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Construction-Vessel

This demo simulates a marine vessel doing crane operations while dynamically positioned. System plants and controllers are modularized according to responsibility and to preserve numerical stability.

FMUs are listed in Table 1.

Table 1: List of FMUs in the Construction Vessel demo.

FMU name Description
Vessel Model Simulates the motions of a marine vessel exposed to environmental forces
Power Plant Simulates the vessel’s power plant
Thrust Allocation Maps thrust orders from DP to thruster setpoints
Thruster Model Maps thruster setpoints to forces acting on the vessel
Wind Model Models wind forces acting on the vessel
Wave Model Models first and second order wave forces as disturbances in vessel position
Winch Models the crane and winch
DP Controller DP controller for keeping the vessel at a fixed position
Reference Model Reference model for smoothing the setpoint provided to DP

System Overview

Thrusters

The simulated vessel has five thrusters: two azimuth thrusters and three tunnel thrusters. Their location with respect to midships is listed in Table 2

Table 2: Thruster Layout

Thruster Location w.r.t midships [x, y, z] m
Tunnel Thruster 1 [31, 0, 2.1]
Tunnel Thruster 2 [28.9, 0, 1.9]
Tunnel Thruster 3 [24.75, 0, 1.9]
Port Azimuth Thruster [-36.45, -4, 1.414]
Starboard Azimuth Thruster [-36.45, 4, 1.414]

Power Plant

The power plant is responsible for providing power to the thruster, crane and hotel loads. Its topology is shown in Figure 1.

Figure 1: Power plant topology

Connections

Connections between FMUs are defined using CSE’s internal system structure format. An equivalent simulator topology is shown in the Simulink diagram in Figure 2

Figure 2: Model connections

FMUS

Every model in the demo is implemented as a Functional Mockup Unit (FMU). FMUs are a common framework for sharing models generated from different tools such as Simulink, SimulationX etc. All FMUs in this demo is compiled for Windows only.

Winch

The winch FMU combines winch dynamics and control. Inside is a PID controller producing torque commands for the winch model with load depth as the control objective. Users interact with the controller by specifying the load depth setpoint.

The winch model calculates load depth by modelling the winch as a second order dynamic system. Vessel position is necessary to adjust load depth for heave motions. The model outputs load depth, motor speed and power consumption for use in the power plant FMU.

Interface descriptions are given in Table 3 and Table 4.

Table 3: Winch model inputs and outputs (I/O).

Name I/O Unit Description
vessel_position.north I m Vessel’s north position in NED frame
vessel_position.east I m Vessel’s east position in NED frame
vessel_position.down I m Vessel’s down position in NED frame
vessel_position.roll I rad Vessel’s roll orientation in NED frame
vessel_position.pitch I rad Vessel’s pitch orientation in NED frame
vessel_position.yaw I rad Vessel’s yaw orientation in NED frame
load_depth_setpoint I m The desired load depth
load_depth O m Current load depth
motor_speed O rad/s Current winch motor speed
power_consumption O W Power consumed

Table 4: Winch model’s OSP-IS variable groups

Name Comprised variables Description
vessel_position vessel_position.north, vessel_position.east, vessel_position.down, vessel_position.roll, vessel_position.pitch, vessel_position.yaw Vessel’s position in NED (North-East-Down) frame
load_depth load_depth Wrapper group for load depth
motor_speed motor_speed Wrapper group for motor speed
power_consumption power_consumption Wrapper group for power consumed

Reference Model

The reference model produces a smooth setpoint signal based on the desired vessel position. This is achieved by passing the setpoint through a rate limited second order system.

Lists of inputs and outputs are given in Table 5 and Table 6.

Table 5: Reference model inputs and outputs (I/O).

