In 2009, the National Highway Traffic Safety Administration (NHTSA) conducted a study of electric and hybrid cars with regards to pedestrian safety. This study revealed that electric and hybrid cars were twice as likely to cause a pedestrian accident over standard vehicles. A follow-up study in 2011 showed that this number is actually 35% more. One way to decrease these accidents is to assist the pedestrian to hear the car approaching. People have grown accustomed to the sound of traffic and it is instinctual for them to listen for certain noises in the environment as they negotiate the space in and around cars. By adding a familiar sound to the electric and hybrid car’s engine, the audio motor controller (AMC) can help reduce or eliminate this increase in pedestrian accidents.
Basic Design Requirements
Engineering the audio motor controller (AMC) with the intentions of quality requires a design with certain criteria. The Product Design Specification (PDS) focused on safety, materials, cost, environmental restrictions and regional regulations. To meet the pedestrian safety goal, the external speakers’ location and environmental factors were addressed. The driver’s safety was assessed and parameters regarding heat generation and ventilation were developed. The materials used must be able to resist thermal conductivity, melting temperature, and specific heat capacity. The environmental conditions that the AMC is designed to withstand include temperature changes, water wear, and vehicle vibration. Regional regulations took product testing, improvement, customer feedback and required markings into account. Given that regional regulations have dictated the need for Acoustic Vehicle Alerting Systems, similar products have been developed and the cost will need to be comparable.
Proof of Concept
Team 11A’s proof of concept verifies the Audio Motor Controller’s potential to perform essential functions. The goal of the proof of concept is to test the sensitivity level required for the Accelerometer (similar to the one that will be purchased) and to ensure the speakers demonstrate the decibel level required to warn a pedestrian of incoming traffic.
Using a golf cart, team 11A will test the audible level of the speaker system using two smartphone applications. The first is the application XLR8, which uses the internal accelerometer of the phone to generate a mimic vehicle engine sound. The phone using this application will be hard mounted inside the golf cart during testing. The second is Physics Toolbox, which allows a pedestrian to measure the how loud the audio output is at multiple range increments.
The second test will utilize a standard combustion vehicle and again both smartphone applications. With both phones hard mounted inside the vehicle, the team will collect data for several different acceleration, braking and turning situations allowing proper accelerometer selection.
Product Design Specifications
The product design specification was based on the project requirement specifications (PRS). The specifications ranged from materials, usability, labeling, etc. The PDS step provides standards for the design of the Audio Motor Controller. In addition, the sponsor also had input on what is specifically required in the PDS.
One of the main product specification specifically required by the sponsor is “3.PRS.1.2” in which a third-party device should be compatible with targeted vehicles. To simplify, the sponsors wants the product to also works for an internal combustion vehicle. Even though the design revolves around an electric vehicle, by utilizing an accelerometer as a sensor, the product will work with virtually anything that accelerates. As a result, the current design is definitely satisfied the specification required by the sponsor.
Another important PDS that was implemented after the engineering analysis of the product is “3.PRS.11.” It stated that the product must operate in a well-ventilated portion of the vehicle to dissipate heat. During the engineering analysis, Matt discovered that the heat generated inside the control box has to be well ventilated in order to maintain function of the Audio Motor Controller. The consequence of an overheating of the controller box could potentially cause fire. As a result, a box material and design shape has to be carefully considered to withstand a specified temperature.
Detailed Characteristics of Audio Motor Controller (AMC)
The AMC works using three main components: a data collection device, a logic chip and an audio output system. The data collection system collects essential data while you drive the vehicle and sends it to the logic chip. The logic chip is programmed to utilize the data received and output an audio signal based on the data to mimic standard engine sounds. The audio system receives the signal from the logic chip and outputs audio both inside and outside the vehicle.
Data Collection Device
The data collection device for the AMC is an accelerometer called the ADXL337. The accelerometer measures acceleration in the X, Y and Z axis. The ADXL337 is an analog accelerometer, therefore it will produce voltage levels related to acceleration. The ADXL337 operates at 1.8 to 3.6 V. It can work in temperatures of -40 to 85 ͒C; therefore, it can operate in extreme conditions.
The ADXL337 will be connected to an Arduino Uno. The Power supply, Self-Test, and Ground will be connected to the Arduino’s power section, while the X, Y, and Z will be connected to the analog inputs of the Arduino. The Arduino will receive acceleration readings based on voltage change from the accelerometer. The Arduino will the process the data in order to communicate with output system.
Audio Output System
The last step is to interpret accelerometer data and output it as varying decibel levels using loudspeakers. A theoretical code will be used to control what melody to play and how long it should play. The speakers used for the output system is BOSS MCBK420B Bluetooth speaker system. It operates from 80Hz to 15kHz, which satisfies the NHTSA standards. The speakers and amplifier is weather rated; therefore, it can withstand normal vehicle operating conditions.
Purpose of Audio Motor Controller (AMC)
The purpose of the Audio Motor Controller (AMC) being developed is to comply with the safety regulations outlined by the National Highway Traffic Safety Administration (NHTSA). According to the NHTSA, there has been a significant rise in pedestrian incidents due to the lack of audible output of electric vehicles. Regulations are currently planned for the calendar year of 2018 to address the issue, which the AMC will comply with. The qualitative goals of this project are to provide a sense of safety to the public while operating electric vehicles in urban environments. AMC product has accomplished using an acoustically pleasing tone to prevent any annoyance or discomfort felt by pedestrians. The warning sound will vary with acceleration to properly warn the pedestrians of oncoming traffic.
