1 ISE Ch. 17/18 Human–Machine System The boundary between the human and the machine is the “user interface.” Information flows from human to machine through controls. Displays include instruments, labels, and accompanying printed instructions and warnings. HUMAN CONTROLS MACHINE DISPLAYS Physical Environment

2 ISE Ch. 17/18 Guideline 1: Select the Proper Type of Control Types of systems:  Open-loop  Closed-loop Discrete vs continuous Select part of the body to implement mental command Choose mechanical interface between human body and machine interior  Consider amount of human power required  Consider errors and speed CONTROLS

3 ISE Ch. 17/18 Guideline 2: Select the Proper Control Characteristics Force People variables:  Muscles used  User population  Percentile designed for  Control variables Control options  Keys and pushbuttons  Knobs  Cranks Control variables:  Purpose  Design  Hand wheels  Foot/leg controls CONTROLS

4 ISE Ch. 17/18 Control Options Keys and Pushbuttons Knobs Cranks CONTROLS

5 ISE Ch. 17/18 Control Options (cont.) Hand Wheels Foot–Leg Controls CONTROLS

6 ISE Ch. 17/18 Guideline 3: Prevent Unintended Activation More severe consequences require greater precautions. Consider that operators may bypass the guard if it makes operation difficult. All equipment should have an emergency stop control. Consider two reaction times:  Human (sensing, deciding, carrying out)  Machine CONTROLS

7 ISE Ch. 17/18 Methods of Reducing Accidental Activation Key or special tool activation (locks) Interlocks Barriers or covers Recessing Spacing Resistance Direction CONTROLS

8 ISE Ch. 17/18 Guideline 4: Prevent Incorrect Identification Labeling Color Shape ____________________ ____________________ ____________________ CONTROLS

9 ISE Ch. 17/18 Size Mode of operation Location ____________________ ____________________ ____________________ ____________________ ____________________ ____________________ CONTROLS

10 ISE Ch. 17/18 Guideline 5: Make Accomplishments Equal Intentions Require verification of critical commands. Make complex sequences of actions user- friendly. Use more care and testing for actions with multiple steps. Check input for validity. For continuous controls, consider control/response ratio. Control positions often act as displays. CONTROLS

11 ISE Ch. 17/18 Population Stereotypes Engineer’s habit patterns may not be the user’s habit patterns. Stereotypes are often country-specific (light switches, water faucets, car blinkers).  See table 17.9, pg. 323 for US conventional control movements Consider labeling. CONTROLS

12 ISE Ch. 17/18 Guideline 6: Properly Locate and Arrange the Controls Arrangement of Controls  Group related controls and displays together.  Minimize layout complexity.  Have blank space on the panel. Hand Controls  Keyboards  Manipulative controls Knobs Switches  Force controls Foot Controls  Avoid foot controls for standing operators.  For continuous control, leg should fully extend at bottom of stroke.  For discrete control, use one leg.  Have straight line between pedal and back support.  Comfort may be more important than force capability.  Design to avoid fatigue. CONTROLS

13 ISE Ch. 17/18 Human–Machine System: Displays Causes of Failure:  Legibility or detectability  Understanding

14 ISE Ch. 17/18 Displaying Information Information Display DISPLAYS

15 ISE Ch. 17/18 Guideline 1: Select Legible Characters Font  Use printed characters  Avoid Roman numerals  Upper/lower case: For short messages, use all caps For text or longer messages, use mixed-case with large open spaces in letters  For VDT, use more pixels and lower dot pitch Size  Character height = K × Distance from eye K = 0.004, 0.006, , radians  Visual angle should be 15–25 min of arc 1 min of arc = rad DISPLAYS

16 ISE Ch. 17/18 DISPLAYS

17 ISE Ch. 17/18 DISPLAYS

18 ISE Ch. 17/18 Guideline 2: Arrange Characters & Symbols Text – clear and legible Codes – don’t rely on memory Abbreviations – use with caution ____________________ ____________________ ____________________ ____________________ DISPLAYS

19 ISE Ch. 17/18 Guideline 3: Decide on Type of Display General Considerations Task/job – what’s the purpose of the display? User characteristics Standardization (see examples, next slide) Menus – lists of options Deep vs Shallow Structure according to how information is used Minimize complexity / maximize understanding DISPLAYS

20 ISE Ch. 17/18 DISPLAYS

21 ISE Ch. 17/18 Display Types Menus – lists of options Tables – make the information easy to find Formulas – simplify calculations ____________________ ____________________ ____________________ ____________________ DISPLAYS

22 ISE Ch. 17/18 Graphs – make relationships visible Symbolic Messages – be sure they’re understood Maps – locate in space and time _____________________ _____________________ _____________________ _____________________ DISPLAYS Display Types

23 ISE Ch. 17/18 Guideline 4: Project Your Message Slides  35 mm slides  Computer projection Transparencies Video DISPLAYS

24 ISE Ch. 17/18 Guideline 5: Select the Instrument Display Discrete: finite choice of options Continuous: point on a scale  Analog  Digital Representational: provide diagram or picture Video Compatible with:  Operator’s internal representation of the variable  Control operation DISPLAYS

25 ISE Ch. 17/18 Warning Messages Type of failure:  False signals  Missing signals  Multiple signals Should be both visual and aural Should be within primary field of view Should provide guidance information Urgency / immediacy of warning should match severity of danger DISPLAYS

26 ISE Ch. 17/18 Guideline 6: Locate/Arrange the Display Location Arrangement ____________________ ____________________ ____________________ ____________________ DISPLAYS