Fiala Wheel 2DOF

Fiala wheel 2DOF wheel with disc, drum, or mapped brake

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Libraries:
Vehicle Dynamics Blockset / Wheels and Tires

Description

The Fiala Wheel 2DOF block implements a simplified tire with lateral and longitudinal slip capability based on the E. Fiala model^[1]. The block uses a translational friction model to calculate the forces and moments during combined longitudinal and lateral slip, requiring fewer parameters than the Combined Slip Wheel 2DOF block. If you do not have the tire coefficients needed by the Magic Formula, consider using this block for studies that do not involve extensive nonlinear combined lateral slip or lateral dynamics. If your study does require nonlinear combined slip or lateral dynamics, consider using the Combined Slip Wheel 2DOF block.

The block determines the wheel rotation rate, vertical motion, and forces and moments in all six degrees-of-freedom (DOFs) based on the driveline torque, brake pressure, road height, wheel camber angle, and inflation pressure. You can use this block for these types of analyses:

• Driveline and vehicle simulations that require low frequency tire-road and braking forces for vehicle acceleration, braking, and wheel rolling resistance calculations with minimal tire parameters.

• Wheel interaction with an idealized road surface.

• Ride and handling maneuvers for vehicles undergoing mild combined slip. For this analysis, you can connect the block to driveline and chassis components such as differentials, suspension, and vehicle body systems.

• Yaw stability. For this analyses, you can connect this block to more detailed braking system models.

• Tire stiffness and unsprung mass interactions with ground variations, load transfer, or chassis motion using the block vertical DOF.

The block integrates rotational wheel, vertical mass, and braking dynamics models. For the slip-dependent tire forces and moments, the block implements the Fiala tire model.

You can set your own user-defined model parameter values or use a built-in tire model.

If you install the Extended Tire Features for Vehicle Dynamics Blockset support package, you can click the Plot steady state force, moment response button to generate these plots:

• Lateral force [N] vs Slip angle [rad]

• Self-aligning moment [Nm] vs Slip angle [rad]

• Longitudinal force [N] vs Longitudinal slip []

• Longitudinal force [N] vs Lateral force [N]

With the support package, you can also import tire parameter values defined in the Fiala Wheel 2DOF block to a tireModel object or export tire parameter values from a tireModel object to the Fiala Wheel 2DOF block. For more information, see tireModel.get and set.

Use the Tire type parameter to either input tire parameter values or select a fitted tire parameter set.

Goal	Action
Input user-defined tire parameter values.	Update the block parameters with user-defined parameter values: Set Tire type to User defined. In the Wheel and Tire Parameters section, input user-defined values. Click Apply.
Select one of the built-in Fiala tire models to drive the lateral and longitudinal calculations. [link].	Update the applicable block parameters with values from a built-in tire model: Set Tire type to the tire that you want to implement. Options include: Light passenger car 205/60R15 Light passenger car 245/60R16 Mid-size passenger car 235/45R18 Performance car 225/40R19 SUV 265/50R20 Light truck 275/65R18 Commercial truck 295/75R22.5 Click Update block with applicable tire values. In the Wheel and Tire Parameters section, the block updates the applicable Longitudinal and Lateral parameters. Click Apply.

Use the Brake Type parameter to select the brake.

Action	Brake Type Setting
No braking	None
Implement brake that converts the brake cylinder pressure into a braking force	Disc
Implement simplex drum brake that converts the applied force and brake geometry into a net braking torque	Drum
Implement lookup table that is a function of the wheel speed and applied brake pressure	Mapped

To calculate the rolling resistance torque, specify one of these Rolling Resistance parameters.

Setting	Block Implementation
None	None
Pressure and velocity	Method in Stepwise Coastdown Methodology for Measuring Tire Rolling Resistance. The rolling resistance is a function of tire pressure, normal force, and velocity.
ISO 28580	Method specified in ISO 28580:2018, Passenger car, truck and bus tyre rolling resistance measurement method — Single point test and correlation of measurement results.
Magic Formula	Magic formula equations from 4.E70 in Tire and Vehicle Dynamics. The magic formula is an empirical equation based on fitting coefficients.
Mapped torque	Lookup table that is a function of the normal force and spin axis longitudinal velocity.

To calculate vertical motion, specify one of these Vertical Motion parameters.

Setting	Block Implementation
None	Block passes the applied chassis forces directly through to the rolling resistance and longitudinal force calculations.
Mapped stiffness and damping	Vertical motion depends on wheel stiffness and damping. Stiffness is a function of tire sidewall displacement and pressure. Damping is a function of tire sidewall velocity and pressure.
External deflection	The block uses the defined sidewall deflection directly in the effective radius calculation.

Rotational Wheel Dynamics

The block calculates the inertial response of the wheel subject to:

• Axle losses

• Brake and drive torque

• Tire rolling resistance

• Ground contact through the tire-road interface

The input torque is the summation of the applied axle torque, braking torque, and moment arising from the combined tire torque.

$$T_i=T_a-T_b+T_d$$

For the moment arising from the combined tire torque, the block implements tractive wheel forces and rolling resistance with first-order dynamics. The rolling resistance has a time constant parameterized in terms of a relaxation length.

$$T_d(s)=\frac{1}{\frac{L_e}{\left|\omega \right|R_e}s+1}(F_x{R}_e+M_y)$$

To calculate the rolling resistance torque, you can specify one of these Rolling Resistance parameters.

