Try to get invovled by leaning in on their design disussions and sometimes add your ideas just to get involved and they may or may not like them but at least they know that you care enough to know what they are doing.
You may also want to have a "students only" meeting (lock mentors in another room) and talk to the other team memebers to see what they think. If you come to the conclusion that this may be an issue take one of the mentors to the side and question them about it. If that does not work at the end of the day call a meeting to order before you guys go home and tell them that this is a serious issue. (Speak your mind). If you get your point across they will listen. If the same problem occurs let them know again so they don't forget.
I hope you end up finding your place. GOOD LUCK!
P.S we are from Michigan as well. I remember you guys from one of the competitions. We are team 1718, The Fighting Pi, we may see each other at another regional. GOOD LUCK!! (I also had the same type of problem ast year which was our rookie year, but the advice above did help me, thank goodness for moms.)