# Predictive Driver

Predictive driver controller to track longitudinal speed and lateral path

• Library:
• Vehicle Dynamics Blockset / Vehicle Scenarios / Driver

## Description

The Predictive Driver block implements a controller that generates normalized steering, acceleration, and braking commands to track longitudinal velocity and a lateral reference displacement. The normalized commands can vary between -1 to 1. The controller uses a single-track (bicycle) model for optimal single-point preview control.

### Configurations

External Actions

Use the External Actions parameters to create input ports for signals that you can use to simulate standard test maneuvers. The block uses this priority order for the input commands: disable (highest), hold, override.

This table summarizes the external action parameters.

Goal

External Action Parameter

Input Ports

Data Type

Override the accelerator command with an input acceleration command.

Accelerator override

EnablAccelOvr

Boolean

AccelOvrCmd

double

Hold the acceleration command at the current value.

Accelerator hold

AccelHldBoolean

Disable the acceleration command.

Accelerator disable

AccelZeroBoolean

Override the decelerator command with an input deceleration command.

Decelerator override

EnablDecelOvr

Boolean

DecelOvrCmd

double

Hold the decelerator command at current value.

Decelerator hold

DecelHldBoolean

Disable the decelerator command.

Decelerator disable

DecelZeroBoolean

Override the steering command with an input steering command.

Steering override

EnblSteerOvr

Boolean

SteerOvrCmd

double

Hold the steering command at the current value.

Steering hold

SteerHldBoolean

Disable the steering command.

Steering disable

SteerZeroBoolean

Controllers

Use the Longitudinal control type, cntrlType parameter to specify one of these control options.

Setting

Block Implementation

PI

Proportional-integral (PI) control with tracking windup and feed-forward gains.

Scheduled PI

PI control with tracking windup and feed-forward gains that are a function of vehicle velocity.

Predictive

Optimal single-point preview (look ahead) control model developed by C. C. MacAdam1, 2, 3. The model represents driver steering control behavior during path-following and obstacle avoidance maneuvers. Drivers preview (look ahead) to follow a predefined path. To implement the MacAdam model, the block:

• Represents the dynamics as a linear single track (bicycle) vehicle

• Minimizes the previewed error signal at a single point T* seconds ahead in time

• Accounts for the driver lag deriving from perceptual and neuromuscular mechanisms

Use the Lateral control type, controlTypeLat parameter to specify the type of lateral control. The table specifies the block implementation.

Setting

Block Implementation

Predictive (default)

Optimal single-point preview (look ahead) control model developed by C. C. MacAdam1, 2, 3. The model represents driver steering control behavior during path-following and obstacle avoidance maneuvers. Drivers preview (look ahead) to follow a predefined path.

Stanley

Controller that uses the Stanley4 method to minimize the position error and the angle error of the current pose with respect to the reference pose.

On the Reference Control pane, use the:

• Vector input for poses parameter to input the to specify the input.

SettingImplementation
off (default)

Block uses the longitudinal, lateral, and yaw reference (LongRef, LatRef, LatRef) input ports and the feedback (LongFdbk, LatFdbk, LatFdbk) input ports for the reference and feedback pose.

on

Block uses input ports, RefPose and CurrPose, for the reference and feedback pose, respectively.

• Include dynamics parameter to specify the type of model for the controller to use.

SettingImplementation
off (default)

Controller uses a kinematic bicycle model that is suitable for path following in low-speed environments such as parking lots, where inertial effects are minimal.

on

Controller uses a dynamic bicycle model that is suitable for path following in high-speed environments such as highways, where inertial effects are more pronounced.

Shift

Use the Shift type, ShftType parameter to specify one of these shift options.

Setting

Block Implementation

None

No transmission. Block outputs a constant gear of 1.

Use this setting to minimize the number of parameters you need to generate acceleration and braking commands to track forward vehicle motion. This setting does not allow reverse vehicle motion.

Reverse, Neutral, Drive

Block uses a Stateflow® chart to model reverse, neutral, and drive gear shift scheduling.

Use this setting to generate acceleration and braking commands to track forward and reverse vehicle motion using simple reverse, neutral, and drive gear shift scheduling. Depending on the vehicle state and vehicle velocity feedback, the block uses the initial gear and time required to shift to shift the vehicle up into drive or down into reverse or neutral.

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

Scheduled

Block uses a Stateflow chart to model reverse, neutral, park, and N-speed gear shift scheduling.

