Schweizer 1-26 Glider Flight Simulator
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Schweizer 1-26 Glider Flight Simulator for The National Soaring Museum.
Project P6003
Team Members Fall-Spring Jonah Williams Brittany Soracco
Winter-Spring Kara Mather Ryan Stoddard November 11, 2005
Table of Contents Schweizer 1-26 Glider Flight Simulator...... 1 for...... 1 The National Soaring Museum...... 1 Project P6003...... 1 Team Members...... 1 Winter-Spring...... 1 Table of Contents...... 2 1.0 Abstract...... 4 2.0 Introduction...... 4 3.0 Background...... 5 3.1 Overview...... 5 3.2 Simulating Motion...... 6 3.3 Aircraft Flight Dynamics...... 6 4.0 Needs Assessment...... 7 4.1 Software...... 8 4.1.1 Flight Dynamics...... 8 4.1.2 Visualization...... 8 4.1.3 Motion Cuing...... 8 4.2 Hardware...... 8 4.2.1 User Controls...... 8 4.2.2 Visual Display...... 9 4.2.3 Motion Control...... 9 4.2.4 Exhibit Assembly...... 9 5.0 Concept Development...... 9 5.1 Software...... 9 5.1.1 Flight Dynamics...... 9 5.1.1.1 Pre-Existing Software...... 9 5.1.1.2 Pre-Existing Software with User Defined Flight Characteristics...... 9 5.1.1.3 Custom Flight Dynamics Software...... 10 5.1.2 Visualization...... 10 5.1.2.1 Simple Custom Visualization...... 10 5.1.2.2 Complex Custom Visualization...... 10 5.1.2.3 Pre-Existing Dynamics and Visualization...... 10 5.1.2.4 Pre-Existing Visualization Only...... 10 5.1.2.5 Software Engineering Project...... 10 5.1.3 Motion Cuing...... 10 5.1.3.1 Gravity Align Cuing...... 10 5.1.3.2 Inertial Cuing...... 11 5.1.3.3 Inertial Cuing with Washout...... 11 5.2 Hardware...... 11 5.2.1 User Controls...... 11 5.2.1.1 Cockpit Instruments...... 11
2 5.2.1.2 Glider Controls (Stick, Rudder Pedals, Air Brake, Trim, Tow Cable Release) 11 5.2.1.3 Simulation Controls...... 11 5.2.1.4 Safety Systems...... 11 5.2.1.5 Operator’s Station...... 11 5.2.2 Visual Display...... 12 5.2.2.1 Ceiling Mounted Projector: Wall Mounted Screen...... 12 5.2.2.2 Platform Mounted Projector: Wall Mounted Screen...... 12 5.2.2.3 Nose Mounted Projector: Cockpit Mounted Rear Projection Screen....12 5.2.2.4 Rear Mounted Projector: Cockpit Mounted Screen...... 12 5.2.2.5 Curved projection Surface...... 12 5.2.2.6 Nose Mounted Projector: Canopy Replacement Rear Projector Screen...12 5.2.2.7 Platform Mounted Flat-screens...... 12 5.2.3 Motion Control...... 12 5.2.3.1 Proprietary Sarnicola Smoothing ISA Card...... 12 5.2.3.2 ISA DAC...... 12 5.2.3.3 USB DAC...... 13 5.2.4 Exhibit Assembly...... 13 5.2.4.1 Reinforce Cockpit Floor...... 13 5.2.4.2 Close Glider Body...... 13 5.2.4.3 Enclose Tripod...... 13 5.2.4.4 Replace Wings...... 13 5.2.4.5 Create Smaller “Aesthetic” Wings...... 13 6.0 Feasibility Assessment...... 13 6.1 Software...... 13 6.1.1 Flight Dynamics...... 13 6.1.1.1 Pre-Existing Software...... 13 6.1.1.2 Pre-Existing Software with User Defined Flight Characteristics...... 14 6.1.1.3 Custom Flight Dynamics Software...... 14 6.1.3 Visualization...... 15 6.1.2.1 Simple Custom Visualization...... 15 6.1.2.2 Complex Custom Visualization...... 15 6.1.2.3 Pre-Existing Dynamics and Visualization...... 15 6.1.2.4 Pre-Existing Visualization Only...... 15 6.1.2.5 Software Engineering Project...... 16 6.1.3 Motion Cuing...... 16 6.1.3.1 Gravity Align Cuing...... 16 6.1.3.2Inertial Cuing...... 16 6.1.3.3 Inertial Cuing with Washout...... 16 6.2 Hardware...... 17 6.2.1 User Controls...... 17 6.2.1.1 Cockpit Instruments...... 17 6.2.1.2 Glider Controls (Stick, Rudder Pedals, Air Brake, Trim, Tow Cable Release) 17 6.2.1.3 Simulation Controls...... 17 6.2.1.4 Safety Systems...... 18
3 6.2.1.5 Operator’s Station...... 18 6.2.2 Visual Display...... 18 6.2.2.1 Ceiling Mounted Projector: Wall Mounted Screen...... 18 6.2.2.2 Platform Mounted Projector: Wall Mounted Screen...... 18 6.2.2.3 Nose Mounted Projector: Cockpit Mounted Rear Projection Screen....19 6.2.2.4 Rear Mounted Projector: Cockpit Mounted Screen...... 19 6.2.2.5 Curved projection Surface...... 19 6.2.2.6 Nose Mounted Projector: Canopy Replacement Rear Projector Screen...19 6.2.2.7 Platform Mounted Flat-screens...... 19 6.2.3.0 Motion Control...... 20 6.2.3.1 Proprietary Sarnicola Smoothing ISA Card...... 20 6.2.3.2 ISA DAC...... 20 6.2.3.3 USB DAC...... 20 6.2.4.0 Exhibit Assembly...... 20 6.2.4.1 Reinforce Cockpit Floor...... 20 6.2.4.2 Close Glider Body...... 20 6.2.4.3 Enclose Tripod...... 20 6.2.4.4 Replace Wings...... 21 6.2.4.5 Create Smaller “Aesthetic” Wings...... 21 7.0 Final Concept...... 21 7.1 Software...... 21 7.1.1 Flight Dynamics...... 21 7.1.2 Visualization...... 21 7.1.3 Motion Cuing...... 22 7.2 Hardware...... 22 7.2.1 User Controls...... 22 7.2.2 Visual Display...... 22 7.2.3 Motion Control...... 23 7.2.4 Exhibit Assembly...... 23 8.0 Bill of Materials...... 23 9.0 Senior Design I part II...... 25 10.0 Conclusion...... 25 11.0 Refrences...... 25 12.0 Appendix...... 25 12.1 Work Breakdown...... 26 12.2 Data Flow Chart...... 26 12.3 Gantt Chart...... 26 12.4 Concept Sketches...... 26 1.0 Abstract Abstract, a summary of the report 2.0 Introduction
The National Soaring Museum has had a long standing interest in increasing the interactive portion of its exhibits. Towards this end they have spoken with Sarnicola
4 Simulation Systems and received the loan of a three degree of freedom motion platform for use in construction of a flight simulator modeling the Schweizer 1-26 glider.
