8.5 Head Joints

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8.5.1 Status Interface

1. Head Joint Status

• Description: Obtain the status of head joints, including current position, speed, current, and temperature. Applicable to Walker Tienkung · Embodied Intelligence.

• Communication type: topic

• Topic name: /head/status

• Message definition: bodyctrl_msgs::msg::MotorStatusMsg

• Message format:

  std_msgs/Header header
  MotorStatus[] status
  
  # MotorStatus definition:
  uint16 name         # MotorName
  float32 pos         # rad
  float32 speed       # rad
  float32 current     # A
  float32 temperature # MOS temperature
  uint32 error

  error field definition:

  Value	Description
  33072	Device offline
  33073	Joint position out of range
  1	Motor over‑temperature
  2	Over‑current
  3	Under‑voltage
  4	Joint MOS over‑temperature
  5	Stall
  6	Over‑voltage
  7	Phase loss
  8	Encoder error

  ros2 topic echo /head/status

8.5.2 Control Interfaces

warning

You need to ensure that the robot body service (body_control) is running; only then will the head motor rotation interface work properly. (The simplest way is to make sure the proc_manager service is started and that you have pressed the A button on the remote controller to complete the self-check.)

1. Position Mode

• Description: Position control interface for head joints. Requires desired position, desired speed, and maximum current. Applicable to Walker Tienkung · Embodied Intelligence.

• Communication type: topic

• Topic name: /head/cmd_pos

• Message definition: bodyctrl_msgs::msg::CmdSetMotorPosition

• Message format:

  std_msgs/Header header
  SetMotorPosition[] cmds
  
  # SetMotorPosition.msg
  uint16 name   # MotorName
  float32 pos   # rad
  float32 spd   # rad/s
  float32 cur   # A

• Command examples:

  ros2 topic pub /head/cmd_pos bodyctrl_msgs/msg/CmdSetMotorPosition "{cmds: [{name: 1, pos: 0.1, spd: 0.2, cur: 5.0 }]}"
  
  ros2 topic pub /head/cmd_pos bodyctrl_msgs/msg/CmdSetMotorPosition "{cmds: [{name: 1, pos: 0.0, spd: 0.2, cur: 5.0 }]}"
  
  ros2 topic pub /head/cmd_pos bodyctrl_msgs/msg/CmdSetMotorPosition "{cmds: [{name: 2, pos: -0.1, spd: 0.2, cur: 5.0 }]}"
  
  ros2 topic pub /head/cmd_pos bodyctrl_msgs/msg/CmdSetMotorPosition "{cmds: [{name: 2, pos: 0.1, spd: 0.2, cur: 5.0 }]}"
  
  ros2 topic pub /head/cmd_pos bodyctrl_msgs/msg/CmdSetMotorPosition "{cmds: [{name: 3, pos: -0.1, spd: 0.2, cur: 5.0 }]}"

2. Hybrid Force‑Position Mode

• Description: Hybrid force‑position control interface for head joints. Requires desired position, desired speed, feed‑forward torque, and kp/kd gains. Applicable to Walker Tienkung · Embodied Intelligence.

• Communication type: topic

• Topic name: /head/cmd_ctrl

• Message definition: bodyctrl_msgs::msg::CmdMotorCtrl

• Message format:

  std_msgs/Header header
  MotorCtrl[] cmds
  
  # MotorCtrl.msg
  uint16 name
  float32 kp
  float32 kd
  float32 pos
  float32 spd
  float32 tor

3. Velocity Mode

• Description: Velocity control interface for joints. Requires desired speed and maximum current. Applicable to Walker Tienkung · Embodied Intelligence.

• Communication type: topic

• Topic name: /head/cmd_vel

• Message definition: bodyctrl_msgs::msg::CmdSetMotorSpeed

• Message format:

  std_msgs/Header header
  SetMotorSpeed[] cmds
  
  # SetMotorSpeed.msg
  uint16 name  # MotorName
  float32 spd  # rad/s
  float32 cur  # A

4. Head Joint Zeroing

• Description: Zeroing interface for head joints. When this interface is called, the current position of the specified head motor is set as the zero position. When the D button on the remote controller is used to return to zero, the joint will move to this position. Typically used together with a dedicated zeroing tool; use with caution if such a tool is not available. Applicable to Walker Tienkung · Embodied Intelligence.

• Communication type: topic

• Topic name: /head/cmd_set_zero

• Message definition: std_msgs::msg::String

• Message format:

  Send the joint ID as a string to perform zeroing.
  Head joint IDs: 1, 2, 3