I am currently in a computer engineering class and I have been asked to design a product that can guide blind people. In my fictitious product I am going to implement a module to detect distances (a simple laser range finder that consumes 10 mA when Idle and 100 mA when it shoots a beam), a speech recognition module (which consumes 1 micro Ampere when idle), and also a GPS system. This means my device will be constantly processing input from the distance sensor and the GPS system. It will also output instructions like "turn left" based on the destination address the user entered via a voice command, and it will also tells the user observations like "There is an obstacle directly ahead".
I have been asked to estimate the processing power required by this device, and also the amount of volatile and non volatile memory required. It is all of course based on estimations, and the components used can range from 2014 to 3 years into the future (2017). Are there any estimation methods to define the processing power required? And more specifically, how is processing power quantified? In terms of non volatile memory I believe the only information I need to store are addresses the user inputs, and the commands the system can enter and the commands the system can output. Thank you for any advice!