The National Soaring Museum proposed a Multidisciplinary Engineering senior project to convert the motion platform into a flight simulator modeling the Schweizer 1- 26 glider for use as an exhibit. The flight simulator will implement hardware to take input from the original cockpit controls of the glider to control a flight simulation. The project will utilize the tripod motion platform provided to simulate the physical motion of the airplane. Additionally, the simulation will have at least a basic level of visual feedback to give the user a sense of motion and position.
3.0 Background 3.1 Overview Simulation Systems is a commercial manufactures of motion simulator platforms. They have donated one of their old prototype platforms to the National Soaring Museum and RIT to construct a flight simulator exhibit for the museum. This motion platform was designed in 1994 and its control systems were not designed for use as a final produce. The project team must therefore update the control systems to allow the motion platform to be used in conjunction with a modern software flight simulator. The Sarnicola platform is provides 3 degrees of freedom (pitch, roll, and surge) using a tripod of linear actuators. The simulator design must therefore use visual cues only for yaw, heave, and sway motions.
Schweizer 1-26 Glider
Simulator Motion Platform and 1-26 Cockpit
5 3.2 Simulating Motion The basis for any motion simulation is to reproduce the various sensory “cues” a pilot or passenger would experience in the actual vehicle. Due to the behavior of human perceptions it is important that the pilot experience all of the major cues they expect to encounter during the simulation. Failure to provide these cues or to synchronize them appropriately will result in motion sickness or vertigo for the pilot. The primary concern during the design of the simulator is therefore to provide both visual an acceleration cues to the pilot. Visual cues are easily obtained from modern software flight simulators using three dimensional rendered environments. Acceleration cues are much harder to produce. Fortunately studies have found that it is not necessary to reproduce either the magnitude or the duration of an acceleration cue accurately. If an acceleration begins when expected with an appropriate relative magnitude the pilot’s brain will “fill in” the remaining information based on visual cues and the pilot will believe their position has changed appropriately.
Fixed motion platforms cannot reproduce all accelerations, due to their limited movement along each axis. Therefore most control systems will apply a scaling factor to the amplitude of any acceleration and “wash out” the duration of the acceleration. This allows the motion platform to return to a neutral position quickly, leaving the full range of motion available to produce the next acceleration cue. 3.3 Aircraft Flight Dynamics An aircraft’s orientation and velocity can be described using a six degree of freedom model as shown below. Yaw, pitch, and roll describe the rotational motion of the aircraft while surge(longitudinal), heave(vertical), and sway(lateral) describe its displacement.
6 In order to determine the change in an aircraft’s orientation a flight simulator will consider the position of the control surfaces of the aircraft and the current orientation and velocity of the aircraft. Control inputs will shift the orientation of the aircraft in an appropriate direction however the magnitude of this change is dependant on the airspeed over the control surfaces. Calculating the behavior of air flows over control surfaces is prohibitively expensive and cannot be accomplished in real time to any reasonable degree of accuracy. Therefore modern flight simulators construct a large table of values relating the airspeed of different control surfaces to a set of constants defining the responsiveness of the aircraft to attitude changes along a specific axis. When run the simulation continually compares the orientation of the aircraft to the table and retires a set of constants defining its responsiveness to control inputs. 4.0 Needs Assessment The initial requirements presented to the senor project team were threefold:
1.) Use low level programming skills to obtain user control of the motion actuators through the stick and rudder control system in the cockpit, 2.) Implement hardware that will allow the cockpit controls to send appropriate signals to the computer, and 3.) Develop a terrain view system that allows a simulated flight trajectory to be projected onto a screen in front of the simulator, giving the user a sense of flight through visual cues.
In order to develop these requirements into a cohesive set of features our senior project team performed preliminary research and then had a design meeting with the director of the National Soaring Museum. During this meeting we toured the National Soaring Museum facilities to get a better idea of the existing exhibits as well as the location and function of the exhibit we are developing. Additionally research, ideas for the project, specific requirements, work priorities and concerns were discussed. From this meeting the team was able to produce a better breakdown of the required components of the exhibit as discussed below in 4.1 and 4.2. Additionally during the visit several members
7 of the senior project team rode in or piloted gliders in order to get a better impression of the experience that needs to be re-created. This experience was particularly helpful in the development of visual display ideas.
