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Robotics
Sensors and Actuators
Inputs that collect data and outputs that create motion
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Robots use sensors and actuators to interact with the world. Sensors are the input parts that collect information, such as light, sound, distance, touch, temperature, and motion. Actuators are the output parts that make something happen, such as spinning a wheel, moving an arm, lighting an LED, or playing a sound. Understanding this input, controller, output pattern helps students see how robots sense, decide, and act.
Key Facts
- Sensors provide input signals to a robot controller.
- Actuators receive output signals from a robot controller.
- Robot action loop: sense, process, act, repeat.
- Speed = distance ÷ time.
- A servo motor usually turns to a chosen angle, often from 0° to 180°.
- A simple control rule can be written as: if distance < 20 cm, then stop motor.
Vocabulary
- Sensor
- A sensor is a device that detects information from the environment and sends it to the robot controller.
- Actuator
- An actuator is a device that changes electrical energy into action, such as motion, light, sound, or force.
- Controller
- A controller is the robot brain that reads sensor inputs, follows instructions, and sends commands to actuators.
- Input
- Input is information entering a system, such as a distance reading from an ultrasonic sensor.
- Output
- Output is the response made by a system, such as a motor turning or an LED glowing.
Common Mistakes to Avoid
- Calling a motor a sensor is wrong because a motor creates motion instead of detecting information.
- Forgetting the controller is wrong because sensors do not usually control actuators directly in a robot system.
- Mixing up analog and digital signals is wrong because some sensors give many possible values while others give only simple on or off states.
- Ignoring power needs is wrong because motors, servos, solenoids, speakers, and bright LEDs may need more current than a small controller pin can safely provide.
Practice Questions
- 1 A robot uses an ultrasonic sensor and measures an object 15 cm away. Its rule is: if distance < 20 cm, stop the DC motor. What should the robot do?
- 2 A robot wheel travels 120 cm in 6 seconds. What is its speed in cm/s?
- 3 A classroom robot has a camera, microphone, touch sensor, DC motor, servo, LED, and speaker. Sort each part into input, output, or controller-related parts, and explain your choices.