Define Virtual Vehicle Components: Passenger Vehicle

Use the Virtual Vehicle Composer to define the components in your chosen vehicle architecture. In the Data and Calibration pane, make selections for the chassis, suspension, tires, powertrain, environment, and so forth.

The Virtual Vehicle Composer model template starts with a set of default components. In the Data and Calibration pane, you can modify the parameters of a default component, or select a different component to fit your project. The component types are listed in the menu tree on the left side of the app. You can choose and parameterize specific components on the right side.

For each component type, you can specify it in one of two ways:

• From a list within the Virtual Vehicle Composer, select an available component and modify its parameters. Depending on the component, you can enter different parameters, load a file containing different parameters, or use a resize option.

• If Model template is set to Simulink, you can choose a component using the Custom component catalog. This is an XML file that points to custom components stored externally to the app. These custom components can be modified Virtual Vehicle Composer components or externally created Simulink models that are compatible with Virtual Vehicle Composer.

The component options depend on the products installed and your Setup selections.

Chassis

The Chassis section includes parameters associated with the body of the vehicle, such as the sprung mass and its center of mass (CM), moments of inertia, wheelbase and track width, and aerodynamic force coefficients.

These assumptions apply to the passenger vehicle chassis:

• The vehicle body is rigid. All components mounted to the vehicle body are rigidly attached.

• The sprung mass includes all components mounted to the body, and the height of its center of mass (CM) is specified relative to the axle plane.

• Unsprung masses, such as tires, wheels, brakes, and suspensions, are accounted for by setting the tire mass equal to their sum.

Steering System

If Vehicle dynamics is set to Combined longitudinal and lateral vehicle dynamics, you can specify the steering system type and parameters.

If you set Model template to Simulink, you can choose from three options for Steering system:

• Kinematic Steering — Calculate the steered wheel angles based on a steering ratio and Ackerman percentage, with no system compliance.

• Mapped Steering — Use a rack and pinion system where the steered wheel angles are mapped to the steering wheel rotation and rack displacement, with no system compliance.

• Steering System — Incorporate the geometry of a rack and pinion system that also includes compliance, friction, and power assist.

With Model template set to Simscape, you have one choice for Steering system:

• Multibody Steering System — Incorporate rack and pinion geometry in a Simscape™ Multibody™ Link model. This option does not include system compliance.

Front and Rear Suspensions

If Vehicle dynamics is set to Combined longitudinal and lateral vehicle dynamics, you can specify the suspension types and parameters.

With Model template set to Simulink, you have two choices for Front Suspension:

• Kinematics and Compliance Independent Suspension Front

• MacPherson Front Suspension

With a Model template set to Simulink, you have three choices for Rear Suspension:

• Kinematics and Compliance Independent Suspension Rear

• Solid Axle Rear Suspension

• Kinematics and Compliance Twist Beam Suspension Rear

The kinematics and compliance options use output from a kinematics and compliance test machine or from a more detailed model.

With Model template set to Simscape, you have only one option each for the front and rear axles:

• Simscape Suspension Front

• Simscape Suspension Rear

These options are double-wishbone suspensions modeled in Simscape Multibody Link without compliance.

Tire and Wheel Systems

You select tire and wheel systems separately for the front and rear axles. Tire properties are modeled by equations whose parameters must be fit as a set. The available options depend on the Vehicle dynamics and the Model template selected. The choices are the same front to rear.

With Model template set to Simulink and Vehicle dynamics set to Longitudinal vehicle dynamics, you have two Front Tire options:

• MF Tires Longitudinal Front

• Combined Slip Tires Longitudinal Front

You have two options for Rear Tire:

• MF Tires Longitudinal Rear

• Combined Slip Tires Longitudinal Rear

These options all use the Magic Formula introduced by Pacejka. The MF Tires Longitudinal Front and MF Tires Longitudinal Front options include options for modifying rolling resistance.

With Model template set to Simulink and Vehicle dynamics set to Combined longitudinal and lateral vehicle dynamics, you have two options for Front Tire:

• MF Tires Longitudinal and Lateral Front, which uses the Magic Formula

• Fiala Tires Longitudinal and Lateral Front, which uses a Fiala tire model

You have two options for Rear Tire:

• MF Tires Longitudinal and Lateral Rear, which uses the Magic Formula

• Fiala Tires Longitudinal and Lateral Rear, which uses a Fiala tire model

With Model template set to Simscape and Vehicle dynamics set to Longitudinal vehicle dynamics, you have one option for Front Tire:

• MF Tires Longitudinal Front, which uses the Magic Formula

And one option for Rear Tire:

• MF Tires Longitudinal Rear, which uses the Magic Formula

With Model template set to Simscape, and Vehicle dynamics set to Combined longitudinal and lateral vehicle dynamics, there is one option for Front Tire:

• Simscape MF Tires Front, which uses the Magic Formula in a Simscape representation

You have one option for Rear Tire:

• Simscape MF Tires Rear, which uses the Magic Formula in a Simscape representation

Brake System

The brake system consists of the hardware on the front and rear axles, and options for an anti-lock braking system (ABS) and a traction control system (TCS). You have three choices each for Front Brake Type and Rear Brake Type:

• Disc

• Drum

• Mapped

For the Disc and Drum options, the model uses the physical parameters of the brake mechanism to calculate braking torque as a function of brake fluid pressure. For the Mapped option, the braking torque is a mapped function of wheel rotation speed and brake fluid pressure.