One important requirement that is taken account in all categories is reusability. The National Soaring Museum has requested that as many of the project components as possible be easily reproducible and reusable. This is both to create additional identical simulators and for use in other applications at the National Soaring Museum. In particular the National Soaring Museum is interested in the possibility of building several stationary simulators to compliment the one built for this project.
4.1 Software The software portions of the project are those sections which will be implemented primarily or exclusively using computer software. While several of these sections will communicate with hardware components these areas of the project can be considered to be software oriented.
4.1.1 Flight Dynamics Flight dynamics covers the calculation of an aircraft’s change in position and heading in response to the pilot’s control inputs and the current atmospheric conditions. In order to reproduce the behavior of the Schweizer 1-26 it is necessary to determine the flight characteristics of the aircraft. The flight simulator will use these characteristics to determine the aircraft’s behavior.
4.1.2 Visualization In order to provide the simulator pilot with a sense of motion, heading, and position the flight simulator will provide an approximation of the pilot’s view from the cockpit. The visualization will provide the pilot with feedback on the position of the plane. This requires at least a horizon line indicator to show the aircraft’s attitude. Ideally it will also enhance the simulation experience by providing a full rendered view of the terrain visible from the aircraft.
4.1.3 Motion Cuing Motion cueing is the process by which physical cues are delivered to the user of the simulator in order to reproduce the feeling of motion. The cuing algorithms used will determine when and how the platform should be moved to approximate the movement of the simulated glider. An important issue with motion cueing is preventing motion sickness resulting from mismatched visual and physical feedback. 4.2 Hardware
4.2.1 User Controls The user controls include everything that the user interacts with physically when operating the simulator. These must include the original joystick and rudder pedals.
8 These controls will also include an emergency stop button both inside and outside the cockpit. Physical displays such as flight instruments are also included in this category.
4.2.2 Visual Display The visual display is the means by which the visualization will be presented to the user. The goal is for the user to have a large clear view of the visualization both to enable them to better pilot the simulated glider and to enhance the simulation experience.
4.2.3 Motion Control Motion control is the means by which the platform will actually be moved. The software motion cuing will decide where the airplane should be and how it will move to get there. The motion control system will then convert that positional data into analog signals and alter them as necessary to control the motion platform. Additionally this will include any physical or electronic systems needed to convert the physical motion of user inputs into a usable input to the simulator.
4.2.4 Exhibit Assembly The exhibit assembly is a broad category that includes any changes made to the physical assembly of the glider body and motion platform to make them more suitable as a museum exhibit. This is the most flexible of the categories in terms of deliverables. 5.0 Concept Development 5.1 Software
5.1.1 Flight Dynamics
5.1.1.1 Pre-Existing Software There are several commercial and open source flight simulators that have a fairly high level of accuracy. One could be used to perform the flight dynamics calculations using the flight characteristics from a pre-existing glider model.
MS Flight Simulator Flightgear X-Plane
5.1.1.2 Pre-Existing Software with User Defined Flight Characteristics Alternately a pre-existing flight dynamics engine could be used to perform flight dynamics calculations for the Schweizer 1-26 glider. This would require the flight characteristics of the airplane to be calculated from basic information about the airplane. This flight characteristic information would then need to be formatted in such a way as to be compatible with the engine being used.
9 5.1.1.3 Custom Flight Dynamics Software Instead of using pre-existing software the project team could produce their own custom flight dynamics software. In this case the flight characteristics of the Schweizer 1-26 glider would still need to be calculated. Then software would need to be written to take this information and simulate the forces being applied to an airplane in flight.
5.1.2 Visualization
5.1.2.1 Simple Custom Visualization The first custom visualization option would be to program a very simple visualization showing only a horizon line. This would give the user an idea of the orientation of the simulated aircraft. The inputs to such a program would be the current position data from the flight dynamics application.
5.1.2.2 Complex Custom Visualization An additional custom visualization option would be to program a more intricate visualization. A complex visualization is desirable because it adds an element of realism to the simulation.
5.1.2.3 Pre-Existing Dynamics and Visualization An alternative would be to use a pre-existing visualization that operates with a pre-existing flight dynamics engine. This would prevent any input or output problems as the programs are already designed to work together. Additionally most commercial or open source programs can provide very high quality visuals.
5.1.2.4 Pre-Existing Visualization Only Using a pre-existing visualization tool without a flight dynamics engine would allow for an extremely good visualization without having to be limited in the choice of flight engine.
5.1.2.5 Software Engineering Project A Software Engineering Senor Project could be sponsored to implement the visualization software. This would require assembling a team of Software Engineering students in order to provide a complex visualization application to meet the project’s specifications. It has the possibility to produce not only a good visualization but also to add an exhibit front end to the software. The Software engineering team may then choose to use any idea Concept 5.1.2.1-5.1.2.4 or combination there-of or choose a different approach.
5.1.3 Motion Cuing
5.1.3.1 Gravity Align Cuing Gravity Align Cuing is the use of gravity to reproduce a constant acceleration. For example tipping the nose of the cockpit up to reproduce forward acceleration
10 5.1.3.2 Inertial Cuing Inertial cuing would reproduce the accelerations that would be produced by a glider by moving the platform to produce the feeling of acceleration in the correct direction.
5.1.3.3 Inertial Cuing with Washout Adding a washout filter to inertial cuing eliminates sustained accelerations and allows the motion platform to settle back into a neutral position in preparation for subsequent cues. The washout filter provides a strong initial acceleration at the onset of a cue which then falls off quickly to prevent the platform from reaching its maximum extension. 5.2 Hardware
5.2.1 User Controls
5.2.1.1 Cockpit Instruments The cockpit instruments providing air speed, altitude, rate of climb, and compass heading need to be implemented in order to provide feedback to the pilot. These instruments could be displayed as part of the visualization or physically mounted in the instrument panel.
