ED-3 Worksheet: Pugh Decision Matrix and Scoring Justification

1. Need Statement and Evaluation Objectives

The fundamental need statement for this engineering exploration project is to design and manufacture a mechatronic perpetual calendar that autonomously tracks and updates the date without manual user intervention or reliance on hazardous chemical battery backups. To quantitatively evaluate the four conceptual designs generated in the previous phase, specific objectives have been extracted from this need statement and assigned meaningful weights on a scale of one to ten. Safety is established as the most critical objective with a weight of nine, as the device must operate safely within a domestic or academic environment without leaking battery acid. Ease of use is assigned a weight of seven to ensure the final product requires minimal manual calibration. Both the use of standard mechatronic parts and the overall manufacturing cost are given a weight of six to reflect the constraints of the institutional modular kit. Finally, portability is assigned a weight of five, as the calendar is primarily intended to be a stationary desktop device rather than a mobile unit.

2. Conceptual 2D Sketches

3. Pugh Decision Matrix

The Pugh decision matrix acts as a mathematical evaluation tool to select the optimal mechatronic architecture. [insert footnote 4 here] The calculations below have been independently verified: Design 3 achieves a positive score of 22 against a negative score of 11, resulting in the highest net total of 11, mathematically confirming the ESP32 network architecture as the winning concept.

Design Objectives	Weights	Design 1	Design 2	Design 3	Design 4
Safety	9	s	s	+	s
Ease of use	7	s	+	+	+
Portability	5	s	s	-	s
Use of standard parts	6	s	+	+	+
Cost	6	s	-	-	-
Score (+)		0	13	22	13
Score (-)		0	6	11	6
Total		0	7	11	7

4. Justification for the Scores Given

Design No.	Objective	Score Allocated	Justification for the Score
1	Safety	s	Serves as the fundamental baseline datum for all comparative measurements in the Pugh chart.
	Ease of use	s	Serves as the fundamental baseline datum for all comparative measurements in the Pugh chart.
	Portability	s	Serves as the fundamental baseline datum for all comparative measurements in the Pugh chart.
	Use of standard parts	s	Serves as the fundamental baseline datum for all comparative measurements in the Pugh chart.
	Cost	s	Serves as the fundamental baseline datum for all comparative measurements in the Pugh chart.
2	Safety	s	Retains chemical backup batteries, offering no safety enhancement over the baseline.[
	Ease of use[	+	Automates calendar tracking through RTC hardware, reducing manual inputs.
	Portability	s	Operates independently of external networks, mirroring the baseline model.
	Use of standard parts	+	Integrates standard I2C communication protocols for reliable data transfer.
	Cost	-	Procurement of dedicated RTC hardware increases overall component expenses.
3	Safety	+	Eliminates hazardous chemical batteries by relying on internet time servers.
	Ease of use	+	Completely automates temporal synchronisation via Network Time Protocol.
	Portability	-	Strictly requires a continuous Wi-Fi connection to function correctly.
	Use of standard parts	+	Implements globally recognised wireless communication standards.
	Cost	-	ESP32 chip and multi-sensor displays significantly raise manufacturing costs.
4	Safety	s	Relies on standard hardware power cycles with no specific safety upgrades.
	Ease of use	+	Simplifies user interaction using matrix keypads and standard libraries.
	Portability	s	Functions as a standalone local device without network restrictions.
	Use of standard parts	+	Utilises standard C programming libraries and pre-programmed EEPROM.
	Cost	-	Additional interface hardware components elevate the final prototype cost.