Estimating processing power required
@ Jarrod Christman is absolutely correct. This, however, can be simplified quite a bit. I assume since this is a CSE class that you don't go in depth on the intricacies of electrical design and thus will refrain for a systems approach. Let us ignore all of the components of the system except the MCU, which will be doing your processing.

Go ahead and look for a nice MCU (I recommend an STM32). They have wonderful datasheets, and in there you will find the MIPS count which will be millions of IPS (instructions per second). Use this as a baseline for how many operations you can compute in a given time. Now with your CS background you should be able to find how many operations you need based on your algorithm (which is hopefully O(N)). Past this there are inefficiencies and specs for temperatures, noise based on the layout, and the list goes on.

If you really get into this you should look at what sensors you need, look at their sampling rate, and thus see how fast you can pull data from them. This will let you know a more realistic time for getting the processing data. I almost guarantee that the processor can compute faster than you can extricate sensor data. This becomes very important when you consider that a sensor for the blind should have real time processing. If you can't get data fast enough, blind guy WILL crash.

I believe these considerations will get you off to a good start. From there, look at any special considerations which all of these parts say to look into. You'll be led down a rabbit hole far to big, and then come back and ask more questions. Cheers.