5.2.1.2 Glider Controls (Stick, Rudder Pedals, Air Brake, Trim, Tow Cable Release) In order to control the simulated glider inputs must be collected from the cockpit controls. The stick, rudder pedals, air brake, trim control, and tow cable release should all provide inputs to the software simulations. These sensors could provide either analog or digital inputs depending on the type of sensor used ie: linear potentiometers, digital rotary sensors, modified USB joysticks.
5.2.1.3 Simulation Controls In order to start and stop the simulation from inside the cockpit a set of user controls may be desirable. The placement of a small set of buttons on the instrument panel would allow the pilot to navigate menus and select simulation options.
5.2.1.4 Safety Systems In order to protect the pilot and museum visitors it is necessary to include an emergency stop control both inside and outside the cockpit such that motion platform can be halted from inside and outside the cockpit. As an additional feature this emergency stop could notify the software simulation whenever the motion platform is stopped.
5.2.1.5 Operator’s Station The simulation should provide a set of standard desktop computer controls to allow a museum employee to monitor and control the simulator. This interface should be able to start and stop the simulation, adjust simulation parameters, and administer the computer system controlling the simulator.
11 5.2.2 Visual Display
5.2.2.1 Ceiling Mounted Projector: Wall Mounted Screen A projector could be mounted on the ceiling above the exhibit to project a large image onto the wall in front of the motion platform. This image would remain in the same place on the wall while the platform moves.
5.2.2.2 Platform Mounted Projector: Wall Mounted Screen A projector mounted on the motion platform could project a large image on the wall in front of the platform. The projected image would move with the motion platform.
5.2.2.3 Nose Mounted Projector: Cockpit Mounted Rear Projection Screen A projector mounted on the glider nose could project at a rear projection screen mounted at the front of the glider canopy.
5.2.2.4 Rear Mounted Projector: Cockpit Mounted Screen A projector mounted on the back of the glider would project onto a screen mounted on the motion platform in front of the cockpit.
5.2.2.5 Curved projection Surface Any of the platform mounted projection screens could be curved to wrap partially around the user. This would provide a better peripheral view.
5.2.2.6 Nose Mounted Projector: Canopy Replacement Rear Projector Screen The original cockpit canopy has been removed from the glider. It could be replaced with a rear projection screen over a frame of a similar shape. A projector mounted on the nose could then project a correctly distorted image onto this screen to provide an immersive viewing experience.
5.2.2.7 Platform Mounted Flat-screens Flat-screen monitors could be mounted onto the platform around the cockpit. The visualization would span across the multiple monitors to produce a continuous image.
5.2.3 Motion Control
5.2.3.1 Proprietary Sarnicola Smoothing ISA Card The proprietary Sarnicola ISA card uses feedback from linear potentiometers on the motion platform to determine the platform’s current position and perform a smooth transition to a new position...
5.2.3.2 ISA DAC An ISA digital to analog converter was provided with the motion platform. It was originally designed to provide an analog control signal to the custom Sarnicola ISA board.
12 5.2.3.3 USB DAC Alternately the ISA DAC could be replaced with a USB DAC. This digital to analog converter would perform the same function but using a different technology to talk to the computer.
5.2.4 Exhibit Assembly
5.2.4.1 Reinforce Cockpit Floor The current floor of the cockpit will not support the full weight of an adult pilot. It could be replaced with a sturdier material such as wood or thicker metal so that there would be no danger of it falling through the floor and causing injury to a passenger or damage to the glider.
5.2.4.2 Close Glider Body The back of the glider body is currently open with sharp edges. It could be closed off. This could be done with a variety of materials such as cloth, metal or wood. Closing off the back would protect the controls that would be placed inside, protect people touching the exhibit from the sharp edges and give the exhibit a more finished look
5.2.4.3 Enclose Tripod Enclosing the tripod with a physical barrier would prevent children from attempting to touch machinery that could be dangerous.
5.2.4.4 Replace Wings The Rochester institute of Technology is in possession of a cut portion of the original glider’s wings. Exhibit space permitting these could be reattached for a better visual presentation of the aircraft.
5.2.4.5 Create Smaller “Aesthetic” Wings Smaller complete wings could be created to be attached to the glider. This would be a purely aesthetic alteration to indicate the position of the glider’s wings to museum visitors. 6.0 Feasibility Assessment 6.1 Software
6.1.1 Flight Dynamics
6.1.1.1 Pre-Existing Software Several commercial and open source simulators were considered for use as pre- existing software. The three with the most promising features were;
MS Flight Simulator Flightgear
13 X-Plane
However, none of these commercial products have flight characteristics for a glider similar enough to the Schweizer 1-26 to produce a truly accurate representation of the aircraft. The National Soaring Museum would like an exhibit that is as realistic as possible. Consequently using the existing flight characteristics of a commercial program is not an adequate solution.
6.1.1.2 Pre-Existing Software with User Defined Flight Characteristics The use of a pre-existing application to perform flight dynamics calculations can produce a very good model of an airplane’s flight given the correct parameters. Flightgear in particular also has an open file format to record flight characteristics that will be compatible with their flight dynamics engine. The flight characteristics themselves can be calculated from the basic information about the airplane. There is extensive information available about the physical properties of the Schweizer 1-26 glider because it is a very popular model often used in competition. Additionally the senior project team has access, through the National Soaring Museum, to a working Schweizer 1-26 glider if any information is unavailable from other sources.
6.1.1.3 Custom Flight Dynamics Software Instead of using pre-existing software the project team could produce their own custom flight dynamics software. In this case the flight characteristics of the Schweizer 1-26 glider would still need to be calculated. This is feasible as discussed above. The formatting of the data would be transparent as the team would specify the format needed for their own engine.
