Question

Draw a problem formulator diagram for the following:

"The visor on a car blocks the sun during the day and headlights from oncoming traffic at night, either one of which could blind the driver, causing an unsafe condition that could lead to a wreck."

Instruction:

Rule 1: Use either 3 or 4-word noun phrases

Rule 2: Every function name must begin with a noun

Rule 3: Eliminate articles (e.g., ‘the’ and ‘a’) Rule 4: Capture a single relationship in each function name.

Rule 4: When possible, make the function name describe a condition or state

Rule 5: Never use ‘it’ (replace ‘it’ with the name of the thing you are referring to)

To create a Problem Formulator Diagram (PFD), we have to identify useful functions and harmful functions and write the name of each function properly. Each useful function and harmful function captures a relationship between two components of the system. We need to be as concise as possible, so every function name should have either 3 or 4 words. All function names must begin with a noun. These nouns must come from either the I/O abstract description or the S/S abstract description (inputs, outputs, or parts of the system). The next word in a function name is usually a verb or a preposition. The last word is many times a noun again from I/O or S/S but sometimes is a gerund (a verb turned into a noun usually by adding 'ing') or an adjective. Here are some examples of good function names. Note, the verb describes the relationship between the two components: "Person loads dirty clothes," "Person pushes the start button," "Motor is running," "Motor turns the shaft," "Shaft turns the propeller," "Propeller pushes boat."

Here are some incorrect function names: "The person pushes the start button on the control panel" ... too many words, includes the articles ("the"), and captures more than one relationship. This should be broken up into two functions like this: "Person pushes start button" and "Button on control panel" "Starts motor running" ... does not start with a noun (so is not a noun phrase). This should be written as: "motor is running" ... this is a statement of condition. It tells us what state the motor is in. These make great function names.

Answer 1

The problem formulator diagram is attached.

The car visor being pulled down results in the sun being blocked during the day and oncoming headlights blocked during the night. The glare of the sun or headlights, if not blocked can blind the driver; this results in an unsafe drive which can cause an accident. Every function name is three words of and starting with a noun, as required.