Name I/O Unit Description
setpoint.north I m Desired north position in NED frame
setpoint.east I m Desired east position in NED frame
setpoint.yaw I rad Desired yaw orientation in NED frame
filtered_setpoint.north O m Reference filtered DP setpoint north
filtered_setpoint.east O m Reference filtered DP setpoint east
filtered_setpoint.yaw O rad Reference filtered DP setpoint yaw

Table 6: Reference model’s OSP-IS variable groups

Name Comprised variables Description
vessel_setpoint vessel_setpoint.north, vessel_setpoint.east, vessel_setpoint.yaw Vessel position setpoint in NED (North-East-Down) frame
filtered_vessel_setpoint filtered_vessel_setpoint.north, filtered_vessel_setpoint.east, filtered_vessel_setpoint.yaw Reference filtered vessel position setpoint in NED (North-East-Down) frame

Vessel Model

The vessel model FMU simulates vessel dynamics. Its inputs are environmental forces produced by the wind and wave models and the thruster states from the thruster model. The resultant thrust force is calculated using the thruster layout in Table 2.

The output is the vessel’s velocity expressed in the BODY frame and position expressed in NED.

Lists of inputs and outputs are given in Table 7 and Table 8.

Table 7: Vessel model inputs and outputs (I/O).

Name I/O Unit Description
wave_forces.surge I N Wave force in surge expressed in BODY
wave_forces.sway I N Wave force in sway expressed in BODY
wave_forces.heave I N Wave force in heave expressed in BODY
wave_forces.roll I Nm Wave moment in roll expressed in BODY
wave_forces.pitch I Nm Wave moment in pitch expressed in BODY
wave_forces.yaw I Nm Wave moment in yaw expressed in BODY
wind_forces.surge I N Wind force in surge expressed in BODY
wind_forces.sway I N Wind force in sway expressed in BODY
wind_forces.heave I N Wind force in heave expressed in BODY
wind_forces.roll I Nm Wind moment in roll expressed in BODY
wind_forces.pitch I Nm Wind moment in pitch expressed in BODY
wind_forces.yaw I Nm Wind moment in yaw expressed in BODY
thruster_states.tunnel_thruster_1.power_consumption I W Power consumed by tunnel thruster 1
thruster_states.tunnel_thruster_1.thrust I N Thrust produced by tunnel thruster 1
thruster_states.tunnel_thruster_2.power_consumption I W Power consumed by tunnel thruster 2
thruster_states.tunnel_thruster_2.thrust I N Thrust produced by tunnel thruster 2
thruster_states.tunnel_thruster_3.power_consumption I W Power consumed by tunnel thruster 3
thruster_states.tunnel_thruster_3.thrust I N Thrust produced by tunnel thruster 3
thruster_states.main_propeller_port.power_consumption I W Power consumed by port azimuth thruster
thruster_states.main_propeller_port.thrust I N Thrust produced by port azimuth thruster
thruster_states.main_propeller_port.azimuth I deg Azimuth of port azimuth thruster
thruster_states.main_propeller_starboard.power_consumption I W Power consumed by starboard azimuth thruster
thruster_states.main_propeller_starboard.thrust I N Thrust produced by starboard azimuth thruster
thruster_states.main_propeller_starboard.azimuth I deg Azimuth of starboard azimuth thruster
body_velocity.surge O m/s Vessel’s surge velocity expressed in BODY
body_velocity.sway O m/s Vessel’s sway velocity expressed in BODY
body_velocity.heave O m/s Vessel’s heave velocity expressed in BODY
body_velocity.roll O rad/s Vessel’s roll velocity expressed in BODY
body_velocity.pitch O rad/s Vessel’s pitch velocity expressed in BODY
body_velocity.yaw O rad/s Vessel’s yaw velocity expressed in BODY
ned_position.north O m Vessel’s north position expressed in NED
ned_position.east O m Vessel’s east position expressed in NED
ned_position.down O m Vessel’s down position expressed in NED
ned_position.roll O rad Vessel’s roll orientation expressed in NED
ned_position.pitch O rad Vessel’s pitch orientation expressed in NED
ned_position.yaw O rad Vessel’s yaw orientation expressed in NED

