Motorcycle Crash Detection and Alert System Zack Stein April 1, 2013 MCEN 5228: Microsystems Integration Mechanical Engineering Department University of Colorado at Boulder Boulder, CO 80309 ABSTRACT: There is a large void in post- crash motorcycle emergency alert systems. My project focuses on designing a system that will integrate many components into a life saving accelerometer system for a motorcyclist unfortunate enough to be involved in an accident. PROJECT DESCRIPTION: Motorcyclists are 35 times more likely to experience a fatal accident than passenger vehicle operators. 1 With such a high number of accidents per year, safety is a critical concern for many riders. Studies have shown that decreasing the response time for emergency services increases chances for survival by a significant margin. 2 Currently the market Figure 1- Image depicting a motorcycle crash for motorcycle safety equipment is saturated with helmets, jackets, and other protective articles of clothing. My project attempts to fill a void with life- saving post 1 (MotorcycleAccident.org, 2013) 2 (Blackwell & Kaufman, 2002) crash technologies. Current post- crash technologies only sound sirens and flashers that would not be helpful in a rural location. 3 I have found no current systems that contact emergency response personal via the cellular network. My idea for the microsystems project is to create a system of accelerometers and microcontrollers that will do two important life- saving actions. First the system would monitor the acceleration readings from each of the accelerometers ensuring that no high- g accelerations are detected like those seen in a crash. If the system senses a high- g acceleration, an emergency signal would be sent out via a GSM connected module or through ones smartphone. The other key aspect to the system would be usage of the individual accelerometers to alert the emergency response teams of any possible injury locations due to high- g accelerations at specific locations around the rider s body. This system, along with a standalone GSM module or smartphone, could help revolutionize emergency response for accidents. DESIGN IDEAS: After researching available options for semiconductor chips and microsystems, I have found that this project is significantly less about designing a new 3 (Limelite Inc, 2013) 1
stand- alone system than it is about integrating multiple already- available systems. The following is a list of the possible components that will be required to create a functioning system: Arduino GSM Shield 4 This circuit board allows for a stand- alone Arduino board to be connected to a GSM network with the usage of a SIM card. This board is the alternative to using a smartphone. Arduino Micro 5 The ADXL377 is a high- G accelerometer that has been used in Indy car safety systems for many years. 8 Since it has proven successful in Indy car safety systems, I know that such an accelerometer would work for my crash detection system. I also chose this device due to its relatively low weight as well as the cost at $4.79 each, when purchasing in bulk. BLE Mini Bluetooth 4.0 iphone module 9 While there are many options for microcontrollers and development boards, I chose the Arduino Micro due to its relevantly easy user- interface, small size, and high number of inputs (20 digital and 12 analog). 6 This should allow me to design a system with a high number of accelerometers while keeping the system small and lightweight. ADXL377: 3- AXIS ACCELEROMETER 7 4 (Dangi internet Electronics S.L., 2013) (Dangi internet Electronics S.L., 2013) 5 (Dangi internet Electronics S.L., 2013) 6 (Dangi internet Electronics S.L., 2013) 7 (Analog Devices, 2013) The above module would replace the GSM board in my design. While I feel that having a standalone board would be better for crash survival as well as low power consumption, I am realistic with the market moving towards smartphone apps and integration. This module would allow my Arduino Micro to relay information to a smartphone application that could monitor the data in real- time. Design Conclusion: 8 (Analog Devices, 2013) 9 (Red Bear Company Limited, 2013) 2
