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HUD Motorcycle Helmet

Rogue Rios, Aaron Dennis, Kevin Pearson, Evan Stalter 3/14/10 I pledge my honor that I have abided by the Stevens Honor System

Individual Tasks: Rogue Rios: Researched the fundamental principles surround GPS technology and heads up display. He also researched the benefits of a HUD and found citations used in other sections of the report. Aaron Dennis: Researched HUD technologies and wrote about the physical specs of the actual designs considered. Researched different physical locations to project from and prototypes of designs already started. Kevin Pearson: focused his search on IEEE papers in order to discover various ways of accomplishing global positioning based on small chips. As well as finding different implementations of GPS. Kevin also discovered calibration techniques for the clock systems inside GPS units. Evan Stalter: Researched the physical projection means for the HUD. Focused on the projection filters as well as the means by which the user would interpret the images. Also focused on the off axis projection problem. Primarily he researched the feasibility of integrating the technology into the helmet. Background:

Background General Research on HUDs:

Most consumer vehicles already display a plethora of information to the operator with through various pointers on the dashboard. Anything displayed on the dash requires the driver to glance down for a moment (earning it the title Heads Down Display). This problem is compounded even more when a car has a GPS or LCD screen of some kind displaying dynamic information, as it is a continuous distraction to the driver. In motorcycles, this distraction problem is generally related only to the information on the dashboard (there are people out there

who use a GPS on a motorcycle). However, motorcycles are much more dangerous to be distracted in critical moments in because it does not provide you a safety net of metal as a car would. Here we'll pull up a graph: Here we can see the control condition: the driver looking through his windshield in a car straight ahead at the road gives him the greatest ability to react quickly in an emergency situation. The other three bars on this graph represent information displays present elsewhere in the vehicle (the dash, the center console/CD player, on top of the dash). Since a HUD brings the information from these locations directly into the driver's field of view as he looks forward at the road, the safety benefit of a HUD over an HDD is obvious. In an experiment conducted in a virtual driving environment (4), requiring braking under certain conditions and examining driving under different levels, similar results were elicited. In a simulated delivery of goods, response time to speed variation and urgent events with a HUD was significantly lower than the trials with a HDD. Unfortunately, the HUD also increased the visual stress (how much effort was needed to see the information) over the HDD. This point shows a crucial design problem even for our motorcycle project: We cannot overload the driver with information on his HUD. It needs to be clean, easy to read, and not overwhelming. It might seem useful to display turn here, turn there, speed, time, distance, etc, but visual real estate is important. This same paper also suggests a possible fix, "Researchers should further investigate the issue of information clutter. Future studies may also consider adding auditory signals to the

Figure 4: Average brake reaction time when viewing on display in different positions(3)

display modality..." indicate that audio supplements to more limited visual information display might be a possible solution to visual stress increases (4).

Geographical Navigation:

A GPS location is merely a set of coordinates relative to the satellites. We have plenty of physical maps though, and when properly processed as digital information, they can be used for navigation and pathing. A Geographical Information System (GIS) is exactly that, and is necessary in some form in any pathing application. In one paper, the use of a GPS receiver is coupled with something many people have access to today: internet via cell phone, to connect to a web server containing the geographical data necessary for navigation. In a structure like this, an application is setup server-side to run all geographical calculations (1) (finding new center, distance calculations, the actual pathing algorithms), which would reduce the need for expensive hardware mounted inside or project (should a similar route be followed). In our case, Google Maps already contains the ability to do multiple route calculations, and already has multiple mobile implementations that are free, so the possibility is there. Unfortunately, using such a system would make our helmet system dependent on an internet connection, which is more likely to be absent (dead phones, no phones, cheap phones) than a GPS signal. If we want autonomy, we need to think robotic. An autonomous robot will only be able to operate in an environment in one of two ways: learning its environment, or having the knowledge of this environment already. The paper that describes using the latter

method also implements this onto a server that controls the multiple robots (5). In our system, we are looking for a way to implement autonomy in path-following, not finding (although we will need limited ability to get the rider back on route). In order to consume less system resources on our mobile platform, desiring not to use a server, we might have to use path that is already precalculated from a service like Google Maps. However we will still need some of the rudimentary functions and algorithms reported in this same paper.

