ProstateBRP OpenIGTLink Communication June 2013

The following table shows message exchange diagram for the communication between 3D Slicer (and other navigation software) and the robot in each workhpase.

Notations

• STRING(NN, SS)
  • NN: Device name in the OpenIGTLink header. (Max. 20 bytes)
  • SS: String in the message body. (Max. 65536 bytes)
• STATE(NN, CC:SS:EE:MM) (see http://openigtlink.org/protocols/v2_status.html )
  • NN: Device type in the OpenIGTLink header. (Max. 20 bytes)
  • CC: Code
  • SS: Subcode
  • EE: Error name (Max 20 bytes)
  • MM: Message
• TRANSFORM(NN, TT)
  • NN: Device type in the OpenIGTLink header. (Max. 20 bytes)
  • TT: 4x4 linear transformation matrix

Diagram

3D Slicer (operator)	Message	Robot Controller	Radiologist	Note
Start-up
The operator presses "Start-up" button
Send command to robot	>> STRING(CMD_XXXX, START_UP) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, START_UP) <<	Echo back an acknowledgement command was received, but not yet completed		XXXX is the same unique query ID as the START_UP message.
		Start up and initialize the hardware. Run the robot homing procedure if necessary (skip if already successfully completed). Move robot to home (loading) configuration.
	<< STATUS(START_UP, OK:??:??) << DEVICE_NAME=START_UP C=1(OK), SubCode=??, ErrorName=??	Confirm when robot is initialized TODO: Refine error/status codes
Display the result of start up process.
Planning
The operator opens the planning panel
	>> STRING(CMD_XXXX, PLANNING) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, PLANNING) <<	Echo back an acknowledgement command was received		XXXX is the same unique query ID as the PLANNING message.
		Do nothing except keep track of current state, robot is awaiting next workphase.
Show that the robot is in PLANNING phase.
Calibration
The operator opens the calibration panel
	>> STRING(CMD_XXXX, CALIBRATION) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, CALIBRATION) <<	Echo back an acknowledgement command was received		XXXX is the same unique query ID as the CALIBRATION message.
		Do nothing except keep track of current state, robot is awaiting calibration transform
Show that the robot is in CALIBRATION phase.
Nav Software (3D Slicer or RadVision) calculates calibration matrix
	>> TRANSFORM(CLB_XXXX, 4x4 calibration matrix in RAS coordinates) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< TRANSFORM(ACK_XXXX, 4x4 calibration matrix in RAS coordinates) <<	Echo back an acknowledgement transform was received		XXXX is the same unique query ID as the CLB message.
		Update calibration transform, set flag that registration has been set externally, reply with confirmation
	<< STATUS(CALIBRATION, OK:??:??) << DEVICE_NAME=CALIBRATION C=1(OK), SubCode=??, ErrorName=??	Confirm that calibration was received and robot is ready for next workphase (targeting)
Show that calibration successfully sent to robot.
Targeting
The operator enters "Targeting" mode
	>> STRING(CMD_XXXX, TARGETING) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, TARGETING) <<	Acknowledge receiving targeting command		XXXX is the same unique query ID as the TARGETING message.
		Confirm if robot is ready for targeting; check if calibration was received; return robot to home (loading) position, if needed.
	<< STATUS(TARGETING, OK:??:??) << DEVICE_NAME=TARGETING C=1(OK), SubCode=??, ErrorName=??	Confirm robot has entered targeting mode
	<< STATUS(TARGETING, DNR:??:??) << DEVICE_NAME=TARGETING C=13(DeviceNotReady), SubCode=??, ErrorName=??	ERROR CASE: If not able to enter targeting mode (i.e. calibration not received, reply with Code:13 (Device Not Ready)
The operator select a target, Nav software creates a 4x4 matrix for desired 6-DOF robot pose to reach the target
	>> TRANSFORM(TGT_XXXXX, 4x4 target matrix in RAS coordinates) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< TRANSFORM(ACK_XXXXX, 4x4 target matrix) <<	Acknowledge receipt of target transformation by echoing back		XXXX is the same unique query ID as the TARGETING message.
		Calculate if target pose is reachable based on the kinematics, reply with status and set target
	<< STATUS(TARGET, OK:??:??) << DEVICE_NAME=TARGETING C=1(OK), SubCode=??, ErrorName=??	Reply with OK if target was accepted
	<< TRANSFORM(TARGET, 4x4 target matrix) <<	Send actual target pose in robot controller if one was set (corresponds to when status comes back OK)