Setting	Block Implementation
None	Block sets rolling resistance, My, to zero.
Pressure and velocity	Block uses the method in SAE Stepwise Coastdown Methodology for Measuring Tire Rolling Resistance. The rolling resistance is a function of tire pressure, normal force, and velocity, specifically: $$M_y=R_e\{a+b\left|V_x\right|+c{V}_x{}^2\}\left\{F_z{}^{\beta }{p}_i{}^{\alpha }\right\}\tanh \left(4V_x\right)$$
ISO 28580	Block uses the method specified in ISO 28580:2018, Passenger car, truck and bus tyre rolling resistance measurement method — Single point test and correlation of measurement results. The method accounts for normal load, parasitic loss, and thermal corrections from test conditions, specifically: $$M_y=R_e(\frac{F_z{C}_r}{1+K_t(T_{amb}-T_{meas})}-F_{pl})\tanh (\omega )$$
Magic Formula	Block calculates the rolling resistance, My, using the Magic Formula equations from 4.E70 in Tire and Vehicle Dynamics. The magic formula is an empirical equation based on fitting coefficients.
Mapped torque	For the rolling resistance, My, the block uses a lookup table that is a function of the normal force and spin axis longitudinal velocity.

If the brakes are enabled, the block determines the braking locked or unlocked condition based on an idealized dry clutch friction model. Based on the lock-up condition, the block implements these friction and dynamic models.

If	Lock-Up Condition	Friction Model	Dynamic Model
$\begin{array}{l}\omega \ne 0\\ \text{or}\\ T_S<\left|T_i+T_f-\omega b\right|\end{array}$	Unlocked	$$\begin{array}{l}{T}_f=T_k\text{,}\\ \text{where}\\ T_k=F_c{R}_{eff}{\mu }_k\tanh \left[4\left(-{\omega }_d\right)\right]\\ T_s=F_c{R}_{eff}{\mu }_s\\ R_{eff}=\frac{2(R_o{}^3-R_i{}^3)}{3(R_o{}^2-R_i{}^2)}\end{array}$$	$$\dot{\omega }J=-\omega b+T_i+T_o$$
$\begin{array}{l}\omega =0\\ \text{and}\\ T_S\ge \left|T_i+T_f-\omega b\right|\end{array}$	Locked	$$T_f=T_s$$	$$\omega =0$$

The equations use these variables.

Variable	Value
ω	Wheel angular velocity
a	Velocity-independent force component
b	Linear velocity force component
c	Quadratic velocity force component
Le	Tire relaxation length
J	Moment of inertia
My	Rolling resistance torque
Ta	Applied axle torque
Tb	Braking torque
Td	Combined tire torque
Tf	Frictional torque
Ti	Net input torque
Tk	Kinetic frictional torque
To	Net output torque
Ts	Static frictional torque
Fc	Applied clutch force
Fx	Longitudinal force developed by the tire road interface due to slip
Reff	Effective clutch radius
Ro	Annular disk outer radius
Ri	Annular disk inner radius
Re	Effective tire radius while under load and for a given pressure
Vx	Longitudinal axle velocity
Fz	Vehicle normal force
Cr	Rolling resistance constant
Tamb	Ambient temperature
Tmeas	Measured temperature for rolling resistance constant
Fpl	Parasitic force loss
Kt	Thermal correction factor
ɑ	Tire pressure exponent
β	Normal force exponent
pi	Tire pressure
μs	Coefficient of static friction
μk	Coefficient of kinetic friction

Longitudinal Force

The block implements the longitudinal force as a function of wheel slip relative to the road surface using these equations.

Calculation	Equation
Critical slip	$$\kappa {\text{'}}_{Critical}=\left|\frac{\mu F_z}{2C_{\kappa }}\right|$$
Longitudinal force	$$F_x=\{\begin{array}{c}{C}_k \kappa \text{'}\text{ when }\left|{\kappa }^{\text{'}}\right|\le {\kappa }^{\text{'}}{}_{Critical}\\ \text{tanh}(4\kappa \text{'})\left(\mu \left|F_z\right|-\left|\frac{{\left(\mu F_z\right)}^2}{4\kappa \text{'}{C}_{\kappa }}\right|\right) \text{ when }\left|{\kappa }^{\text{'}}\right|>{\kappa }^{\text{'}}{}_{Critical}\end{array}$$
Friction coefficient	$\mu =({\mu }_s-({\mu }_s-{\mu }_k){\kappa }_{k\alpha }){\lambda }_{\mu }$
Slip coefficient	${\kappa }_{k\alpha }=\sqrt{\kappa {\text{'}}^2+{\text{tan}}^2(\alpha \text{'})}$

The equations use these variables.

Variable	Value
κ'	Slip state
Fx	Longitudinal force acting on axle along tire-fixed x-axis
Cκ	Longitudinal stiffness
Fz	Vertical contact patch normal force along tire-fixed z-axis
μ	Friction coefficient
μs	Coefficient of static friction
μk	Coefficient of kinetic friction
κka	Comprehensive slip coefficient
α'	Slip angle state
λμ	Friction scaling

Lateral Force

The block implements the lateral force as a function of wheel slip angle state using these equations.

Calculation	Equation
Critical slip angle	$\alpha {\text{'}}_{Critical}=\text{atan}(\frac{3\mu \left|F_z\right|}{C_a})$
Lateral force	$$\begin{array}{l}{F}_y=\{\begin{array}{c}-\text{tanh}(4\alpha \text{'})\mu \left|F_z\right| \text{ when }\left|\alpha \text{'}\right|>\alpha {\text{'}}_{Critical}\\ -\tanh \left(4\alpha \text{'}\right)\mu \left|F_z\right|\left(1-{\xi }^3\right)+\gamma C_{\gamma }\text{ when }\left|\alpha \text{'}\right|\le \alpha {\text{'}}_{Critical}\end{array}\\ \\ \xi =1-\frac{C_a\left|\text{tan}(\alpha \text{'})\right|}{3\mu \left|F_z\right|}\end{array}$$

The equations use these variables.

Variable	Value
α'	Slip angle state
Fy	Lateral force acting on axle along tire-fixed y-axis
Fz	Vertical contact patch normal force along tire-fixed z-axis
Cɣ	Camber stiffness
Cα	Lateral stiffness per slip angle
μ	Friction coefficient

Vertical Dynamics

The block implements these equations for the vertical dynamics.

