Design and Technology: Product Design (9252) | Systems approach to designing

Welcome to the Systems Approach!

Hello! Designing a product isn't just about making something look good; it's about making sure it works efficiently and reliably. This chapter is super important because it teaches you how to look at any product—from a simple toaster to a complex robot—as a collection of interconnected parts. This is called the Systems Approach.

Don't worry if this sounds technical! We will break down complex ideas using everyday examples. By the end of these notes, you’ll be able to analyse almost any product like a professional designer!

Why is the Systems Approach Important?

• It helps designers understand how different parts of a product rely on each other.
• It makes troubleshooting (finding problems) much easier.
• It allows for the creation of automated or smart products.

The Foundations: What is a System?

In Design and Technology, a system is simply a group of parts that work together in an organised way to achieve a specific goal or function.

Think of it like a recipe: You need ingredients (Input), you follow instructions (Process), and you get a delicious meal (Output). A technical system works in exactly the same way!

The Core Model: IPO (Input – Process – Output)

Every system, no matter how simple or complex, can be broken down into three fundamental stages:

Input → Process → Output

Memory Trick: Think IPO – "I Put Out" (What I put in, what comes out).

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1. Input: What Goes In

The Input is everything needed to start the system or make it work. Inputs come in three main forms:

Types of Input:

• Materials: The physical things that will be changed or used (e.g., raw plastic, water, fabric).
• Energy: The power source that runs the process (e.g., electricity, batteries, human power/kinetic energy).
• Information/Data: The instructions telling the system what to do or when to start (e.g., pressing a button, a temperature setting, a signal from a sensor).

Example: Turning on a kettle.
The input is: Water (Material), Electricity (Energy), and Pressing the ‘On’ Switch (Information).

2. Process: What Happens Inside

The Process is the action or series of actions that transform the input into the output. This is where the work gets done.

Key Features of the Process:

• It involves mechanisms, electronic components, or chemical reactions.
• It is controlled by the information received at the input stage.
• The process stage transforms the input (e.g., a motor spinning, a heating element turning on, a piece of wood being cut).

Example: The kettle process.
The process is: The heating element converts electrical energy into thermal energy, causing the water to heat up and boil.

3. Output: What Comes Out

The Output is the result of the system running. This includes the desired result, but also any unintended or side effects.

Types of Output:

• The Desired Outcome: The product or action the system was designed for (e.g., hot water, a cut shape, a painted item).
• Waste or By-products: Unwanted materials or energy (e.g., heat loss, steam, scrap material, noise).
• Signals: Information that might be used elsewhere (e.g., a light turning on, a sound alarm).

Example: The kettle output.
The output is: Hot water (Desired outcome) and Steam/Heat loss (By-product).

Control and Feedback: Making Systems Smarter

Simple systems just run their course (like the simple toaster—you set the time and it stops, regardless of whether the toast is perfect). But modern products need to be smart! They need to check their results and adjust themselves. This is where Control and Feedback come in.

4. Control: Directing the Process

The Control element manages the process. It decides *when* things happen, *how fast*, and *for how long*.

• Control systems often involve electronic circuits, microprocessors, or mechanical timing devices.
• The input information (like setting a timer or choosing a program) tells the control system what its target is.

Analogy: The conductor of an orchestra. The control system is like the conductor, making sure every instrument (part) plays its role at the right time.

5. Feedback: The Check and Adjust Loop

Feedback is essential for creating high-quality, reliable, and automatic systems. It is information about the Output that is sent back to the Input/Control stage to make adjustments.

It allows the system to check if it has met its target and correct any errors.

Example: A Home Thermostat.

1. Target: Set the temperature to 20°C (Input/Control).
2. Process: Heater runs.
3. Output Check: A sensor measures the current room temperature (18°C).
4. Feedback: The sensor sends the 18°C reading back to the control system.
5. Adjustment: The control system sees 18°C is too low, so it keeps the heater running (Process adjusted).

Key Term: Feedback relies on a sensor (a component that detects changes in the environment, like temperature, light, or pressure) to gather information about the output.

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Open-Loop vs. Closed-Loop Systems

Designers categorise systems based on whether they use feedback or not. This is a crucial concept for your exam!

Open-Loop Systems (No Feedback)

An Open-Loop System runs its process for a fixed time or sequence, regardless of the output. It assumes the process will work correctly every time.

• They are simple and cheaper to produce.
• They are less accurate and cannot correct errors.

Example: A simple toaster. You press the lever, set the dial, and the heating element runs for the set time. If the voltage drops and the element doesn't get hot enough, or if the bread is already slightly burned, the toaster doesn't know and won't adjust the time.

Closed-Loop Systems (Uses Feedback)

A Closed-Loop System constantly measures the output and uses feedback to adjust the process to ensure the target is met.

• They are more complex and expensive due to sensors and control logic.
• They are highly accurate, reliable, and automatic.

Example: An automatic washing machine. The machine might have a sensor (feedback) that measures the load size or the clarity of the rinse water. If the water is still soapy, the system automatically adds another rinse cycle (adjustment to the process).

Applying the Systems Model: Step-by-Step Analysis

Let’s analyse a slightly more complex product: a Self-Regulating Iron (with a temperature control dial).

Step 1: Input

The inputs are:

• Energy: Electricity from the wall socket.
• Material: Water for steam (if applicable).
• Information: Setting the temperature dial (e.g., choosing 'Cotton' setting).

Step 2: Process & Control

The electricity flows to the heating element. The Control system (often a microchip or thermostat switch) manages this flow based on the temperature dial setting.

Step 3: Output Check (Feedback)

How does the iron know when it’s hot enough?

• Sensor/Feedback: A thermistor or thermostat detects the current temperature of the metal soleplate (Output).

Step 4: Adjustment

The sensor feeds the temperature information back to the control system.

• If the soleplate temperature is too low, the control keeps the heating element on.
• If the soleplate temperature reaches the set point (e.g., 200°C), the control switches the heating element off.

Step 5: Final Output

The final output is the hot soleplate (ready to iron) and waste heat.

Did you know? This iron is a closed-loop system because it constantly checks its temperature and adjusts the power flow accordingly!

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Key Takeaway

Understanding the IPO-Feedback structure allows you to systematically design products that are robust and reliable. When designing, always ask yourself: "What are the inputs? How will the process be controlled? And how will I check if the output is correct?"