Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Explain logic and loop diagrams for robot control.
• Create simple logic diagrams for control processes.
• Develop loop diagrams to show control flow.
• Evaluate control system designs using these diagrams.
• Collaborate with peers to share and critique diagrams.

Lesson summary

This lesson introduces the fundamental concepts of how robots and automated systems are controlled. In our daily lives in Ghana, we see control systems everywhere: from the traffic lights in Accra that manage the flow of 'trotros' and cars, to the automatic hand sanitiser dispensers that became common during the COVID-19 pandemic, to the automated changeover switch that starts a generator when ECG power goes off. Understanding how to plan and design these systems using logic and loop diagrams is the first step to building them.

Lesson notes

A. What is a Control System?

A control system is a system that manages, commands, directs, or regulates the behaviour of other devices or systems to achieve a desired result. Think of it as the "brain" of an operation. All control systems, simple or complex, can be broken down into three fundamental parts: Input: The information or signal the system receives from the environment. This is often from a sensor. Process: The "thinking" part. The controller makes a decision based on the input and its programmed instructions. Output: The action the system takes in response to the decision. This is often carried out by an actuator (like a motor, light, or pump).

Ghanaian Example: Automatic Water Pump for a Polytank Input: A float sensor inside the Polytank detects that the water level is low. Process: The controller receives the "low level" signal and decides to turn on the pump. Output: The electric pump (actuator) turns on, and water begins to fill the tank. B. Types of Control Systems: Open-Loop vs. Closed-Loop Open-Loop Control: This system works without feedback. It performs its action based on a timer or a pre-set instruction and does not check the result of its action. Example: A simple bread toaster. You set it for 2 minutes. It toasts for 2 minutes and stops. It doesn't use a sensor to check if the bread is perfectly brown; it just follows the time command. Closed-Loop (Feedback) Control: This system is "smarter." It uses a sensor to measure the output and *feeds that information back* to the controller. The controller then compares the actual result with the desired result and makes adjustments. This creates a "loop" of information. Example: An air conditioner (A/C). You set the desired temperature to 20°C. A thermostat (sensor) constantly measures the room's actual temperature. If it's 24°C, the controller keeps the compressor (actuator) running. When the room cools to 20°C, the controller turns the compressor off. This feedback loop maintains the desired temperature. C. Logic Diagrams (Flowcharts)

A logic diagram, commonly known as a flowchart, is a visual representation of the sequence of steps and decisions needed to perform a process. It shows the logical flow of instructions.

Evaluation guide

• Evaluate the use of logic and loop diagrams and demonstrate their use in control
• systems' design.
• Problem -Based Learning: Introduces learners to standard loop and logic diagram representations
• of components and how they are used in control systems' design. Learners draw loop and logic