	<< STATUS(TARGET, DNR:??:??) << DEVICE_NAME=TARGET C=13(DeviceNotReady), SubCode=??, ErrorName=??	ERROR CASE: If not in targeting mode, reply with Code:13 (Device Not Ready)
	<< STATUS(TARGET, CE:??:??) << DEVICE_NAME=TARGET C=10(ConfigurationError), SubCode=??, ErrorName=??	ERROR CASE: If not a valid target (i.e. out of workspace), reply with Code:10 (ConfigurationError)
Display the reachable target position set in robot controller.
The operator confirms the target position set in the controller, and press "MOVE"
	>> STRING(CMD_XXXX, MOVE_TO_TARGET) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, MOVE_TO_TARGET) <<	Echo back an acknowledgement command was received (not yet completed)		XXXX is the same unique query ID as the MOVE_TO_TARGET message.
Alert the clinician to hold footpedal to align the robot			Clinician engages interlock (footpedal in scanner room) to enable robot motion. Robot will only move when interlock is engaged following a move command.
		The robot moves to the target and streams its pose during motion
	<< TRANSFORM(CURRENT_POSITION, 4x4 current robot pose matrix in RAS coordinates) <<	Stream current robot pose in RAS coords as moving. Can also be requested (see below).
Display the current robot position as it moves toward the target.
		Display that the robot is at the target. Send confirmation.
	<< STATUS(MOVE_TO_TARGET, OK:??:??) << DEVICE_NAME=DONE_MOVING C=1(OK), SubCode=??, ErrorName=??	Reply with OK when robot reaches target
	<< TRANSFORM(CURRENT_POSITION, 4x4 current robot pose matrix in RAS coordinates) <<	Push out final robot pose in RAS coords as moving. (same format as previous stream - ensures last one is at final position)
Display the current final robot position at the target.
Needle Insertion (Manual)
Ask to lock the robot
			The operator presses "Lock" button
	>> STRING (CMD_XXXX, MANUAL) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, MANUAL) <<	Echo back an acknowledgement command was received (not yet completed)		XXXX is the same unique query ID as the MANUAL message.
		Cut motor power to prevent motion of the robot base. This also eliminates causes of MR interference for insertion under live imaging.
	<< STATUS(MANUAL, OK:??:??) << DEVICE_NAME=MANUAL C=1(OK), SubCode=??, ErrorName=??	Reply with OK when robot is in a safe, locked state
			Insert a needle, optionally under live MR imaging. Perform intervention with the needle (biopsy or seed placement).
			Retract the needle
Ask to unlock the robot and confirm needle is retracted
			The operator presses "Unlock"
				Return to the TARGETING phase (Slicer sends STRING(ACK_XXXXX, TARGETING) )
Additional Commands
The operator presses "Stop" button
	>> STRING(CMD_XXXX, STOP) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, STOP) <<	Acknowledge receiving targeting command		XXXX is the same unique query ID as the STOP message.
		The robot stops all motion. Stays in current state/workphase.
	<< STATUS(STOP, 4:??:??) << DEVICE_NAME=STOP C=1(OK), SubCode=??, ErrorName=??
The operator presses "Emergency" button
	>> STRING(CMD_XXXX, EMERGENCY) >>			XXXX is a unique query ID (string of any ASCII letters up to 16 bytes)
	<< STRING(ACK_XXXX, EMERGENCY) <<	Acknowledge receiving targeting command		XXXX is the same unique query ID as the STOP message.
		The robot stops all motion and disables/locks motors. Switches to Emergency state/workphase. ?? IS THIS THE DESIRED ACTION
	<< STATUS(EMERGENCY, 4:??:??) << DEVICE_NAME=DONE_MOVING C=4(Emergency), SubCode=??, ErrorName=??
Request current robot pose (or target or calibration transforms)
	>> GET_TRANSFORM(CURRENT_POSITION) >>
		The robot transmits current pose ("CURRENT_POSITION") through IGTLink upon request. This also works for requesting "TARGET_POSITION" and "CALIBRATION" transforms stored in robot controller.
	<< TRANSFORM(CURRENT_POSITION, 4x4 current robot pose matrix in RAS coordinates) <<
Request the robot status/workphase
	>> GET_STATUS(CURRENT_STATUS) >> ?? CONFIRM COMMAND STRUCTURE FOR STATUS REQUEST
		Sends current state/workphase. ?? SHOULD IT SEND OTHER INFO TOO
	<< STATUS(XXXXX, YYYYY) <<			XXXXX is workphase (e.g. TARGETING), YYYYY is status.
		Robot controller sends errors or notifications through IGTLink. Transmitted asynchronously with error text in message body. To be used with limit events, hardware failures, invalid commands, etc.
	<< STATUS(ERROR, Error Text) <<