Project Overview Introduction & Product Analysis Drawing & communication Sensing abilities in robots Programming Robots Mechanisms and Systems Designing new products & Packaging Presentation and Rendering Biomimicry Concept Modelling Concept presentations

LESSON 03

LEARNING ABOUT SENSORS LESSON 3 STARTER Learning objective: Learn about sensors, sensing within robots, and their application in industry. Learn ways of establishing the sensing ability of robots. Develop new ideas for robots using different sensors. LEARNING ABOUT SENSORS What is a sensor? A sensor (also known as a detector) is a device that measures a physical quantity and converts that measurement into a signal that can be read electronically. Robots use sensors for a number of reasons. Sometimes robots need to acknowledge the presence of something (a product) before they can carry out a job. So a robot packaging boxes with chocolate bars needs to first know that the box is ready in front of it. A sensor replaces the human ability to use our fives common senses. What are they? New words: sensor

Sensing Abilities of robots How can a robot sense? Discussion with your peers Why would a robot car want to sense it surroundings? “Cars are driven by humans. During a driving test and in order to pass, a human will need to use a sense of sight to see hazards, a sense of hearing to acknowledge hazards that are not immediately visible, a sense of touch to operate controls of the car, a sense of smell to identify potential fuel or fire hazards, and perhaps only a sense of taste is not required.” In order for a robot car to operate as a human does with the same level of safety, it would need to be able to employ the same sensing abilities. Though we have the sensors needed to achieve this, why do we not have robot cars on our roads (as we see in the futuristic movies?)

Sensing Abilities of robots VEX Robotics Sensors VEX is a robotics design system for educational use that secondary schools can offer to help students like you to design and build robots. To help students learn how to design industry standard robot solutions, VEX provides a range of sensors. Here are some and what they do… A Light Sensor This sensor detects different levels of light and darkness. The robot receives a signal from the sensor and interprets it as a voltage. This voltage can be used by a robot to trigger a response, which might be to stop moving (when it finds darkness) or move towards a light. New words: voltage

Sensing Abilities of robots VEX Sensors Ultrasonic range finder Much like a bat flies through the air avoiding obstacles in the pitch black, an ultrasonic range finder sends out a sound signal which bounces off an object and returns to the sensor informing the robot how close it is getting to an obstacle as it moves. A bump switch This bump switch is a very simple sensor which allows the robot to “crash” into obstacles, hitting the bumper surface, which closes an electrical circuit. As it closes, a electronic signal travels to the robot informing it a collision has occurred, allowing the robot to respond. New words: switch, signal

Sensing Abilities of robots VEX Sensors Limit switch Similar to a bump switch, a limit switch closes a circuit which triggered. The only difference is that the sensor acknowledges very small delicate “touches” rather than collisions. This allows the robot to sense very small or fine movements and respond. Shaft encoders The sensors detect rotational movement. They would be fitted in pairs to the axel of a robot vehicle (through the hole) and record the rotation of the axel as a robot moved. They allow a robot to “know” exactly where it is. New words: shaft is also known as an axel on vehicles

Sensing Abilities of robots VEX Sensors Line follower These three sensors are very useful in detecting a changing surface. By pointing all three sensors down onto the ground under a robot, and lining each alongside one another, the robot can detect changing signals between each sensor. If a signal changes from a sensor (which would be caused by the surface of the floor changing colour) then the robot could receive this signal and change how it is behaving. These sensors allow robots to follow lines on the floor.

Sensing Abilities of robots Human Senses Of the five human senses, which can be replicated (or imitated) in VEX sensors and with which sensor. Task: Complete the table below on your hand-out. SENSE Y/N EXAMPLE Touch Smell Sight Hearing Taste Bump switch or Limit switch Light sensor and line sensors Ultrasonic range finder

Sensing Abilities of robots Hexbug Sensing abilities Task: You are going to employ a range of “tests” to decipher and prove that a Hexbug can sense. Cup your hands over the Hexbug Clap your hands loudly over the Hexbug Touch the antenna on the Hexbug head Put obstacles in the way of the Hexbug Does it stop moving? Yes = It senses light. Does it change direction? Yes = It senses sound. Does it change direction? Yes = It senses touch. Does it avoid them? Yes = It senses infra red light.

Sensing Abilities of robots Hexbug Sensing abilities Results. Which Hexbug was able to sense what? The crab sensed… How can you prove it? Where is the sensor? The original sensed… How can you prove it? Where is the sensor? The larva sensed… How can you prove it? Where is the sensor? The ant sensed… How can you prove it? Where is the sensor? The scarab sensed… How can you prove it? Where is the sensor?

Sensing Abilities of robots Hexbug ideas Ideas Task: Consider what senses have not been achieved in a Hexbug so far. Smell & Taste What insect or creature could the Hexbug be? What would it do? Why would it sense this (what would be it’s purpose?)

LESSON 3 PLENARY As a class, let us consider the following questions? A. Why do robots sense things? B. What sensors can be applied and in which situations? C. How could a robot be blinded? D. What animals in nature have similar sensing abilities?

Summary Today you have: Learning objective: Learn about sensors, sensing within robots, and their application in industry. Learn ways of establishing the sensing ability of robots. Develop new ideas for robots using different sensors. Today you have: Learnt what different sensors can be applied in the field of robotics Developed methods of testing the ability of robot sensors Developed ideas for new robots using sensors