Use this setting to generate acceleration and braking commands to track forward and reverse vehicle motion using reverse, neutral, park, and N-speed gear shift scheduling. Depending on the vehicle state and vehicle velocity feedback, the block uses these parameters to determine the:

• Initial gear

• Upshift and downshift accelerator pedal positions

• Upshift and downshift velocity

• Timing for shifting and engaging forward and reverse from neutral

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

External

Block uses the input gear, vehicle state, and velocity feedback to generate acceleration and braking commands to track forward and reverse vehicle motion.

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

Units

Use the and Longitudinal velocity units, velUnits and Angular units, angUnits parameter to specify the units for the input and output ports.

Gear Signal

Use the parameter to create the GearCmd output port. The GearCmd signal contains the integer value of the commanded vehicle gear.

Gear

Integer

Park

80

Reverse

-1

Neutral

0

Drive

1

Gear

Gear number

Output Handwheel Angle

Use the Output handwheel angle parameter to specify the units for the steering ports.

Setting

Block Implementation

Port

off (default)

Commanded steer angle, normalized from -1 through 1. The block uses the tire wheel angle saturation limit Tire wheel angle limit, theta parameter to normalize the command.

SteerCmd — Output

Overrides the steering command with an input steering command normalized from -1 through 1.

SteerOvrCmd — Input

on

Commanded steer angle, in units specified by Angular units, angUnits.

SteerCmd — Output

Overrides the steering command with an input steering command, in units specified by Angular units, angUnits.

SteerOvrCmd — Input

To enable adaptive drift control, select Advanced Options > Enable drift management.

Consider enabling drift control to improve path and speed tracking. If the block determines that drifting improves path and or speed tracking, the controller re-plans the tracking horizon with a best-fit stable drifting path. The controller will opt out of the drifting under any of these conditions:

• Drifting is no longer possible.

• Drifting deviates too much from original predetermined path.

• Drifting compares unfavorably to normal driving when speed-tracking.

### Controller: PI Speed-Tracking

If you set the control type to PI or Scheduled PI, the block implements proportional-integral (PI) control with tracking windup and feed-forward gains. For the Scheduled PI configuration, the block uses feed forward gains that are a function of vehicle velocity.

To calculate the speed control output, the block uses these equations.

Setting

Equation

PI

$y=\frac{{K}_{ff}}{{v}_{nom}}{v}_{ref}+\frac{{K}_{p}{e}_{ref}}{{v}_{nom}}+\int \left(\frac{{K}_{i}{e}_{ref}}{{v}_{nom}}+{K}_{aw}{e}_{out}\right)dt+{K}_{g}\theta$

Scheduled PI

$y=\frac{{K}_{ff}\left(v\right)}{{v}_{nom}}{v}_{ref}+\frac{{K}_{p}\left(v\right){e}_{ref}}{{v}_{nom}}+\int \left(\frac{{K}_{i}\left(v\right){e}_{ref}}{{v}_{nom}}+{K}_{aw}{e}_{out}\right){e}_{ref}dt+{K}_{g}\left(v\right)\theta$

$\begin{array}{l}\text{where:}\\ \\ {e}_{ref}={v}_{ref}-v\\ {e}_{out}={y}_{sat}-y\\ \\ {y}_{sat}=\left\{\begin{array}{cc}-1& y<-1\\ y& -1\le y\le 1\\ 1& 1

The velocity error low-pass filter uses this transfer function.

To calculate the acceleration and braking commands, the block uses these equations.

$\begin{array}{l}{y}_{acc}=\left\{\begin{array}{cc}0& {y}_{sat}<0\\ {y}_{sat}& 0\le {y}_{sat}\le 1\\ 1& 1<{y}_{sat}\end{array}\\ \\ {y}_{dec}=\left\{\begin{array}{cc}0& {y}_{sat}>0\\ -{y}_{sat}& -1\le {y}_{sat}\le 0\\ 1& {y}_{sat}<-1\end{array}\end{array}$

The equations use these variables.

 vnom Nominal vehicle speed Kp Proportional gain Ki Integral gain Kaw Anti-windup gain Kff Velocity feed-forward gain Kg Grade angle feed-forward gain θ Grade angle τerr Error filter time constant y Nominal control output magnitude ysat Saturated control output magnitude eref Velocity error eout Difference between saturated and nominal control outputs yacc Acceleration signal ydec Braking signal v Velocity feedback signal vref Reference velocity signal

### Controller: Predictive Speed-Tracking

If you set the Longitudinal control type, cntrlType or Lateral control type, cntrlType to Predictive, the block implements an optimal single-point preview (look ahead) control model developed by C. C. MacAdam1, 2, 3. The model represents driver steering control behavior during path-following and obstacle avoidance maneuvers. Drivers preview (look ahead) to follow a predefined path. To implement the MacAdam model, the block:

• Represents the dynamics as a linear single track (bicycle) vehicle

• Minimizes the previewed error signal at a single point T* seconds ahead in time

• Accounts for the driver lag deriving from perceptual and neuromuscular mechanisms

Vehicle Dynamics

For lateral and yaw motion, the block implements these linear dynamic equations.

