Christopher Cabrall

• Doctor of Philosophy
• Fellow at Delft University of Technology

Objective We investigated a driver monitoring system (DMS) designed to adaptively back up distracted drivers with automated driving. Background Humans are likely inadequate for supervising today’s on-road driving automation. Conversely, backup concepts can use eye-tracker DMS to retain the human as the primary driver and use computerized control o...

Remote driving operations represents an area of growing promise to exercise human driving capability rather than replace it. Autonomous driving technology is often motivated towards removing humans from the control loop of driving but up to now, has not been able to fully realize such aims. This paper summarizes two experiments that were conducted...

For transitions of control in automated vehicles, driver monitoring systems (DMS) may need to discern task difficulty and driver preparedness. Such DMS require models that relate driving scene components, driver effort, and eye measurements. Across two sessions, 15 participants enacted receiving control within 60 randomly ordered dashcam videos (3-...

Remote driving operations represents an area of growing promise to exercise human driving capability rather than replace it. Autonomous driving technology is often motivated towards removing humans from the control loop of driving but up to now, has not been able to fully realize such aims. This paper summarizes two experiments that were conducted...

Presentation slides

A public presentation of my PhD Thesis. Human Factors of Driving Automation: Eyes and Scenes. Within the larger Human Factors of Automated Driving (HFAuto) project, the goal of this thesis was ‘to develop a system that is able to monitor the driver’s vigilance’. The approach taken was to investigate vigilance from a cognitive systems engineering (e...

This work aimed to organise recommendations for keeping people engaged during human supervision of driving automation, encouraging a safe and acceptable introduction of automated driving systems. First, heuristic knowledge of human factors, ergonomics, and psychological theory was used to propose solution areas to human supervisory control problems...

The final copy of my approved PhD thesis from TU Delft (vers. 80, 23 May 2019). List of revisions since original posted version (vers. 74, 20 Feb 2019): - Chp. 4.2., revised according to reviewer feedback (vers. 75, 24 Apr 2019). - various formatting adjustments for print (vers. 80, 22 May 2019) This PhD thesis document is a collection of severa...

Background: Automated driving is often proposed as a solution to human errors. However, fully automated driving has not yet reached the point where it can be implemented in real traffic. This study focused on adaptively allocating steering control either to the driver or to an automated pilot based on momentary driver distraction measured from an...

This work aimed to organize recommendations for keeping people engaged during human supervision of driving automation, encouraging a safe and acceptable introduction of automated driving systems. First, heuristic knowledge of human factors, ergonomics, and psychological theory was used to propose solution areas to human supervisory control problems...

In pioneering work, Senders (1983) tasked five participants to watch a bank of six dials, and found that glance rates and times glanced at dials increase linearly as a function of the frequency bandwidth of the dial’s pointer. Senders did not record the angle of the pointers synchronously with eye movements, and so could not assess participants’ vi...

The topic of situation awareness has received continuing interest over the last decades. Freeze-probe methods, such as the Situation Awareness Global Assessment Technique (SAGAT), are commonly employed for measuring situation awareness. The aim of this paper was to review validity issues of the SAGAT and examine whether eye movements are a promisin...

Enclosed is a collection of pre-prints and work in progress (.zip of .pdfs) of the studies planned to be included as chapters within my tentative 2018 PhD thesis "Use of Driving Scenes and Relative Assessments of Eyes across Levels of Driving Automation"

Sheridan and Verplank's (1978) 'levels of automation' dimension has proved useful and widely relevant across human factors and automation interaction researchers. In respects to the recently vast increase of automation in different forms, especially in transportation domains, we propose an extended automation taxonomy via additional dimensions. Spe...

Human factors researchers are well familiar with Sheridan and Verplank’s (1978) ‘levels of automation’. Although this automation dimension has proved useful, the last decade has seen a vast increase of automation in different forms, especially in transportation domains. To capture these and future developments, we propose an extended automation tax...

Across the automotive industry, manufacturers have recently released various Partial Automation systems (SAE Level 2) which allow simultaneous/combined execution of both lateral and longitudinal vehicle control at the same time, yet still require active human supervision/engagement. Current reactive trends will be reviewed across major automotive p...

A majority (95%) of crashes can be attributed to humans, with the highest cause category (41%) involving errors of recognition (i.e., inattention, distraction, inadequate surveillance) [1]. Driving safety research often claims that as much as 90% of the information that drivers use is visual. However, these claims have been hampered by a lack of nu...

A common challenge with processing naturalistic driving data is that humans may need to categorize great volumes of recorded visual information. By means of the online platform CrowdFlower, we investigated the potential of crowdsourcing to categorize driving scene features (i.e., presence of other road users, straight road segments, etc.) at greate...