Table 8: Vessel model’s OSP-IS variable groups

Name Comprised variables Description
wind_forces wind_forces.surge, wind_forces.sway, wind_forces.heave, wind_forces.roll, wind_forces.pitch wind_forces.yaw Wind forces acting on vessel in BODY frame
wave_forces wave_forces.surge, wave_forces.sway, wave_forces.heave, wave_forces.roll, wave_forces.pitch wave_forces.yaw Wave forces acting on vessel in BODY frame
tunnel_thruster_1 thruster_states.tunnel_thruster_1.power_consumption, thruster_states.tunnel_thruster_1.thrust Input group for tunnel thruster 1
tunnel_thruster_2 thruster_states.tunnel_thruster_2.power_consumption, thruster_states.tunnel_thruster_2.thrust Input group for tunnel thruster 2
tunnel_thruster_3 thruster_states.tunnel_thruster_3.power_consumption, thruster_states.tunnel_thruster_3.thrust Input group for tunnel thruster 3
main_propeller_port thruster_states.main_propeller_port.power_consumption, thruster_states.main_propeller_port.thrust, thruster_states.main_propeller_port.azimuth Input group for tunnel main propeller port
main_propeller_starboard thruster_states.main_propeller_starboard.power_consumption, thruster_states.main_propeller_starboard.thrust, thruster_states.main_propeller_starboard.azimuth Input group for tunnel main propeller starboard
ned_position ned_position.north, ned_position.east, ned_position.down, ned_position.roll, ned_position.pitch ned_position.yaw Vessel position in NED
body_velocity body_velocity.surge, body_velocity.sway, body_velocity.heave, body_velocity.roll, body_velocity.pitch body_velocity.yaw Vessel velocity in BODY

Thrust Allocation

The thrust allocation FMU transforms the force commands from DP to thruster setpoints. The setpoints are passed to the thruster model which calculates the resultant force.

Lists of inputs and outputs are given in Table 9 and Table 10.

Table 9: Thrust allocation inputs and outputs (I/O).

Name I/O Unit Description
force_command.surge I N Desired force in surge expressed in BODY
force_command.sway I N Desired force in sway expressed in BODY
force_command.yaw I Nm Desired moment in yaw expressed in BODY
thrust_command.main_propeller_port.azimuth O deg Azimuth command to port azimuth thruster
thrust_command.main_propeller_port.rpm O [ 0…1 ] RPM command to port azimuth thruster
thrust_command.main_propeller_starboard.azimuth O deg Azimuth command to starboard azimuth thruster
thrust_command.main_propeller_starboard.rpm O [ 0…1 ] RPM command to starboard azimuth thruster
thrust_command.tunnel_thruster_1.rpm O [ 0…1 ] RPM command to tunnel thruster 1
thrust_command.tunnel_thruster_2.rpm O [ 0…1 ] RPM command to tunnel thruster 2
thrust_command.tunnel_thruster_3.rpm O [ 0…1 ] RPM command to tunnel thruster 3

Table 10: Thrust Allocation’s OSP-IS variable groups

Name Comprised variables Description
force_command force_command.surge, force_command.sway, force_command.yaw Force command from DP
tunnel_thruster_1_command thrust_command.tunnel_thruster_1.rpm. Command to tunnel thruster 1
tunnel_thruster_2_command thrust_command.tunnel_thruster_2.rpm. Command to tunnel thruster 2
tunnel_thruster_3_command thrust_command.tunnel_thruster_3.rpm. Command to tunnel thruster 3
main_propeller_port_command thrust_command.main_propeller_port.rpm., thrust_command.main_propeller_port.azimuth. Command to main propeller port
main_propeller_starboard_command thrust_command.main_propeller_starboard.rpm., thrust_command.main_propeller_starboard.azimuth. Command to main propeller starboard

Thruster Model

The thruster model simulates thruster dynamics using setpoints produced by the thrust allocator. The output is a thruster state structure consisting of power consumption, thrust and, for azimuth thrusters, azimuth angle.

Lists of inputs and outputs are given in Table 11 and Table 12.

Table 11: Thruster model inputs and outputs (I/O).

