Libraries.Robots.Lego.InfraredSensor Documentation

The InfraredSensor class is an object representation of the LEGO Mindstorms EV3 Infrared Sensor. It is used to measure distance between the robot and other physical objects. The range at which this sensor works is from around 5 to 40 centimeters. Additionally, the EV3 remote, also called a beacon, interacts with the robot through this sensor.

Example Code

use Libraries.Robots.Lego.InfraredSensor
use Libraries.Robots.Lego.Motor
use Libraries.Robots.Lego.Sound
use Libraries.Robots.Lego.Screen

class Main
action Main
    InfraredSensor infraredSensor
    Motor motor
    Sound sound
    Screen screen
    
    integer command = 0
    infraredSensor:SetPort(infraredSensor:PORT_4)   //tells the program that there is an infrared sensor connected to port 4 of the robot
    repeat while true
        if infraredSensor:GetDistance() < 25
            screen:Output("Object nearby.", 0)
            sound:Buzz()
        else
            screen:Clear()
            command = infraredSensor:GetRemoteCommand(infraredSensor:CHANNEL_1)  //determines what button was pressed on the EV3 remote over channel 1
            if command = 1                    //forward
                motor:SetSpeed("B", 480)
                motor:SetSpeed("C", 480)
                motor:RotateForward("B")
                motor:RotateForward("C")
            elseif command = 2                //backward
                motor:SetSpeed("B", 480)
                motor:SetSpeed("C", 480)
                motor:RotateBackward("B")
                motor:RotateBackward("C")
            elseif command = 3                //right
                motor:SetSpeed("B", 480)
                motor:SetSpeed("C", 480)
                motor:Stop("B")
                motor:RotateForward("C")
            elseif command = 4                //left
                motor:SetSpeed("B", 480)
                motor:SetSpeed("C", 480)
                motor:Stop("C")
                motor:RotateForward("B")
            else
                motor:Stop("B")
                motor:Stop("C")
            end
        end
    end
end
end

Inherits from: Libraries.Language.Object

Variables Table

VariablesDescription
integer BUTTONS_BOTTOM_LEFT_TOP_LEFT
integer BUTTONS_TOP_LEFT_TOP_RIGHT
integer CHANNEL_4
integer PORT_2
integer BUTTONS_TOP_RIGHT_BOTTOM_RIGHTThis action lets the program know which port on the robot that the infrared sensor being used is plugged into. As such, this action must be called before any other action in the InfraredSensor class will work.
integer BUTTON_BOTTOM_RIGHT
integer CHANNEL_1
integer CHANNEL_2
integer BUTTON_TOP_LEFT
integer BUTTON_CENTER
integer BUTTON_TOP_RIGHT
integer BUTTONS_BOTTOM_LEFT_BOTTOM_RIGHT
integer PORT_3
integer CHANNEL_3
integer BUTTONS_BOTTOM_LEFT_TOP_RIGHT
integer BUTTON_BOTTOM_LEFT
integer PORT_4
integer BUTTONS_TOP_LEFT_BOTTOM_RIGHT
integer PORT_1

Actions Documentation

Compare(Libraries.Language.Object object)

This action compares two object hash codes and returns an integer. The result is larger if this hash code is larger than the object passed as a parameter, smaller, or equal. In this case, -1 means smaller, 0 means equal, and 1 means larger. This action was changed in Quorum 7 to return an integer, instead of a CompareResult object, because the previous implementation was causing efficiency issues.

Parameters

Return

integer: The Compare result, Smaller, Equal, or Larger.

Example

Object o
Object t
integer result = o:Compare(t) //1 (larger), 0 (equal), or -1 (smaller)

Equals(Libraries.Language.Object object)

This action determines if two objects are equal based on their hash code values.

Parameters

Return

boolean: True if the hash codes are equal and false if they are not equal.

Example

use Libraries.Language.Object
use Libraries.Language.Types.Text
Object o
Text t
boolean result = o:Equals(t)

GetDistance()

This action uses the infrared sensor to measure the distance between it and a physical object directly ahead of it. The reliable range for measuring distance is up to around 50 centimeters.

Return

integer: an integer representation that corresponds to units of centimeters between the sensor and object. The reflectivity of the object may cause the number to be inaccurate. Possible return values range from 5 to around 50, depending on the object.

Example

use Libraries.Robots.Lego.InfraredSensor
use Libraries.Robots.Lego.Motor
use Libraries.Robots.Lego.Sound

InfraredSensor infraredSensor
Motor motor
Sound sound

infraredSensor:SetPort(infraredSensor:PORT_3)   //tells the program that the infrared sensor is plugged into port 3 of the robot
motor:RotateForward("B")
motor:RotateForward("C")
repeat until infraredSensor:GetDistance() < 40  //the robot moves forward until getting close to an object
end
sound:BeepTwice()

GetHashCode()

This action gets the hash code for an object.

Return

integer: The integer hash code of the object.

Example

Object o
integer hash = o:GetHashCode()

GetRemoteCommand(integer channel)

This action retrieves a command, or button press, from an EV3 remote.

Parameters

  • integer channel: is used to find an EV3 remote using the same channel. There are 4 valid channels: 1, 2, 3, and 4. There are class constants available for this parameter. The remote's channel appears on the remote between the buttons and below it is a switch that moves up and down that changes the remote's channel. When the switch is all the way up, the remote's channel is 1 and when the switch is all the way down, the remote's channel is 4.

