Head APIs

HeadFactory

The HeadFactory class provides the following method for creating a head instance.

• Method:

  create_head_from_config(config_path: str) -> HeadInterface

• Parameter:

  Parameter

  Description

  config_path

  Path to the configuration file. The configuration file must be a JSON file. { "head_type":"ti5", # Head vendor "head_name":"ti5_head", # Head name "head_joint_num":2, # Number of head joints "can_device":"can0", # CAN device name "can_id":0, # CAN node ID (0x00~0xFF) "motor_params":[ # Motor parameters { "motor_id":5, # Motor ID "reduction_ratio":51, # Reduction ratio "position_max":90, # Maximum rotation angle "position_min":-90.0, # Minimum rotation angle "speed_max":30, # Maximum rotation speed "speed_min":-30, # Minimum rotation speed "acc_max":10, # Maximum rotation acceleration "acc_min":-10 # Minimum rotation acceleration } ] }

• Return value:

  An HeadInterface instance if creation succeeds, otherwise None.

HeadInterface

The HeadInterface class provides a series of public methods for controlling the head, such as obtaining head joint angles and controlling head trajectories. Ensure a head instance has been created before using these methods.

Connect to the Head

After creating a head instance, you can establish a connection to the head using the following method.

• Method:

  connect(self) -> alphabot.core.AbcErrorCode

• Return Value:

  AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.

Disconnect from the Head

You can disconnect from the head using the following method.

• Method:

  disconnect(self) -> alphabot.core.AbcErrorCode

• Return Value:

  AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.

Joint Motion

In joint space, a motion trajectory is planned to drive each joint of the head to the specified target joint positions.

• Method:

  move_joint_position(
      self,
      joints: list[float],
      v: int,
      block: bool
  ) -> alphabot.core.AbcErrorCode

• Parameters:

  Parameter	Description
  joints	Target joint positions, in degrees.
  v	Percentage of the maximum joint linear velocity and acceleration used for planning. Valid range: 0-100.
  block	Blocking mode flag. Accepts False or True. - False: Non-blocking mode. The method returns immediately after successfully sending the motion command to the controller. - True: Blocking mode. The method waits until the head completes the motion or an error occurs before returning.

• Return Value:

  AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.

Angle Pass-through

Joint angles are sent to the head via CAN FD (Controller Area Network Flexible Data-rate), bypassing trajectory planning by the controller. If the method is called correctly, the head executes the motion immediately.

Note

• The pass-through control performance is affected by the communication cycle and trajectory smoothness; therefore, a stable communication cycle is required to avoid large fluctuations.
• When using this feature, it is recommended to plan smooth trajectories to ensure stable operation of the head.

• Method:

  move_joint_position_canfd(self, joints: list[float]) -> alphabot.core.AbcErrorCode

• Parameter:

  Parameter	Description
  joints	Target joint positions, in degrees.

• Return Value:

  AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.

Get Current Joint Angles

• Method:

  get_joint_degree(self) -> tuple[alphabot.core.AbcErrorCode, list[float]]

• Return Value:

  A tuple containing two elements.

  Element Type	Description
  AbcErrorCode	AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.
  list[float]	Current joint angles.

Get Error Information

• Method:

  get_error_flag(self) -> tuple[alphabot.core.AbcErrorCode, list[int]]

• Return Value:

  A tuple containing two elements.

  Element Type	Description
  AbcErrorCode	AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.
  list[int]	Error codes.

Compute Forward Kinematics

• Method:

  forward_kinematics(
      self,
      joints: list[float]
  ) -> tuple[alphabot.core.AbcErrorCode, alphabot.core.Pose]

• Parameter:

  Parameter	Description
  joints	Joint angles.

• Return Value:

  A tuple containing two elements.

  Element Type	Description
  AbcErrorCode	AbcErrorCode.SUCCESS indicates success. For other error codes, please refer to AbcErrorCode.
  Pose	Pose computed by forward kinematics. For details, please refer to Pose.

Get Head Name

• Method:

  get_name(self) -> str

• Return Value:

  The name of the head instance.

AbcHeadState

Attribute	Data Type	Description
err_code	list[int]	Error codes for each joint
joints_current	list[float]	Current for each joint
joints_positions	list[float]	Angle for each joint
joints_speed	list[float]	Speed for each joint
timestamp	typing.Any	Timestamp