Controls

Copyright 2002 David A. Wheeler, Ph.D., PHR, CMT NoStress@mail.com   Last updated 09/19/05 01:54 PM

Discrete control
Continuous control

Control Resistance

  • Elastic: proportional to displacement (springs)
    • returns to neutral
    • deadman control
  • Frictional
    • static friction
      • friction between two stationary objects
      • hard to get moving
      • used in discrete controls
    • sliding friction
      • friction between two moving objects
      • continues during movement
      • used in continuous controls
    • rolling friction
      • friction between an object rolling over another
      • the point of contact is stationary for an instant (not slipping) as the object moves
      • mouse 
  • Viscous
    • through fluid
    • friction proportional to velocity squared
    • smooths out motion, high frequency movements (vibration) are removed
    • used in high vibration environment
  • Inertial
    • friction proportional to mass of object
    • revolving door, flywheel

Tracking

  • Compensatory display
    • cursor stationary
    • target moves
    • kinesthetic
  • Pursuit display
    • cursor moves
    • target may or may not move
    • cognitive
Tracking Strategies
  • Anticipation
  • Following
  • Dither: small control movement around neutral
Hand vs Foot

Hand: Fine motor movements, your feet are doing something else

Foot: Strength, your hands are doing something else

Predictor display: use if there is time lag in system
    Submarine, nuclear power plant

Control/Display ratio: For every system there is an optimal control display ratio

  • Control Movement/Display Movement
  • small C/D = High Sensitivity (sports car)
  • large C/D = Low Sensitivity (family sedan)

Order of control (from derivative of position with respect to time)

  • Zero (position)
  • First (velocity)
  • Second (acceleration)
  • Third (jerk)

Hard for the human brain to work with anything other than zero or first order of control.


 
 
 
 




 

Send mail to CompanyWebmaster with questions or comments about this web site.
Copyright 2005 CompanyLongName
Last modified: 10/04/05