sensors for business an technology device

Sensor technology introduction

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