Single Lane Change

The form is the only place that you should change the lane change event. Vehicle velocity and the lane change geometry are the parameters that can be changed. All lane change data and vehicle path graphics are defined parametrically using these four inputs. The ground Z coordinate is a calculated value (designated by a blue background) and is calculated using the left front wheel CG Z location and the tire rolling radius from the tire data form.

The road graphics are included to illustrate the path being driven and are defined parametrically using the data in the single lane change form. All road graphics are used to illustrate the lane dimensions, but they are not of the actual road used for calculating tire forces. Road graphics should never require editing unless the event is being fundamentally changed.

A ball joint is included in the Single lane change event. The joint attaches a dummy body to the steering rack. The joint is included to make certain events work in ADAMS. Attach the dummy body to the steering rack if building a model manually.

Nine markers are included in the Single Lane Change event. The markers are used to define the lane graphics (cones and the lane road surface).

The path outline markers point to the path outline points for their XYZ location. The points are parametrically defined using the event input data. Path origin is the origin of all lane change graphics and is parametrically defined to be the CG of the vehicle body.

None of the markers should require any user input.

Three motions are included in the event. The steering motion to the vehicle is provided by the steering controller and acts on a revolute joint that connects the steering column to the vehicle body. If a steering column is not included in the model, the joint acts between the steering rack input shaft and the vehicle body.

Steering Wheel Motion

Applies a rotation motion at the steering wheel joint. The motion is initially set to the linear type of value 0 but is modified through the event template to an expression.

Front Wheel Motion

Applied at the front wheel spindle and is of type linear and value 0.

Rear Wheel Motion

Applied at the rear wheel spindle and is of type linear and value 0.

The front and rear wheel motions act on the wheel spindle revolute joints that connect the wheel hub to the knuckle. The motion is initially zero (fixing the wheels to the knuckle) so the model converges statically. The motions are deactivated after the static equilibrium analysis to allow the tires to rotate during the dynamic analysis.

Seventeen points are defined in the event. All points are used to create the lane graphics and cones graphics used to illustrate the lanes. The points contain parametric logic to define their X, Y, and Z locations. You should not need to modify any points.

Path Origin

Point that locates the origin of the path from where the vehicle starts. This is parametrically set to the vehicle body CG location.

Path Outline1

Point used for path graphics; defined parametrically using a variety of data from the model.

Path Outline2-N

Additional points used for path graphics; defined parametrically in a similar scheme to Path Outline 1.

Cone1

Point used to define the cone graphics; defined parametrically to sit at the edge of the road surface along the path to illustrate the road.

Cone2-N

Additional points used to define the cone graphics; defined parametrically to sit at the edge of the road surface along the path to illustrate the road.

There is one solver variable in the Single Lane Change event. The steer path variable is a user-written subroutine call which returns the steering wheel angle that should be applied to follow the desired path. The motion of the steering wheel is set to this variable in the lane change template. You should not need to edit any portion of the steer path variable.

The template is solver specific and only the MotionSolve template is documented. The template is inserted in the solver deck after the </Model> command and controls the execution of the event.

The if (tire_dataset.opt_omega.ival) logic is included to handle legacy models which used the omega method of tire rotation. This method is obsolete and the value will always be equal to 1. The logic will be removed in a future release.

The first four deactivate commands deactivate the motion between the wheels and the knuckle, allowing them to rotate. The last two deactivate commands turn off the body clamps. Body clamps hold the body rigid during static analysis.

The Motion_Joint command reassigns the value of the steering wheel joint from zero to the value calculated by the steering controller, essentially turning on the steering controller.

The Simulate transient command starts the transient simulation and establishes the output time step and end time of the simulation. The data can be edited to change the event. Additional XML commands can be added to enhance the solution. The commands are described in the MotionSolve Reference Guide > Command Statements.

<ResOutput
     angle_type          = "YPR"
  />
  <ResOutput
     mrf_file            = "TRUE"
  />
  <ResOutput
     plt_file            = "TRUE"
  />
  <H3DOutput
     switch_on           = "TRUE"
     increment           = "1"
  />
  <ResOutput
     abf_file            = "TRUE"
  />
  
{if (tire_dataset.opt_omega.ival ==1)}
<!--Initial static analysis -->

<Simulate
	analysis_type = "Static"
	end_time      = "0.0"
/>	
{endif}
<Deactivate
	element_type = "MOTION"
	element_id = "{mot_frnt_wheel.l.idstring}"
/>
<Deactivate
	element_type = "MOTION"
	element_id = "{mot_frnt_wheel.r.idstring}"
/>
<Deactivate
	element_type = "MOTION"
	element_id = "{mot_rear_wheel.l.idstring}"
/>
<Deactivate
	element_type = "MOTION"
	element_id = "{mot_rear_wheel.r.idstring}"
/>
{if (tire_dataset.opt_omega.ival ==2)}
<!--Initial static analysis -->

<Simulate
	analysis_type = "Static"
	end_time      = "0.0"
/>	
{endif}
<Deactivate
	element_type = "JPRIM"
	element_id = "{j_clamp_1_body.idstring}"
/>
<Deactivate
	element_type = "JPRIM"
	element_id = "{j_clamp_2_body.idstring}"
/>
<Motion_Joint
     id                  = "{wh_motion.idstring}"
     expr                = "VARVAL({sv_path.idstring})"
  />
<Simulate
     analysis_type       = "Transient"
     end_time            = "6"
     print_interval      = "0.05"
  />
<Stop/>