# MV-8000: Open Loop Events

In this tutorial, you will learn how to assemble the vehicle for full vehicle simulations using Assembly Wizard and how to attach the driver using Task Wizard.

The Altair Driver is a set of MotionView models and libraries that allow MotionView users to control and script vehicle events.

Event example include the following:
• Single Lane Change
• Double Lane Change
• User Defined Path Following
• Fish Hook Event, etc.
This is achieved by creating an interface to the five vehicle inputs:
• Steering
• Throttle
• Gear
• Brake
• Clutch
You can use the Altair Driver to simulate any number of full vehicle events using multiple features:
• Scripting: break up the simulation into different maneuvers; select the controllers for vehicle inputs and define conditions that end each maneuver.
• Open-loop, closed-loop, and user-defined controllers to control.
• Longitudinal speed or acceleration.
• Vehicle path or lateral acceleration.
• Switching controllers during a simulation.
• Defining path and speed profiles parametrically, in a table, or by referencing a data file.

## Assemble the Vehicle

In this step, you will assemble the vehicle using the Assembly Wizard.

1. Start a new MotionView session.
2. Ensure the MBD-Vehicle Dynamics Tools preference file loaded is for all of the MotionView functionality of the Advanced Driver to work properly.
3. From the menu bar, select Model > Assembly Wizard.
In Script an Open Loop Acceleration Event, a linear torque map powertrain will be used to avoid the complexity of adding controllers for gear and clutch.
4. Select the Full vehicle with advanced driver option.
This takes care of all the dependencies of the advanced driver.
5. Click Next.
6. Choose the default selections in the following Assembly Wizard pages.
Page Label Selection Default (Yes/No)
1 Model type Full vehicle with driver No
2 Driveline configuration Front wheel drive Yes
3 Vehicle body Body Yes
4 Instrumentation Instrumentation Yes
5 Front subframe None Yes
6 Front suspension Frnt macpherson susp (1 pc. LCA) Yes
7 Steering Linkages Rackpin steering Yes
8 Rear subframe None Yes
10 Powertrain Linear torque map powertrain Yes
11 Signal generator Driver signal generator Yes
12 Tires Auto Tires Yes
13 Steering column Steering column 1 (not for Abaqus) Yes
14 Steering boost None Yes
15 Front struts Frnt strut (with inline jts) Yes
16 Front stabilizer bars None Yes
17 Rear struts Rear strut (with inline jts) Yes
18 Rear stabilizer bars None Yes
19 Front jounce bumpers None Yes
20 Front rebound bumpers None Yes
21 Rear jounce bumpers None Yes
22 Rear rebound bumpers None Yes
23 Disk brakes Disk brakes Yes
24 Front Driveline Independent fwd Yes
25 Driver System Altair Driver Yes
26 Next Finish No

In this step, you will use the Task Wizard to load the driver analysis.

2. Select AltairDriverFile from the Type drop-down menu.
Tip:

Selecting (Altair Driver icon) will open up the Altair Driver panel. This automatically resolves all of the vehicle attachments for the Altair Driver.

Selecting the AltairDriverFile 0 will open up the driver event panel. Selecting the Event Editor button will open the Altair Driver File dialog.

## Write an Altair Driver File Driving Event

In this step, you will script an open loop acceleration, open loop sinusoidal steering, and an open loop driven braking event.

Driver requires an event script or the Altair driver file (ADF) to run any driving event. ADF can be edited using any text editor or by clicking the Edit Driver File button on the driver panel.

## Script an Open Loop Acceleration Event

In this step, you will script an event with 50% throttle, 0% brake and 0 steering angle.

An event can be broken down into smaller sub-events or maneuvers. You will model this as a single maneuver event.

