xpkg_carrier Interface Description

Payload Carrier Interface

Public APIs

Publish

Subscribe

Parameter

Detailed Description

/carrier_state

This topic publishes the current state of the payload carrier.

• Type: nav_msgs/Odometry

  std_msgs/Header header
      uint32 seq
      time stamp
      string frame_id
  string child_frame_id
  geometry_msgs/PoseWithCovariance pose
      geometry_msgs/Pose pose
          geometry_msgs/Point position
              float64 x
              float64 y
              float64 z
          geometry_msgs/Quaternion orientation
              float64 x
              float64 y
              float64 z
              float64 w
      float64[36] covariance
  geometry_msgs/TwistWithCovariance twist
      geometry_msgs/Twist twist
          geometry_msgs/Vector3 linear
              float64 x
              float64 y
              float64 z
          geometry_msgs/Vector3 angular
              float64 x
              float64 y
              float64 z
      float64[36] covariance
  

• Usage:
  • header
    • stamp is the timestamp of the message
    • frame_id is the base link of the chassis, typically base_link
  • child_frame_id
    • The name of the base link of the carrier, typically carrier_link
  • pose
    • The current pose of the carrier
    • The pose.pose.position.z indicates the height of the carrier
    • Unit: meters ($m$)
  • twist
    • The current velocity of the carrier
    • The twist.twist.linear.z indicates the rising speed of the carrier
    • Unit: meters per second ($m/s$)
• Example:

  msg_time = msg.header.stamp.to_sec()
  height = msg.pose.pose.position.z
  rising_speed = msg.twist.twist.linear.z
  print(f"The height at {msg_time} is {height}.")
  print(f"The rising speed at {msg_time} is {rising_speed}.")
  

/carrier_cmd_vel

This topic receives the target velocity of the payload carrier.

• Type: geometry_msgs/TwistStamped

  std_msgs/Header header
      uint32 seq
      time stamp
      string frame_id
  geometry_msgs/Twist twist
      geometry_msgs/Vector3 linear
          float64 x
          float64 y
          float64 z
      geometry_msgs/Vector3 angular
          float64 x
          float64 y
          float64 z
  

• Usage:
  • header
    • stamp is the timestamp of the message
    • frame_id is the base link of the chassis, typically base_link
  • twist
    • The target velocity of the carrier (only for velocity control mode)
    • The twist.linear.z indicates the rising speed of the carrier (negative values indicate falling)
    • Unit: meters per second ($m/s$)
• Example:

  msg = geometry_msgs.msg.TwistStamped()
  msg.header.stamp = rospy.Time.now()
  msg.header.frame_id = "base_link"
  msg.twist.linear.z = 0.2
  

/carrier_cmd_pos

This topic receives the target pose of the payload carrier.

• Type: geometry_msgs/PoseStamped

  std_msgs/Header header
      uint32 seq
      time stamp
      string frame_id
  geometry_msgs/Pose pose
      geometry_msgs/Point position
          float64 x
          float64 y
          float64 z
      geometry_msgs/Quaternion orientation
          float64 x
          float64 y
          float64 z
          float64 w
  

• Usage:
  • header
    • stamp is the timestamp of the message
    • frame_id is the base link of the chassis, typically base_link
  • pose
    • The target pose of the carrier (only for position control mode)
    • The pose.position.z indicates the height of the carrier
    • Unit: meters ($m$)
• Example:

  msg = geometry_msgs.msg.PoseStamped()
  msg.header.stamp = rospy.Time.now()
  msg.header.frame_id = "base_link"
  msg.pose.position.z = 0.2