In matrix notation:

The single-point model assumes a minimum previewed error signal at a single point T* seconds ahead in time. a* is the driver ability to predict the future vehicle response based on the current steering control input. b* is the driver ability to predict the future vehicle response based on the current vehicle state. The block uses these equations.

$\begin{array}{l}{a}^{*}=\left({T}^{*}\right){m}^{T}\left[I+\sum _{n=1}^{\infty }\frac{{F}^{n}{\left({T}^{*}\right)}^{n}}{\left(n+1\right)!}\right]g\\ {b}^{*}={m}^{T}\left[I+\sum _{n=1}^{\infty }\frac{{F}^{n}{\left({T}^{*}\right)}^{n}}{n!}\right]\\ {m}^{T}=\left[\begin{array}{cccccc}1& 1& 1& 0& 0& 0\end{array}\right]\end{array}$

The equations use these variables.

 a, b Forward and rearward tire location, respectively m Vehicle mass I Vehicle rotational inertia CɑF Front tire cornering coefficient CɑR Rear tire cornering coefficient a*, b* Driver prediction scalar and vector gain, respectively x Predicted vehicle state vector v Lateral velocity r Yaw rate Ψ Front wheel heading angle y Lateral displacement F System matrix δ, δF Steer angle and front axle steer angle, respectively γ Grade angle g Control coefficient vector U Forward (longitudinal) vehicle velocity T* Preview time window ƒ(t+T*) Previewed path input T* seconds ahead u Tractive force mT Constant observer vector; provides vehicle lateral position ar Static rolling and driveline resistance br Linear rolling and driveline resistance cr Aerodynamic rolling and driveline resistance Fr Rolling resistance

Optimization

The single-point model implemented by the block finds the steering command that minimizes a local performance index, J, over the current preview interval, (t, t+T).

$J=\frac{1}{T}{\int }_{t}^{t+T}{\left[f\left(\eta \right)-y\left(\eta \right)\right]}^{2}d\eta$

To minimize J with respect to the steering command, this condition must be met.

$\frac{dJ}{du}=0$

You can express the optimal control solution in terms of a current non-optimal and corresponding nonzero preview output error T* seconds ahead1, 2, 3.

${u}^{o}\left(t\right)=u\left(t\right)+\frac{e\left(t+{T}^{*}\right)}{{a}^{*}}$

The block uses the preview distance and vehicle longitudinal velocity to determine the preview time window.

${T}^{*}=\frac{L}{U}$

The equations use these variables.

 T* Preview time window ƒ(t+T*) Previewed path input T* sec ahead y(t+T*) Previewed plant output T* sec ahead e(t+T*) Previewed error signal T* sec ahead u(t), uo(t) Steer angle and optimal steer angle, respectively L Preview distance J Performance index U Forward (longitudinal) vehicle velocity

Driver Lag

The single-point model implemented by the block introduces a driver lag. The driver lag accounts for the delay when the driver is tracking tasks. Specifically, it is the transport delay deriving from perceptual and neuromuscular mechanisms. To calculate the driver transport delay, the block implements this equation.

$H\left(s\right)={e}^{-s\tau }$

The equations use these variables.

 τ Driver transport delay y(t+T*) Previewed plant output T* sec ahead e(t+T*) Previewed error signal T* sec ahead u(t), uo(t) Steer angle and optimal steer angle, respectively J Performance index

### Controller: Stanley Lateral Path-Tracking

If you set Lateral control type, controlTypeLat to Stanley, the block implements the Stanley method4. To compute the steering angle command, the Stanley controller minimizes the position error and the angle error of the current pose with respect to the reference pose. The driving direction of the vehicle determines these error values.

To compute the steering angle command, the controller minimizes the position error and the angle error of the current pose with respect to the reference pose.

• The position error is the lateral distance from the vehicle center-of-gravity (CG) to the reference point on the path.

• The angle error is the angle of the vehicle with respect to reference path.

## Ports

### Input

expand all

Reference velocity, vref, in units specified by Longitudinal velocity units, velUnits.

Longitudinal center of mass (CM) displacement reference, in the inertial reference frame, in m.

#### Dependencies

To enable this port:

1. Set Lateral control type, controlTypeLat to Stanley.

2. Clear Vector input for poses.

Lateral center of mass (CM) displacement reference, in the inertial reference frame, in m.