Name I/O Unit Description
thrust_command.main_propeller_port.azimuth I deg Azimuth command to port azimuth thruster
thrust_command.main_propeller_port.rpm I [ 0…1 ] RPM command to port azimuth thruster
thrust_command.main_propeller_starboard.azimuth I deg Azimuth command to starboard azimuth thruster
thrust_command.main_propeller_starboard.rpm I [ 0…1 ] RPM command to starboard azimuth thruster
thrust_command.tunnel_thruster_1.rpm I [ 0…1 ] RPM command to tunnel thruster 1
thrust_command.tunnel_thruster_2.rpm I [ 0…1 ] RPM command to tunnel thruster 2
thrust_command.tunnel_thruster_3.rpm I [ 0…1 ] RPM command to tunnel thruster 3
thruster_states.tunnel_thruster_1.power_consumption O W Power consumed by tunnel thruster 1
thruster_states.tunnel_thruster_1.thrust O N Thrust produced by tunnel thruster 1
thruster_states.tunnel_thruster_2.power_consumption O W Power consumed by tunnel thruster 2
thruster_states.tunnel_thruster_2.thrust O N Thrust produced by tunnel thruster 2
thruster_states.tunnel_thruster_3.power_consumption O W Power consumed by tunnel thruster 3
thruster_states.tunnel_thruster_3.thrust O N Thrust produced by tunnel thruster 3
thruster_states.main_propeller_port.power_consumption O W Power consumed by port azimuth thruster
thruster_states.main_propeller_port.azimuth O deg Azimuth of port azimuth thruster
thruster_states.main_propeller_port.thrust O N Thrust produced by port azimuth thruster
thruster_states.main_propeller_starboard.power_consumption O W Power consumed by starboard azimuth thruster
thruster_states.main_propeller_starboard.azimuth O deg Azimuth of starboard azimuth thruster
thruster_states.main_propeller_starboard.thrust O N Thrust produced by starboard azimuth thruster

Table 12: Thruster Model’s OSP-IS variable groups

Name Comprised variables Description
tunnel_thruster_1_command thrust_command.tunnel_thruster_1.rpm. Command to tunnel thruster 1
tunnel_thruster_2_command thrust_command.tunnel_thruster_2.rpm. Command to tunnel thruster 2
tunnel_thruster_3_command thrust_command.tunnel_thruster_3.rpm. Command to tunnel thruster 3
main_propeller_port_command thrust_command.main_propeller_port.rpm., thrust_command.main_propeller_port.azimuth. Command to main propeller port
main_propeller_starboard_command thrust_command.main_propeller_starboard.rpm., thrust_command.main_propeller_starboard.azimuth. Command to main propeller starboard
tunnel_thruster_1_state thrust_command.tunnel_thruster_1.power_consumed, thrust_command.tunnel_thruster_1.rpm Tunnel thruster 1 state
tunnel_thruster_2_state thrust_command.tunnel_thruster_2.power_consumed, thrust_command.tunnel_thruster_2.rpm Tunnel thruster 2 state
tunnel_thruster_3_state thrust_command.tunnel_thruster_3.power_consumed, thrust_command.tunnel_thruster_3.rpm Tunnel thruster 3 state
main_propeller_port_state thruster_states.main_propeller_port.power_consumption, thruster_states.main_propeller_port.thrust, thruster_states.main_propeller_port.azimuth Main propeller port state
main_propeller_starboard_state thruster_states.main_propeller_starboard.power_consumption, thruster_states.main_propeller_starboard.thrust, thruster_states.main_propeller_starboard.azimuth Main propeller starboard

DP Controller

The DP controller FMU calculates the forces necessary to keep the vessel at a desired position. The position setpoint is provided by the reference model and the current position by the vessel model. The forces calculated by DP is used as input the thrust allocation FMU. The control algorithm is simple and consists only of a PID controller for each degree of freedom.

Lists of inputs and outputs are given in Table 13 and Table 14.

Table 13: DP controller inputs and outputs (I/O).

