Model Specifications

Detailed technical specs for every platform model in LOTUSim. For a quick "what's available" overview instead, see Models Available.

All models listed here are in prototype stage and have not yet been fully validated. Known limitations are called out per model below. This document will be updated as implementation progresses.

Maintainer for all models: Naval Group (lotusim_support@naval-group.com)

---

Shared across all models

These characteristics are currently identical for every model in LOTUSim.

Field	Value
Degrees of freedom (DoF)	6DoF
Recommended time step	dt = 0.001 s, real_time_factor = 1.0
Platform convention	NED
Axes definition	X = forward, Y = left, Z = up (most CAD defaults); gravity along -Z
Convention vs. simulator	Gazebo and most CAD tools use a right-handed convention (X forward, Z up). LOTUSim applies a coordinate transform (Z → -Y) for consistency.
Multi-agent interaction	Not yet implemented for any model
Communication	Commands sent and position checked via LOTUSim messages
/use_sim_time	Handled via lotusim_msgs; both sim and real time are possible. See ROS 2 clock and time design
Performance & robustness testing	Not yet formally tested for any model (scalability, repeatability, and logging behavior)

Note: environmental constants (g = 9.81 m/s², ρ = 1025 kg/m³, ν = 1.18e-6 m²/s) are configured once per simulation in the Xdyn YAML's environmental constants section. See the Xdyn User Guide.

---

BlueROV2

Field	Value
Family type	Submarine
Use goal	Algorithm tests
Repo link	LOTUSim model Derived from: UUVControl/bluerov2
Simulation Modes	Visual + Dynamics
Actuators	8 Thrusterss, wageningen B-series - wake coefficient 0.2, relative rotative efficiency 0.8, thrust deduction factor 0.2, blade area ratio 0.3
Commands	RPM via Xdyn or waypoint follower
External Forces	Gravity, basic buoyancy, linear & quadratic damping
Visual fidelity	Advanced (model scale: 0.025)
Calibration status	Partially calibrated, parameters partly from the Blue Robotics repo, partly internal
Known limitations	-

---

Commando

Field	Value
Family type	Surface
Use goal	Algorithm tests
Repo link	https://github.com/naval-group/LOTUSim/tree/main/assets/models/commando
Simulation Modes	Visual + Dynamics
Actuators	None modeled
Commands	Via waypoint follower
External Forces	Gravity, non-linear hydrostatic, quadratic damping
Visual fidelity	Medium
Calibration status	Not calibrated
Known limitations	No actuators modeled. The mesh is a cube.

---

DTMB Hull

Field	Value
Family type	Surface
Use goal	Algorithm tests
Repo link	dtmb_hull. Model: DTMB 5415 boat hull http://www.simman2008.dk/5415/combatant.html
Simulation Modes	Visual + Dynamics
Actuators	2× propeller + rudder (propeller+rudder) - wake coefficient 0.15, relative rotative efficiency 0.8, thrust deduction factor 0.2, blade area ratio 0.3
Commands	Select PSPropRudd or SBPropRudd, then set RPM via Xdyn or use the waypoint follower
External Forces	Gravity, non-linear hydrostatic, non-linear Froude-Krylov, linear damping
Visual fidelity	Stable
Calibration status	Calibrated - parameters from the DTMB 5415 reference data
Validated in	circling_ship_example scenario
Known limitations	-

---

FREMM

Field	Value
Family type	Surface
Use goal	Demonstration
Repo link	https://github.com/naval-group/LOTUSim/tree/main/assets/models/fremm
Simulation Modes	Visual + Dynamics
Actuators	Propellers, rudders
Commands	via waypoint follower or xdyn with the propellers
External Forces	Gravity, non-linear hydrostatic, linear &quadratic damping
Visual fidelity	High
Calibration status	Partially calibrated
Known limitations	The mesh is a cube.

---

WAM-V

Field	Value
Family type	Surface
Use goal	Demonstration
Repo link	https://github.com/naval-group/LOTUSim/tree/main/assets/models/wamv
Simulation Modes	Visual + Dynamism
Actuators	none implemented
Commands	via waypoint follower
External Forces	Gravity, quadratic + linear damping, basic buoyancy
Visual fidelity	High
Calibration status	Not calibrated
Known limitations	The mesh is over-simplified

---

LRAUV

Field	Value
Family type	Submarine
Use goal	Demonstration
Repo link	https://github.com/naval-group/LOTUSim/tree/main/assets/models/lrauv
Simulation Modes	Visual + Dynamics
Actuators	Propeller (wageningen B-series)
Commands	via xdyn for the propeller and via waypoint follower
External Forces	Gravity, non-linear hydrostatic , non-linear Froude-Krylov, diffraction, buoyancy, radiation damping
Visual fidelity	Medium
Calibration status	Not calibrated
Known limitations	not the actual propeller being used

---

PHA

Field	Value
Family type	Surface
Use goal	Demonstration
Repo link	https://github.com/naval-group/LOTUSim/tree/main/assets/models/pha
Simulation Modes	Visual + Dynamism
Actuators	Propellers, rudders
Commands	via xdyn for the propeller and via waypoint follower
External Forces	Gravity, non-linear hydrostatic, linear & quadratic damping
Visual fidelity	High
Calibration status	Not calibrated
Known limitations	-