You have three choices for the Brake Control Unit:

• Open Loop

• Bang Bang ABS

• Five-State ABS and TCS

The Open Loop option applies brake fluid pressure based on driver command and bias settings, with no control unit. the Bang Bang ABS option implements an ABS feedback controller that regulates tire slip by switching fluid pressure between two states at each wheel, to hold slip at its maximum traction value. The Five-State ABS and TCS option operates similarly, but uses logic-switching based on wheel deceleration and vehicle acceleration to modulate the braking pressure at each wheel to control slip. This option also provides traction control.

Powertrain: Vehicle Control Unit

Passenger vehicles with battery-electric and hybrid-electric powertrains use a vehicle control unit (VCU) to manage the energy used by the electric motors and discharged or stored by the battery.

The powertrain architecture uniquely determines the vehicle control unit setting. For example, if Powertrain architecture is set to Electric Vehicle 1EM, then Vehicle control unit is EV 1EM with BMS.

Powertrain: Engine and Engine Control Unit

Depending on the powertrain architecture, you have up to twelve options for Engine:

• Four spark-ignition (SI) engines fueled by gasoline

• Four spark-ignition engines fueled by hydrogen

• Three compression-ignition (CI) engines fueled by diesel fuel

• An FMU engine

The engines are modeled in several ways:

• SI Mapped Engine, SI H2 Mapped Engine, and CI Mapped Engine use detailed look-up tables from steady-state operation. The data inputs include power, air mass flow rate, fuel flow, exhaust temperature, efficiency, and emission performance.

• SI Simple Engine, SI H2 Simple Engine, and CI Simple Engine estimate engine torque and fuel flow rate using a steady-state table of maximum torque versus engine speed, along with two scalar fuel mass properties, and one scalar engine efficiency parameter.

• SI Engine, SI H2 Engine, and CI Engine physically model the engine from intake port to exhaust port, including transient operating conditions. These models take into account the ambient values of atmospheric temperature and pressure.

• SI Deep Learning Engine and SI H2 Deep Learning Engine use a deep learning model that is generated from transient training data. This model type is capable of responding to rapid changes in operating conditions.

• FMU Engine uses an FMU (functional mockup unit) model that you supply.

Each engine has an engine control unit (ECU). The Engine Control Unit is automatically set to the appropriate type for the Engine selected:

• Simple ECU for SI Simple Engine, SI H2 Simple Engine, CI Simple Engine, and FMU Engine.

• SI Engine Controller for SI Mapped Engine, SI Engine, SI Deep Learning Engine, SI H2 Mapped Engine, SI H2 Engine, and SI H2 Deep Learning Engine

• CI Engine Controller for CI Mapped Engine and CI Engine

Powertrain: Transmission and Transmission Control Unit

Depending on the Powertrain architecture setting, you may have a choice of Transmission:

• Ideal Fixed Gear Transmission is an idealized transmission without clutch or synchronization detail. Use this setting to model the gear ratios and power loss when you do not need a detailed transmission model.

• Automatic Transmission with Torque Converter uses planetary gears.

• Automated Manual Transmission is a manual transmission with additional actuators and an electronic control unit (ECU) to regulate clutch and gear selection based on commands from a controller. Clutch and synchronizer engagement rates are linear and adjustable.

The only choice for Transmission Control Unit is PRNDL Controller. The controller commands forward, reverse, neutral, park, and N-speed gear shifts according to the selected shift schedule.

Powertrain: Drivetrain

The drivetrain distributes power to the driven wheels by some combination of interconnections, differentials, and individual electric motors.

Depending on the selection for Powertrain architecture, the options for Drivetrain are:

• Front Wheel Drive

• Rear Wheel Drive

• All Wheel Drive

• All Wheel Driven by 2EM

• All Wheel Driven by 3EM Front

• All Wheel Driven by 3EM Rear

• All Wheel Driven by 4EM

For Front Wheel Drive, the drivetrain drives both wheels on the front axle through a differential. For Rear Wheel Drive, the drivetrain drives both wheels on the rear axle through a differential. For All Wheel Drive, the drivetrain drives all four wheels through a transfer case, and differentials on both axles. These three options apply when the power comes from a single propulsion unit, such as an internal combustion engine, a hybrid powertrain, or a single electric motor.