#### Dependencies

To enable this port, do one of these:

• Set Lateral control type, controlTypeLat to Stanley and clear Vector input for poses.

• Set Lateral control type, controlTypeLat to Predictive.

Vehicle yaw angle, Ψo, in the inertial reference frame, in units specified by Angular units, angUnits.

#### Dependencies

To enable this port:

• Set Lateral control type, controlTypeLat to Stanley

• Clear Vector input for poses

Enable steering command override.

#### Dependencies

To enable this port, select Steering override.

Data Types: Boolean

Steering override command.

Use the Output handwheel angle parameter to specify the units for the steering ports.

Setting

Block Implementation

Port

off (default)

Commanded steer angle, normalized from -1 through 1. The block uses the tire wheel angle saturation limit Tire wheel angle limit, theta parameter to normalize the command.

SteerCmd — Output

Overrides the steering command with an input steering command normalized from -1 through 1.

SteerOvrCmd — Input

on

Commanded steer angle, in units specified by Angular units, angUnits.

SteerCmd — Output

Overrides the steering command with an input steering command, in units specified by Angular units, angUnits.

SteerOvrCmd — Input

#### Dependencies

To enable this port, select Steering override.

Data Types: double

Boolean signal that holds the steering command at the current value.

#### Dependencies

To enable this port, select Steering hold.

Data Types: Boolean

Disable steering command.

#### Dependencies

To enable this port, select Steering disable.

Data Types: Boolean

Enable acceleration command override.

#### Dependencies

To enable this port, select Acceleration override.

Data Types: Boolean

Acceleration override command, normalized from 0 through 1.

#### Dependencies

To enable this port, select Acceleration override.

Data Types: double

Boolean signal that holds the acceleration command at the current value.

#### Dependencies

To enable this port, select Acceleration hold.

Data Types: Boolean

Disable acceleration command.

#### Dependencies

To enable this port, select Acceleration disable.

Data Types: Boolean

Enable deceleration command override.

#### Dependencies

To enable this port, select Deceleration override.

Data Types: Boolean

Deceleration override command, normalized from 0 through 1.

#### Dependencies

To enable this port, select Deceleration override.

Data Types: double

Boolean signal that holds the deceleration command at the current value.

#### Dependencies

To enable this port, select Deceleration hold.

Data Types: Boolean

Disable deceleration command.

#### Dependencies

To enable this port, select Deceleration disable.

Data Types: Boolean

Gear

Integer

Park

80

Reverse

-1

Neutral

0

Drive

1

Gear

Gear number

#### Dependencies

To enable this port, set Shift type, shftType to External.

Reference pose, specified as an [x, y, Θ] vector. x and y are in meters, and Θ are in units specified by Angular units, angUnits.

x and y specify the reference point to steer the vehicle toward. Θ specifies the orientation angle of the path at this reference point and is positive in the counterclockwise direction.

The reference point is the point on the path that is closest to the vehicle CG. You can use the either the Z-up or Z-down vehicle coordinate system, as long you use the same coordinate system (Z-up or Z-down) for block inputs and parameters.

#### Dependencies

To enable this port:

1. Set Lateral control type, controlTypeLat to Stanley.

2. Select Vector input for poses.

Data Types: single | double

Longitudinal vehicle velocity, U, in the vehicle-fixed frame, in units specified by Longitudinal velocity units, velUnits.

Current pose of the vehicle, specified as an [x, y, Θ] vector. x and y are in meters, and Θ is in units specified by Angular units, angUnits.

x and y specify the location of the vehicle, which is defined as the vehicle CG. You can use the either the Z-up or Z-down vehicle coordinate system, as long you use the same coordinate system (Z-up or Z-down) for block inputs and parameters.

#### Dependencies

To enable this port, set Lateral control type, controlTypeLat to Stanley and select Vector input for poses.

Data Types: single | double

Lateral CM displacement, yo, in the inertial reference frame, in m.

#### Dependencies

To enable this port, do either of these:

• Set Lateral control type, controlTypeLat to Stanley and clear Vector input for poses.

• Set Lateral control type, controlTypeLat to Predictive.

Lateral vehicle velocity, vo , in the vehicle-fixed frame, in m/s.

#### Dependencies

To enable this port, Set Lateral control type, controlTypeLat to Predictive.

Vehicle yaw angle, Ψo, in the inertial reference frame, in units specified by Angular units, angUnits.

#### Dependencies

To enable this port, do either of these:

• Set Lateral control type, controlTypeLat to Stanley and clear Vector input for poses.

• Set Lateral control type, controlTypeLat to Predictive.

Yaw rate, ro, in the vehicle-fixed frame, in units specified by Angular units, angUnits per sec.