1. Open any text editor and copy and paste the following text into it.
Important: All blank lines must be removed prior to saving the file.
$-----------------------------------------------------------------ALTAIR_HEADER$ This block is required for version control
FILE_VERSION 	= 1.0
FILE_FORMAT 	= 'ASCII'
$--------------------------------------------------------------------------UNITS$In this block we specify the units in which this file should be read
[UNITS]
(BASE)
{length  force      	angle       mass   time}
$--------------------------------------------------------------------VEHICLE_IC$In this block we specify the initial conditions specifically initial speed of the
$vehicle with respect to the vehicle IC marker in the driver attachments [VEHICLE_INITIAL_CONDITIONS] VX0 = -20.0 VY0 = 0.0 VZ0 = 0.0$--------------------------------------------------------------STEERING_STANDARD
$This block specifies the saturation and cutoff frequency for the low pass filter for$steering output signal. These signals are global and are active for the entire event
[STEER_STANDARD]
MAX_VALUE 			= 3.141593
MIN_VALUE 			= -3.141593
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 		= 0.0
$--------------------------------------------------------------THROTTLE_STANDARD$This block specifies the saturation and cutoff frequency for the low pass filter for
$throttle output signal [THROTTLE_STANDARD] MAX_VALUE = 1.0 MIN_VALUE = 0.00 SMOOTHING_FREQUENCY = 10.0 INITIAL_VALUE = 0.5$---------------------------------------------------------------BRAKING_STANDARD
$This block specifies the saturation and cutoff frequency for the low pass filter for$brake output signal
[BRAKE_STANDARD]
MAX_VALUE 			= 1.0
MIN_VALUE 			= 0.0
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 		= 0.0
$-----------------------------------------------------------------MANEUVERS_LIST$This block provides the list of all the maneuvers, simulation time for each maneuver
$maximum solver step size (hmax) and print interval [MANEUVERS_LIST] { name simulation_time h_max print_interval} 'MANEUVER_1' 5.0 0.01 0.01$---------------------------------------------------------------------MANEUVER_1
[MANEUVER_1]
$This block provides the ties controllers to each driver output TASK = 'STANDARD' (CONTROLLERS) {DRIVER_SIGNAL PRIMARY_CONTROLLER ADDITIONAL_CONTROLLER} STEER OL_STEER_0 NONE THROTTLE OL_0.5 NONE BRAKE OL_0 NONE$---------------------------------------------------------OL_STEER
$This is controller block containing all the information required by$the driver to construct the controller. Different controllers have
$different requirements. Here we are using open loop constant type$of controller.
[OL_STEER_0]
TAG	= 'OPENLOOP'
TYPE	= 'CONSTANT'
VALUE	= 0.0
$---------------------------------------------------------OL_BRAKE [OL_0] TAG = 'OPENLOOP' TYPE = 'CONSTANT' VALUE = 0.0$---------------------------------------------------------OL_THROTTLE
[OL_0.5]
TAG	= 'OPENLOOP'
TYPE	= 'CONSTANT'
VALUE	= 0.5
2. Save the file.
3. Source the file in the Altair Driver File browser.
Note: The Edit driver file button can be used to edit the file.
4. Click to run the simulation.
5. After the simulation is over and the solver creates the h3d and plt files, from the menu bar, click Analysis > View Reports.
6. Select the recent run in the View Reports dialog and click OK.
7. The noise in the steering is numerical error of negligible magnitude – 0 for all practical purposes. Throttle is constant at 0.5 (driver throttle, brake and clutch outputs are normalized so, 50%) and brake is constant at 0.
8. Next we will try slightly different initial conditions. We will start the throttle at 0 and brake at 100%. Click the Edit Driver File button to open up the file editor.
9. Change the INITIAL_VALUE attribute in the THROTTLE_STANDARD block in the ADF, from 0.5 to 0.
[THROTTLE_STANDARD]
MAX_VALUE 			= 1.0
MIN_VALUE 			= 0.00
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 			= 0.5 0
10. Similarly, change the INITIAL_VALUE attribute in the BRAKE_STANDARD block in the ADF, from 0.0 to 1.0.
[BRAKE_STANDARD]
MAX_VALUE 			= 1.0
MIN_VALUE 			= 0.0
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 			= 0.0 1.0
12. Run the simulation and study the results.
13. Now, we see that throttle and brake start from respective initial values and step up to the controller outputs. The time taken to step up is roughly (5x1/SMOOTHING_FREQUENCY).

## Model an Open Loop Sinusoidal Steering Event

In this step, you will model a simple event with constant 20% throttle, constant 0% throttle and sinusoidal steering input with amplitude of 60 degrees (∏/3 radians) and frequency of 0.5 Hz.

