PROJECT DESCRIPTION
Our goal is to develop crew information
requirements to support manual command of the Space Launch System (SLS). Manual command is a proposed implementation of manual steering in which the crew prescribes a desired vehicle state, such as a desired attitude, and the ascent Flight Control System acts to reduce the error between the commanded state and the vehicle’s current state. We use Cognitive Work Analysis, a human factors methodology, to analyze the transitions between automated flight and manually commanded flight of SLS and determine what information the crew needs in each flight mode. This project contributes to NASA’s objectives regarding human-computer interface technologies for flight and ground systems. Furthermore, the work is benefitting Tennessee State University by expanding its capacity to compete for funding opportunities from NASA and other federal agencies related to human-technology interaction. Funds from the project are being used to support two undergraduate researchers.
ACCOMPLISHMENTS
This project uses Cognitive Work Analysis to develop information requirements for SLS displays. This method, which involves five phases, analyzes a system by identifying constraints on operator behavior. Each phase examines various constraints on work and offers tools for analyzing workers’ behavior in the system. For example, control task analysis (CTA) — the phase we have just completed — examines the information processing activities required for proper system operation during different modes of system operation. The results of each phase of the analysis feed into the next phase.
This work complements other work in industry and academia that has used the Cognitive Work
Analysis framework to analyze crew and operator information requirements in systems that operate at different levels of automation. After completing the Cognitive Work Analysis, we will conduct an Information Availability Analysis of the SLS crew displays. This portion of the proposed activities will examine the current SLS crew displays to determine whether their current design supports the range of tasks that will be required for manual command of SLS. We will use the results of the Cognitive Work Analysis as the basis for this analysis.
In September 2019, we completed a CTA of SLS manual command. CTA is the second phase of a Cognitive Work Analysis, and it describes the input/output transformations between information provided to a system’s operators and the actions that the system operators take on the basis of this information. This work was performed using the results from the first phase of Cognitive Work Analysis, a Work Domain Analysis of SLS Core Stage flight during nominal conditions and manual command conditions, which had been completed previously.
Guidance
Know System State: Error
Have Information: Current Attitude Rates
Classify System State: Calculate Error Between Desired Attitude
and Current Attitude, and Desired Rate and Current Rate
Know Procedure: Set of Commands Gather Information:
RGAs + RINU
Execute Actions: Move Core Stage Engines
Flight Control System Navigation
Determine Procedure: Generate Corrective Angular
Acceleration Commands 1 2 3 4 5 6 7
The CTA method involves identifying the tasks that need to be completed in order for proper system operation, regardless of who completes the tasks. The decision ladder analysis is helpful for clarifying how the system handles information processing steps such as observing,
diagnosing the system state, and
predicting consequences. Furthermore, it represents various types of information (e.g., numeric values, system states, goals, procedures) that a system uses. We conducted two CTAs. First, we analyzed information processes within SLS that occur during nominal core stage flight, which is fully automated. Figure 1 shows the completed decision ladder analysis. The decision ladder illustrates the closed-loop information processes that occur during nominal core stage flight, beginning with gathering information from vehicle sensors (1) and ending with
moving the core stage engines (8). As this analysis shows, nominal core stage flight does not require crew input.
To examine crew information requirements during the transition between nominal core stage flight and manually commanded core stage flight, we conducted a second CTA. To perform this analysis, we used a recent innovation in Cognitive Work Analysis methods, in which a decision ladder is constructed for each actor in a complex system. Thus, Figure 2 contains separate decision ladders for the crew and vehicle. The flow of information through the decision ladders shows how the crew becomes aware that manual command has been activated by gathering information from crew displays or communication with the Mission Control Center (steps 1-4) and takes actions to command the desired attitude and attitude rate of the SLS vehicle (steps 5-8). As the right side of the figure shows, the vehicle carries out the actions required to attain the commanded attitude. Our analyses revealed the importance of keeping the crew appraised of the vehicle’s transition from automated flight to manually commanded flight and considering the most efficient methods of obtaining crew input during manually commanded flight. The decision ladder analysis shown in Figure 2 illustrates several points of interaction between SLS and the crew, indicated by the horizontal lines at the figure’s center. These interactions can be classified
into three types, which correspond to three functional purposes of the SLS system listed in Figure 1: (1) communicate information to users, (2) receive command input from users, and (3) provide feedback to users. These three types of interaction
carry implications for crew display design. For example, during a transition to manual command, the crew requires information about the vehicle’s transition to a manual commanded mode. Thus, the current Orion/SLS displays should be evaluated in terms of how they present the activation of manual command to the crew.
SUMMARY
This project examines how transitions between different automation modes requires considering how best to inform users of the current system state, incorporate user input, and provide feedback to users. We use an established human factors methodology, Cognitive Work Analysis, to identify the information requirements necessary to support transitions between different modes of SLS core stage flight. Our work thus far has illustrated the importance of designing effective human-computer interaction between the vehicle and the crew. Future work on this project will examine constraints
on behavior during core stage flight, function allocation between crew and automation, and the skills, rules, and knowledge required for operator performance during manually commanded core stage flight.
PRINCIPAL INVESTIGATOR: Joshua Shive PARTNER: Tennessee State University
FUNDING ORGANIZATION: Cooperative Agreement Notice
Know System State:
Error Know Goal State:Desired Attitude
Have Information: Current Attitude Rates
Classify System State: Calculate Error Between Desired Attitude
and Current Attitude, and Desired Rate and Current Rate
Know Procedure: Set of Commands Gather Information:
RGAs + RINU
Execute Actions: Move Core Stage Engines
Determine Procedure: Generate Corrective Angular
Acceleration Commands Know System State:
Manual Command Activated
Know Procedure: Desired Attitude
Receive Input from Users Communicate Information to Users Provide Feedback to Users ORION/SLS INTERFACE VEHICLE CREW Alert: MCC Communication, Display Flag Gather Information: Visual Displays, Audio Communication
Execute Actions: Command Desired Attitude
and Attitude Rate
1 2 3 4 5 6 7
FIGURE 2. Decision ladders showing the transition between