The document provides an introduction to robotics sensors, explaining their function in helping robots perceive their environment, distinguishing between two main types: analog and digital sensors. It details the operation of a bump sensor, various coding concepts such as variables and while loops, and instructions for implementing a simple program to control a motor based on sensor input. Overall, it serves as a foundational guide for understanding and programming sensor usage in robotics.

1. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Introduction to Sensors

2. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
What are sensors?
• Your answers here!

3. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
What are sensors?
• A sensor tells a robot one simple thing about it’s
environment
– Temperature
– Distance
– Light intensity
• Allow robots to see and feel the physical world
through which they travel
• Two main types of sensors: digital and analog

4. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Analog Sensors
• Can provide a range of feedback
• The robot will interpret feedback from the sensor
as a number from 0 to a pre-defined maximum
(1024 for most Vex sensors)
• A light sensor has many states:
– If it is very bright, the sensor will return a number
close to 30
– If it is very dark, the sensor will return a number close
to 1000

5. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Digital Sensors
• Can distinguish between two different “states”
• The meaning of the states depends on the
sensor
• A bumper sensor has two “states”
– If it is pressed, it is a 0
– If it is not pressed, it is a 1

6. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Variables
• A value-holding “container” with a label
• You can retrieve the value in this “container”
when it is needed
» There are different types of values you can store
in variables.
» You will use the “int” type, which allows you to
store any whole number from 0 to a large
number (positive or negative)
» You can assign a starting value to your variable
which will store that value at the start of the
program

7. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Bump Sensor Introduction
• Open the project “BUMPERTEST.ECP”
• Download it to your robot and open the terminal
window

8. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Understanding bump sensor code
• Comments - allows you to leave notes to
yourself and others about your code
• The compiler ignores comments

9. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Understanding bump sensor code
• While Loop – block of code that repeats itself as
long as the condition inside the parenthesis is
true
– The == operator returns true if both sides are equal,
and false if they are not equal
– In our code loop will always equal 1, so this loop will
run forever

10. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Understanding bump sensor code
• Bumper sensor – stores the value of the digital
input 6 to the variable “bumper”
– Now the robot knows if the bump sensor is being
pressed in (0) or not (1)

11. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Understanding bump sensor code
• Print to screen – displays information in the
terminal window
– This particular code displays the value of the bump
sensor
For now, make sure your settings are as
follows:
* Variable: the variable you want to display
* Message: the message with the variable
* Directive: %d
* Type-cast: int

12. Vex 1.0 © 2005 Carnegie Mellon Robotics Academy Inc.
Writing your own code
• We are going to write a program that runs one
motor until a bump sensor is pressed in
• Begin by opening easyC