simscape.multibody.compileBlockDiagram

R2026b

Generate compiled multibody object from Simulink model

Since R2026b

Syntax

cmb = simscape.multibody.compileBlockDiagram(modelName)

Description

cmb = simscape.multibody.compileBlockDiagram(modelName) compiles the Simulink^® model specified by modelName and generates a simscape.multibody.CompiledMultibody object. You can use the CompiledMultibody object to compute the states and dynamics of the multibody system using the Simscape™ Multibody™ MATLAB classes. You can then query various physical quantities such as joint primitive positions, velocities, and accelerations, and constraint forces and torques. The model must be loaded into memory and contain a Simscape Multibody network.

Examples

Compile Simulink Model and Compute Dynamics

This example shows how to generate a CompiledMultibody object from a Simulink model and use it to compute dynamics.

Open the four-bar Simulink model and compile it to obtain a CompiledMultibody object.

import simscape.Value simscape.op.* simscape.multibody.*
openExample("sm/FourBarExample");
modelName = "FourBar";
load_system(modelName);
cmb = simscape.multibody.compileBlockDiagram(modelName);

Create an operating point to specify the joint primitive position and velocity targets and compute the state of the multibody system.

jointState = OperatingPoint;
jointState("Base-Crank Revolute/Rz/q") = Target(60, "deg", "High");
jointState("Base-Rocker Revolute/Rz/q") = Target(90, "deg", "Low");
jointState("Base-Crank Revolute/Rz/w") = Target(2.5, "rev/s", "High");
state = computeState(cmb, jointState);

Apply a torque to the bottom-right joint and compute the dynamics of the multibody system. Then, query the acceleration of another joint primitive in the mechanism.

dict = JointActuationDictionary;
dict("Base-Rocker Revolute/Rz") = RevolutePrimitiveActuationTorque(Value(10,"N*m"));
dynamicsResult = computeDynamics(cmb, state, dict);
results = componentResults(cmb, "Connector-Rocker Revolute", dynamicsResult);
accel_top_right = results.Rz.Acceleration

accel_top_right =
   1.3271e+04 (rad/s^2)

Input Arguments

modelName — Simulink model name

string scalar | character vector

Name of a Simulink model that contains a Simscape Multibody network, specified as a string scalar or character vector. The model must be loaded into memory before calling this function. Do not include the .slx file extension in the model name.

The model must contain exactly one Simscape Multibody network. If the model contains multiple independent multibody networks, the function throws an error.

Data Types: char | string

Output Arguments

cmb — Compiled multibody system

simscape.multibody.CompiledMultibody object

Compiled multibody system, returned as a simscape.multibody.CompiledMultibody object. You can use the CompiledMultibody object to compute the states and dynamics of the multibody system. You can then query various physical quantities such as joint primitive positions, velocities, and accelerations, and constraint forces and torques.

More About

Translation of Simulink Model to MATLAB

When you generate a CompiledMultibody object from a Simulink model, these rules apply:

• Block parameters and input signals — The function embeds all block parameters using their compile-time values. The function cannot translate input signals into the CompiledMultibody object. If a block parameter accepts a value from an input signal, the function handles it in one of these ways:

  • For most blocks, the function throws an error. For example, if the Mechanism Configuration block has uniform gravity set to Time-Varying, the function throws an error.

  • For joint actuation modes, the function ignores these settings during translation. To configure joint actuations in , use a simscape.multibody.JointActuationDictionary or simscape.multibody.JointAccelerationDictionary object.

  • For External Force and Torque blocks, the function ignores the signal input provided to these blocks during translation. To apply external forces and torques in , use a simscape.multibody.ExternalForceTorqueDictionary.

  The function also ignores all fault configurations in the model. Fault settings do not affect the kinematics or dynamics analysis performed through the CompiledMultibody object.

• Uniform gravity — The function does not embed the gravity value from the Mechanism Configuration block into the CompiledMultibody object. To apply uniform gravity when computing dynamics, pass a simscape.multibody.UniformGravity object to computeDynamics. If the model contains a Gravitational Field block, passing a UniformGravity object to computeDynamics throws an error.

• Unconnected frame ports — If the multibody model has an unconnected frame port, the function throws an error regardless of the Unconnected frame ports diagnostic setting in the Configuration Parameters.

Component Paths

The CompiledMultibody object generated from a Simulink model uses Simulink block paths to identify components and frame connectors. Use the same paths that you would use to reference blocks in the Simulink model. For example, use Body/Suspension Joint to reference a Prismatic Joint named Suspension Joint inside a subsystem named Body.

To obtain a block path, select a block in the Simulink model and call gcb or gcbp at the MATLAB command line. You can also use find_system to locate blocks.

Version History

Introduced in R2026b