1. Open any text editor and copy and paste the following text into it.
Important: All blank lines must be removed prior to saving the file.
$-----------------------------------------------------------------ALTAIR_HEADER [ALTAIR_HEADER] FILE_TYPE = 'ADF' FILE_VERSION = 1.0 FILE_FORMAT = 'ASCII'$--------------------------------------------------------------------------UNITS
[UNITS]
(BASE)
{length  force      	angle       mass   time}
$--------------------------------------------------------------------VEHICLE_IC [VEHICLE_INITIAL_CONDITIONS] VX0 = -20.0 VY0 = 0.0 VZ0 = 0.0$--------------------------------------------------------------STEERING_STANDARD
[STEER_STANDARD]
MAX_VALUE 			= 3.141593
MIN_VALUE 			= -3.141593
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 		= 0.0
$--------------------------------------------------------------THROTTLE_STANDARD [THROTTLE_STANDARD] MAX_VALUE = 1.0 MIN_VALUE = 0.00 SMOOTHING_FREQUENCY = 10.0 INITIAL_VALUE = 0.2$---------------------------------------------------------------BRAKING_STANDARD
[BRAKE_STANDARD]
MAX_VALUE 			= 1.0
MIN_VALUE 			= 0.0
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 			= 0.0
$-----------------------------------------------------------------MANEUVERS_LIST [MANEUVERS_LIST] { name simulation_time h_max print_interval} 'MANEUVER_1' 10.0 0.01 0.01$---------------------------------------------------------------------MANEUVER_1
[MANEUVER_1]
$This block provides the ties controllers to each driver output TASK = 'STANDARD' (CONTROLLERS) {DRIVER_SIGNAL PRIMARY_CONTROLLER ADDITIONAL_CONTROLLER} STEER OL_STEER NONE THROTTLE OL_THROTTLE NONE BRAKE OL_BRAKE NONE$---------------------------------------------------------OL_STEER.
$SIGNAL_CHANNEL tells the driver which solver variable in Signal Generator to over-ride$with the EXPRESSION value. The EXPRESSION should be consistent with MOTIONSOLVE.
[OL_STEER]
TAG			 = 'OPENLOOP'
TYPE			= 'EXPRESSION'
SIGNAL_CHANNEL 	  = 0
EXPRESSION 	      = 'DTOR(60)*SIN(2*PI*0.5*TIME)'
$---------------------------------------------------------OL_THROTTLE [OL_THROTTLE] TAG = 'OPENLOOP' TYPE = 'CONSTANT' VALUE = 0.2$---------------------------------------------------------OL_BRAKE
[OL_BRAKE]
TAG	= 'OPENLOOP'
TYPE	= 'CONSTANT'
VALUE	= 0.0
2. Run the simulation and study the results.

## Model an Open Loop Curve Driven Braking Event

In this step, you will model a simple event with braking signal as a curve.

1. Open text editor and copy and paste the following text into it.
Important: All blank lines must be removed prior to saving the file!
$-----------------------------------------------------------------ALTAIR_HEADER [ALTAIR_HEADER] FILE_TYPE = 'ADF' FILE_VERSION = 1.0 FILE_FORMAT = 'ASCII'$--------------------------------------------------------------------------UNITS
[UNITS]
(BASE)
{length  force      	angle       mass   time}
$--------------------------------------------------------------------VEHICLE_IC [VEHICLE_INITIAL_CONDITIONS] VX0 = -20.0 VY0 = 0.0 VZ0 = 0.0$--------------------------------------------------------------STEERING_STANDARD
[STEER_STANDARD]
MAX_VALUE 			= 3.141593
MIN_VALUE 			= -3.141593
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 		= 0.0
$--------------------------------------------------------------THROTTLE_STANDARD [THROTTLE_STANDARD] MAX_VALUE = 1.0 MIN_VALUE = 0.00 SMOOTHING_FREQUENCY = 10.0 INITIAL_VALUE = 0.0$---------------------------------------------------------------BRAKING_STANDARD
[BRAKE_STANDARD]
MAX_VALUE 			= 1.0
MIN_VALUE 			= 0.0
SMOOTHING_FREQUENCY 	= 10.0
INITIAL_VALUE 			= 0.0
$-----------------------------------------------------------------MANEUVERS_LIST [MANEUVERS_LIST] { name simulation_time h_max print_interval} 'MANEUVER_1' 10.0 0.001 0.01$---------------------------------------------------------------------MANEUVER_1
[MANEUVER_1]
$This block provides the ties controllers to each driver output TASK = 'STANDARD' (CONTROLLERS) {DRIVER_SIGNAL PRIMARY_CONTROLLER ADDITIONAL_CONTROLLER} STEER OL_STEER NONE THROTTLE OL_THROTTLE NONE BRAKE OL_BRAKE NONE$---------------------------------------------------------OL_STEER.
$SIGNAL_CHANNEL tells the driver which solver variable in Signal Generator to over-ride$with the EXPRESSION value. The EXPRESSION should be consistent with MOTIONSOLVE.
[OL_STEER]
TAG	= 'OPENLOOP'
TYPE	= 'CONSTANT'
VALUE	= 0.0
$---------------------------------------------------------OL_THROTTLE [OL_THROTTLE] TAG = 'OPENLOOP' TYPE = 'CONSTANT' VALUE = 0.0$---------------------------------------------------------OL_BRAKE
[OL_BRAKE]
TAG	= 'OPENLOOP'
TYPE	= 'CURVE'
BLOCK	= 'BRAKE_CRV'
\$---------------------------------------------------------CURVE_DATA
[BRAKE_CRV]
INDEPENDENT_VARIABLE 	= 'TIME'
DEPENDENT_VARIABLE		= 'BRAKE_SIGNAL'
INTERPOLATION			= 'LINEAR'
{TIME	BRAKE_SIGNAL}
0	0
1	0
2	0.2
3	0.5
4	0.8
5   1.0
6   1.0
7   0
10  0
2. Run the simulation and study the results.