Phase V Initial Updated Design Proposal with Enabling Technologies:

Cockpit Redesign for Accommodation of Disabled Pilots

Chris C. Beeney

February 20, 2019

Embry Riddle Aeronautical University

UNSY 431: Unmanned Systems Human Factors Considerations

Evaluation of the Existing/Current System Design

In this section, the current design of a typical cockpit will be evaluated in regards to the yoke, the rudder pedals, and the brakes specifically.  The reason for the current design of each system, their shortcomings, and the human factors that affect them will be considered.

The yoke is also known as the control stick.  In some designs this is a literal stick (with or without handles) and in others it looks like half a steering wheel for a car.  The yoke was built to manually control the plane using pulleys and later hydraulics with actuators.  The technology of the time was before the invention of computers, so everything was manual.  At the time, human factors were not the focus of design, so the mechanical implementation of the yoke expected the pilot to conform to the system.  This becomes a problem for pilots that are amputees.  In the past, people missing an arm could not fly reasonably but newer technologies in prosthetics allow those with missing limbs to interact with the yoke.  In order to do so, the prosthetic needs to be attached to the yoke and becomes a flight risk if the unit detaches from the pilot (Hawkins, 2014).  

The need for nose correction in the air prompted the invention of a rudder.  Typically the rudder consists of two pedals that are attached to each other.  The pilot must press down on one or the other with their foot to control the rudder.  Rudders were also invented before the digital age and are manually operated; some of the newer ones use hydraulics with actuators like the yoke.  Also like the yoke, rudders were designed with the thought that pilots must conform to the system.  To that end, some amputees must attach the rudder to their amputated leg with a band and do a dance to operate it (Hawkins, 2014).  The act of using a rudder is also tedious work because it is essentially a series of minute corrections in direction.  One aspect of human factors considerations is to avoid putting the user in monotonous jobs (Salvendy, 2012).  Fitt’s principles point out that machines are very good at performing repetitive tasks and could help alleviate this shortcoming (de Winter, & Dodou, 2014).

The braking system has existed since airplanes had wheels.  Braking has always been a manual ordeal because it involves kinetic friction.  The shortcoming in this system pertains only to those with amputated legs.  Double amputees have a hand control to operate the brake (Hawkins, 2014).  This is another example of the system being designed a certain way and expecting the user to adapt to it; an additional unit had to be added for the double leg amputee to adapt.

Proposed Task Assignment Using Fitt’s Principles

In this section, Fitt’s principles will be used to determine which of the three subtasks above should be re-assigned to be performed by a machine.  Paul Fitts created a list of 11 statements describing which actions are performed better by a machine or by a human (de Winter, & Dodou, 2014).  A brief summary of the subtasks addressed in this paper can be seen in Table 2 but will be discussed in detail in the following paragraphs.

The yoke is required in order to steer the plane.  Directionality is very important when flying a plane and requires an understanding of the surrounding environment.  But a steady course could be automated.  Because of this, a human should be in control of the yoke but may be assisted by a machine using autopilot.  A semi-automated yoke would offer the pilot stabilized control; the plane will return to wings level mode after the yoke is used to steer in the desired direction (Barnhart, Marshall, Most, & Shappee, 2016).  Fitt’s second statement applies when arguing for human control because pattern recognition is crucial for navigating; especially when recognizing a runway at night.  Fitt’s third statement applies when arguing for human control because improvisation is sometimes needed such as unexpected collision avoidance.  Fitt’s fifth and sixth statements apply (often together) when arguing for human control because deductive reasoning and the ability to make judgements are important aspects of steering the plane during times such as course correcting for inclement weather on the horizon (de Winter, et. al., 2014).  Fitt’s first statement applies when arguing for machine control because the autopilot can smoothly apply the needed force to re-align the plane with the horizon precisely.