Calculation	Equation
Vertical response	$\ddot{z}m=F_{ztire}+mg-Fz$
Tire normal force	$F_{ztire}={\rho }_{z}k-b\dot{z}$
Vertical sidewall deflection	${\rho }_z=z_{gnd}-z,z\ge 0$

The equations use these variables.

Variable	Value
z	Tire deflection along tire-fixed z-axis
zgnd	Ground displacement along tire-fixed z-axis
Fztire	Tire normal force along tire-fixed z-axis
Fz	Vertical force acting on axle along tire-fixed z-axis
ρz	Vertical sidewall deflection along tire-fixed z-axis
k	Vertical sidewall stiffness
b	Vertical sidewall damping

Overturning, Aligning, and Scaling

This table summarizes the overturning, aligning, and scaling implementation.

Calculation	Implementation
Overturning moment	The Fiala model does not define an overturning moment. The block implements this equation, requiring minimal parameters. $M_x=F_y{R}_e\text{cos}(\gamma )$
Aligning moment	The block implements the aligning moment as a combination of yaw rate damping and slip angle state. $$\begin{array}{l}{M}_z=\{\begin{array}{c}\dot{\psi }{b}_{M_z}\text{ when }\left|\alpha \text{'}\right|>\alpha {\text{'}}_{Critical}\\ \tanh \left(4{\alpha }^{\text{'}}\right)w\mu \left|{\text{F}}_z\right|\left(1-\xi \right){\xi }^3+\dot{\psi }{b}_{M_z}\text{ when }\left|\alpha \text{'}\right|\le \alpha {\text{'}}_{Critical}\end{array}\\ \\ \xi =1-\frac{C_a\left|\text{tan}(\alpha \text{'})\right|}{3\mu \left|F_z\right|}\end{array}$$
Friction scaling	To vary the coefficient of friction, use the ScaleFctr input port.

The equations use these variables.

Variable	Value
Mx	Overturning moment acting on axle about tire-fixed x-axis
Mz	Aligning moment acting on axle about tire-fixed z-axis
Re	Effective contact patch to wheel carrier radial distance
ɣ	Camber angle
k	Vertical sidewall stiffness
b	Vertical sidewall damping
$\dot{\psi }$	Tire angular velocity about the tire-fixed z-axis (yaw rate)
w	Tire width
α'	Slip angle state
bMz	Linear yaw rate resistance
Fy	Lateral force acting on axle along tire-fixed y-axis
Cɣ	Camber stiffness
Cα	Lateral stiffness per slip angle
μ	Friction coefficient
Fz	Vertical contact patch normal force along tire-fixed z-axis

Tire and Wheel Coordinate Systems

To resolve the forces and moments, the block uses the Z-Up orientation of the tire and wheel coordinate systems.

• Tire coordinate system axes (X_T, Y_T, Z_T) are fixed in a reference frame attached to the tire. The origin is at the tire contact with the ground.

• Wheel coordinate system axes (X_W, Y_W, Z_W) are fixed in a reference frame attached to the wheel. The origin is at the wheel center.

Z-Up Orientation¹

Brakes

Disc

If you specify the Brake Type parameter as Disc, the block implements a disc brake. This figure shows the side and front views of a disc brake.

A disc brake converts brake cylinder pressure from the brake cylinder into force. The disc brake applies the force at the brake pad mean radius.

The block uses these equations to calculate brake torque for the disc brake.

$T=\{\begin{array}{c}\frac{\mu P\pi B_a{}^2{R}_m{N}_{pads}}{4} \text{ when }N\ne 0\\ \frac{{\mu }_{static}P\pi B_a{}^2{R}_m{N}_{pads}}{4} \text{ when }N=0\end{array}$

$$Rm=\frac{Ro+Ri}{2}$$

The equations use these variables.

Variable	Value
T	Brake torque
P	Applied brake pressure
N	Wheel speed
Npads	Number of brake pads in disc brake assembly
μstatic	Disc pad-rotor coefficient of static friction
μ	Disc pad-rotor coefficient of kinetic friction
Ba	Brake actuator bore diameter
Rm	Mean radius of brake pad force application on brake rotor
Ro	Outer radius of brake pad
Ri	Inner radius of brake pad

Drum

If you specify the Brake Type parameter as Drum, the block implements a static (steady-state) simplex drum brake. A simplex drum brake consists of a single two-sided hydraulic actuator and two brake shoes. The brake shoes do not share a common hinge pin.

The simplex drum brake model uses the applied force and brake geometry to calculate a net torque for each brake shoe. The drum model assumes that the actuators and shoe geometry are symmetrical for both sides, allowing a single set of geometry and friction parameters to be used for both shoes.

The block implements equations that are derived from these equations in Fundamentals of Machine Elements.

$\begin{array}{l}{T}_{rshoe}=\left(\frac{\pi \mu cr(\cos {\theta }_2-\cos {\theta }_1)B_a{}^2}{2\mu (2r\left(\cos {\theta }_2-\cos {\theta }_1)+a\left({\cos }^2{\theta }_2-{\cos }^2{\theta }_1\right)\right)+a\left(2{\theta }_1-2{\theta }_2+\sin 2{\theta }_2-\sin 2{\theta }_1\right)}\right)P\\ \\ T_{lshoe}=\left(\frac{\pi \mu cr(\cos {\theta }_2-\cos {\theta }_1)B_a{}^2}{-2\mu (2r\left(\cos {\theta }_2-\cos {\theta }_1)+a\left({\cos }^2{\theta }_2-{\cos }^2{\theta }_1\right)\right)+a\left(2{\theta }_1-2{\theta }_2+\sin 2{\theta }_2-\sin 2{\theta }_1\right)}\right)P\end{array}$

$T=\{\begin{array}{c}{T}_{rshoe}+T_{lshoe}\text{ when }N\ne 0\\ (T_{rshoe}+T_{lshoe})\frac{{\mu }_{static}}{\mu }\text{ when }N=0\end{array}$

The equations use these variables.

