Feed-forward Traction Controller

The feed-forward controller requires information about the vehicle and powertrain to predict vehicle behavior. Hence, it is important to have an Altair powertrain in the vehicle model vehicle parameters like mass and brake information.

Types

  • VELOCITY CONTROL - Demand signal is a velocity profile with time or distance traveled as independent variable.
  • ACCELERATION CONTROL - Demand signal is an acceleration profile with time or distance traveled as independent variable.
  • Demand signal can be constant, expression, user defined curve, or MotionView Signal (similar to Open Loop controller).
[FEEDFORWARD_TRACTION]
TAG = 'FEEDFORWARD'
TYPE = 'FOLLOW_VELOCITY'
LOOK_AHEAD_TIME = 0.5
DEMAND_SIGNAL = 'DEMAND_SPEED'
[FEEDFORWARD LONGITUDINAL CONTROLLER]
TAG Attr- string REQUIRED

<FEEDFORWARD>
TYPE Attr - string OPTIONAL
  • Options
    FOLLOW_ACCELERATION to follow an acceleration profile or FOLLOW_VELOCITY to follow a velocity profile.
  • By default assumes FOLLOW_VELOCITY.
LOOK_AHEAD_TIME Attr - real OPTIONAL
  • Integrates states to (current time + look ahead time) to predict.
  • If absent, uses the default value of 0.5 sec.
DEMAND_SIGNAL Attr - string REQUIRED

Block name that contains the demand signal. See the Demand Signal Block topic to learn more about all of the available methods.
Note:
  • In the case of steady state error, primarily because of inaccurate/inadequate vehicle information, an Integral controller can be registered in ADDITIONAL controllers.
  • Greater look ahead times lead to sluggish but smoother throttle and brake signals, while shorter look ahead times will give quicker but more abrupt signals.