However flight dynamics software is extremely complex. Developing such software from scratch would require not only extensive research into aerodynamics but a significant amount of coding. The man-hours needed would be extremely significant and would hinder other sections of software that need to be developed, specifically in the area of motion control.
Even if time and manpower were not an issue this type of software is inherently complex. It would need to calculate the position and acceleration in all directions of the airplane and do so quickly enough to run in real time even with the additional delay added by both the visualization and motion control software. Altering the algorithms used for time efficiency without sacrificing accuracy is something that can take an indeterminate amount of time.
As an example of the complexity the JSBsim project, which is a flight dynamics engine has had 6 people working on it since January of 2001.
14 6.1.3 Visualization
6.1.2.1 Simple Custom Visualization A simple horizon line visualization would provide enough user visual feedback on the glider’s orientation for an individual to pilot the simulation. An extremely simple visualization would be possible to complete within the context of the other software commitments for this senior project. Additionally, such a simulation would not tax the available hardware and would not cause lag.
However such an experience would not be particularly immersive and would not be an especially good looking museum exhibit. The major function of this project is to provide an exhibit that would both entertain children and interest experienced glider pilots. A more detailed visual display would be extremely desirable for meeting both of these goals because it adds an element of realism to the simulation.
6.1.2.2 Complex Custom Visualization While a complex visualization adds realism to the simulation it is also extraordinarily complex to produce. Additionally graphics work is particularly complex and needs to be designed specifically for the operating system being used. Graphics work to present a visual image in response to user input is additionally difficult to design due to the speed at which the program needs to operate.
To give an idea of the complexity of such a program Microsoft Flight Simulator started as an EE master’s thesis in 1975. The functional flight simulator then was not produced until 1980 with two people working full time on the project. Now that the company is owned my Microsoft it takes a full software development team working full time between one and two years to release another iteration of the software. Flight gear, an open source flight simulator program has had hundreds of volunteers working on it over the course of several years.
6.1.2.3 Pre-Existing Dynamics and Visualization The use of a pre-existing visualization would create a more realistic and immersive environment than could be produced by the members of the senior project team. Such a visualization would also already be designed to run efficiently and react quickly to user input.
A visualization with attendant flight dynamics software would make it easy to bridge the complex formatting gap between information about the location and orientation of the plane and a visualization of the planes movement. Having the two pieces of software work together would also make it much easier to add terrain and other effects.
6.1.2.4 Pre-Existing Visualization Only Pre-existing flight visualizations of the quality desired that have no attendant flight dynamics are not available. However most flight simulation programs can act as
15 visualization tools, taking in properly formatted flight dynamics information from an outside program and producing a visualization in accordance with it.
This option would allow for an extremely good visualization without having to be limited in the choice of flight engine. However such a choice would necessarily be dictated by the flight engine chosen. Additional software would also be required to reformat the output of the flight dynamics program on the fly to produce correctly structured input to the visualization program.
6.1.2.5 Software Engineering Project Creating a software engineering senior project would allow the project team a much wider range of options in producing a visualization. The addition of more people would allow for a rich visualization that brings a high level of realism to the simulation. Additionally such a collaboration would allow the final simulator to have an exhibit interface instead of just a flight visualization. The more polished exhibit front end would be a huge source of additional value for the National Soaring museum.
However, such a project would be the first instance of collaboration between the Software Engineering senior project and the college of engineering multidisciplinary senior project. A substantial amount of coordination would be needed to make this a viable option. However the director of the National Soaring Museum is extremely enthusiastic about the idea, as is the software engineering team we have met with.
6.1.3 Motion Cuing
6.1.3.1 Gravity Align Cuing Gravity alight cuing is used to reproduce a constant acceleration. However, when people feel a constant acceleration they eventually begin to tune out the sensation. This means that over time gravity align cuing has only a very moderate effect on the feeling of motion in the platform. Additionally each of the actuators in the tripod motion platform used only has an extension of 11 inches. Gravity align cuing would take up a significant fraction of this distance making it difficult to perform inertial cuing.
6.1.3.2Inertial Cuing Inertial cuing is extremely effective at reproducing the feeling of motion in a passenger. By tipping the cockpit at an angle the tripod can reproduce the feeling of accelerating in that direction. However, each leg of the tripod only extends 11 inches and so it is difficult for the platform to produce a wide range of accelerations.
6.1.3.3 Inertial Cuing with Washout Adding a washout filter to inertial cuing eliminates sustained accelerations and allows the motion platform to settle back into a neutral position in preparation for subsequent cues. This strong acceleration at the onset of a cue provides most of the impact and feeling of motion. Allowing the signal to fall off rapidly will prevent the platform from reaching its maximum extension which will allow it to produce other cues effectively.
16 Washout is a great choice because it allows the platform to preserve as much of its leg room for future cues as possible while still providing accelerations which give pilots the impression of flying a real aircraft. This is a good balance between providing a realistic current user experience and preparing for future user control decisions. 6.2 Hardware
6.2.1 User Controls
6.2.1.1 Cockpit Instruments Implementing the cockpit instruments as part of the visual display has the advantage of being extremely easy. However, it would make the flight simulator significantly less realistic.
Conversely, mounting realistic instruments in the cockpit instrument panel not only provides the needed information but also adds to the realism of the simulator. The instruments can be controlled by the analog to digital converter discussed in the motion control segment. The major challenge will be finding instruments which can be adapted to be controlled by an input voltage. However the National Soaring Museum has provided the team with a variety of instruments to be used for this purpose.
6.2.1.2 Glider Controls (Stick, Rudder Pedals, Air Brake, Trim, Tow Cable Release) Using linear potentiometers, at least those provided by the project sponsor, was deemed to be unnecessarily costly. The potentiometers provided had a very limited range of motion and the accuracy they offered resulted in a very high cost per sensor.
