Understanding Input Devices
Input device
Hardware components that capture data from the environment and convert it into a form that a computer system can process
Input devices play a crucial role in control systems by providing the necessary data for decision-making and automation.
They can be categorised as:
- Manual Data Entry
- Devices: Keyboard, mouse, joystick, touch screen, touch pad
- Example Use: Adding client or book records in a library
- Direct Data Entry
- Devices: OCR/OMR scanners, MICR reader, barcode scanner
- Example Use: Lending a book, locating borrower details
- Automatic Data Entry
- Devices: Sensors (temperature, sound, pressure, light, etc.)
- Example Use: Controlling the temperature in the library
In control systems, input devices are often sensors that monitor specific physical properties, such as temperature, motion, or pressure because of their automatic nature.
Choosing the Right Input Device
When selecting an input device for a specific situation, consider the following factors:
- Accuracy: How precisely the device can measure the intended quantity.
- Range: The limits within which the device can operate effectively.
- Resolution: The smallest change the device can detect.
- Cost: The price of the device, including installation and maintenance.
- Durability: The device's ability to withstand environmental conditions.
- Compatibility: The degree to which the device integrates with existing systems.
- Always consider the specific requirements of the application when choosing an input device.
- A device that works well in one scenario may be unsuitable in another.
Input Devices Types in Control Systems
| Device Type | Examples / Subtypes | Common Applications | Accuracy | Range | Cost |
|---|---|---|---|---|---|
| Motion Sensors | Infrared (IR), Ultrasonic, Microwave | Automatic doors, security systems, lighting | High | Varies (microwave > ultrasonic) | IR is most affordable |
| Temperature Sensors | Thermistors, Thermocouples, Infrared | Smart heating, refrigeration, industrial | Critical | Must match environment | Moderate to high |
| Pressure Sensors | Piezoelectric, Capacitive, Strain Gauge | Automotive systems, machinery, electronics | Essential | Must fit pressure levels | Moderate to high |
| Proximity Sensors | Inductive, Capacitive, Ultrasonic | Robotics, manufacturing, vehicles | Crucial for safety | Ultrasonic > Inductive | nductive typically more expensive |
| Human Interaction Device (HID) Devices | Keyboard, Mouse, Touchscreen | User input, data entry | Important | N/A | Varies; generally affordable |
| Specialized Devices | Barcode scanners, RFID readers | Retail systems, inventory, access control | Important | Depends on technology (e.g., RFID range) | Moderate to high |
Ethical and Practical Considerations
- Privacy: Devices like cameras and microphones may raise privacy concerns.
- Cost vs. Benefit: Balance the cost of the device with its impact on efficiency and safety.
- Environmental Impact: Consider the sustainability of the device and its materials.
- How do we balance the need for data collection with concerns about privacy and surveillance?
- What ethical responsibilities do engineers have when designing systems that rely on input devices?
Examples Scenario-Based Evaluation
Scenario 1: Automatic Doors in a Supermarket
- Input Device: Motion sensor (infrared or microwave).
- Requirements:
- Accuracy: Must reliably detect approaching customers.
- Range: Sufficient to cover the entrance area.
- Cost: Infrared sensors are cost-effective for this application.
Infrared sensors are preferred for indoor use due to their affordability and reliability in detecting human movement.
Scenario 2: Smart Heating System
- Input Device: Temperature sensor (thermistor).
- Requirements:
- Accuracy: High accuracy to maintain comfortable temperatures.
- Range: Must operate within typical indoor temperature ranges.
- Durability: Should withstand long-term use.
Thermistors are ideal for smart heating systems due to their precision and cost-effectiveness.
Scenario 3: Industrial Pressure Monitoring
- Input Device: Pressure sensor (piezoelectric).
- Requirements:
- Accuracy: Critical for safety and efficiency.
- Range: Must handle high-pressure environments.
- Durability: Resistant to extreme temperatures and corrosive materials.
Piezoelectric sensors are chosen for industrial applications due to their robustness and wide pressure range.
- Can you identify the input devices used in everyday systems, such as elevators or traffic lights?
- How would you choose an input device for a new application, such as a smart home system or a robotic vacuum?
- What ethical considerations might arise when deploying input devices in public spaces?