If Drivetrain is set to All Wheel Drive and has a single power input, then Axle Interconnect defaults to Transfer Case. It includes an open differential with adjustable torque split between front and rear axles.

The last four Drivetrain options are battery-electric powertrains providing all wheel drive in different ways.

• All Wheel Driven by 2EM uses a single motor driving the front wheels through a differential and a single motor driving the rear wheels through a differential.

• All Wheel Driven by 3EM Front uses two motors driving the front wheels separately and a single motor driving the rear wheels through a differential.

• All Wheel Driven by 3EM Rear uses two motors driving the rear wheels separately and a single motor driving the front wheels through a differential.

• All Wheel Driven by 4EM uses a single motor driving each wheel separately.

For each of these four options, the powertrain architecture uniquely determines the Drivetrain setting. For example, setting Powertrain architecture to Electric Vehicle 3EM automatically sets Drivetrain to All Wheel Driven by 3EM Front. Also, these four all wheel drive options have no mechanical connection between front and rear axles, so Axle Interconnect does not appear as an option.

If Drivetrain is set to Front Wheel Drive or All Wheel Drive, you see these options for Front Differential System:

• Open Differential

• Limited Slip Differential

If Drivetrain set to Rear Wheel Drive or All Wheel Drive, you see these options for Rear Differential System:

• Open Differential Rear

• Limited Slip Differential Rear

• Active Differential Rear, only if Model Template is set to Simulink

If you set Rear Differential System to Active Differential Rear, you have two options for the Active differential control:

• No Control

• Rear Differential Controller

If Powertrain architecture is set to an option that drives either axle using two electric motors, you see the corresponding differential setting for that axle. For example, with Powertrain architecture set to Electric Vehicle 4EM:

• Front Differential System is set to Dual EM Drive Front.

• Rear Differential System is set to Dual EM Drive Rear.

Electrical System

The electrical system includes the electric motors and the components supplying the power flow between the battery and the motors. The parameter Electrical System is automatically selected based on the number of electric motors.

Electrical System: DC-DC Converter

Powertrains with one or more electric motors include a DC-DC converter to convert battery voltage to the desired motor voltage. You have two options for DC-DC Converter:

• DC-DC Converter, a bidirectional DC-to-DC converter that supports boost (voltage-increasing) and buck (voltage-reducing) operations

• HVDCPassThrough, which supplies current at battery voltage

Electrical System: Energy Storage

Powertrains with one or more electric motors include a battery to store electrical energy. For Energy Storage, you have two options:

• Mapped Battery (your application)

• Ideal Voltage Source

In mapped batteries, open-circuit voltage and internal resistance are mapped functions of the state-of charge (SOC) and battery temperature. The ideal voltage source is a constant-voltage source that represents an infinite storage capacity.

Electrical System: Electric Machines

Battery-electric and hybrid-electric powertrains use one or more electric motors. The electric motors used in Virtual Vehicle Composer are synchronous AC permanent magnet electric machines, modeled as mapped motors.

For Electric Machine 1, Electric Machine 2, and so forth, the default motor is sized for your application. For example, if Powertrain architecture is set to Hybrid Electric Vehicle IPS, then Electric Machine 1 defaults to Hybrid Electric Vehicle IPS.

Thermal System

The Virtual Vehicle Composer has a thermal system option for battery-electric powertrains to manage the temperatures of the electrical components. The thermal system consists of a radiator loop and a refrigeration loop. Switching a four-way valve toggles the loops between series and parallel modes, and bypass valves can divert flow around the heat exchangers. The figure shows parallel operation with no bypassing.

The thermal system models when you set Model template to Simulink or Simscape are different, but equivalent. Both models use the same Stateflow^® controller.

Driver Model

You have several options for Driver model, depending on your Vehicle dynamics selection:

• Longitudinal Driver

• Predictive Driver

• Predictive Stanley Driver

The parameters you set here reflect the driver technique and reaction time, and the assumptions the driver makes about the vehicle while controlling it.

Trailer

The Virtual Vehicle Composer can attach a one-axle trailer to your Passenger vehicle. You have these options for Trailer:

• No Trailer

• One-Axle Trailer

Environment

Use the Environment parameter to set the ambient air, wind, and road conditions for your tests.

The app uses the ambient absolute air pressure and absolute air temperature in the ideal gas law to calculate air density, which the app then uses to calculate aerodynamic forces. Also, these Engine types take air density into account when calculating engine performance:

• SI Engine

• SI H2 Engine

• CI Engine

Other Engine types are not affected by ambient conditions. Their performance is calculated for temperature and pressure conditions of 293.15 kelvins and 101,325 pascals.