Digital rotary sensors are a good choice for several applications in the controls system. They are inexpensive and provide a digital output signal which can easily be used as a computer input. Rotary sensors can easily be mounted to a pulley in order to record its motion. This type of sensor is a great choice for the rudder peddles as they are run with steel cables that will need to be tied together to provide resistance and link their movements. The movement of those cables around pulleys could easily control a digital rotary sensor.
A modified joystick is a way to get a good user input from a very inexpensive device. The joystick would be modified by attaching the airplane control cables indirectly to the motional sensors of the device. Thus the joystick could produce an output indicating the two dimensional position of the control stick. Such a set up could also be used for the rudder peddles and several other controls. A USB joystick in particular would be able to run off of the same USB buses as the USB DAC being considered.
6.2.1.3 Simulation Controls The simulation controls will depend largely on the requests of the software engineering team. Any USB device would be ideal as there are plans to have a USB hub in mounted
17 in the simulator. Since the input device would be digital in nature there is no concern about how to transfer information to the computer.
Such an input device may be very valuable in creating a more personalized simulation experience. However it may also be too complex for small children.
6.2.1.4 Safety Systems In order to protect the pilot and museum visitors it is necessary to include an emergency stop control both inside and outside the cockpit such that motion platform can be halted from either location. Because the emergency stop must meet electrical codes the senior project team is unable to constructing it. Instead we have asked Dave Hathaway, the Operations Manage of RIT’s Mechanical engineering department, to produce an emergency stop that meets the necessary standards.
6.2.1.5 Operator’s Station The operators station will at minimum be a desktop computer running the chosen flight simulator. Most of the software will be determined by the software engineering team. The only other necessary function of this system is an emergency stop button.
Server hardware will probably be used to make the station more rugged and secure it for travel. Much of the physical shape of the operator’s station will be determined by the parameters of the emergency stop hardware that will be integrated into it.
6.2.2 Visual Display
6.2.2.1 Ceiling Mounted Projector: Wall Mounted Screen A projector mounted on the ceiling above the exhibit to projecting a large image onto the wall in front of the motion platform has several advantages. The projector could be placed wherever desired allowing the team to use a projector with a longer throw distance. Additionally the projected image could be very large and the image quality would not need to be exceptionally high as it would be very far from the user. A visualization produced in such a way would be far from ideal however. The image produced would stay static as the airplane rotated in several directions. This would make it difficult or impossible, depending on the visualization used, to align the image with what the pilot feels they should be seeing. This could cause vertigo and motion sickness. Additionally, an image so far away removes a large portion of the sense of realism from the exhibit. This option also severely limits the placement of the exhibit. Not only must it be placed near a wall but the ceiling must be within a certain range of heights, dependant on the projector. Many of the ceilings in the exhibit installation site are several stories tall or covered in other exhibits.
6.2.2.2 Platform Mounted Projector: Wall Mounted Screen A projector mounted on the motion platform could project a large image on the wall in front of the platform. Because the angle of the image would be stationary relative to the user the problem of a misaligned visualization would not be an issue. However the throw
18 distance would not be as long and the projected image would still be far away from the user. This option also limits the placement of the exhibit, but not as much as 6.2.2.1
6.2.2.3 Nose Mounted Projector: Cockpit Mounted Rear Projection Screen This option could produce an image that is still relatively large and much closer to the user. Mounting a screen on the cockpit would fill a much greater portion of the users view creating a more realistic experience. Mounting the screen and projector both on the cockpit would also make the simulator significantly more portable.
Because the screen is so close to the user a projector with a short throw distance would be needed. Additionally a rear screen projection is often dimmer than a typical projection.
6.2.2.4 Rear Mounted Projector: Cockpit Mounted Screen A projector mounted on the rear of the platform would provide all of the same benefits as a nose mounted projector but with fewer of the drawbacks. The positioning of the projector would allow it to be farther from the screen giving a longer possible throw distance and a wider viewing angle. Additionally this positioning would allow for the projection to be on a standard, non-rear projection, screen making it brighter and more suitable for a variety of display locations.
6.2.2.5 Curved projection Surface A curved projection surface would provide a better peripheral view for an increased sense of realism. However in order to project on a curved screen specialty hardware or software is needed. A projector capable of producing such an effect costs upwards of $30,000, well outside of our project budget. Software capable of producing such an effect could not be produced by the core team but is an option for the software engineering team to research.
6.2.2.6 Nose Mounted Projector: Canopy Replacement Rear Projector Screen Replacing the original cockpit canopy with a rear projection screen provides a maximum of realism. However, to be feasible a complicated distortion of the visualization would need to be performed. Additionally, replacing the cockpit canopy would limit the size of pilot who could comfortably use the exhibit. Beyond that the false canopy may give users a sense of claustrophobia and prevents communication with the pilot during operation.
6.2.2.7 Platform Mounted Flat-screens Monitors are a good choice for the simulation of larger aircraft that have small windows of approximately the same size as a monitor. However for a small glider with a bubble canopy they have a wide variety of issues. Using a single flat screen monitor would give an undesirably small image. However using a multiple monitor setup would create additional problems.
An array of flat screens would have large blank spaces in it where the frames of the monitors obstructed the user’s view. Additionally, the area that could be covered with multiple monitors without exceeding structural constraints, such as weight, is still
19 fairly small. On top of this the monitors are fragile and could be much more easily damaged by a careless user than a projection screen.