Return

integer: an integer representing the key(s) pressed on the EV3 remote. There are class constants available to help determine the return value. Return values correspond to the following key(s) pressed on the EV3 remote: 1 TOP-LEFT 2 BOTTOM-LEFT 3 TOP-RIGHT 4 BOTTOM-RIGHT 5 TOP-LEFT + TOP-RIGHT 6 TOP-LEFT + BOTTOM-RIGHT 7 BOTTOM-LEFT + TOP-RIGHT 8 BOTTOM-LEFT + BOTTOM-RIGHT 9 CENTER 10 BOTTOM-LEFT + TOP-LEFT 11 TOP-RIGHT + BOTTOM-RIGHT

Example

use Libraries.Robots.Lego.InfraredSensor
use Libraries.Robots.Lego.Sound

InfraredSensor infraredSensor
Sound sound

infraredSensor:SetPort(infraredSensor:PORT_4)
integer command = 0
repeat while true
    command = infraredSensor:GetRemoteCommand(infraredSensor:CHANNEL_1)
    if command = 1              //top left remote button
        sound:PlayTone(200, 20)
    elseif command = 2          //bottom left remote button
        sound:PlayTone(400, 20)
    elseif command = 3          //top right remote button
        sound:PlayTone(800, 20)
    elseif command = 4          //bottom right remote button
        sound:PlayTone(1600, 20)
    end
end

GetRemoteDirection(integer channel)

This action is used to find the direction of an EV3 remote with respect to the infrared sensor.

Parameters

  • integer channel: is used to find an EV3 remote using the same channel. There are 4 valid channels: 1, 2, 3, and 4. There are class constants available for this parameter. The remote's channel appears on the remote between the buttons and below it is a switch that moves up and down that changes the remote's channel. When the switch is all the way up, the remote's channel is 1 and when the switch is all the way down, the remote's channel is 4.

Return

integer: an integer representing the relative angle, in degrees, of the remote with respect to the robot. Values returned will be between -180 to 180, where: negative integers represent that the remote is to the left of the sensor, positive integers represent that the remote is to the right of the sensor, and a value of 0 indicates that the remote is directly ahead of the sensor.

Example

use Libraries.Robots.Lego.InfraredSensor
use Libraries.Robots.Lego.Motor

InfraredSensor infraredSensor
Motor motor

infraredSensor:SetPort(infraredSensor:PORT_4)
motor:SetSpeed("B", 720)    //this motor should move the right side of the robot
motor:SetSpeed("C", 720)    //this motor should move the left side of the robot

integer direction = 0
repeat while true
    direction = infraredSensor:GetRemoteDirection(infraredSensor:CHANNEL_1) //tells the program to interact with a remote using channel 1
    if direction > 0            //remote is on the right side of the sensor
        motor:RotateForward("C")
        motor:Stop("B")
    elseif direction < 0        //remote is on the left side of the sensor
        motor:RotateForward("B")
        motor:Stop("C")
    elseif infraredSensor:GetRemoteDistance(1) < 100   //remote straight ahead and remote still in range of the sensor
        output infraredSensor:GetRemoteDistance(1)
        motor:RotateForward("B")
        motor:RotateForward("C")
    else                        //found the remote
        motor:Stop("B")
        motor:Stop("C")
    end
end

GetRemoteDistance(integer channel)

This action is used to find the distance of an EV3 remote with respect to the infrared sensor.

Parameters

  • integer channel: is used to find an EV3 remote using the same channel. There are 4 valid channels: 1, 2, 3, and 4. There are class constants available for this parameter. The remote's channel appears on the remote between the buttons and below it is a switch that moves up and down that changes the remote's channel. When the switch is all the way up, the remote's channel is 1 and when the switch is all the way down, the remote's channel is 4.

Return

integer: an integer representing the centimeters between the infrared sensor and the EV3 remote using the specified channel. Return values are 1 through 100 if the remote is found, otherwise the value will be the maximum integer value (2147483647).

Example

use Libraries.Robots.Lego.InfraredSensor
use Libraries.Robots.Lego.Sound

InfraredSensor infraredSensor
Sound sound

infraredSensor:SetPort(infraredSensor:PORT_4)
repeat while true
    if infraredSensor:GetRemoteDistance(1) <= 20
        sound:PlayTone(1100, 20)
    elseif infraredSensor:GetRemoteDistance(1) <= 40
        sound:PlayTone(900, 20)
    elseif infraredSensor:GetRemoteDistance(1) <= 60
        sound:PlayTone(700, 20)
    elseif infraredSensor:GetRemoteDistance(1) <= 80
        sound:PlayTone(500, 20)
    elseif infraredSensor:GetRemoteDistance(1) <= 100
        sound:PlayTone(300, 20)
    else
        sound:PlayTone(20, 20)
    end
end

SetPort(integer portNumber)

This action lets the program know which port on the robot that the infrared sensor being used is plugged into. As such, this action must be called before any other action in the InfraredSensor class will work.

Parameters

  • integer portNumber: specifies the port on the robot that the infrered sensor is plugged into. The port number corresponds to the actual number printed above the port on the EV3 brick. Valid port numbers are 1, 2, 3 or 4.

Example

use Libraries.Robots.Lego.InfraredSensor

InfraredSensor infraredSensor1
InfraredSensor infraredSensor2
InfraredSensor infraredSensor3

infraredSensor1:SetPort(1)                      //we can have multiple infrared sensors plugged into the robot at once
infraredSensor2:SetPort(2)                      //after setting the ports, we can now use any other action in the ColorSensor class
infraredSensor3:SetPort(infraredSensor3:PORT_3) //we can use a class constant to designate a port, as well