The " drivenger " aim of the current study was to investigate attention-al differentiation of drivers (who are in control) from passengers (who have no control) to inform future driver-in-the-loop monitoring/detection systems and facilitate multiple levels of manual/automated driving. Eye-tracking glasses were worn simultaneously by the driver and...

HFauto Research Highlights

Bachelor student project supervised by PhD students

Top-cited vigilance theory work was collected from each decade since Mackworth’s seminal study. Multi-decade consensus objects (characteristics) for vigilance decrement effects were found to include: observer (isolated), signal (few, random, threshold, unambiguous, transient, spatial uncertainty), noise (similiar to signal, many), task (prolonged,...

Research indicates that crashes between cyclists and car drivers occur even when the cyclist must have seen the approaching car, suggesting the importance of expectancy and attention allocation issues [1]. Once a relevant stimulus is detected in traffic, cyclist must make a judgement regarding whether the trajectory of their own bicycle and the veh...

BACKGROUND. Recent advances in the growing domain of automated driving suggest the need for thoughtful design of human-computer interaction strategies. For example, human drivers can process scene variability on implicit levels, but automated systems require explicit rule-based judgments of similarity and difference. What level of abstraction an au...

Automated driving vehicles of the future will most likely include multiple modes and levels of operation and thus include various transitions of control (ToC) between human and machine. Traditional activation devices (e.g., knobs, switches, buttons, and touchscreens) may be confused by operators among other system setting manipulators and also susc...

Objective This review aimed to characterize tasks applied in driving research, in terms of instructions/conditions, signal types/rates, and component features in comparison to the classic vigilance literature. Background Driver state monitoring is facing increased attention with evolving vehicle automation, and real-time assessment of driver vigil...

A common challenge with processing naturalistic driving data for many different possible driving research interests or applications is that humans may need to categorize great volumes of recorded visual information until automated algorithms might be trained to do so alone. This study, by means of the online platform CrowdFlower, investigated the...

The assessment of mental workload could be helpful to road safety especially if developments of vehicle automation will increasingly place drivers into roles of supervisory control. With the rapidly decreasing size and increasing resolution of cameras as well as exponential computational power gains, remote eye measurements are growing in popularit...

Air traffic management in the New York (NY) metropolitan area presents significant challenges such as excess demand, chronic delays, and inefficient routes. At NASA, a new research effort has been initiated to explore Next Generation Air Transportation System (NextGen) Trajectory Based Operations (TBO) solutions to address lingering problems in the...

The assessment of mental workload could be helpful to road safety especially if developments of vehicle automation will increasingly place drivers into roles of supervisory control. With the rapidly decreasing size and increasing resolution of cameras as well as exponential computational power gains, remote eye measurements are growing in popularit...

Air traffic management in the New York (NY) metropolitan area presents significant challenges including excess demand, chronic delays, and inefficient routes. At NASA, a new research effort has been initiated to explore Next Generation Air Transportation System (NextGen) Trajectory Based Operations (TBO) solutions to address lingering problems in t...

With the continued projection of increases in air traffic density, operations in the National Airspace System (NAS) are expected to exceed human capabilities in the near future [1]. In order to address the bottleneck of human workload capacity, highly automated safety-critical systems are under development to support air traffic controllers. Howeve...

A 2012 Human-In-The-Loop air traffic control simulation investigated a gradual paradigm-shift in the allocation of functions between operators and automation. Air traffic controllers staffed five adjacent high-altitude en route sectors and, during the course of a two-week experiment, worked traffic under different function-allocation approaches ali...

The Airspace Operations Laboratory at NASA Ames conducts research to provide a better understanding of roles, responsibilities, and requirements for human operators and automation in future air traffic management (ATM) systems. The research encompasses developing, evaluating, and integrating operational concepts and technologies for near-, mid-, an...

As part of an ongoing research effort on separation assurance and functional allocation in NextGen, a controller-in-the-loop study with ground-based automation was conducted at NASA Ames' Airspace Operations Laboratory in August 2012 to investigate the potential impact of introducing self-separating aircraft in progressively advanced NextGen time-f...

• Training • Train strategies specifically as well as use of new tools • Introduce tools before the traffic increases • Taskload • When selecting new toolsets include a focus on (reducing) controller taskloadas a criteria • Wait to fully introduce a new tool (as opposed to partial introduction) • Increase aircraft equipage relative to the level of...

In a study, that introduced ground-based separation assurance automation through a series of envisioned transitional phases of concept maturity, it was found that subjective responses to scales of workload, situation awareness, and acceptability in a post run questionnaire revealed as-predicted results for three of the four study conditions but not...

A human-in-the-loop simulation conducted in the Airspace Operations Laboratory (AOL) at NASA Ames Research Center explored the feasibility of a Next Generation Air Transportation System (NextGen) solution to address airspace and airport capacity limitations in and around the New York metropolitan area. A week-long study explored the feasibility of...