Variable	Value
T	Brake torque
P	Applied brake pressure
N	Wheel speed
μstatic	Disc pad-rotor coefficient of static friction
μ	Disc pad-rotor coefficient of kinetic friction
Trshoe	Right shoe brake torque
Tlshoe	Left shoe brake torque
a	Distance from drum center to shoe hinge pin center
c	Distance from shoe hinge pin center to brake actuator connection on brake shoe
r	Drum internal radius
Ba	Brake actuator bore diameter
Θ1	Angle from shoe hinge pin center to start of brake pad material on shoe
Θ2	Angle from shoe hinge pin center to end of brake pad material on shoe

Mapped

If you specify the Brake Type parameter as Mapped, the block uses a lookup table to determine the brake torque.

$T=\{\begin{array}{c}{f}_{brake}(P,N) \text{ when }N\ne 0\\ \left(\frac{{\mu }_{static}}{\mu }\right)f_{brake}(P,N) \text{ when }N=0\end{array}$

The equations use these variables.

Variable	Value
T	Brake torque
$f_{brake}^{}(P,N)$	Brake torque lookup table
P	Applied brake pressure
N	Wheel speed
μstatic	Friction coefficient of drum pad-face interface under static conditions
μ	Friction coefficient of disc pad-rotor interface

The lookup table for the brake torque, $f_{brake}^{}(P,N)$, is a function of applied brake pressure and wheel speed, where:

• T is brake torque, in N·m.

• P is applied brake pressure, in bar.

• N is wheel speed, in rpm.

Examples

Double Lane Change Reference Application

Simulate a full vehicle dynamics model undergoing a double lane change maneuver standard ISO 3888-2. Use for vehicle dynamics ride and handling analysis and chassis controls development, including yaw stability and lateral acceleration limits.

• Open Script

Ports

Input

BrkPrs — Brake pressure

scalar | N-by-1 vector

Brake pressure, in Pa.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Dependencies

To enable this port, set the Brake Type parameter, to one of these types:

• Disc

• Drum

• Mapped

AxlTrq — Axle torque

scalar | N-by-1 vector

Axle torque, T_a, about wheel spin axis, in N·m.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Vx — Longitudinal velocity

scalar | N-by-1 vector

Axle longitudinal velocity, V_x, along tire-fixed x-axis, in m/s.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Vy — Lateral velocity

scalar | N-by-1 vector

Axle lateral velocity, V_y, along tire-fixed y-axis, in m/s.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Camber — Inclination angle

scalar | N-by-1 vector

Camber angle, ɣ, or inclination angle, ε, in rad.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

YawRate — Tire angular velocity

scalar | N-by-1 vector

Tire angular velocity, r, about the tire-fixed z-axis (yaw rate), in rad/s.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Prs — Tire inflation pressure

scalar | N-by-1 vector

Tire inflation pressure, p_i, in Pa.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Gnd — Ground displacement

scalar | N-by-1 vector

Ground displacement along tire-fixed z-axis, in m. Positive input produces wheel lift.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Fext — Axle force applied to tire

scalar | N-by-1 vector

Axle force applied to tire, F_ext, along vehicle-fixed z-axis (positive input compresses the tire), in N.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Dependencies

To enable this parameter, set Vertical Motion to None or Magic Formula.

RadialDeflct — Tire radial deflection

scalar | N-by-1 vector

Tire radial deflection, RadialDeflct. This value is used directly in the effective radius calculation.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Dependencies

To enable this port, set Vertical Motion to External Deflection.

ScaleFctrs — Scale factor

scalar | N-by-1 vector

Scale factor to account for variations in the coefficient of friction.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Output

Info — Block data

bus

Block data, returned as a bus signal containing these block values.

Signal	Description	Units
AxlTrq	Axle torque about wheel-fixed y-axis	N·m
Omega	Wheel angular velocity about wheel-fixed y-axis	rad/s
Fx	Longitudinal vehicle force along tire-fixed x-axis	N
Fy	Lateral vehicle force along tire-fixed y-axis	N
Fz	Vertical vehicle force along tire-fixed z-axis	N
Mx	Overturning moment about tire-fixed x-axis	N·m
My	Rolling resistance torque about tire-fixed y-axis	N·m
Mz	Aligning moment about tire-fixed z-axis	N·m
Vx	Vehicle longitudinal velocity along tire-fixed x-axis	m/s
Vy	Vehicle lateral velocity along tire-fixed y-axis	m/s
Re	Loaded effective radius	m
Kappa	Longitudinal slip ratio	NA
Alpha	Side slip angle	rad
a	Contact patch half length	m
b	Contact patch half width	m
Gamma	Camber angle	rad
psidot	Tire angular velocity about the tire-fixed z-axis (yaw rate)	rad/s
BrkTrq	Brake torque about the vehicle-fixed y-axis	N·m
BrkPrs	Brake pressure	Pa
z	Axle vertical displacement along tire-fixed z-axis	m
zdot	Axle vertical velocity along tire-fixed z-axis	m/s
Gnd	Ground displacement along tire-fixed z-axis (positive input produces wheel lift)	m
GndFz	Vertical sidewall force on ground along tire-fixed z-axis	N
Prs	Tire inflation pressure	Pa
WhlTrq	Wheel torque	N·m
RL	Loaded radius	m
RadialDeflct	Tire radial deflection	m

Omega — Wheel angular velocity

scalar | N-by-1 vector

Wheel angular velocity, ω, about wheel-fixed y-axis, in rad/s.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Fx — Longitudinal axle force

scalar | N-by-1 vector

Longitudinal force acting on axle, F_x, along tire-fixed x-axis, in N. Positive force acts to move the vehicle forward.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Fy — Lateral axle force

scalar | N-by-1 vector

Lateral force acting on axle, F_y, along tire-fixed y-axis, in N.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Fz — Vertical axle force

scalar | N-by-1 vector

Vertical force acting on axle, F_z, along tire-fixed z-axis, in N.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Mx — Overturning moment

scalar | N-by-1 vector

Longitudinal moment acting on axle, M_x, about tire-fixed x-axis, in N·m.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

My — Rolling resistive moment

scalar | N-by-1 vector

Lateral moment acting on axle, M_y, about tire-fixed y-axis, in N·m.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Mz — Aligning moment

scalar | N-by-1 vector

Vertical moment acting on axle, M_z, about tire-fixed z-axis, in N·m.