These components are basic components that could fill the roles required to develop a crash detection system for a motorcycle. With the pieces laid out, I foresee a product being developed that could hit a $200 price point. For a prototype system, the cost for a 10- accelerometer system would be approximately $150. KEY ANTICIPATED ISSUES: While the majority of the components have already been developed, I feel that the biggest challenge to develop a successful product will be integration of the components. While each individual component is small and low power, the system must be interconnected throughout the person s clothing in order to be fully effective. This will require well- engineered solutions in order to maintain comfort and usability. I plan to focus on creating a user- centered design that is both intuitive and follows Apple s philosophy of just working. Besides the engineering required to integrate each of the components into a system, I can also anticipate a single integrated circuit board that would hold all components minus the accelerometers. It is possible to integrate the accelerometers, however, the injury pinpointing would be lost. A more cohesive design for the individual chips would significantly reduce the cost, power dissipation, and size of the product. Another major issue that I will face in the creation of this product is the algorithms used to detect whether or not a crash event has occurred. Due to the nature of the accelerometer mounting locations, each accelerometer will have a different substrate with which it is mounted. As a result, the acceleration values seen on an individual accelerometer may not detect a crash. My plan is to create this algorithm using a trial and error method by mounting the system to actual motorcycle equipment in order to find acceleration values for various locations around the body. In the next semester I plan to apply for an EEF grant in order to bring this project into reality and allow me to purchase test gear and electronics. I anticipate that my system will be extremely useful in helping to mitigate some of the risks involved in travel by motorcycle. ANALYSIS When contemplating the future of this system, I chose to focus on the two most important aspects in order to create a real prototype as quickly as possible. I first chose to analyze a method for integration into current motorcycle equipment. In order to fit all of the required electronics, I chose to take advantage of a currently unused volume on riders backs called the speed hump as seen in Figure 2. This space is currently empty being supported by a piece of curved plastic. My design takes advantage of this space by integrating everything into this volume including the Figure 2- Motorcycle GSM module, the Suit with Speed Hump Arduino microcontroller, and the battery. These components will be protected in a plastic shell in the event of a crash on the rider s back. I began by creating a shell that would fit in this area. After determining 3
the volume that I had to work with, I created simple CAD models for each of the components as seen in Figure 3. The blue Figure 3- Inner Layout for System CAD LAYOUT Arduino Micro is the central component in green Arduino GSM is the red component The Battery is the blue component The accelerometer is the small black component component is the single most important component for creating a successful product, the battery. I chose to further analyze the battery life as it is the key to creating a system that can work for long periods of time without user charge. I began my analysis by focusing on current battery technology and their energy densities. I chose to use the iphone 5 battery as my benchmark. The iphone s battery has dimensions of 82.3mm x 31.3mm x 3.9mm 10. When combining with the total charge of 1440 mah at 3.8 Volts 11, I found that this battery had a density of 1.4334 x 10 8 mah/m 3. Now 10 (r2shyyou, 2012) 11 (GSM Arena, 2013) that I had the battery s power density, I found the total discharge rate for the system. I used average rates for all of the modules. It should be noted, that depending on the demand of both the GSM module and the microcontroller, the power usage could be significantly higher than my calculated value. Due to this fact, I increased the battery volume in order to provide more space for the battery. Within the power loss calculations, I included power loss through conductive threading which I plan to use to connect all of the accelerometers to the central system. The total anticipated power dissipation for the system was calculated to be 156 ma. The components included in this calculation were the GSM module, Arduino microcontroller, twelve accelerometers, and twenty feet of conductive threading. The final step in analyzing