6.2.3.0 Motion Control
6.2.3.1 Proprietary Sarnicola Smoothing ISA Card The proprietary Sarnicola ISA card uses feedback from linear potentiometers on the motion platform to determine the platform’s current position and perform a smooth transition to a new position. The logic on this card is also done entirely in analog electronics. The functionality of this card is specific to the motion platform and would be difficult to reproduce. Additionally, a replacement of this functionality would need to be performed in software which may be much slower than the current solution. The only negative to using this card is that no PC capable of running the visualization needed for this project will also have an ISA slot. This problem can be circumvented by powering the ISA card externally and housing it in a separate enclosure.
6.2.3.2 ISA DAC The included ISA DAC dose not provide any functionality that could not be easily duplicated by a more modern piece of hardware. Additionally the ISA DAC cannot be used on a computer which is not equipped with an ISA bus.
6.2.3.3 USB DAC A USB based DAC would be compatible with whichever PC and operating system are chosen for the project. In addition, it would be extremely easy to interface with and the format for USB communication is an open standard. This will be very important when the Computer Engineers need to write custom device drivers for the platform. USB cables have functional length of 6 feet without signal degradation. Because of this a powered hub would need to be placed in the cockpit assembly. However this is and easy and inexpensive solution that also provides a power source for any USB sensors or user input devices that the simulator will use.
6.2.4.0 Exhibit Assembly
6.2.4.1 Reinforce Cockpit Floor Reinforcing the cockpit floor in some way will be easy to accomplish. The major decision will be the choice of materials which is largely a budgetary and aesthetic concern.
6.2.4.2 Close Glider Body Closing the back of the glider body is also a fairly simple project. Again the concerns are not technical but aesthetic.
6.2.4.3 Enclose Tripod Enclosing the tripod with a physical barrier may be complicated proposition as the tripod platform moves. Additionally, the completed simulator must be moved to the site
20 of the National Soaring Museum. Consequently it would be unwise to build a large, rigid or difficult to transport enclosure. The National Soaring Museum has also agreed to take on this task themselves to create an exhibit in appropriate for the interior of the museum.
6.2.4.4 Replace Wings Replacing the wings is a decision that cannot be made until the National Soaring Museum decides on the exact display space for the glider. The decision on whether to reattach one or both wings is one that is entirely depended on the space provided for the exhibit.
6.2.4.5 Create Smaller “Aesthetic” Wings As with replacing the wings this decision cannot be addressed until the National Soaring Museum has determined the exact location the exhibit will be installed in.
7.0 Final Concept 7.1 Software
7.1.1 Flight Dynamics The project twill be using preexisting software with user defined flight characteristics to produce our flight dynamics. Specifically we will be using the JSBsim flight engine developed by flight gear. This engine is accurate enough to produce the flight dynamics information needed to get a correct simulation. It also has an open format for submitting user defined flight characteristics for a new aircraft.
The senior multidisciplinary project team will also be working with the software engineering project group on this aspect of the software.
7.1.2 Visualization Our senior project team has sponsored a Software Engineering Senior Design Project to produce a working flight dynamics and visualization. This is the first joint project between the College of Engineering Multidisciplinary Design course and the Software Engineering Senior Project. By working with a software engineering team we will be able to produce a much more polished final exhibit with a well designed user interface. This will make the exhibit much easier for the National Soaring Museum to operate.
They will be basing their visualization off of existing FlightGear Software. This will ensure that our first set of deliverables is easy to produce quickly and aid in initial testing. Flight gear also offers a degree of separation between visualization and flight dynamics. This makes it easy for our teams to customize both aspects of the software while still keeping them easy to interface.
21 7.1.3 Motion Cuing Inertial cuing with a washout will be used to provide acceleration cuing to the passenger. It is felt that this will make the best use of the platforms limited range of motion. The major challenge will be in creating a set of cuing algorithms that is accurate but still not excessively processor intensive to run. This program will begin development during our teams second Senior Design I winter 05-06. 7.2 Hardware
7.2.1 User Controls will be hooking the stick to a standard joystick using wires petals will be further examined by ME’s digital rotary sensors or another joystick instruments will be powered with voltages provided by our USB DAC Small stepper motors
The specifics of the user control inputs will be determined more exactly during the second Senior Design I winter 05-06.
Because the emergency stop must meet electrical codes the senior project team is unable to constructing it. Instead we have asked Dave Hathaway, the Operations Manage of RIT’s Mechanical engineering department, to produce an emergency stop that meets the necessary standards. This emergency stop will be incorporated both into the operator’s station and into the cockpit itself.
7.2.2 Visual Display A projector will be used for the visual display. The projector will be mounted on the rear the glider body approximately four feet above the assembly. A large projector screen approximately three and one half by two and one half feet will be mounted on the front of the cockpit. It will likely be notched to fit around the body of the airplane and allow the user a view of some of the area below the plane. This would greatly enhance the simulation experience as in an actual glider most of the landmarks can be seen below the level of the plane.
The specific projector to be used is a BenQ PB2240. It was chosen largely for its very short minimum throw distance of 3.28 feet. The size of the projection at this minimum throw would be 24” by 18”. Mounted as planned for this simulator the actual throw of the projector will be closer to 6”. This will give a calculated projection size of 44” x 33” inches.
This screen may or may not be curved depending on what the specifications of the final visualization are. This depends on the progress of the software engineering project team. This distortion is not a priority for their team but is a requested additional feature if there is development time. Because this decision has not been made a specific screen has not been chosen
22 7.2.3 Motion Control The proprietary Sarnicola ISA Controller board will be used. Its functionally is quite valuable and would be difficult to reproduce under the current system constraints. Because it cannot be powered off of a modern PC the ISA board will have its own enclosure in the operator’s station where it will be independently powered.
