Lesson Notes By Weeks and Term v4 - SHS 2

Lesson Video

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Performance objectives

• Identify different sensors and actuators.
• Plot a rotation-distance graph for a wheeled robot.
• Calculate linear and angular distances covered by a robot.
• Analyze data from rotation-distance graphs.
• Discuss real-life applications in Ghana.

Lesson summary

Welcome, future engineers and innovators! Today, we will explore a fundamental principle that governs how every wheeled robot, from a small toy car to the Mars Rover, moves with precision. We will investigate the direct relationship between the rotation of a robot's wheels and the distance it travels in a straight line. In Ghana, we see wheels in action everywhere – on tro-tros, bicycles, okadas, and even the push-trucks (chassis) we build for fun.

Lesson notes

This lesson connects three key areas: the physical parts of a robot (geometry), how it moves (kinematics), and how we represent that movement (graphing). A. Key Geometric Dimensions of a Wheel

A robot's wheel is a circle. The most important dimensions are: Diameter (d): The distance across the circle, passing through its centre. We measure this in centimetres (cm) or metres (m). Radius (r): The distance from the centre of the circle to its edge. It is half the diameter (`r = d/2`). Circumference (C): The distance around the edge of the circle. This is the most crucial concept for today. If you were to cut the wheel and lay it flat, its length would be the circumference.

The formula for circumference is: C = πd or C = 2πr *(Where π (pi) is a mathematical constant, approximately 3.142 or 22/7)*

This circumference is the exact distance the robot will travel when its wheel completes one full rotation. B. Linear vs. Angular Distance Linear Distance: This is the straight-line distance the robot travels along a surface. We measure it with a ruler or measuring tape (e.g., in centimetres). Angular Distance (Rotation): This is how much the wheel has turned. We can measure it in: Degrees: One full turn is 360°. Revolutions or Rotations: One full turn is 1 rotation. For this lesson, we will use rotations as our primary unit. C. The Core Relationship: From Rotation to Distance

Evaluation guide

• Plot a Rotation -Distance graph for different scenarios of wheeled robots and
• observe how the resultant graph relates to the geometric dimensions of a robot.
• Project-Based Learning: Use a rotation distance graph to explain linear and angular
• distances covered by wheeled robots and derive mathematical relationships that relate the distances covered to the geometric dimensions of the robot used.