Open Loop Controllers

Open-loop controllers define vehicle inputs directly without feedback (for example, steering wheel angle vs. time).

Open-loop controllers can be used for all vehicle inputs. However, without feedback signals, no mechanism exists for the driver to achieve a desired vehicle response (for example, speed or path following). The vehicle’s properties alone determine its response to the open-loop inputs.

Use Cases

  • Using experimental data \ data collected from real life testing such as steering wheel angle or throttle as vehicle inputs.
  • Expression driven outputs - ‘SIN(TIME)’ , ’10.85’.
  • Identifying vehicle properties like yaw-rate gain.
  • Passing the signals computed from user defined controllers thru Altair Driver to the vehicle inputs.

Supported Driver Output Signal(s) - All

  • Steer
  • Throttle
  • Brake
  • Gear
  • Clutch

Open Loop Keyword Types

  • MotionView
    Links MotionView solver-variable
    Link driver signal to user written logic
  • CURVE
    Populate driver signals from curve data
  • EXPRESSION
    Expression driven driver signal
    Expressions syntax must be consistent with MotionSolve
    Example – ‘SIN(TIME)’ or ‘STEP(TIME, 1,0,1,2)’
  • CONSTANT
    Constant driver signal
    FREE
    Only applicable to Steer output signal

    Release/Free the steering during a maneuver

Example open loop controller block in the Altair Driver File:
[OPEN_LOOP_CONSTANT]
TAG   = 'OPENLOOP'
TYPE  = 'CONSTANT'
VALUE = 0.5

This creates a constant signal of value, 0.5.