#### Dependencies

To enable this port, Set Lateral control type, controlTypeLat to Predictive.

### Output

expand all

Bus signal containing these block calculations.

SignalVariableDescription
SteerδF

Commanded steer angle, normalized from 0 through 1

Accelyacc

Commanded vehicle acceleration, normalized from 0 through 1

Decel ydec

Commanded vehicle deceleration, normalized from 0 through 1

Gear

Integer value of commanded gear

Clutch

Clutch command

ErrLatErrErreref

Difference in reference vehicle position and vehicle position.

ErrSqrSum$\underset{0}{\overset{t}{\int }}{e}_{ref}{}^{2}dt$

Integrated square of error.

ErrMax$\mathrm{max}\left({e}_{ref}\left(t\right)\right)$

Maximum error during simulation.

ErrMin$\mathrm{min}\left({e}_{ref}\left(t\right)\right)$

Minimum error during simulation.

LngErrErreref

Difference in reference vehicle speed and vehicle speed

ErrSqrSum$\underset{0}{\overset{t}{\int }}{e}_{ref}{}^{2}dt$

Integrated square of error

ErrMax$\mathrm{max}\left({e}_{ref}\left(t\right)\right)$

Maximum error during simulation

ErrMin$\mathrm{min}\left({e}_{ref}\left(t\right)\right)$

Minimum error during simulation

ExtActionsEnblSteerOvr

Override the steering command with an input deceleration command

SteerOvrCmd

Input steering override command

SteerHld

Hold the steering command at the current value

SteerZero

Disable the steering command

EnblAccelOvr

Override the accelerator command with an input acceleration command

AccelOvrCmd

Input accelerator override command

AccelHld

Hold the acceleration command at the current value

AccelZero

Disable the acceleration command

EnblDecelOvr

Override the decelerator command with an input deceleration command

DecelOvrCmd

Input deceleration override command

DecelHld

Hold the decelerator command at current value

DecelZero

Disable the decelerator command

Commanded steer angle, δF.

Use the Output handwheel angle parameter to specify the units for the steering ports.

Setting

Block Implementation

Port

off (default)

Commanded steer angle, normalized from -1 through 1. The block uses the tire wheel angle saturation limit Tire wheel angle limit, theta parameter to normalize the command.

SteerCmd — Output

Overrides the steering command with an input steering command normalized from -1 through 1.

SteerOvrCmd — Input

on

Commanded steer angle, in units specified by Angular units, angUnits.

SteerCmd — Output

Overrides the steering command with an input steering command, in units specified by Angular units, angUnits.

SteerOvrCmd — Input

Commanded vehicle acceleration, yacc, normalized from 0 through 1.

Commanded vehicle deceleration, ydec, normalized from 0 through 1.

Integer value of commanded vehicle gear.

Gear

Integer

Park

80

Reverse

-1

Neutral

0

Drive

1

Gear

Gear number

#### Dependencies

To enable this port, select Output gear signal.

## Parameters

expand all

### Configuration

External Actions

Select to override the acceleration command with an input acceleration command.

#### Dependencies

Selecting this parameter creates the EnblAccelOvr and AccelOvrCmd input ports.

Select to hold the acceleration command.

#### Dependencies

Selecting this parameter creates the AccelHld input port.

Select to disable the acceleration command.

#### Dependencies

Selecting this parameter creates the AccelZero input port.

Select to override the deceleration command with an input deceleration command.

#### Dependencies

Selecting this parameter creates the EnblDecelOvr and DecelOvrCmd input ports.

Select to hold the deceleration command.

#### Dependencies

Selecting this parameter creates the DecelHld input port.

Select to disable the deceleration command.

#### Dependencies

Selecting this parameter creates the DecelZero input port.

Select to override the steering command with an input steering command.

#### Dependencies

Selecting this parameter creates the EnblSteerOvr and SteerOvrCmd input ports.

Select to hold the steering command.

#### Dependencies

Selecting this parameter creates the SteerHld input port.

Select to disable the steering command.

#### Dependencies

Selecting this parameter creates the SteerZero input port.

Control and Shift

Type of longitudinal control.

Setting

Block Implementation

PI

Proportional-integral (PI) control with tracking windup and feed-forward gains.

Scheduled PI

PI control with tracking windup and feed-forward gains that are a function of vehicle velocity.

Predictive

Optimal single-point preview (look ahead) control model developed by C. C. MacAdam1, 2, 3. The model represents driver steering control behavior during path-following and obstacle avoidance maneuvers. Drivers preview (look ahead) to follow a predefined path. To implement the MacAdam model, the block:

• Represents the dynamics as a linear single track (bicycle) vehicle

• Minimizes the previewed error signal at a single point T* seconds ahead in time

• Accounts for the driver lag deriving from perceptual and neuromuscular mechanisms

Use the Lateral control type, controlTypeLat parameter to specify the type of lateral control. The table specifies the block implementation.