Well prepared traffic scenarios contribute greatly to the success of controller-in-the-loop simulations. This paper describes each stage in the design process of realistic scenarios based on real-world traffic, to be used in the Airspace Operations Laboratory for simulations within the Air Traffic Management Technology Demonstration 1 effort. The s...

A human-in-the-loop simulation was conducted to examine the effects of varying levels of trajectory prediction uncertainty on air traffic controller workload and performance, as well as how strategies and the use of decision support tools change in response. This paper focuses on the strategies employed by two controllers from separate teams who wo...

Two human-in-The-loop simulation experiments were conducted in coordinated fashion to investigate the allocation of separation assurance functions between ground and air and between humans and automation. The experiments modeled a mixed-operations concept in which aircraft receiving groundbased separation services shared the airspace with aircraft...

Studies of future airspace design often predict that automated tools will be available to assist the controller and sometimes complete tasks independently of controller intervention. How this redistribution of functions will change the role of the controller needs to be considered, as does its impact on the controller’s awareness of aircraft moveme...

National Aeronautics and Space Administration (NASA) Air Traffic Management Demonstration-1 (ATD-1) is a multi-year effort to demonstrate high-throughput, fuel-efficient arrivals at a major United States airport using NASA-developed scheduling automation, controller decision-support tools, and Automatic Dependent Surveillance–Broadcast (ADS-B)-enab...

A human-in-the-loop simulation of a Corridors-in-the-sky concept was conducted that focused on investigating the potential benefits and feasibility of the concept with human operators in a realistic environment. In this simulation, the definition of "corridors" was changed from meaning separate corridor airspace with dedicated corridor controllers...

Predicted air traffic increases over the next 25 years may create a significant capacity problem that the United States' National Airspace System will be unable to accommodate. The concept of introducing automated separation assurance was proposed to help solve this problem. However, the introduction of such a concept involves a fundamental paradig...

A human-in-the-loop exploration of a ground-based automated separation assurance concept was conducted that involved the allocation of certain functions between humans and automation. This exploration included operations that were sustained for prolonged periods of time with high levels of traffic in the presence of convective weather and schedulin...

Trajectory-based controller tools developed to support a schedule-based terminal-area air traffic management (ATM) concept have been shown effective for enabling 'green' arrivals along Area Navigation (RNAV) routes in moderately high-density traffic conditions. A recent human-in-the-loop simulation investigated the robustness of the concept and too...

In this paper we discuss the development and evaluation of our prototype technologies and procedures for far-term air traffic control operations with automation for separation assurance, weather avoidance and schedule conformance. Controller-in-the-loop simulations in the Airspace Operations Laboratory at the NASA Ames Research Center in 2010 have...

Investigation of function allocation for the Next Generation Air Transportation System is being conducted by the National Aeronautics and Space Administration (NASA). To provide insight on comparability of different function allocations for separation assurance, two human-in-the-loop simulation experiments were conducted on homogeneous airborne and...

The subject of the current research is a Next Generation Air Transportation System (NextGen) concept that involves automation-assisted separation assurance within the high altitude (at or above 29,000 feet) en route environment. The concept is designed to enable controllers to provide both safe and efficient air traffic services at much higher traf...

As pari of a recent project to identify and prioritize human performance issues (Lee, Sheridan, Poage, Martin, Cabrall & Jobe, 2009) related to NASA's Next Generation Air Transportation System AIM-Airspace Project (NextGen; SLDAST, 2007), a walkthrough of a future Separation Assurance (SA) concept was conducted. The walkthrough revealed that the Hu...

As part of an ongoing research effort into functional allocation in a NextGen environment, a controller-in-the-loop study on ground-based automated separation assurance was conducted at NASA Ames' Airspace Operations Laboratory in February 2010. Participants included six FAA front line managers, who are currently certified professional controllers...

The subject of the current research is a Next Generation Air Transportation System (NextGen) concept that involves automated separation assurance developed to enable controllers to provide both safe and efficient air traffic services at much higher traffic densities than possible today. The study investigated the issue of how responsibility should...

The human factors (HF) impact of sweeping changes in the roles of human operators, as well as the introduction of new technologies, are being studied in NASA's Next Generation Air Transportation System (NextGen). As part of a NASA funded project [1], a walkthrough technique was constructed to examine the effectiveness of using a low-cost method for...

A human-in-the-loop simulation was conducted that examined off-nominal and tactical conflict situations in an advanced next generation air transportation system (NextGen) environment. Traffic levels were set at two times (2X) and three times (3X) current day levels and the handling of tactical conflict situations was done either with or without sup...

NextGen air/ground operations with ground-based automated separation assurance have been initially evaluated with controllers and pilots in the loop at the NASA Ames Research Center. Nominal and off-nominal situations were investigated in a highly automated environment, under 2x and 3x traffic densities. The paper starts with a review of previous s...