When I was in grad school, I saw some of undergraduate students testing one of their projects. They were designing an electronics system that help visually impaired people to navigate around. They would have device placed in their body, that transmits and receives back the reflected signals thus identifying objects and obstacles in the intended path. This was a project that really caught my attention because of the application. I don't know any details about the design though. This has a lot of analog implementation, for transmitting and receiving, Lot of signal processing and mostly on embedded systems or mirco-controller or DSP kit. ( I guess you might be able to determine correlation in received signal to determine obstacle). Maybe you can implement in fixed point to be more resourceful and low cost. If you know FPGA designs, can be very helpful. Lot of algorithms implementation as you have decision making system to design. All of it, I think this is a doable project in 6 months to a year time with 3 people and will give you a significant exposure to design.