Setting

Block Implementation

Predictive (default)

Optimal single-point preview (look ahead) control model developed by C. C. MacAdam1, 2, 3. The model represents driver steering control behavior during path-following and obstacle avoidance maneuvers. Drivers preview (look ahead) to follow a predefined path.

Stanley

Controller that uses the Stanley4 method to minimize the position error and the angle error of the current pose with respect to the reference pose.

On the Reference Control pane, use the:

• Vector input for poses parameter to input the to specify the input.

SettingImplementation
off (default)

Block uses the longitudinal, lateral, and yaw reference (LongRef, LatRef, LatRef) input ports and the feedback (LongFdbk, LatFdbk, LatFdbk) input ports for the reference and feedback pose.

on

Block uses input ports, RefPose and CurrPose, for the reference and feedback pose, respectively.

• Include dynamics parameter to specify the type of model for the controller to use.

SettingImplementation
off (default)

Controller uses a kinematic bicycle model that is suitable for path following in low-speed environments such as parking lots, where inertial effects are minimal.

on

Controller uses a dynamic bicycle model that is suitable for path following in high-speed environments such as highways, where inertial effects are more pronounced.

Shift type.

Setting

Block Implementation

None

No transmission. Block outputs a constant gear of 1.

Use this setting to minimize the number of parameters you need to generate acceleration and braking commands to track forward vehicle motion. This setting does not allow reverse vehicle motion.

Reverse, Neutral, Drive

Block uses a Stateflow chart to model reverse, neutral, and drive gear shift scheduling.

Use this setting to generate acceleration and braking commands to track forward and reverse vehicle motion using simple reverse, neutral, and drive gear shift scheduling. Depending on the vehicle state and vehicle velocity feedback, the block uses the initial gear and time required to shift to shift the vehicle up into drive or down into reverse or neutral.

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

Scheduled

Block uses a Stateflow chart to model reverse, neutral, park, and N-speed gear shift scheduling.

Use this setting to generate acceleration and braking commands to track forward and reverse vehicle motion using reverse, neutral, park, and N-speed gear shift scheduling. Depending on the vehicle state and vehicle velocity feedback, the block uses these parameters to determine the:

• Initial gear

• Upshift and downshift accelerator pedal positions

• Upshift and downshift velocity

• Timing for shifting and engaging forward and reverse from neutral

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

External

Block uses the input gear, vehicle state, and velocity feedback to generate acceleration and braking commands to track forward and reverse vehicle motion.

For neutral gears, the block uses braking commands to control the vehicle speed. For reverse gears, the block uses an acceleration command to generate torque and a brake command to reduce vehicle speed.

Vehicle velocity reference and feedback units.

#### Dependencies

If you set Longitudinal control type, CntrlType control type to Scheduled or Scheduled PI, the block uses the Longitudinal velocity units, velUnits for the Nominal speed, vnom parameter dimension.

If you set Shift Type, shftType to Scheduled, the block uses the Longitudinal velocity units, velUnits for these parameter dimensions:

• Upshift velocity data table, upShftTbl

• Downshift velocity data table, dwnShftTbl

Input and output port angular units.

Specify to create output port GearCmd.

Use the Output handwheel angle parameter to specify the units for the steering ports.

Setting

Block Implementation

Port

off (default)

Commanded steer angle, normalized from -1 through 1. The block uses the tire wheel angle saturation limit Tire wheel angle limit, theta parameter to normalize the command.

SteerCmd — Output

Overrides the steering command with an input steering command normalized from -1 through 1.

SteerOvrCmd — Input

on

Commanded steer angle, in units specified by Angular units, angUnits.

SteerCmd — Output

Overrides the steering command with an input steering command, in units specified by Angular units, angUnits.

SteerOvrCmd — Input

#### Dependencies

To create the SteerOvrCmd input port, select Steering override.

### Reference Control

Longitudinal

Proportional gain, Kp, dimensionless.

#### Dependencies

To create this parameter, set Control type to PI.

Proportional gain, Ki, dimensionless.

#### Dependencies

To create this parameter, set Control type to PI.

Velocity feed-forward gain, Kff, dimensionless.

#### Dependencies

To create this parameter, set Control type to PI.

Grade angle feed-forward gain, Kg, in 1/deg.

#### Dependencies

To create this parameter, set Control type to PI.

Velocity gain breakpoints, VehVelVec, dimensionless.

#### Dependencies

To create this parameter, set Control type to Scheduled PI.