A pair of USB digital to analog converters will also be used to communicate with the platform. Two of these will be needed as each of the USB-1208FS units that will be used can only handle two, 10-bit analog outputs. However they can additionally have 4 differential/8 single-ended analog inputs with a resolution of 12-bits Differential and 11- bits single ended. The device can produce up to 50 kilosample/second so the sample rate will not be a limiting factor. This USB DAC is also relatively inexpensive, $130, compared to a typical DAC with more analog outputs than are needed for this project
USB has a range of six feet with an appropriate signal strength. Because of this a powered USB hub will be inserted into the assembly. This hub will also serve to run any other USB devices we choose to use.
7.2.4 Exhibit Assembly The extent of changes to the exhibit assembly will depend, in part, on how much time is left at the end of the design process. None of the proposed changes are required however clear priorities have been expressed by the National Soaring Museum/
The at a minimum the back of the glider body will be closed and the floor will be replaced. These changes are necessary not only for safe testing but for transportation from RIT to the National Soaring Museum.
The National Soaring Museum is willing to produce their own instillation for the exhibit. This works well because it is important for them that the platform be mobile and that the structure of it fit with the existing exhibits. The project team will be providing the National Soaring Museum with a list of safety concerns about the platform if it is to be used as an exhibit around small children. 8.0 Bill of Materials Category Item Description Price Qty Total Cost Computer Single 1Gb Stick of DDR 1 RAM SDRAM $80.90 $80.90 120Gb 7200 RPM ATA 1 HD $68.51 $68.51 NVIDIA ATX AMD 1 Motherboard $111.00 $111.00 To be determined based on 1 consultation with Software Video card Engineers TBD TBD DVD drive 16X DVD-ROM 48X CD- $21.99 1 $21.99
23 ROM AMD Athlon 64 3700+ San 1 Diego 1GHz FSB 1MB L2 Processor Cache Socket 939 $234.00 $234.00 Server Grade hardware to 1 Case protect exhibit $100 $100 Linux, distribution to be 1 determined based on Operating consultation with Software System Engineers $0 $0 Flight Gear --flight dynamics 1 and visualization software. $0 Software Open Source. $0 616.40 Projector Projector BENQ PB2240 $1,300 1 $1300 Minimum Throw 3.28’ 24” x 18” at minimum throw. 44” x 33’ at a 6 foot throw. Screen To be determined based on 1 consultation with Software Engineers TBD TBD $1300 I/O DAC USB-based DAQ, 4 $149.00 2 $298.00 differential/8 single-ended analog inputs, 12-bit (Diff.)/11- bit (SE) resolution, 2 10-bit analog outputs USB Hub 4 Port powered USB Hub $13.99 1 $13.99 $311.99 Instrument Sensors TBD Winter 05-06 TBD TBD TBD Controls Servo/Stepper TBD Winter 05-06 TBD TBD TBD Motors USB Joystick $30 1 $30 $30 Donated Motion Three degree of freedom Donation Platform motion platform Glider Body Partial body of a Schweizer 1- Donation 26 glider Sarnicola ISA Card to convert computer Donation Controller positional voltage signals to Board platform control signals.
24 Operators Cart to hold emergency stop, Donation Station computer, ISA case. Cockpit air speed, altitude, rate of Instruments climb, compass heading Total Cost $2258.3 9 The projected total cost, even with the existing omissions is well within our budget. The budget allotted was $2000 with additional funding for a projector and screen. Of the $2258.39 allocated $1300 is earmarked for a projector meaning that only $958.39, or less than half, of the initial budget has been allocated. This leaves a very reasonable portion of the budget for expenses that have not yet been determined such as the exact sensors that will be used and the video card.
9.0 Senior Design I part II
The next phase of this senior design project will be conducted in winter quarter of the 2005-2006 school year. During this period Kara Mather & Ryan Stoddard will be taking Senior Design I. This will provide information about the mechanical and aerospace aspects of the project Ryan Stoddards primary concern will be determining how to devlope a set of flight characteristics for the 1-26 and then developing those characteristics Ryan is a licenced pilot who is taking the mechanical engineering aerospace option
Kara mather’s primary concern will be developing a set of cueing algorithm This will be researching cuing algorithms Writing code for them Tweeking them for best performance Both of the team members in Senior Design I will be working to connect the cockpit controls to allow for testing of
Brittany soraccco and jonah Williams will be interacting with the team remotely and developing drivers to control the motion platform to allow kara to test
Concurrently the software engineering project team will officially begin their project coursework. During winter quarter they will finalize their software requirements, assemble the computer that has been purchased, and install the necessary pre-existing software. In addition they will produce two software deliverables. The first is a very simple visualization and flight dynamics system using existing software for testing purposes. The second is a more advanced system that will be produced at the end of the quarter. The software engineering team will be working closely with the multidisciplinary team on all software aspects of the project to ensure compatibility and appropriate resource use. 10.0 Conclusion This quarter during senior design
25 Spent most of our time Developing requirements, visiting soaring museum Talking to software engineers First crossover Developing a plan
Winter quarter senior design one will be devoted to developing a specific plan for the mechanical engineering aspects of the simulator. This will finalize not only the sensors to be used but also the basics of the cuing algorithms and flight characteristics. Additionally, the software engineering project team will start development during winter. They will have two major deliverables. The first, a simple testing aid in the first weeks of the quarter, and the latter a more functional simulation near the end of the quarter.
Spring quarter will be construction phase Intervening time allows for delivery and construction of computer equipment National Soaring Museum very supportive and enthusiastic Cockit instruments Cockpit controls Integrating controls and cuing algorithsm with the flight dynamics Testing the final set up Getting pilots to put hours into the simulator and compare its behavior to that of an actual 1-26 11.0 References 12.0 Appendix 12.1Work Breakdown 12.2Data Flow Chart 12.3 Gantt Chart 12.4 Concept Sketches
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