ROS 1 Interface Operation

SLATE Base Node

The SLATE interfaces with ROS using the slate_base_node from the interbotix_slate_driver package.

Publishers

The slate_base_node publishes to the following topics:

  • odom
    • Type: nav_msgs/Odometry
    • Description: The odometry of the base.
  • battery_state
    • Type: sensor_msgs/BatteryState
    • Description: Battery state information including present voltage and state of charge.

Subscribers

The slate_base_node subscribes to the following topics:

  • cmd_vel
    • Type: geometry_msgs/Twist
    • Description: Velocity commands

Services

The slate_base_node provides the following service servers:

  • set_text

    • Type: std_srvs/SetString
    • Description: Sets the text on the SLATE screen.

  • set_motor_torque_status

    • Type: std_srvs/SetBool
    • Description: If true, enables torque on the drive wheels. If false, disables torque on the drive wheels.

    Note

    Torque is enabled on the drive wheels by default.

  • enable_charging

    • Type: std_srvs/SetBool
    • Description: If true, enables charging via the contact charger.

Parameters

The slate_base_node has the following parameters:

  • publish_tf:
    • Type: bool
    • Description: Setting this to true publishes the odom->base_link TF following REP 105.
    • Default: false
  • odom_frame_name:
    • Type: string
    • Description: The name of the odometry frame when publishing the odom->base_link TF.
    • Default: "odom"
  • base_frame_name:
    • Type: string
    • Description: The name of the base_link frame when publishing the odom->base_link TF.
    • Default: "base_link"

Examples

The slate_base_node is designed to be controlled by other user-written nodes that publish to the cmd_vel topic or call the services provided by the slate_base_node. Below are some examples of how to interact with the slate_base_node using ROS 1 command line tools.

Setting Parameters

You can set parameters for the slate_base_node when running it using the _param flag.

# Enable publishing of the odom->base_link TF
$ rosrun interbotix_slate_driver slate_base_node _publish_tf:=true

# Set the odometry frame name to "my_odom"
$ rosrun interbotix_slate_driver slate_base_node _odom_frame_name:="my_odom"

# Set the base frame name to "my_base"
$ rosrun interbotix_slate_driver slate_base_node _base_frame_name:="my_base"

Calling Services

You can call services provided by the slate_base_node using the rosservice call command.

# Disable charging
$ rosservice call /enable_charging std_srvs/SetBool "{data: false}"

# Set the lights to color BLUE
$ rosservice call /set_light_state interbotix_slate_msgs/SetLightState "{light_state: 4}"

# Set the text to "hello world" on the SLATE screen
$ rosservice call /set_text interbotix_slate_msgs/SetString "{data: 'hello world'}"

# Disable torque on the drive wheels
$ rosservice call /set_motor_torque_status std_srvs/SetBool "{data: false}"

Publishing Velocity Commands

You can publish velocity commands to the slate_base_node using the rostopic pub command. -r 10 sets the publishing rate to 10 Hz.

Warning

These commands will move the base, so make sure the SLATE is in a safe location before running them. Press Ctrl+C to stop the command at any time.

# Publish a velocity command to move forward
$ rostopic pub -r 10 /cmd_vel geometry_msgs/Twist "{linear: {x: 0.1, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.0}}"

# Publish a velocity command to rotate counter-clockwise
$ rostopic pub -r 10 /cmd_vel geometry_msgs/Twist "{linear: {x: 0.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 0.1}}"