What's new

The most recent additions, newest first. Each links to the page that covers it in full.

#State machines

The state machines of Modelica 3.6 chapter 17 now translate and simulate. The example from ModelicaReference.StateMachines runs as written:

model Counter
  inner Integer v(start = 0);
  block Increase
    outer output Integer v;
  equation
    v = previous(v) + 2;
  end Increase;
  Increase increase;
  block Decrease
    outer output Integer v;
  equation
    v = previous(v) - 1;
  end Decrease;
  Decrease decrease;
equation
  initialState(increase);
  transition(increase, decrease, v >= 6, immediate = false);
  transition(decrease, increase, v == 0, immediate = false);
end Counter;

What is supported:

Operators. All the chapter 17 operators work:

• transition(from, to, condition, immediate, reset, synchronize, priority), where the last four arguments must be parameter expressions;
• initialState, activeState, ticksInState() and timeInState().

Transitions.

• Immediate transitions fire in the tick where their condition holds. Delayed transitions take effect at the next tick.
• When several transitions could fire, the one with the lowest priority number wins.
• With synchronize = true, a transition waits until every state machine inside its from-state is in a final state.

Hierarchy. Machines nest inside states, and several machines can run in parallel in one state. An inner machine pauses while its enclosing state is inactive. When the enclosing state is re-entered, the inner machine resumes where it stopped, or restarts in its initial state if the transition resets it.

Variables.

• An outer output variable defined in several states gets one merged definition: v = if activeState(s1) then e1 elseif ... else previous(v).
• inner outer output variables pass the merged value of the inner states up to the enclosing machine.
• Variables of an inactive state hold their values.
• A reset transition reinitializes the variables of its target state to their start values.

Clock. A state machine runs on the clock inferred for its partition. If no clock can be inferred, as in the example above, it runs on a default periodic clock of 1 s.

Inside clocked partitions, time is now the nominal instant of the tick (start + k·interval), not the slightly later instant at which the event was located. This makes timeInState() and comparisons against time exact.

Limitations.

• ticksInState() and timeInState() can only be used in transition conditions.
• Each equation in a state must be solvable for the variable it defines.
• An immediate transition whose condition reads a variable computed by its from-state in the same tick forms an algebraic loop, which is rejected.

#Structure explorer and state selection

The new Structure tab and daedalus structure show the BLT blocks, the incidence matrix, why each state was chosen, and the state Jacobian's eigenvalues and stiffness. States can be pinned or forbidden there, or with --state NAME=prefer on any command, without editing the model, and a check along the run warns when a static choice breaks down. See Structure and state selection.

#Radau, ESDIRK and automatic switching

Two more stiff solvers, Radau IIA (order 5) and ESDIRK (order 4), and auto, which switches between Dopri5 and BDF as the model turns stiff and back. The implicit methods use an exact Jacobian from the compiled model, and the workbench recommends another method when a run's statistics show it is using the wrong kind. See Solvers.

#Sensitivity, uncertainty, calibration and optimization

The Analysis mode and daedalus sensitivity | montecarlo | gsa | calibrate | optimize: exact sensitivities, Monte Carlo prediction bands, Sobol and Morris indices, fitting parameters to measured data with standard errors, and design optimization. See Sensitivity and calibration.

#Experiments, sweeps and share links

Every simulation is kept in the Runs pane to overlay or subtract, Sweep… runs a parameter grid on all cores in the browser, daedalus sweep does the same on the command line, and Share link copies an address that reruns the experiment. See Experiments and sweeps.

#Performance analyzer

Profile (or --profile) records the step sizes, the states that limit them, the time in each algebraic loop, the event log and chattering relations, with hints in plain language. See Performance analyzer.

#Graphical editing

The Diagram view is now an editor for your own models: drag components in, connect them, rotate, flip and set parameters, with undo. Edits change only the text they must. See Workbench.

#AI assistant and MCP server

✦ Assistant in the workbench is a chat with Claude that can read, write, check and simulate models and read the structure and profile reports, with your own API key. daedalus mcp gives Claude Code and other MCP clients the same tools. See AI assistant and MCP.