Name I/O Unit Description
vessel_position.north I m Vessel’s north position in NED frame
vessel_position.east I m Vessel’s east position in NED frame
vessel_position.down I m Vessel’s down position in NED frame
vessel_position.roll I rad Vessel’s roll orientation in NED frame
vessel_position.pitch I rad Vessel’s pitch orientation in NED frame
vessel_position.yaw I rad Vessel’s yaw orientation in NED frame
vessel_setpoint.north I m Desired north position in NED
vessel_setpoint.east I m Desired east position in NED
vessel_setpoint.yaw I rad Desired yaw orientation in NED
force_command.surge O N Desired force in surge expressed in BODY
force_command.sway O N Desired force in sway expressed in BODY
force_command.yaw O Nm Desired moment in yaw expressed in BODY

Table 14: DP controllers’s OSP-IS variable groups

Name Comprised variables Description
ned_position vessel_position.north, vessel_position.east, vessel_position.down, vessel_position.roll, vessel_position.pitch, vessel_position.yaw Vessel position in NED
vessel_setpoint vessel_setpoint.north, vessel_setpoint.east, vessel_setpoint.yaw Vessel setpoint in NED
force_command force_command.surge, force_command.sway, force_command.yaw Force command from DP

Wind Model

The wind model is responsible for modelling external wind forces acting on the vessel.

Lists of inputs and outputs are given Table 15 and Table 16.

Table 15: Wind model inputs and outputs (I/O).

Name I/O Unit Description
vessel_position.north I m Vessel’s north position in NED frame
vessel_position.east I m Vessel’s east position in NED frame
vessel_position.down I m Vessel’s down position in NED frame
vessel_position.roll I rad Vessel’s roll orientation in NED frame
vessel_position.pitch I rad Vessel’s pitch orientation in NED frame
vessel_position.yaw I rad Vessel’s yaw orientation in NED frame
vessel_velocity.surge I m/s Vessel’s surge velocity in BODY
vessel_velocity.sway I m/s Vessel’s sway velocity in BODY
vessel_velocity.heave I m/s Vessel’s heave velocity in BODY
vessel_velocity.roll I rad/s Vessel’s roll velocity in BODY
vessel_velocity.pitch I rad/s Vessel’s pitch velocity in BODY
vessel_velocity.yaw I rad/s Vessel’s yaw velocity in BODY
wind_forces.surge O N Wind force in surge expressed in BODY
wind_forces.sway O N Wind force in sway expressed in BODY
wind_forces.heave O N Wind force in heave expressed in BODY
wind_forces.roll O Nm Wind moment in roll expressed in BODY
wind_forces.pitch O Nm Wind moment in pitch expressed in BODY
wind_forces.yaw O Nm Wind moment in yaw expressed in BODY

Table 16: Wind model’s OSP-IS variable groups

Name Comprised variables Description
ned_position vessel_position.north, vessel_position.east, vessel_position.down, vessel_position.roll, vessel_position.pitch, vessel_position.yaw Vessel position in NED
vessel_velocity vessel_velocity.surge, vessel_velocity.sway, vessel_velocity.heave, vessel_velocity.roll, vessel_velocity.pitch, vessel_velocity.yaw Vessel velocity in BODY
wind_forces wind_forces.surge, wind_forces.sway, wind_forces.heave, wind_forces.roll, wind_forces.pitch wind_forces.yaw Wind forces acting on vessel in BODY frame

Wave Model

The wave model simulates first and second order wave forces acting on the vessel. The model is implemented as a linearized wave spectrum producing position disturbances. Meaning that wave disturbances are added directly to the vessel position calculated by the vessel model FMU.

A complete list of outputs is given in Table 17. ‘ The sea state and response magnitude can be tuned by changing the parameters listed in Table 18.

Table 17: Wave model inputs and outputs (I/O).

Name I/O Unit Description
first_order_disturbances.north O m First order wave disturbances north
first_order_disturbances.east O m First order wave disturbances east
first_order_disturbances.down O m First order wave disturbances down
first_order_disturbances.roll O rad First order wave disturbances roll
first_order_disturbances.pitch O rad First order wave disturbances pitch
first_order_disturbances.yaw O rad First order wave disturbances yaw
drift_disturbances.north O m Wave drift north
drift_disturbances.east O m Wave drift east
drift_disturbances.down O m Wave drift down
drift_disturbances.roll O rad Wave drift roll
drift_disturbances.pitch O rad Wave drift pitch
drift_disturbances.yaw O rad Wave drift yaw