Vector is the number of wheels, N, by 1. If you provide a scalar value, the block assumes that number of wheels is one.

Parameters

Block Options

Tire type — Select type

User defined (default) | Light passenger car 205/60R15 | Light passenger car 245/60R16 | Mid-size passenger car 235/45R18 | Performance car 225/40R19 | SUV 265/50R20 | Light truck 275/65R18 | Commercial truck 295/75R22.5

Use the Tire type parameter to either input tire parameter values or select a fitted tire parameter set.

Goal	Action
Input user-defined tire parameter values.	Update the block parameters with user-defined parameter values: Set Tire type to User defined. In the Wheel and Tire Parameters section, input user-defined values. Click Apply.
Select one of the built-in Fiala tire models to drive the lateral and longitudinal calculations. [link].	Update the applicable block parameters with values from a built-in tire model: Set Tire type to the tire that you want to implement. Options include: Light passenger car 205/60R15 Light passenger car 245/60R16 Mid-size passenger car 235/45R18 Performance car 225/40R19 SUV 265/50R20 Light truck 275/65R18 Commercial truck 295/75R22.5 Click Update block with applicable tire values. In the Wheel and Tire Parameters section, the block updates the applicable Longitudinal and Lateral parameters. Click Apply.

Brake type — Brake type

None | Disc | Drum | Mapped

Use the Brake Type parameter to select the brake.

Action	Brake Type Setting
No braking	None
Implement brake that converts the brake cylinder pressure into a braking force	Disc
Implement simplex drum brake that converts the applied force and brake geometry into a net braking torque	Drum
Implement lookup table that is a function of the wheel speed and applied brake pressure	Mapped

Rolling Resistance — Rolling resistance torque

None (default) | Pressure and velocity | ISO 28580 | Magic Formula | Mapped torque

To calculate the rolling resistance torque, specify one of these Rolling Resistance parameters.

Setting	Block Implementation
None	None
Pressure and velocity	Method in Stepwise Coastdown Methodology for Measuring Tire Rolling Resistance. The rolling resistance is a function of tire pressure, normal force, and velocity.
ISO 28580	Method specified in ISO 28580:2018, Passenger car, truck and bus tyre rolling resistance measurement method — Single point test and correlation of measurement results.
Magic Formula	Magic formula equations from 4.E70 in Tire and Vehicle Dynamics. The magic formula is an empirical equation based on fitting coefficients.
Mapped torque	Lookup table that is a function of the normal force and spin axis longitudinal velocity.

Dependencies

Each Rolling Resistance setting enables additional parameters.

Setting	Parameters Enabled
Pressure and velocity	Velocity independent force coefficient, aMy Linear velocity force component, bMy Quadratic velocity force component, cMy Tire pressure exponent, alphaMy Normal force exponent, betaMy
ISO 28580	Parasitic losses force, Fpl Rolling resistance constant, Cr Thermal correction factor, Kt Measured temperature, Tmeas Parasitic losses force, Fpl Ambient temperature, Tamb
Magic Formula	Rolling resistance torque coefficient, QSY Longitudinal force rolling resistance coefficient, QSY2 Linear rotational speed rolling resistance coefficient, QSY3 Quartic rotational speed rolling resistance coefficient, QSY4 Camber squared rolling resistance torque, QSY5 Load based camber squared rolling resistance torque, QSY6 Normal load rolling resistance coefficient, QSY7 Pressure load rolling resistance coefficient, QSY8 Rolling resistance scaling factor, lam_My
Mapped torque	Spin axis velocity breakpoints, VxMy Normal force breakpoints, FzMy Rolling resistance torque map, MyMap

Vertical Motion — Vertical Motion

None (default) | Mapped stiffness and damping | External deflection

To calculate vertical motion, specify one of these Vertical Motion parameters.

Setting	Block Implementation
None	Block passes the applied chassis forces directly through to the rolling resistance and longitudinal force calculations.
Mapped stiffness and damping	Vertical motion depends on wheel stiffness and damping. Stiffness is a function of tire sidewall displacement and pressure. Damping is a function of tire sidewall velocity and pressure.
External deflection	The block uses the defined sidewall deflection directly in the effective radius calculation.

Dependencies

Setting Vertical Motion to Mapped stiffness and damping enables these parameters:

Setting	Parameters Enabled
Mapped stiffness and damping	Wheel mass, MASS Initial tire displacement, zo Initial velocity, zdoto Initial wheel vertical velocity (wheel fixed frame), zdoto Vertical deflection breakpoints, zFz Pressure breakpoints, pFz Force due to deflection, Fzz Vertical velocity breakpoints, zdotFz Force due to velocity, Fzzdot

Longitudinal and Lateral

Longitudinal stiffness, Ckappa — Longitudinal stiffness

1e7 (default) | scalar | N-by-1 vector

Longitudinal stiffness, C_κ, specified as a scalar or N-by-1 vector, in N. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Lateral stiffness per slip angle, Calpha — Lateral stiffness

4.5e4 (default) | scalar | N-by-1 vector

Lateral stiffness per slip angle, C_α, specified as a scalar or N-by-1 vector, in N/rad. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Camber stiffness, Cgamma — Camber stiffness

1e3 (default) | scalar | N-by-1 vector

Camber stiffness, C_ɣ, specified as a scalar or N-by-1 vector, in N/rad. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Kinematic friction, muMin — Kinematic friction

0.8 (default) | scalar | N-by-1 vector

Kinematic friction, μ_k, specified as a scalar or N-by-1 vector, dimensionless. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Static friction, muMax — Static friction

1 (default) | scalar | N-by-1 vector

Static friction, μ_s, specified as a scalar or N-by-1 vector, dimensionless. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Longitudinal relaxation length, Lrelx — Longitudinal relaxation length

0.05 (default) | scalar | N-by-1 vector

Longitudinal relaxation length, L_relx, specified as a scalar or N-by-1 vector, in m. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Lateral relaxation length, Lrely — Lateral relaxation length

0.15 (default) | scalar | N-by-1 vector

Lateral relaxation length, L_rely, in m/rad.