Currently implemented functions for robots requests (5)

GPS Devices and Logic:

IEEE articles and papers confirmed that the smallest section of the chipset would be the GPS portion. Navigation and GPS are not quite the same and cannot be considered together in research. Two distinct modules were found for implementation. CMOS GPS Receiver - This GPS device used multiple CMOS circuits to determine position. The device uses 56-mW which is low in power, which makes finding a battery easier. The chipset is also only 23 mm2 which makes it small that it can fit within a helmet without discomfort, or a bulky box coming out of the back/side. The chipset uses a 1-bit stream instead of a 2-bit stream, as the 2-bit stream would apparently make the chipset bigger. A 1-bit stream simplifies the ADC (analog to digital converter), while only losing 2dB in ratio of signal to noise. This seems more favorable since the group would be able to understand a 1-bit stream of logic better than a 2-bit stream in a system we've never used before. The amount of power for the

antenna creates the most amount of noise, but the signal to noise ratio is still low enough that interference is not a problem. Multiple other issues arise with the small size of this board. The CPU must be designed to not interfere with the GPS frequency; in order to do this a specific kind of CPU was chosen. Much of the rest of the technical talk is above us, for the moment, but the important parts of the design were understood to a degree. Fortunately, the simple facts still prove this an acceptable board for our intention. The antenna and system work between -40* to 105* C; the design also uses a CMOS design that was shown in many figures, too many for this slide however. The board is also compared to many other boards in terms of inputs and outputs; it seems to do just as well as other boards for being so small. Price was not discussed. GPS Software Receiver - The other more favorable design of GPS that was found was a simple chipset that used only a processor, memory, RF to IF Downverter, and then the PC interface. While the other article focused on the raw design of the CMOS circuitry, this paper offered a top-ended view of how the GPS in this receiver is actually calculated. The design is said to process most of the data of the stream from satellites within 1ms, which is quick and accurate. It takes the device around 5ms to figure out the fine frequency between its antennae and the satellites being communicated, however. This lag may be noticeable to users. The paper goes into great detail of how the logic below actually calculates the GPS signal and determines location. This is most useful as the group now understands the basics of GPS algorithms, and may come in handy when deciding how to proceed into developing the navigation. The paper also goes into detail about the continuous updating of information. 1 ms of stream from satellites can be processed in 0.15ms time on the processor, this is efficiently used as the memory fills up from information from the satellites, and then proceeds to dump it on the board every 10ms, so the total delay is 2ms. While one stream is being emptied into the processor, the other buffer fills

up with new information, and released when the other is emptied. This process streamlines the GPS algorithm, and "seamlessly" integrates data from the GPS. The paper also suggests that for "highly maneuverable vehicles," to input the streams into a "Kalman filter position estimator". This seems very useful to the group as motorcycles are very maneuverable devices.

On the left, the size of the CMOS GPS chips (Sonowal, pg. 548). On the right is the logic loop for GPS on the Software GPS device. (Gramegna, Pg. 233)

Heads up display technology:

One of the key components of this project will be to display the output from the GPS system onto a lens or the inside of the driver's helmet. In order to do so, the group needs to break down the task into the process of displaying the information. Heads up displays can be used in a number of ways. What is typically done is use a

projector (not unlike a projector from a classroom) to send the image through a lens to the intended display. However, when this happens, the display will show the items intended but The solution to this problem is to design a

will also show the negative space around them.

screen to receive the image that can only accept an image of a certain color. In this regards, we

can make the output of our lcd display show only the items we want to see in that color, so they will show up on the screen. feature. This is rather simple quantum physics as well as a very useful

We can design a filter that only accepts the energy associated with the wavelength of a

certain color of light. Everything else will pass directly through. However, this in itself can create problems as the filter screen itself may be a distraction. Another important issue we have to address is where the screen will actually be located. If we were designing with a car, the windshield is flat and easy to project on. However, the curved surface of a motorcycle helmet makes the projection much harder. In order to rectify the problem, the projector itself would need to mimic the shape of the helmet surface. If this is not done, the light may reflect from the surface of the lens onto another location on the lens, and make the images distorted or distract the driver. This can be solved by making the display

element hit the screen at a 90* angle, causing the reflection to return direct to the user, where it will not be noticed.11 Here, we really only have two options. We can build an external clip that attaches to the helmet that projects an image onto the outside of the screen. This is a fairly good idea, but it also can expose the projector screen itself to the elements, allowing for potential unwanted dirt buildup.10 We can also project inside of the helmet, but would have to be cautious of the users head movement. This seems like the more rational of the choices, and can be done

with a few different methods. Among these are the use of a prism, and the use of fiber optics. Projection through prisms is not a trivial task however it has been done before. In U.S. patent 6,181,4759 Optical system and Image display Apparatus, the inventors use a Free Form Surface (FFS) prism to project the directly in the line of

Figure 1: FFS Light Paths

sight of the subject 1 . Though this may not be the way the group to approach the projection it is an option. The optical system and image display apparatus has an "ocular optical system for leading the image displayed by the image display device to an observer's eyeball without formatting an intermediate real image". (Takayoshi Togino, 2001) This means that the user can see both the projected image from the image display device, as well as the scene in front of them without changing the real image. This could be beneficial to the team because it would eliminate the problems of projection onto the front screen of the helmet. However, there are some drawbacks to using this system such as limited field of view (FOV)