Velocity feed-forward gain values, KffVec, as a function of vehicle velocity, dimensionless.

#### Dependencies

To create this parameter, set Control type to Scheduled PI.

Proportional gain values, KpVec, as a function of vehicle velocity, dimensionless.

#### Dependencies

To create this parameter, set Control type to Scheduled PI.

Integral gain values, KiVec, as a function of vehicle velocity, dimensionless.

#### Dependencies

To create this parameter, set Control type to Scheduled PI.

Grade angle feed-forward values, KgVec, as a function of vehicle velocity, in 1/deg.

#### Dependencies

To create this parameter, set Control type to Scheduled PI.

Nominal vehicle speed, vnom, in units specified by the Reference and feedback units, velUnits parameter. The block uses the nominal speed to normalize the controller gains.

#### Dependencies

To create this parameter, set Control type to PI or Scheduled PI.

Anti-windup gain, Kaw, dimensionless.

#### Dependencies

To create this parameter, set Control type to PI or Scheduled PI.

Error filter time constant, τerr, in s. To disable the filter, enter 0.

#### Dependencies

To create this parameter, set Control type to PI or Scheduled PI.

Predictive

Driver response time, τ, in s.

#### Dependencies

To enable this parameter, Set Longitudinal control type, cntrlType or Lateral control type, controlTypeLat to Predictive.

Driver preview distance, L, in m. Used to determine the preview time window, T*.

#### Dependencies

To enable this parameter, Set Longitudinal control type, cntrlType or Lateral control type, controlTypeLat to Predictive.

Effective vehicle total tractive force, Kpt, in N.

#### Dependencies

To create this parameter, set Longitudinal control type, cntrlType to Predictive.

Static rolling and driveline resistance coefficient, aR, in N. Block uses the parameter to estimate the constant acceleration or braking effort.

#### Dependencies

To create this parameter, set Longitudinal control type, cntrlType to Predictive.

Rolling and driveline resistance coefficient, bR, in N·s/m. Block uses the parameter to estimate the linear velocity-dependent acceleration or braking effort.

#### Dependencies

To create this parameter, set Longitudinal control type, cntrlType to Predictive.

Aerodynamic drag coefficient, cR, in N·s^2/m^2. Block uses the parameter to estimate the quadratic velocity-dependent acceleration or braking effort.

#### Dependencies

To create this parameter, set Longitudinal control type, cntrlType to Predictive.

Gravitational constant, g, in m/s^2.

#### Dependencies

To create this parameter, set Longitudinal control type, cntrlType to Predictive.

Stanley

Select this parameter to create the RefPose and CurrPose input ports.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley.

The controller computes this command using the Stanley method, whose control law is based on both a kinematic and dynamic bicycle model. To change between models, use this parameter.

SettingImplementation
off

Controller uses a kinematic bicycle model that is suitable for path following in low-speed environments such as parking lots, where inertial effects are minimal.

on

Controller uses a dynamic bicycle model that is suitable for path following in high-speed environments such as highways, where inertial effects are more pronounced.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley.

Position gain of the vehicle when it is in forward motion, specified as a positive scalar. This value determines how much the position error affects the steering angle. Typical values are in the range [1, 5]. Increase this value to increase the magnitude of the steering angle.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley.

Position gain of the vehicle when it is in reverse motion, specified as a positive scalar. This value determines how much the position error affects the steering angle. Typical values are in the range [1, 5]. Increase this value to increase the magnitude of the steering angle.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley.

Yaw rate feedback gain, specified as a nonnegative real scalar. This value determines how much weight is given to the current yaw rate of the vehicle when the block computes the steering angle command.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley and select Include dynamics.

Steering angle feedback gain, specified as a nonnegative real scalar. This value determines how much the difference between the current steering angle command, SteerCmd, and the current steering angle, CurrSteer, affects the next steering angle command.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Stanley and select Include dynamics.

Consider enabling drift control to improve path and speed tracking. If the block determines that drifting improves path and or speed tracking, the controller re-plans the tracking horizon with a best-fit stable drifting path. The controller will opt out of the drifting under any of these conditions:

• Drifting is no longer possible.

• Drifting deviates too much from original predetermined path.

• Drifting compares unfavorably to normal driving when speed-tracking.

Desired sideslip, in units defined by Angular units.

#### Dependencies

To enable this parameter, set Enable drift management.

Imposed sideslip error proportional gain, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

Imposed lateral error proportional gain, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

Imposed lateral error derivative gain, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

Imposed yaw rate error proportional gain, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

Wheel speed feedback gain, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

Desired wheel speed time constant, dimensionless.

