Autonomous Blackbox Recovery Watercraft - Arduino Uno

Hello everyone, just wondering where/how I should get started regarding developing an autonomous, above-water, object recovery vehicle using the Arduino Uno.

Goal:
To search for, identify, and recover a mock blackbox unit approximately sized 3cm3.

Details:

  1. Completely Autonomous.
  2. Above-water craft.
  3. Software controls mechanisms such as movement, identification, and recovery.
  4. Budget <$100
  5. Mock blackbox is magnetic, emits radio-frequency beacon, flash an led, colored bright orange.
  6. Blackbox will be randomly located in a 5m radius, 30cm deep water pool.

Questions:

  1. What should I start looking at in terms of software to program search patterns and behaviors based on sensor inputs?

  2. The craft is intended to just go in straight a certain direction until sensing proximity of a wall, then turning. How do I tie in all sensor data and let the robot interpret/ act on it?

Notes:
This is a first year Engineering project and has been done before, just wondering how to get started and what I should read/understand.

Mechanical and electrical side of the engineering is not within the scope of the question. Just software and interfacing with the Arduino Uno.

Sorry if I am not giving enough details, I’ll clarify to the best of my ability if needed.

Thanks.

Most important thing seems to me to be the process of detecting the signal and figuring out its direction. I wouldn't waste time on anything else until I knew how I was going to do that.

...R