Figure 2: Offaxis projection

and a low f-number. To achieve an optical see-through head-mounted display (OST-HMD) with a low enough f-number and a wide enough FOV would be beyond the scope of the group's knowledge and would require more knowledge of optics. (Dewen Cheng, 2009)6 We believe that another non-FFS prism could do the trick for the projection. However, if we chose this option we have to take into account the curvature of the front shield. In U.S. patent 6,353,503 8 for an "Eyeglass display lens system employing off-axis optical design" the inventor describes a process which allows for the projection of an image off-axis from the eye and still has an undistorted image. The patent describes the use of a two lenses attached together which makes up the eyeglass lens. The image is then projected through the image display device to the first lens which has an index of reflection great enough to reflect the image to the eyeball. (Spitzer M. B., 2002) As with the first patent, this does not describe our system, yet the


See Figure 1

knowledge that is provided in the patent can give the group sufficient knowledge on how to handle off-axis projection. The final option that the group can use is described in U.S. patent 5,715,337


for a "Compact

display system". This option again, would be hard for the group to fabricate. It operates with a light source and signal/beam steering to progressively scan the image onto the screen. In figure 6 you can see the flowchart to how this projection system works. (Spitzer M. B., 1998)

SWOT Analysis: Strengths - Given the prices provided by some of the referenced material, this should be a relatively cheap project, sans the actual motorcycle helmet. Two choices with screens, OLED or LED Projection, which adds flexibility. offers many different GPS chip designs that utilize many ways of accomplishing positioning and calibration, this is useful if we find one design doesn't work. Weaknesses - Input method, possibly needs to be a pre-determined route via Google Maps. Too much information displayed on the HUD proves to be less useful than no HUD at all, the group must be careful including enough to navigate, but not too much to overwhelm the user. Opportunities - Lots of room for innovation on all aspects of the project. With a large amount of resources on the subsystems of our project, the entire project has the ability to be profoundly efficient. Threats - There are no leaps and bounds the group must accomplish to understand the fundamentals of the subsystems for our project.

Works Cited 1. Design and implementation of GPS&GIS -based mobile navigation system Li He; Jieming Wu; Xiaoling Fu;. Network Infrastructure and Digital Content, 2009. IC-NIDC 2009. IEEE International Conference on (978-1-4244-4898-2) 6-8 Nov. 2009.p.953 Source: IEEE Electronic Library Online ( Link to content: 2 Is unreferenced in this document, but may be useful as recommended reading to better understand GIS. 2. A Study for 3D Virtual Campus Navigation System Based on GIS Dan Luo; Guoxin Tan; Liuying Wen; Shujun Zhai;. Wireless Communications, Networking and Mobile Computing, 2008. WiCOM '08. 4th International Conference on (978-1-4244-2107-7) 12-14 Oct. 2008.p.1 Source: IEEE Electronic Library Online ( Link to content: 3.Chu, K., R. S. Brewer, and S. R. H. Joseph. "Traffic and Navigation Support through an Automobile Heads Up Display (A-HUD)." i Department of Information and Computer Sciences Technical Report (2008) SCOPUS. 12 Mar. 2010 <>. 4.Yung-Ching Liu, Ming-Hui Wen, Comparison of head-up display (HUD) vs. head-down display (HDD): driving performance of commercial vehicle operators in Taiwan, International Journal of HumanComputer Studies, Volume 61, Issue 5, November 2004, Pages 679-697, ISSN 1071-5819, DOI: 10.1016/j.ijhcs.2004.06.002. ( 5.Josep M. Mirats Tur, Claudio Zinggerling, Andreu Corominas Murtra, Geographical information systems for map based navigation in urban environments, Robotics and Autonomous Systems, Volume 57, Issue 9, 30 September 2009, Pages 922-930, ISSN 0921-8890, DOI: 10.1016/j.robot.2009.06.003. ( Keywords: Map-based navigation; Mobile robotics; Geographical Information Systems (GIS)

6: Dewen Cheng, Y. W. (2009). Design of an optical see-through head-mounted display with a low fnumber and large field of view using a freeform prism. Beijing: Department of Optoelectronic Engineering, Beijing Institute of Technology. 7: Spitzer, M. B. (1998). Patent No. 5715337. United States of America.

8: Spitzer, M. B. (2002). Patent No. 6353503. United States of America. 9: Takayoshi Togino, K. (2001). Patent No. 6181475. United States of America. 10: 11: 12: Nomi Sonowal, Rajeev Yadav and S. Kannan. Real Time GPS Software Receiver with New Fast Signal Tracking Method., Centre for Air-Borne Systems, Bangalore, India. 2008 13: G. Gramegna, P. Mattos, M. Losi, S. Das, M. Franciotta, N. Bellantone, M. Vaianna, V. Mandara, M. Paparo. A 56-mW 23-mm2 Single-Chip 180-nm CMOS GPS Receiver With 27.2-mW 4.1-mm2 Radio., Journal of Solid-State Circuits, Vol. 41. March 2006

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