As a result of complying with the NHTSA, AMC will be a standard product that consumers can rely on to satisfied the government regulations regarding a lack of audible output of electric vehicles. In addition, AMC is designed to be easy to installed product without requiring any professionals help. Moreover, with the product cost of less than $200, AMC is an ideal product that specifically targets the average consumer.
While our product is based mainly on purchased components, it required a lot of effort in other ways. The control box is a prefabricated item designed specifically for use with Arduino Uno products and is injection molded ABS plastic. A small notch had to be added to the control box to allow the product to properly house the battery and connector. This was done using a hot cutting knife and a Dremel tool.
Once the Arduino Uno was placed into the box, the battery connector was modified. This extended the wires to accommodate the required length needed to connect the battery to the Arduino Uno at the end of the box using solder and additional wire. The accelerometer and Bluetooth devices were then added to the control box locating and bonding them in place nearby the Arduino Uno. Stable location of the accelerometer was seen as a key requirement of the assembly of the product to ensure proper results. All products were bonded into location using hot glue.
The programming of the Arduino Uno proved to be both tedious and complicated. The code required to register the accelerometer input and output an audible alert signal took a lot of time and continued focus. Once the team discovered that is was possible to modify the HC-05 Bluetooth adapter code from slave to master, we were able to develop the coding to allow the system to wirelessly connect to the speaker system for the audible alert output. Finally, after mounting the control box system on a RC car using 3M VHB tape, the team had its final prototype complete.
Fig. 1. Matt is modifying the control box to have a small notch for the battery connector. The battery connector wire need to extended out from the control box to be able to plug into the Arduino.
Fig. 2. This is a control box to enclose a 9V battery, Arduino Uno, Accelerometer Sensor, and Bluetooth Chip. Since this is a third party manufactured control box, the box was designed to fit every component into the enclosure.
Fig. 3. These are the pre-assembly parts for the Audio Motor Controller (AMC). Since every part are made by third party manufacture, the team did not have to fabricate any parts of the AMC. As mentioned earlier, only a slight modification to the controller box was made to accommodate the 9V that powers the Arduino Uno.
Testing and Results
The Audio Motor Controller (AMC) was tested using a radio-controlled car (RC car). The test consisted of an acceleration from zero to maximum velocity in the fastest time possible, hard turning and a fast deceleration. The test has completed a total of six times over the course of six days to ensure repeatability of the product (as seen in Table I). Through each test, there was not a single incident when the product failed in any way. The AMC performed beyond expectations in terms of quality and accuracy.
AMC attached to RC car product testing phase.
The problem with the electric vehicle is they are too silent and have increased the chances of pedestrian accidents. The whole idea behind the AMC is to provide electric vehicle drivers with the opportunity to alert pedestrians when their vehicle is approaching. The product was able to accomplish the team’s goal by outputting an audible alert sound when accelerating and decelerating. The AMC doesn’t entirely make things easier for the user. However, the AMC may prevent pedestrian accidents which would most definitely make things easier for the user in terms of legal reasons. Positive feedback from the public on innovation day and previously compiled surveys indicate that many users of electric vehicles feel that an audio output is important for safety. The final design of the AMC directly matches the purpose of a warning audio output and performs exceptionally well.
Meet the Team
Currently at a senior standing in Mechanical Engineering at UNR, Brian Tobey will be graduating with a GPA over 3.2. During the school year he works part time at International Gaming Technology designing prototype parts for slot machines, and learning directly from top Mechanical Engineers in the company. Brian, being native to the Nevada area, currently resides on the Pyramid Lake Paiute Reservation. After graduation, he plans on working directly with the Paiute tribal council to improve the quality of life for Native Americans.
Jeremiah Cayanan is currently a senior undergraduate in mechanical engineering expected to graduate in May of 2017. He started interning at Ormat Technologies in April. The job entails updating plant drawings and learning it’s day to day operations. Jeremiah is originally from the Philippines. After graduation, he plans to work with Ormat to develop and improve power plants in the state of Nevada.
Somkiat Albert Yeesuntes is a senior undergraduate student majoring in mechanical engineering. He expects to graduate in May 2017 at the University of Nevada, Reno. He has an Associate of Science Engineering Emphasis degree from Truckee Meadow Community College. Originally, Somkiat is from Thailand. He moved to the United States at the age of ten. Residing in the U.S., Somkiat feels an obligation to fulfill his duty as a naturalized U.S. citizen to better improved this great nation through engineering. After graduation, Somkiat is looking forward to working as an engineer to produce a cutting edge technology for the U.S. military.
James Del Castillo
James Del Castillo is a senior at the University of Nevada, Reno and is pursuing a degree in mechanical engineering. He currently holds an Associate’s degree with engineering emphasis from Truckee Meadows Community College. James served in the military and is federally licensed to fix aircraft. He currently works on campus in the building maintenance department and plans on becoming an aircraft inspector upon graduating.
Matthew Catterson is now a senior at the University of Nevada, Reno after taking a significant break during his education. He is currently a full time employee at Tripp Enterprises, where he is a project manager. He has well over 10 years of experience in engineering and project management working at local companies such as IGT, Quality Plastics, and SDG (now Scientific Games). He has been the lead designer on several patented projects, and currently seeks to complete a graduate MBA degree after completing his undergraduate career. He plans on utilizing his education to pursue an upper level management position at Tripp Enterprises in the future.
Team 11 Bookkeeping would like to take an opportunity to thank the people, industry, and the university for helping in the development of the AMC. The AMC project would not be possible without the help of:
- The University of Nevada, Reno for providing teaching staff and amenities during the design and production of the AMC.
- TRIPP Enterprises for sponsoring the project.
- Ryan C. Tung for the mentorship during the design phase of the project.
- Jessica Connolly for providing the workspace and putting up with the team during the troubleshooting phase.