Lateral relaxation length, L_rely, specified as a scalar or N-by-1 vector, in m/rad. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other longitudinal and lateral parameters.

N is the number of wheels and must match the input signal dimensions.

Rolling Resistance

Pressure and Velocity

Velocity independent force coefficient, aMy — Velocity-independent force coefficient

84e-4 (default) | scalar

Velocity-independent force coefficient, a, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Pressure and velocity.

Linear velocity force component, bMy — Linear velocity force component

6.2e-4 (default) | scalar

Linear velocity force component, b, in s/m.

Dependencies

To enable this parameter, set Rolling Resistance to Pressure and velocity.

Quadratic velocity force component, cMy — Quadratic velocity force component

1.6e-4 (default) | scalar

Quadratic velocity force component, c, in s^2/m^2.

Dependencies

To enable this parameter, set Rolling Resistance to Pressure and velocity.

Tire pressure exponent, alphaMy — Tire pressure exponent

-0.003 (default) | scalar

Tire pressure exponent, ɑ, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Pressure and velocity.

Normal force exponent, betaMy — Normal force exponent

0.97 (default) | scalar

Normal force exponent, β, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Pressure and velocity.

ISO 28580

Parasitic losses force, Fpl — Parasitic force loss

10 (default) | scalar

Parasitic force loss, F_pl, in N.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Rolling resistance constant, Cr — Rolling resistance constant

1e-3 (default) | scalar

Rolling resistance constant, C_r, in N/kN. ISO 28580 specifies the rolling resistance unit as one newton of tractive resistance for every kilonewtons of normal load.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Thermal correction factor, Kt — Thermal correction factor

0.008 (default) | scalar

Thermal correction factor, K_t, in 1/degC.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Measured temperature, Tmeas — Temperature during testing

298.15 (default) | scalar

Measured ambient temperature, T_meas, near tire during tire testing, in K.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Ambient temperature, Tamb — Temperature in application environment

298.15 (default) | scalar

Measured ambient temperature, T_amb, near tire in application environment, in K. For example, the measured ambient temperature is the ambient temperature near the tire when the vehicle is on the road.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Input ambient temperature — Option to input ambient temperature

off (default) | on

Select to create input port Tamb to input the measured ambient temperature.

The measured ambient temperature, T_amb, is the temperature near tire in application environment, in K. For example, the measured ambient temperature is the ambient temperature near the tire when the vehicle is on the road.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Magic Formula

Rolling resistance torque coefficient, QSY1 — Torque coefficient

0.007 (default) | scalar

Rolling resistance torque coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Longitudinal force rolling resistance coefficient, QSY2 — Force resistance coefficient

0 (default) | scalar

Longitudinal force rolling resistance coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Linear rotational speed rolling resistance coefficient, QSY3 — Linear speed coefficient

0.0015 (default) | scalar

Linear rotational speed rolling resistance coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Quartic rotational speed rolling resistance coefficient, QSY4 — Quartic speed coefficient

8.5e-05 (default) | scalar

Quartic rotational speed rolling resistance coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Camber squared rolling resistance torque, QSY5 — Camber resistance torque

0 (default) | scalar

Camber squared rolling resistance torque, in 1/rad^2.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Load based camber squared rolling resistance torque, QSY6 — Load resistance torque

0 (default) | scalar

Load based camber squared rolling resistance torque, in 1/rad^2.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Normal load rolling resistance coefficient, QSY7 — Normal resistance coefficient

0.9 (default) | scalar

Normal load rolling resistance coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Pressure load rolling resistance coefficient, QSY8 — Pressure resistance coefficient

-0.4 (default) | scalar

Pressure load rolling resistance coefficient, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Rolling resistance scaling factor, lam_My — Scaling factor

1 (default) | scalar

Rolling resistance scaling factor, dimensionless.

Dependencies

To enable this parameter, set Rolling Resistance to Magic Formula.

Mapped

Spin axis velocity breakpoints, VxMy — Spin axis velocity breakpoints

-20:1:20 (default) | vector

Spin axis velocity breakpoints, in m/s.

Dependencies

To enable this parameter, set Rolling Resistance to Mapped torque.

Normal force breakpoints, FzMy — Normal force breakpoints

0:200:1e4 (default) | vector

Normal force breakpoints, in N.

Dependencies

To enable this parameter, set Rolling Resistance to Mapped torque.

Rolling resistance torque map, MyMap — Rolling resistance torque map

array

Rolling resistance torque versus axle speed and normal force, in N·m.

Dependencies

To enable this parameter, set Rolling Resistance to Mapped torque.

Aligning

Tire nominal section width, WIDTH — Tire nominal section width

scalar

Tire nominal section width, WIDTH, in m.

Linear yaw rate resistance, bMz — Linear yaw rate resistance

0 | scalar

Linear yaw rate resistance, b_Mz, in N·m·s/rad.

Brake

Static friction coefficient, mu_static — Static friction coefficient

0.3 (default) | scalar | N-by-1 vector

Static friction coefficient, specified as a scalar or N-by-1 vector, dimensionless. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Disc, Drum, or Mapped.

