The cockpit display utilizes scalable vector graphics (SVGs) for the basic six displays. The modifications to the gauges utilize many of the GUI elements available within the devel- opment framework, such as progress bars and sliders. By using SVGs and setting layout guidelines for the various elements, the entire display can be scaled to screen resolutions both large and small, without a loss in visual fidelity. The GUI is operated by modifying the positions of various parts of the gauge graphics and values of the additional elements.
The gauges utilize user datagram protocol (UDP) in order to receive data from the Simulink system that in turn are used to update the various displays.
After receiving the data packet containing the values seen in Table 3.9, each display element is updated by calculating the amount of rotation or movement needed to display the corresponding value. Some of the display elements also change color to indicate various regions of operation and to reduce the amount of attention the gauges demand from the pilot.
5.1.1
Altimeter
Figure 5.2: The Altimeter Gauge.
Simulink provides the altitude in the correct units already, so the received value is used to set the altimeter needles. The altimeter analyzes the altitude to determine the rotation from 0◦ for the needles indicating hundreds of feet and thousands of feet, respectively. The rotation in degrees for the needles indicating hundreds and thousands of feet are given by Equations 5.1.1 and 5.1.2, respectively.
Rotation100s= 36 ∗ (Altitude)mod1000 (5.1.1)
5.1.2
Heading Indicator
Figure 5.3: The Heading Indicator
The heading indicator displays the Euler angle ψ of the aircraft. The value displayed by the heading indicator is the value of ψ in degrees. The value from Simulink is converted from radians to degrees, and then the heading indicator is rotated by that angle, with 0◦corresponding to true north.
5.1.3
Vertical Speed Indicator
Figure 5.4: The Vertical Speed Indicator.
The vertical speed indicator uses the vertical speed in hundreds of feet from Simulink to drive the needle. The needle has saturation points that prohibit the needle from moving into an invalid region. Currently, the vertical speed indicator is bounded to the range [-22, 22]. The 0 mark of the dial corresponds to 180◦on a circle. The needle is allowed to move a maximum of 176◦in either direction. The amount of rotation in degrees of the needle from 0◦is given by Equation 5.1.3.
Rotationneedle =
M axrotation
Boundupper
∗ V elocityvertical (5.1.3)
5.1.4
Airspeed Indicator
Figure 5.5: The Airspeed Indicator.
The airspeed indicator displays the airspeed of the aircraft in knots. The value received from Simulink is already in the correct units. The amount of rotation will depend the maximum value the indicator would display if were to use the full 360◦to display markings. Current implementation only shows up to 200 knots, but for calculation purposes, the gauge could display up to 240 knots. This value was determined by doubling the value pointed to halfway around the needle’s full rotation. The rotation of the airspeed needle is then calculated by Equation 5.1.4. Rotationneedle= 36 ∗ Airspeed2 (M axDisplay6 )2 if Airspeed < M axDisplay 6 36 ∗ M axDisplayAirspeed 6 − 36 if Airspeed ≥ M axDisplay 6 (5.1.4)
5.1.5
Attitude Direction Indicator
The attitude direction indicator (ADI) uses the aircraft’s pitch (θ) and roll (φ) to indicate the aircraft’s orientation relative to the Earth’s horizon. The θ and φ received from Simulink
Figure 5.6: The Attitude Director Indicator.
are converted from radians to degrees prior to adjusting the display. The horizon is then translated in the x and y directions, and then rotated. The dial surrounding the horizon is also rotated along with the horizon. The shifting of the horizon is dictated by Equations 5.1.5, 5.1.6, 5.1.7, and 5.1.8 where r is the magnitude of maximum allowable pitch angle for the dial, and θ and φ are in degrees. The current implementation sets r equal to 165. The items are rotated by −φ degrees from their center.
d = r ∗ sin(−θ) (5.1.5)
dx = d ∗ sin(φ) (5.1.6)
dy = d ∗ cos(φ) (5.1.7)
[Xshif t, Yshif t] = [−dx, −dy] (5.1.8)
5.1.6
Turn Coordinator
The turn coordinator relays the rate of turn as well as the amount of slip or skid in the turn. There are two separate elements to the turn coordinator: an aircraft display that shows the turn rate, and a ball that shows the amount of slip or skid in the turn. The rate of turn is equivalent to the rate of change in ψ. On the turn coordinator are markings that are below level flight. These markings correspond to the standard rate turn. The standard rate of turn will vary by aircraft, but is often equivalent to a full 360◦turn completed in 2 minutes. Equation 5.1.9 utilizes the z-axis angular velocity, and the minutes corresponding
Figure 5.7: Turn Coordinator with Slip/Skid Ball.
to the aircraft’s desired standard rate to calculate the rate of turn. This is then multiplied by a scalar value to obtain the amount of rotation the display will use. This scalar value is equivalent to the amount of degrees from level the standard rate of turn markings are located. Rate of T urn = ˙ ψ M inutesstandard (5.1.9) The slip/skid is calculated using the y- and z-axis accelerations of the aircraft. The amount of rotation in degrees from center for the slip/skid ball is given by Equation 5.1.10.
Rotationball =
5 ∗ accelerationy
−accelerationz
∗180
π (5.1.10)
It is worth noting that the scalar value multiplying the y-axis acceleration may vary by aircraft and should be found by comparing simulator results to baseline data from an equivalent aircraft.
5.1.7
Throttle and RPM Indicators
The throttle and engine RPM displays utilize user interface elements not unlike a progress bar. These displays use the throttle percentage and thousands of rotations per minute (RPM x 1000) received from Simulink, and set the fill of the bar accordingly. The color of the bars are set to change based on different thresholds, adding to the information provided to the pilot. The thresholds will vary based on aircraft, as will the maximum of the RPM displays.
Figure 5.8: Throttle and Engine RPM Display.
5.1.8
Flap and Spoiler Position Indicators
Figure 5.9: Flap and Spoiler Position Indicators.
The flap and spoiler indicators interface elements are sliders that move based on the angular deflection of each of these surfaces. The sliders are given bounds that match the surface bounds seen in Table 3.4. Simulink sends the angular deflection of these surfaces as reported by the sensor models, so no additional modification is needed.
5.1.9
Landing Gear and Brake Indicators
The position of the landing gear and the application of the landing gear wheel brakes are given via color changing display elements. The landing gear indicator is labeled ‘GEAR’, and is green when the gear is fully deployed, and red any time the gear is not fully deployed. The brake indicator is labeled ‘BRAKE’, and is gray until a threshold level of pressure is applied to the brakes, at which point it turns red.
5.1.10
Reference Speed Indicator
Figure 5.11: Flight Control System Reference Speed Indicator.
The reference speed indicator is a digital readout of the current reference speed that the pilot has set. This reference speed is a setting that is implemented in the iReCoVeR flight control law. This readout directly displays the number that the pilot currently has set via the cockpit controls.
5.1.11
Yoke and Rudder Pedal Position Indicators
As a reference to the pilot, the location of the yoke and rudder pedals is displayed. This is achieved with a slider for the longitudinal yoke displacement, a slider for the rudder pedal position and a dial for the lateral yoke displacement. The yoke and rudder pedal displacements are provided from Simulink, as outlined in Table 3.9. The sliders and dial share the same bounds as the signals they represent, allowing for the value received from Simulink to be displayed without modification. These indicators are provided to the pilot as to help display the current trim set for the longitudinal, lateral and rudder positions.