Slowly Increasing Steer Reference Generator

Generate slowly increasing steer maneuver reference signals

Description

The Slowly Increasing Steer Reference Generator block sets the parameters that configure the slowly increasing steer maneuver.

The block generates steering, accelerator, and brake commands to conduct a linearly increasing steering maneuver. The steering command begins at the specified rate once the vehicle reaches the longitudinal velocity setpoint. After the vehicle achieves the maximum steering angle, the vehicle maintains the steering angle for a desired duration. The block then reduces the steering angle to zero at the same rate. A longitudinal controller regulates the vehicle at the prescribed speed throughout the maneuver.

Use the Steady-state solver mode parameter to specify the initial conditions for the maneuver. By default, the parameter is set to Initialize from model, and the simulation starts with the vehicle at rest at the specified initial position. If you want to start the simulation at the non-zero steady-state velocity:

1. Set Steady-state solver mode to Solve using block parameters.

2. On the Steady-State Solver tab, specify the initial conditions, workspace variable, and solver settings. Click Generate steady state solution.

3. After the simulation completes, set Steady-state solver mode to Resume from a workspace variable.

4. Set Steady-state solution to start from, ssVar to the workspace variable you specified in step 2.

5. Run the simulation.

Examples

Increasing Steering Reference Application

Simulate a full vehicle dynamics model undergoing a slowly increasing steering maneuver according to standard SAE J266. Use for lateral vehicle dynamics ride and handling analysis and chassis controls development, including the steering response.

• Open Script

Ports

Input

VehFdbk — Vehicle feedback

Bus

Bus containing vehicle feedback signals, including velocity, acceleration, and steering wheel torque.

Output

Ref — Vehicle reference signals

Bus

Bus containing the vehicle reference signals, including longitudinal and lateral displacement, and steering.

Parameters

Maneuver

Steady-state solver mode — Start maneuver from steady-state

Initialize from model (default) | Solve using block parameters | Resume from a workspace variable

Use the Steady-state solver mode parameter to specify the steady-state initial conditions for the maneuver. By default, the simulation will not find or start the simulation at the steady-state operating points.

Setting	Description
Initialize from model	Simulation starts maneuver at the simulation start time specified by Maneuver start time, t_start at longitudinal velocity of 0.
Solve using block parameters	Simulation finds the steady-state operating points using the parameters on the Steady-State Solver tab.
Resume from a workspace variable	Simulation starts at the steady-state operating points workspace variable specified by Steady-state solution to start from, ssVar.

Steady-state solution to start from, ssVar — Workspace variable with steady-state operating points

char

Workspace variable containing the steady-state operating points.

Dependencies

To enable this parameter, set Steady-state solver mode to Resume from a workspace variable.

Maneuver start time, t_start — Start time

scalar

Maneuver start time, in s.

Dependencies

To enable this parameter, set Steady-state initial conditions to Initialize from model.

Longitudinal speed setpoint, xdot_r — Target velocity

50 (default) | scalar

Target velocity.

Longitudinal speed setpoint units, xdotUnit — Units

mph (default)

Units for target velocity.

Handwheel rate, omega_hw — Handwheel rate

scalar

Handwheel rate, in deg/s.

Maximum absolute handwheel angle, theta_max — Maximum handwheel

scalar

Maximum handwheel angle, in deg.

Steering hold time after max angle reached, t_stop — Steering hold

scalar

Steering hold, in s.

Lateral acceleration absolute threshold, ay_max — Lateral acceleration

scalar

Lateral acceleration threshold, in g.

Steady-State Solver

Initial longitudinal position, X_o — Initial longitudinal position

175 (default) | scalar

Initial vehicle CG position along the earth-fixed X-axis, in m.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Initial lateral position, Y_o — Initial lateral position

scalar

Initial vehicle CG position along the earth-fixed Y-axis, in m.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Initial heading (yaw) angle, psi_o — Initial yaw angle

scalar

Initial vehicle yaw angle about the earth-fixed Z-axis, in rad.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Steady-state solver tolerance, ssTol — Solver velocity tolerance

scalar

Steady-state solver velocity tolerance.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Maximum simulated time to reach steady-state, ssMaxTime — Max time

scalar

Maximum simulated time to reach steady-state, in s.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Workspace variable name to generate, ssWSName — Steady-state operating points

scalar

Name of workspace variable containing steady-state operating points.

Dependencies

To enable this parameter, set Steady-state initial conditions to Solve using block parameters.

Version History

Introduced in R2019a