Kinetic friction coefficient, mu_kinetic — Kinetic friction

0.2 (default) | scalar | N-by-1 vector

Kinematic friction coefficient, specified as a scalar or N-by-1 vector, dimensionless. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Disc, Drum, or Mapped.

Disc

Disc brake actuator bore, disc_abore — Bore distance

0.05 (default) | scalar | N-by-1 vector

Disc brake actuator bore, specified as a scalar or N-by-1 vector, in m. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Disc.

Brake pad mean radius, Rm — Radius

0.177 (default) | scalar | N-by-1 vector

Brake pad mean radius, specified as a scalar or N-by-1 vector, in m. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Disc.

Number of brake pads, num_pads — Number of brake pads

2 (default) | scalar | N-by-1 vector

Number of brake pads, specified as a scalar or N-by-1 vector, dimensionless. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Disc.

Drum

Drum brake actuator bore, disc_abore — Bore distance

0.0508 (default) | scalar | N-by-1 vector

Drum brake actuator bore, specified as a scalar or N-by-1 vector, in m. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other brake parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Brake Type to Drum.

Shoe pin to drum center distance, drum_a — Shoe pin to drum center distance

0.123 (default) | scalar

Shoe pin to drum center distance, in m.

Dependencies

To enable this parameter, set Brake Type to Drum.

Shoe pin center to force application point distance, drum_c — Shoe pin center to force application point distance

0.212 (default) | scalar

Shoe pin center to force application point distance, in m.

Dependencies

To enable this parameter, set Brake Type to Drum.

Drum internal radius, drum_r — Drum internal radius

0.15 (default) | scalar

Drum internal radius, in m.

Dependencies

To enable this parameter, set Brake Type to Drum.

Shoe pin to pad start angle, drum_theta1 — Shoe pin to pad start angle

0 (default) | scalar

Shoe pin to pad start angle, in deg.

Dependencies

To enable this parameter, set Brake Type to Drum.

Shoe pin to pad end angle, drum_theta2 — Shoe pin to pad end angle

126 (default) | scalar

Shoe pin to pad end angle, in deg.

Dependencies

To enable this parameter, set Brake Type to Drum.

Mapped

Brake actuator pressure breakpoints, brake_p_bpt — Brake actuator pressure breakpoints

vector

Brake actuator pressure breakpoints, in bar.

Dependencies

To enable this parameter, set Brake Type to Mapped.

Wheel speed breakpoints, brake_n_bpt — Wheel speed breakpoints

vector

Wheel speed breakpoints, in rpm.

Dependencies

To enable this parameter, set Brake Type to Mapped.

Brake torque map, f_brake_t — Lookup table for brake torque

array

The lookup table for the brake torque, $f_{brake}^{}(P,N)$, is a function of applied brake pressure and wheel speed, where:

• T is brake torque, in N·m.

• P is applied brake pressure, in bar.

• N is wheel speed, in rpm.

Dependencies

To enable this parameter, set Brake Type to Mapped.

Wheel

Rotational damping, br — Rotational damping

scalar | N-by-1 vector

Rotational damping, specified as a scalar or N-by-1 vector, in N·m·s/rad. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other rotational parameters.

N is the number of wheels and must match the input signal dimensions.

Tire rotational inertia (rolling axis), IYY — Tire rotational inertia

scalar | N-by-1 vector

Tire rotational inertia (rolling axis), specified as a scalar or N-by-1 vector, in kg·m². If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other rotational parameters.

N is the number of wheels and must match the input signal dimensions.

Initial wheel rotational velocity, omegao — Initial wheel rotational velocity

scalar | N-by-1 vector

Initial wheel rotational velocity, specified as a scalar or N-by-1 vector, in rad/s. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other rotational parameters.

N is the number of wheels and must match the input signal dimensions.

Tire unloaded radius, UNLOADED_RADIUS — Tire unloaded radius

0.309384029954441 (default) | scalar

Tire unloaded radius, in m.

Vertical

Tire mass, m — Tire mass

9.46491996974568 (default) | scalar | N-by-1 vector

Tire mass, specified as a scalar or N-by-1 vector, in kg. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other vertical parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Initial tire displacement, zo — Initial tire displacement

0 (default) | scalar | N-by-1 vector

Initial tire displacement, specified as a scalar or N-by-1 vector, in m. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other vertical parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Initial wheel vertical velocity (wheel fixed frame), zdoto — Initial wheel velocity

0 (default) | scalar | N-by-1 vector

Initial wheel vertical velocity, specified as a scalar or N-by-1 vector, in m/s. If you specify a scalar, the block uses that value for all wheels. If you specify a vector, you must specify vectors for the other vertical parameters.

N is the number of wheels and must match the input signal dimensions.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Gravitational acceleration, GRAVITY — Gravitational acceleration

-9.81 (default) | scalar

Gravitational acceleration, in m/s^2.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Mapped Stiffness and Damping

Vertical deflection breakpoints, zFz — Vertical deflection breakpoints

[0 .01 .1] (default) | vector

Vector of sidewall deflection breakpoints corresponding to the force table, in m.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Pressure breakpoints, pFz — Pressure breakpoints

[10000 1000000] (default) | vector

Vector of pressure data points corresponding to the force table, in Pa.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Force due to deflection, Fzz — Force due to deflection

[0 1e3 1e4; 0 1e4 1e5] (default) | vector

Force due to sidewall deflection and pressure along wheel-fixed z-axis, in N.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Vertical velocity breakpoints, zdotFz — Vertical velocity breakpoints

[-20 0 20] (default) | scalar

Vector of sidewall velocity breakpoints corresponding to the force due to velocity table, in m.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Force due to velocity, Fzzdot — Force due to velocity

[500 0 -500;250 0 -250] (default) | array

Force due to sidewall velocity and pressure along wheel-fixed z-axis, in N.