#MSL accuracy scoreboard

The scoreboard compares every MSL 4.1.0 example with the Modelica Association's reference results, signal by signal: 424 of 534 match, 49 run but differ somewhere, 56 fail and 5 hit the time limit. It breaks the results down by package, shows the signals that differ and the error text for each model, and links each example to the workbench.

See Modelica Standard Library.

#Python API

The daedalus Python package (crates/daedalus-py, built with maturin) runs the compiler in-process, with no server and no licence: load a model, change parameters, simulate to NumPy arrays or pandas, linearize and export FMUs.

import daedalus

m = daedalus.Model("library/Daedalus", "Daedalus.Examples.TorqueConverter.StallTest")
m.set_parameters({"engine.J": 0.3})
r = m.simulate(stop=2.0, vars=["rpm_engine"])
r.time, r["rpm_engine"]

See Python API, which also maps OMPython and Dymola calls onto it.

#.mos scripts, steady states and trim

daedalus run script.mos runs Dymola and OpenModelica regression scripts: loadModel, simulateModel, simulate, simulateExtendedModel, linearizeModel, val, loops and conditionals. daedalus steady finds equilibria with an exact Jacobian and reports their stability, and with --free and --target it trims, for example the input that holds an output at a set value. See Scripts and steady states.

#3-D animation for every example

After Simulate, models with shapes open in the new Animation view: a WebGL scene with studio lighting, camera presets, follow and chase cameras, X-ray selection and WebM recording. It draws every Modelica.Mechanics.MultiBody shape in a result, including STL and OBJ meshes, and the bundled examples got their own visuals through Daedalus.Visualizers: cars that drive the cycles side by side, the landing gear dropping onto the runway, the aileron turning on its hinge.

See 3-D animation.

#Multibody suspensions, rigs and a full car

library/MultiBodyVehicle builds vehicle models on Modelica.Mechanics.MultiBody: double-wishbone, pushrod, multilink and MacPherson corners, an anti-roll bar, a tyre with lift-off, wheel pads and aero loaders, and a 6-DOF car. Nine examples cover suspension kinematics, a K&C rig, a seven-post rig, step steer, lane change and a one-sided bump, and all nine match OpenModelica 1.26.1 to within 0.04 % of each signal's range while running several times faster.

See Multibody vehicles.

#Back and forward between classes

Every class you open is a browser history entry with its own address (/#Package.Model), so Back and Forward, Alt+← and Alt+→, mouse side buttons and the arrows next to the class name walk through them, and a link opens a class directly. The workbench colours now follow the light or dark system theme everywhere, diagrams included. See Workbench.

#Release binaries

Pushing a version tag builds and publishes a GitHub Release with the CLI, the FMI runtime and the example library for Linux, macOS (Apple Silicon and Intel) and Windows, plus the daedalus-casadi Python wheel. See Getting started.

#Optimal control, MPC and estimation with CasADi

daedalus export-casadi hands the index-reduced DAE to CasADi, and the daedalus_casadi Python package solves optimal control problems by direct collocation, runs model predictive control and estimates states and parameters with moving horizon estimation, all referring to model variables by their Modelica names.

See Optimal control.

#Modelica Standard Library 4.1.0 in the browser

The workbench loads MSL 4.1.0 (Modelica, ModelicaServices, Complex) out of the box. The package browser lists all of it within seconds, and a class is parsed only when it is opened or simulated. A nightly job compares every MSL example with the Modelica Association's reference results. See Modelica Standard Library.

#Linearization

daedalus linearize gives the exact state-space matrices A, B, C and D around the initial point or after simulating to a time, as text, JSON or an OpenModelica-style linearized_model. See Linearization.

#FMI 2.0 export

daedalus fmu writes one FMU with both Model Exchange and Co-Simulation, validated with FMPy in CI. See FMI 2.0 export.

#Multibody closed loops

Planar kinematic loops on a free body, driven loops and steady-state initialization now work, which is what the suspension models above are built on.

#In progress

This is being built now and gets its page here when it lands:

• external C libraries (Modelica.Utilities, Math.Random and friends) and more lookup-table support.

The longer-term plan is in the Roadmap.