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leJOS ROS API

This package provides the leJOS ROS API. There is an alternate package - nxt_lejos_lcp_proxy - which provides a very similar API and does not need a responder running on the NXT, but this package is much faster, and is recommended.

Example

Even though the API description looks quite complicated, it's very easy to configure the bindings. Here is an example configuration:

nxt_robot:
  - type: motor
    name: r_wheel_joint
    port: PORT_A
    desired_frequency: 20.0

  - type: motor
    name: l_wheel_joint
    port: PORT_B
    desired_frequency: 20.0

  - type: gyro
    name: gyro
    frame_id: gyro_link
    port: PORT_3
    offset: 0
    desired_frequency: 20.0

  - type: ultrasonic
    frame_id: ultrasonic_link
    name: ultrasonic_sensor
    port: PORT_2
    desired_frequency: 10.0

  - type: differential_pilot
    name: pilot
    port: PORT_AC
    desired_frequency: 10.0
    track_width: 16.0
    wheel_diameter: 5.6
    reverse: true

Motor

leJOS ROS API for the NXT motor

Subscribed Topics

~<name> (nxt_msgs/JointVelocity)

• The joint velocity to apply at the joint

Published Topics

~joint_state (sensor_msgs/JointState)

• The current power, position, and velocity of the servo motors.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "motor".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_A, PORT_B or PORT_C.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the actuator and sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

Ultrasonic Sensor

leJOS ROS API for the ultrasonic sensor

Published Topics

~<name> (sensor_msgs/Range)

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "ultrasonic".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Touch Sensor

leJOS ROS API for the touch sensor

Published Topics

~<name> (nxt_msgs/Contact)

• The state of the touch sensor (touching or not).

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "touch".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Color Sensor

leJOS ROS API for the color sensor

Published Topics

~<name> (nxt_msgs/Color)

• Color value measured from the color sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "color".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Gyro Sensor

leJOS ROS API for the gyro sensor

Published Topics

~<name> (nxt_msgs/Gyro)

• Rotation rate data from the gyro sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "gyro".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Acceleration Sensor

leJOS ROS API for the acceleration sensor

Published Topics

~<name> (nxt_msgs/Accelerometer)

• The three axis measured values form the accelerometer sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "accelerometer".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Light Sensor

leJOS ROS API for the light sensor

Published Topics

~<name> (nxt_msgs/Intensity)

• Intensity value measured from the light sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "light".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Sound Sensor

leJOS ROS API for the intensity sensor

Published Topics

~<name> (nxt_lejos_msgs/Decibels)

• Decibels measured from the sound sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "sound".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Compass Sensor

leJOS ROS API for the compass sensor

Published Topics

~<name> (nxt_lejos_msgs/Compass)

• Heading value measured from the compass sensor.

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "compass".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_1, PORT_2, PORT_3, or PORT_4.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.

Differential Pilot

leJOS ROS API for the differential pilot

Subscribed Topics

~dns_command (nxt_lejos_msgs/DNSCommand)

• Differential pilot commands.

~cmd_vel (geometry/Twist)

• The desired linear and angular x,y,z of the base.

Published Topics

~tf (tf/tfMessage)

• tf transforms

~odom (nav_msgs/Odometry)

• odometry data

Parameters

~nxt_robot/type (string, default: None)

• The type should be set to "differential_pilot".

~nxt_robot/port (string, default: None)

• This should be one of the brick ports: PORT_AB, PORT_AC, or PORT_BC.

~nxt_robot/desired_frequency (double, default: None)

• The desired update frequency for the sensor.

~nxt_robot/name (string, default: None)

• The topic name for the sensor data.

~nxt_robot/frame_id (string, default: None)

• The frame that the sensor data is published in.