the theoretical life of my device was determining the volume of the battery. Using Solidworks sensors, I found that the blue battery in Figure 3 has a volume of 243.5 cm 3. To put this into perspective a standard non- replaceable battery for a Macbook Pro has a volume of 276 cm 3 so my battery is a definitely a manufacturable volume 12. Using the iphone 5 s battery power density found in combination with the volume of the battery and the total power dissipation, I found that my system would be able to operate for approximately 225 hours. While this is most likely an overestimate of the true life of the system, it allows me to get an estimation for the current design. When creating a prototype of the system, I plan to use off- the- shelf laptop batteries to power the device. These will be approximately the same size and weight as the current design. 12 (Amazon, 2013) 4
CONCLUSION A system similar to the one described in this report would allow motorcycling to become significantly safer by allowing emergency services to locate a downed rider. I hope that I will receive a grant in the coming months in order to implement a prototype that could end up saving the lives of thousands of individuals. While upcoming technologies will create an even more impressive system, the technology is currently available to implement the motorcycle safety system today. MATLAB CODE close all clear all clc x=82.3/1000; %m http://forums.macrumors.com/showthread.php?t =1497391 y=31.3/1000; %m z=3.9/1000; %m volume=x*y*z; %m^3 total_power=1440; %mah power_density=total_power/volume %mah/m^3 battery_voltage=3.8; %V http://www.cowae.com/the-iphone5-multicharger-battery-components-exposurecapacity-1440mah-voltage-3-8v.html arduino_gsm=100; %ma peaks at 2A with standby at 1.5mA http://imall.iteadstudio.com/im120417009.htm l arduino_micro=50; %ma http://arduino.cc/en/main/arduinoboardmicro accelerometer=0.3; %ma http://www.analog.com/en/mems-sensors/memsaccelerometers/adxl377/products/product.html thread_resistance=300; %Ohm/Foot https://www.sparkfun.com/products/8544 thread_length=20; power_required=arduino_gsm+arduino_micro+acc elerometer*12+battery_voltage^2/(thread_resi stance*thread_length)*1000 %ma %charge time for a single iphone battery charge_life=total_power/power_required; %hours %determine battery size based on time required desired_hours=25; battery_size=power_required*desired_hours/po wer_density; %determine battery life off of solidworks model current_design_size=14.86*0.000016387 % m^3 design_time=current_design_size*power_densit y/power_required total_power=current_design_size*power_densit y Works Cited: Amazon. (2013). MacBook Pro 15 inches Unibody Battery A1321-661- 5211, 661-5476. Retrieved April 30, 2013, from Amazon: http://www.amazon.com/macbook- inches- Unibody- Battery- A1321/dp/B0044EKJDQ Analog Devices. (2013). ADXL377: 3- AXIS HIGH g ANALOG MEMS ACCELEROMETER. Retrieved April 4, 2013, from Analog Devices: http://www.analog.com/en/mems- sensors/mems- accelerometers/adxl377/products/product.ht ml Blackwell, T. H., & Kaufman, J. S. (2002, April 9). Response time effectiveness: comparison of response time and survival in an urban emergency medical services system. Retrieved April 4, 2013, from PUBMED.GOV: http://www.ncbi.nlm.nih.gov/pubmed/11927 452 Dangi internet Electronics S.L. (2013). Arduino GSM Shield (integrated antenna). Retrieved April 4, 2013, from Arduino Store: http://store.arduino.cc/ww/index.php?main_ page=product_info&cpath=11&products_id=2 44 Dangi internet Electronics S.L. (2013). Arduino Micro. Retrieved April 4, 2013, from Arduino Store: http://store.arduino.cc/ww/index.php?main_ page=product_info&cpath=11&products_id=2 45 GSM Arena. (2013). Apple iphone 5. Retrieved April 29, 2013, from GSM Arena: http://www.gsmarena.com/apple_iphone_5-4910.php Limelite Inc. (2013). Crash Alert: Emergency Response System. Retrieved April 4, 2013, from Crash Alert: http://www.motorcyclecrashalert.com/ MotorcycleAccident.org. (2013). Motorcycle Accidents Statistics And Possible Causes. Retrieved April 2, 2013, from MotorcycleAccident.org: http://www.motorcycleaccident.org/motorcy cle- accidents- statistics- and- possible- causes/ r2shyyou. (2012, November 27). iphone 5 battery dimensions (LxWxH)? Retrieved April 29, 2013, from Mac Rumors: http://forums.macrumors.com/showthread.p hp?t=1497391 Red Bear Company Limited. (2013). BLE Mini. Retrieved April 4, 2013, from Red Bear Labs: http://redbearlab.com/blemini/ 5