Dependencies

To enable this parameter, set Vertical Motion to Mapped stiffness and damping.

Simulation Setup

Maximum normal force, FZMAX — Maximum normal force

10000 (default) | scalar

Maximum normal force, in N. Used with all vertical force calculations.

Minimum normal force, FZMIN — Minimum normal force

0 (default) | scalar

Minimum normal force, in N. Used with all vertical force calculations.

Maximum pressure, PRESMAX — Maximum pressure

1003118 (default) | scalar

Maximum pressure, PRESMAX, in Pa.

Minimum pressure, PRESMIN — Minimum pressure

9982 (default) | scalar

Minimum pressure, PRESMIN, in Pa.

Max allowable slip ratio (absolute), KPUMAX — Max allowable slip ratio

0.999 (default) | scalar

Max allowable slip ratio (absolute), KPUMAX, dimensionless.

Minimum allowable slip ratio (absolute), KPUMIN — Minimum allowable slip ratio

-0.999 (default) | scalar

Minimum allowable slip ratio (absolute), KPUMIN, dimensionless.

Max allowable slip angle (absolute), ALPMAX — Max allowable slip angle

1.5708 (default) | scalar

Max allowable slip angle (absolute), ALPMAX, in rad.

Minimum allowable slip angle (absolute), ALPMIN — Minimum allowable slip angle

-1.5708 (default) | scalar

Minimum allowable slip angle (absolute), ALPMIN, in rad.

Maximum allowable camber angle, CAMMAX — Maximum allowable camber angle

0.173 | scalar

Maximum allowable camber angle CAMMAX, in rad.

Minimum allowable camber angle, CAMMIN — Minimum allowable camber angle

-0.173 | scalar

Minimum allowable camber angle, CAMMIN, in rad.

Minimum ambient temperature, TMIN — Minimum ambient temperature

0 (default) | scalar

Minimum ambient temperature, T_MIN, in K.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Maximum ambient temperature, TMAX — Maximum ambient temperature

400 (default) | scalar

Maximum ambient temperature, T_MAX, in K.

Dependencies

To enable this parameter, set Rolling Resistance to ISO 28580.

Plotting

Install Extended Tire Features — Option to install Extended Tire Features for Vehicle Dynamics Blockset™ support package

button

Click Install Extended Tire Features to install the Extended Tire Features for Vehicle Dynamics Blockset support package. With the support package, you can plot steady-state force and moment tire responses from the Fiala Wheel 2DOF Block Parameters dialog box.

Plot steady state force, moment response — Option to plot steady-state force and moment tire responses

button

Click Plot steady state force, moment response to generate these plots:

• Lateral force [N] vs Slip angle [rad]

• Self-aligning moment [Nm] vs Slip angle [rad]

• Longitudinal force [N] vs Longitudinal slip []

• Longitudinal force [N] vs Lateral force [N]

Dependencies

To enable this parameter, click Install Extended Tire Features.

References

[1] Fiala, E. "Seitenkrafte am Rollenden Luftreifen." VDI Zeitschrift, V.D.I.. Vol 96, 1954.

[2] Highway Tire Committee. Stepwise Coastdown Methodology for Measuring Tire Rolling Resistance. Standard J2452_199906. Warrendale, PA: SAE International, June 1999.

[3] ISO 28580:2018. Passenger car, truck and bus tyre rolling resistance measurement method — Single point test and correlation of measurement results. ISO (International Organization for Standardization), 2018.

[4] Pacejka, H. B. Tire and Vehicle Dynamics. 3rd ed. Oxford, UK: SAE and Butterworth-Heinemann, 2012.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2019a

R2024b: New Tire type option

Starting in R2024b, you can specify Tire type to use the new built-in tire model, Light passenger car 245/60R16.

R2024b: New Vertical Motion option

Starting in R2024b, specifying Vertical Motion as External Deflection enables the RadialDeflct port. Use this port to define the sidewall deflection when interfacing with a tire in cases where forces are not provided.

R2024b: New signals added to the Info port bus

Starting in R2024b, the Info port bus contains these new signals.

Signal	Description
RadialDeflct	Tire radial deflection
RL	Loaded radius
WhlTrq	Wheel torque

R2024b: Renamed block parameters

Starting in R2024b, these parameters have been renamed.

Old Name	New Name
Wheel width	Tire nominal section width
Unloaded radius	Tire unloaded radius
Initial rotational velocity	Initial wheel rotational velocity
Wheel mass	Tire mass
Rotational inertia	Tire rotational inertia

R2024a: New Tire type parameter

Starting in R2024a, the Fiala Wheel 2DOF block includes the Tire type parameter to select a fitted parameter set from six different tire sizes.

R2024a: Plot steady-state force and moment responses

If you have the Extended Tire Features for Vehicle Dynamics Blockset support package installed, you can use the new Plot steady state force, moment response button to generate plots.

R2022b: Specify Brake and Tire Parameters for Each Wheel

Starting from R2022b, you can to use the Fiala Wheel 2DOF block to specify brake and tire characteristics for each wheel on your vehicle. Specifically, the block allows N-by-1 vectors for these parameters:

• Static friction coefficient, mu_static

• Kinetic friction coefficient, mu_kinetic

• Disc brake actuator bore, disc_abore

• Brake pad mean radius, Rm

• Number of brake pads, num_pads

• Drum brake actuator bore, disc_abore

• Initial rotational velocity, omegao

• Rotational damping, br

• Wheel mass, m

• Rotational inertia (rolling axis), IYY

• Initial tire displacement, zo

• Initial wheel vertical velocity (wheel fixed frame), zdoto

• Longitudinal stiffness, Ckappa

• Lateral stiffness per slip angle, Calpha

• Camber stiffness, Cgamma

• Kinematic friction, muMin

• Static friction, muMax

• Longitudinal relaxation length, Lrelx

• Lateral relaxation length, Lrely

N is the number of wheels and must match the input signal dimensions.