#### Dependencies

To enable this parameter, set Enable drift management.

### Vehicle Parameters

Forward location of tire, a, in m. Distance from vehicle cg to forward tire location, along vehicle longitudinal axis.

Rearward location of tire, b, in m. Absolute value of distance from vehicle cg to rearward tire location, along vehicle longitudinal axis.

Vehicle mass, m, in kg.

#### Dependencies

To enable this port, do either of these:

• Set Lateral control type, controlTypeLat to Stanley and select Include dynamics.

• Set Lateral control type, controlTypeLat to Predictive.

Cornering stiffness coefficient, CαF , in N/rad.

#### Dependencies

To enable this port, do either of these:

• Set Lateral control type, controlTypeLat to Stanley and select Include dynamics.

• Set Lateral control type, controlTypeLat to Predictive.

Cornering stiffness coefficient, CαR , in N/rad.

#### Dependencies

To enable this port, set Lateral control type, controlTypeLat to Predictive.

Vehicle rotational inertia, I, about the vehicle yaw axis, in N·m·s^2.

#### Dependencies

To enable this parameter, Set Lateral control type, controlTypeLat to Predictive.

Steering ratio, Ksteer. The value has no dimension.

#### Dependencies

To enable this parameter, select Output handwheel angle.

Tire wheel angle limit, θ, in rad.

### Shift

Reverse, Neutral, Drive

Integer value of the initial gear. The block uses the initial gear to generate acceleration and braking commands to track forward and reverse vehicle motion.

Gear

Integer

Park

80

Reverse

-1

Neutral

0

Drive

1

Gear

Gear number

#### Dependencies

To create this parameter, set Shift type, shftType to Reverse, Neutral, Drive or Scheduled. If you specify Reverse, Neutral, Drive, the Initial Gear, GearInit parameter value can be only -1, 0, or 1.

Time required to shift, tShift, in s. The block uses the time required to shift to generate acceleration and braking commands to track forward and reverse vehicle motion using reverse, neutral, and drive gear shift scheduling.

#### Dependencies

To create this parameter, set Shift type, shftType to Reverse, Neutral, Drive.

Scheduled

Integer value of the initial gear. The block uses the initial gear to generate acceleration and braking commands to track forward and reverse vehicle motion.

Gear

Integer

Park

80

Reverse

-1

Neutral

0

Drive

1

Gear

Gear number

#### Dependencies

To create this parameter, set Shift type, shftType to Reverse, Neutral, Drive or Scheduled. If you specify Reverse, Neutral, Drive, the Initial Gear, GearInit parameter value can be only -1, 0, or 1.

Pedal position breakpoints for lookup tables when calculating upshift and downshift velocities, dimensionless. Vector dimensions are 1 by the number of pedal position breakpoints, m.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

Upshift velocity data as a function of pedal position and gear, in units specified by the Reference and feedback units, velUnits parameter. Upshift velocities indicate the vehicle velocity at which the gear should increase by 1.

The array dimensions are m pedal positions by n gears. The first column of data, when n equals 1, is the upshift velocity for the neutral gear.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

Downshift velocity data as a function of pedal position and gear, in units specified by the Reference and feedback units, velUnits parameter. Downshift velocities indicate the vehicle velocity at which the gear should decrease by 1.

The array dimensions are m pedal positions by n gears. The first column of data, when n equals 1, is the downshift velocity for the neutral gear.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

Time required to shift, tClutch, in s.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

Time required to engage reverse from neutral, tRev, in s.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

Time required to engage park from neutral, tPark, in s.

#### Dependencies

To create this parameter, set Shift type, shftType to Scheduled.

## References

[1] MacAdam, C. C. "An Optimal Preview Control for Linear Systems". Journal of Dynamic Systems, Measurement, and Control. Vol. 102, Number 3, Sept. 1980.

[2] MacAdam, C. C. "Application of an Optimal Preview Control for Simulation of Closed-Loop Automobile Driving ". IEEE Transactions on Systems, Man, and Cybernetics. Vol. 11, Issue 6, June 1981.

[3] MacAdam, C. C. Development of Driver/Vehicle Steering Interaction Models for Dynamic Analysis. Final Technical Report UMTRI-88-53. Ann Arbor, Michigan: The University of Michigan Transportation Research Institute, Dec. 1988.

[4] Hoffmann, Gabriel M., Claire J. Tomlin, Michael Montemerlo, and Sebastian Thrun. "Autonomous Automobile Trajectory Tracking for Off-Road Driving: Controller Design, Experimental Validation and Racing." American Control Conference. 2007, pp. 2296–2301. doi:10.1109/ACC.2007.4282788

## Version History

Introduced in R2018a