CS topic 7

Control system

A control system is a system that manages, commands, directs or regulates the behavior of other devices or systems to achieve a desired output.

How does a control system work?

Takes digital input from sensors. Sensors feed data into a microprocessor based on environment around it. Microprocessor processes data. Sends a digital output used to control the device.

Advantages of a control system

• A computer can respond much more quickly than humans

• Can run without a break/24hrs

• Less error-prone than humans

• Consistent, unambiguous

• Can be placed in environments hazardous to humans

Disadvantages of a control system

• Technical malfunction can occur

• Cannot react to unexpected events

• Relies on a consistent supply of electricity

Microprocessor

• Performs Arithmetic and logical control operations

• Accepts electrical signal

• Performs calculations and data processing

• Collection of logic gates

Microcontroller

Used where task is fixed and predefined (embedded systems)

CPU, RAM, Interface all integrated into one chip

Transducers

• Converts one form of energy into another

• Sensors and actuators

• converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa.

  • Converts electrical energy to physical motion

Senors

Convert one form of energy into another

Sensors: Variations in a physical quantity into an electrical signal.

Convert physical measurements, such as temperature, pressure, or light, into electrical signals that can be processed and analyzed by a control system.

Actuator

Converts inputted electrical energy to physical motion

Turns control signal into mechanical action

Requires control device and source of energy

Active sensors

Has to use electricity in order to produce the output signal

Passive sensors

Does not require its own electricity, and gains from the outside world. Generates an output signal in response to some external stimulus

Analogue sensors

Produce a voltage or signal output response which is proportional to the change in the quantity that they are measuring (the stimulus).

\
Can take any value within a certain range and has infinte readings.

Digital sensors

Convert physical measurements into a sequence of binary digits (zeros and ones). Discrete ouput

Examples of Analogue sensors

Temperature sensors, light sensors, sound sensors, pressure sensor

Examples of Digital sensors

Proximity sensors, PIR sensors

Converting from Analog to Digital

Convert analog data from sensor into digital data, read by computers.

\
Analog signal is sampled at regular intervals, the digital values obtained are then encoded into a binary code that can be processed by a microcontroller

Feedback

Signal sent back to system. Based on result or environmental action send signal back to microprocessor to receive optimal results.

Open Loop System

Doesnt take feedback, and repeats the same action based on input.

Input is not adjusted based on output.

Closed Loop System

Takes feedback into account. Corrects Errors in output by using Feedback Loop.

\
Continuously monitors its output and adjusts its input to maintain stability.

Autonomous Agents

Intelligent agent operating on owners behalf without any interference. Software entities that carry out some set of operations independent from direct instruction by user/owner.

Characteristics of Autonomous Agents

Operates without interference.

**Autonomy:** Can independently select tasks in order to achieve a goal

**Reactive**: Senses environments and reacts based on this input in pursuit of its own agenda.

**Concurrency/sociality:** Can interact with other agents

**Persistence:** Consistently works in pursuit of its goal

Centralized control system

• All components are controlled by a centralized processing unit

• Located in a single location

• Direct control of the operation of individual nodes and flow information from a single server

Distributed control system

• Different components are controlled by a number of different processing units

  • All work towards a common goal

• Spread across multiple locations, interconnected through a network

• Distrubuited process and control across multiple locations and interconnected nodes

Advantages of a Centralized control system

• Easier to maintain and troubleshoot

• only one processor

• More control + security

Disadvantages of a Centralized control system

• If the sensor/controller/actuator fails, whole system fails

• Less power

• Less flexibility

Advantages of a Distributed control system

• Good performance, shared processing load

• Reliability: If one or more computers go offline it is not going to have a huge effect on the overall processing

• Scalability: easy to increase the amount of processing power

• Flexibility: More/diff types of tasks can be completed

Disadvantages of a Distributed control system

• Harder to maintain

• More complex software

• Cost: The additional hardware required to facilitate communication between nodes can increase the cost of the system.

• Security: With multiple nodes in the system, there are more potential points of attack for security breaches.

Embedded system

• Dedicated function within a larger mechanical or electrical system

• small, low-power, and low-cost

Social and ethical issues with Embedded systems

• Security: Embedded systems that are connected to the internet or other networks are vulnerable to cyber attacks, which can compromise the security and integrity of the system

• Privacy concerns

• They are typically designed for a specific task or application and are not easily reprogrammed for new or different tasks.

• They can be difficult to troubleshoot and debug because they are highly integrated and often operate without human intervention.

Advantages of Embedded system

• They are compact, low-cost, and consume less power.

• They are customizable, allowing the designer to choose the components and software that best meet the system's requirements.

• They can be easily integrated into larger systems and networks

Proximity sensor

A proximity sensor is a sensor that detects the presence or absence of an object without physical contact.

These sensors emit an electromagnetic field or beam of radiation, and when an object enters the field or interrupts the beam, the sensor detects the change and provides an electrical signal output.

Humidity Sensor

Measures the amount of moisture in the air and provides an electrical signal output proportional to the humidity

Pressure Sensor

Measures the pressure of gas or liquid and provides an electrical signal output proportional to the pressure

Accelerometer sensor

Measures acceleration and provides an electrical signal output proportional to the acceleration.

Infrared Sensor

Detects infrared radiation and provides an electrical signal output proportional to the detected radiation

Force Sensor

A sensor that measures the force applied to it, such as a strain gauge or a load cell

Ultrasonic Sensor

A sensor that uses sound waves to measure distance, commonly used in robotics and industrial applications

Optical Sensor

A sensor that measures changes in light intensity, commonly used in photometry, colorimetry, and motion detection applications

Examples of Actuators

1. Electric Motor: An actuator that converts electrical energy into mechanical energy, commonly used in robotics, industrial automation, and automotive applications.

2. Hydraulic Cylinder: An actuator that uses pressurized hydraulic fluid to create linear motion, commonly used in heavy machinery and industrial automation.

3. Piezoelectric Actuator: An actuator that uses piezoelectric materials to create precise and rapid motion, commonly used in semiconductor manufacturing and microelectromechanical systems (MEMS)

4. Lightbulbs

Examples of Transducers

1. Microphone - a device that converts sound waves into electrical signals.

2. Thermocouple - a device that converts temperature differences into electrical voltage.

3. Pressure sensor - a device that measures pressure and converts it into an electrical signal.

4. Accelerometer - a device that measures acceleration and converts it into an electrical signal.

Analogue data

Any continuous signal or information that varies in a smooth and continuous manner over time. Analog data can be represented by a physical quantity, such as voltage, current, or pressure, and can take on an infinite number of values within a defined range.