Developing an Accessible Calculator for the Visually Impaired
Problem Statement
Most calculators are too reliant on visual displays and not designed to accomodate those who are visually impaired. Current calculators that have been designed to be accessible to those who are visually impaired do not have the functions present on many scientific calculators that are required by many users, especially students.
Design Approach
Our initial idea, as seen in the concept drawing on the right, intended to connect a pre-existing scientific calculator, namely, the TI-NSpire CXII, with a modified numerical keypad. The keypad would contain braille keys and be used to interpret and deliver user input to the calculator and produce the output through a built-in speaker. All calculations would be performed by the calculator while the keypad primarily acts as the method of relaying inputs and outputs between the user and the calculator.
Our next approach aimed to incorporate more complex functions by configuring a pre-existing keyboard rather than designing our own keypad. The keyboard would allow for much more functions to become available to the user as opposed to the keypad, which contains a much more limited assortment of keys. The keyboard would contain braille keys, which certain keys replaced with functions, such as, for example, the shift key being replaced with a trigonometric function. In addition, a Raspberry Pi would be used as an intermediary between the keyboard and the calculator, which would be used to interpret inputs and outputs as well as contain a speaker to deliver the output to the user using text-to-speech.
Final Prototype
Our final prototype chose to remove the need for the external calculator, instead performing the calculations on the Wolfram API installed on a Raspberry Pi. The Raspberry Pi is connected to an external speaker, which would be used to deliver the output of the calculations via espeak, a text-to-speech software built into the Raspberry Pi. The Pi is also wired to an external keyboard modified to contain braille keycaps for user input into the calculator.
In order to deliver the input from the keyboard to the API, as well as deliver the information back to the user using text-to-speech, a Python script was created to connect the individual pieces of the project. The script, which runs on Pi startup, takes user input from the keyboard, delivers it to the Wolfram API, collects the outputted information, and translates it to the user through espeak.
Additional Information
If you would like more information on our project, feel free to view our Project Handout or our Design Study.