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This tutorial explores two case studies, "Return from Salyut" and "Rental Car," to analyze human action cycles and design flaws. Learn about the valve closing situation in Salyut and the Gulf of Execution in the redesign of P-47 Thunderbolt fighter planes.
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Tutorial 6:Case Study “Return from Salyut” “Rental Car” SY DE 142 – June 28, 2004 Introduction to Human Systems Engineering Waterloo, Ontario, Canada
Outline • Case 1: “Return from Salyut” • Question and Discussion on Case 1 • Case 2: “Rental Car” • Questions and Discussion on Case 2
Case Study #1Return from Salyut • Time: June 3, 1971 • Place: Suyoz 11 spacecraft • Synopsis: Firing of the explosive bolts -connecting the command module with the orbital module - opened the pressure evaluation valve. • Result: All three cosmonauts were dead.
Return from SalyutQuestions 1. Break down the valve closing situation in terms of Human Action Cycle. 2. Why were the cosmonauts unable to close the valve? 3. Why didn't the cosmonauts in the Salyut capsule have suits?
Return from Salyut HAC • Goal: Restore oxygen to the capsule. (or “Stop oxygen leak”) • Intention: Close the valve. • Sequence of Actions: Turn the valve. • Execution of Actions: Physically turning the valve • World: Valve turns and each turn closes it further. • Perceive state of the world: Visual change in valve control, feel of valve turning • Interpret: Valve has turned and is closing • Evaluate: Has valve turned enough to stop oxygen leak? No. Goal not achieved.
Return from Salyut Solutions 2. Why were the cosmonauts unable to close the valve? It required more turns than were physically possible to execute under conditions of lost oxygen. The designers of the valve had not taken into consideration its conditions of use.
3. Why didn't the cosmonauts in the Salyut capsule have suits? The capsule was being used for three cosmonauts instead of the two it was designed for. This is an example of a system being used outside of its design parameters.
Rental Car Overview • Time: Middle of World War II • Place: US Army Air Base, Small Pacific Island • Synopsis: Redesign of P-47 Thunderbolt fighter plane was about to cost a pilot’s life in the middle of an attack from the Japaneseairfighters
Rental CarQuestions • Use “Action Cycle” analysis to describe the situation that occurred in this case. • Identify the Gulf of Execution in this case. What does this suggest for design?
Rental CarSolutions • Goal: survive the Japanese attack and protect the planes • Intention: flying a P-47 Thunderbolt • Sequence of actions: run to the ready-room, find a free plane, identify controls, use controls to fly the plane • Actions: physical actions of running, finding, identifying, eluding (could not find controls to fly the plane)
Rental Carcont….. Solutions • World: the plane was raced up, down, across, and around the airstrip on the island, bombs dropping • Perception state of the world: physically seeing and sensing the plane moving relative to the bombs dropping • Interpreting the perception: Plane did not fly, but the bombs did not hit the plane • Evaluation of interpretation: the goal was achieved even though the plane did not take off.
Rental CarGulf of Execution • Occurs between intention and action • Example: intending to fly the plane (intention) and not finding the controls that will allow you to do that (action) • Suggests poor control/display design, lack of consistency with prior designs, not intuitive, no consideration that use will be under circumstances where there may not be time to train the pilots on the new design.