Table 18: Wave model parameters

Name Unit Description
wave_height m Significant wave height of sea state
peak_frequency rad/s Peak frequency of sea state
k_north - Tuning constant for first order wave disturbances north
k_east - Tuning constant for first order wave disturbances east
k_down - Tuning constant for first order wave disturbances down
k_roll - Tuning constant for first order wave disturbances roll
k_pitch - Tuning constant for first order wave disturbances pitch
k_yaw - Tuning constant for first order wave disturbances yaw
north_drift_limit m Max wave drift north
east_drift_limit m Max wave drift east
yaw_drift_limit rad Max wave drift yaw

Power System

The power system simulates the power plant shown in Figure 4. There is no feedback from the plant to the thruster and the crane. Meaning that both act as if they have unlimited available power. However, power consumption is fed to the power system which calculates bus frequency, voltage and produced power

List of inputs and outputs is given in Table 19 and Table 20.

Table 19: Wave model inputs and outputs (I/O).

Name I/O Unit Description
bus_1_loads.active_power I W Active power of external load connected to bus 1
bus_1_loads.reactive_power I Var Reactive power of external load connected to bus 1
bus_2_loads.active_power I W Active power of external load connected to bus 2
bus_2_loads.reactive_power I Var Reactive power of external load connected to bus 2
is_bus_connected I - Bus 1 and bus 2 are connected if true
thruster_states.tunnel_thruster_1.power_consumption I W Power consumed by tunnel thruster 1
thruster_states.tunnel_thruster_1.thrust I N Thrust produced by tunnel thruster 1
thruster_states.tunnel_thruster_2.power_consumption I W Power consumed by tunnel thruster 2
thruster_states.tunnel_thruster_2.thrust I N Thrust produced by tunnel thruster 2
thruster_states.tunnel_thruster_3.power_consumption I W Power consumed by tunnel thruster 3
thruster_states.tunnel_thruster_3.thrust I N Thrust produced by tunnel thruster 3
thruster_states.main_propeller_port.power_consumption I W Power consumed by port azimuth thruster
thruster_states.main_propeller_port.azimuth I deg Azimuth of port azimuth thruster
thruster_states.main_propeller_port.thrust I N Thrust produced by port azimuth thruster
thruster_states.main_propeller_starboard.power_consumption I W Power consumed by starboard azimuth thruster
thruster_states.main_propeller_starboard.azimuth I deg Azimuth of starboard azimuth thruster
thruster_states.main_propeller_starboard.thrust I N Thrust produced by starboard azimuth thruster
bus_1_frequency O rad/s Frequency of bus 1
bus_1_voltage_imag O V Imaginary part of bus 1 voltage
bus_1_voltage_real O V Real part of bus 1 voltage
bus_2_frequency O rad/s Frequency of bus 2
bus_2_voltage_imag O V Imaginary part of bus 2 voltage
bus_2_voltage_real O V Real part of bus 2 voltage
bus_power[1,1] O W Power produced on bus 1
bus_power[1,2] O W Power produced on bus 2

Table 20: Power System’s OSP-IS variable groups

Name Comprised variables Description
bus_1_loads bus_1_loads.active_power, bus_1_load.reactive_power Power loads on bus 1
bus_2_loads bus_2_loads.active_power, bus_2_load.reactive_power Power loads on bus 2
winch_power bus_1_loads.active_power Power consumed by the winch
tunnel_thruster_1_state thrust_command.tunnel_thruster_1.power_consumed, thrust_command.tunnel_thruster_1.rpm Tunnel thruster 1 state
tunnel_thruster_2_state thrust_command.tunnel_thruster_2.power_consumed, thrust_command.tunnel_thruster_2.rpm Tunnel thruster 2 state
tunnel_thruster_3_state thrust_command.tunnel_thruster_3.power_consumed, thrust_command.tunnel_thruster_3.rpm Tunnel thruster 3 state
main_propeller_port_state thruster_states.main_propeller_port.power_consumption, thruster_states.main_propeller_port.thrust, thruster_states.main_propeller_port.azimuth Main propeller port state
main_propeller_starboard_state thruster_states.main_propeller_starboard.power_consumption, thruster_states.main_propeller_starboard.thrust, thruster_states.main_propeller_starboard.azimuth Main propeller starboard

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