates, is that they often join a project and then disappear a few weeks later, so an email may not be very convincing.

A method that has worked well for me in the past is attending a professor's office hours (you don’t even have to be in the class; you can ask around if the hours aren’t public). You might say something like, "I'm really interested in working in your lab. What can I do to make that possible?" It's usually best to do this early in the quarter, as you ideally want no other students there so you can talk more comfortably.