The rudder is required to assist in directing the plane appropriately.  The plane would be more difficult to align to the planned trajectory without the rudder.  Because the rudder consists of reactive minute actions, it could be automated entirely.  As with the yoke, stabilized control would afford the plane with the appropriate level of rudder adjustments without human intervention.  Fitt’s second statement arguing for machine control applies because rudder control is a repetitive routine task.  Fitt’s fourth statement arguing for machine control applies because the machine can perform complex calculation to compensate for cross winds if it determines that the plane is off planned course.  Fitt’s fifth statement applies when arguing for machine control because machines can handle many tasks at once easily so calculating wind speed and adjusting the rudder while checking planned trajectory against GPS will not be an issue.

The brake is important for keeping the aircraft from rolling before and after flight.  Usually the plane will need to taxi to the runway and then wait for ground control to authorize the flight once it is safe.  Without brakes, the plane would begin to accelerate as soon as the engine is turned on and take off regardless of whether the pilot has navigated to the runway or not.  Upon landing, the brakes are essential for stopping the plane safely.  Without artificial intelligence to determine when to apply brakes, these are best left to the human.  Fitt’s third statement applies when arguing for human control because takeoff procedures are usually flexible; the pilot must wait until ground control clears the takeoff.  Fitt’s fourth statement applies when arguing for human control because the pilot must recognize the appropriate time to apply the brakes.

Table 2

Summary of the Proposed System Task Assignments

Task	Human Assignment	Machine Assignment
Brake	x
Rudder		x
Steer	x	x

Initial System Component Design

            A new digital console should be created to house controls for the steering and braking subtasks as well as override rudder control.  The console should be attached to the side of the cockpit on an adjustable arm so that users of differing arm lengths can adjust for reach comfort of differing body types (Salvendy, 2012).  The main console should be a touch screen along with minimal important buttons. See figure 1 for overall position.

Figure 1

The yoke actions can be represented with a D-Pad configuration on the touch screen console in a digital format.  With the arrows or bars spaced far enough to avoid accidentally selecting the wrong direction but close enough to be operated by one hand.  The icons that represent the directionality of the plane can easily be connected to actuators that control the external mechanics of the plane much like the newer hydraulic systems in place already.  See Figure 2 for a closer look at the console’s digital screen.

Figure 2

The rudder actions should be automated by the autopilot but a separate toggle should be placed on the console bezel in case an override is required.  This way the pilot has the option of toggling the rudder left, right, or neutral as needed but does not need to constantly make adjustments under normal circumstances. See Figure 3 for console bezel design.

Figure 3

            The brakes should be a manual lever that provides haptic feedback which is important in the braking process. The lever can be attached to the bottom of the console, perhaps a long bar that extends the length of the console. This can be seen in Figure 3.

Description of Enabling Technologies

            The Alio Ground Control Station (GCS) is a fully touch capable unit.  This GCS could be modified to fit in the cockpit.  A new bezel would need to be created that includes the manual toggle and brake lever.  The professional unit costs $8,000 from Chloeta.

Table 2

Summary of the Proposed Enabling Technologies

Enabling Tech Description	Vendor(s)	Estimated Cost	Description of Application in System Design
GCS touchscreen	Chloeta	$8,000	Touchscreen for aircraft control

Reference List

Barnhart, R. K., Marshall, D. M., Most M.T., & Shappee, E. (2016). Introduction to unmanned
aircraft systems. (2nd ed.). Boca Raton, FL: CRC Press, Taylor & Francis Group.

Chloeta. (n.d.). UAS Alio Ground Control Station. Retrieved from https://www.chloeta.com/wp-content/uploads/Spec-Sheet-UAS-Alio-Ground-Control-Station.pdf

 de Winter, J. C. F., & Dodou, D. (2014). Why the fitts list has persisted throughout the history of function allocation. Cognition, Technology & Work, 16(1), 1-11. doi:http://dx.doi.org.ezproxy.libproxy.db.erau.edu/10.1007/s10111-011-0188-1

Hawkins, K. (Aug. 14, 2014). How do amputees fly planes? BBC News. Retrieved from https://www.bbc.com/news/magazine-28785171

Salvendy, G. (Ed.). (2012). Handbook of human factors and ergonomics. Retrieved from https://ebookcentral.proquest.com