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Virtual
Rumble Strip Design Project
Requirements Specification (Updated 9/29/05)
The way to improve safety is to improve warning systems. A smart car that knows when a problem is occurring would be able to warn drivers of the problem before it happened. The system should be non-intrusive during normal driving situations, but be effective in warning the driver when there is a problem at hand. Proper detection of the lanes and systems to warn drivers must be easy to use and maintain. This document is the requirement specifications sheet for just such a system of accident prevention. It should be reasonably cheap compared to the cost of the car and easily readable by all drivers. The Deliverables: There are five deliverables as listed below:
Special
Restrictions:
Principles of Operation: The car system should be used on proper highways. A competent driver should always be using the vehicle, and should not rely on the system for 100% control. The system will recognize when it is on a highway system and assess the location of the car in relation to the middle of the lane. Safety systems will be used to warn the driver if the car is moving out of this area, and do so safely. Audible or visual warnings are to be given if the car is moving out of the lane. User Interface: The user interface will be no more then a set of warning lights or audible warnings. The system will work when on a highway with correct markings. Input: The input is the position of the lane the car is traveling down in relation to the car. The data obtained from the road will vary with the state of the road. The device is expected to work on a dry and moderately clean road. The position of the road to the car will be calculated using sensors that detect a line or lines on the road. Using multiple sensors will allow the car’s computer to calculate where the line is in relation to the car, enabling the car to tell exactly where it is in the lane. The sensors will not only take in the lines as data, but also the lack of lines and the data will be processed to determine position. Another input will come from the transmitter for the remote control car. The car will respond to any driving command that is stock for the device. In addition, the virtual rumble strip device will be able to be toggled on and off using a button on the transmitter. The act of toggling this device by itself should not in any way effect the control of the vehicle. All commands from the transmitter will be transmitted by radio frequency. The transmitter is not expected to work over a distance greater then 20 feet, though it may work at a much larger range, depending on the model car we choose. Output: The outputs will be a group of light-emitting diodes (LEDs) positioned on top of the car in a line parallel to the road, that light to represent the position of the car with respect to the center of the road. The LEDs used should be all the same color, and should be easily viewed from any angle. In the off state, it should appear as though there is no light being emitted, where as in the on state, it should be bright, to eliminate confusion. The LEDs will respond to the lane as follows: 1. When the system is toggled off, the LEDs should not light. 2. When toggled on, all of the LEDs should light for 1 second, and then display the correct data as explained in the next 3 items. 3. If the car is in the center of the lane, no LEDs should light. 4. If the car is not in the center of the lane, the LED(s) that is (are) lit should be the closest to the center of the road. 5. No more then 2 LEDs should be lit at any time except at start up. User’s
Manual: This device will alert you
if your car is drifting out of your lane of traffic on the highway. A simple system of lights will tell you how
far you have drifted out of your lane, and will indicate where you should
move to get back to your lane. To use
the system simply activate the switch on the transmitter. All of the lights should flash on, at this
point. If any of the lights do not
flash on, that light is burnt out and will need to be replaced. Now that the system is on, reading the LEDs is simple!
The LEDs will always indicate where the
center of the road is. This means if
you drift to the left, you will find that the first LED to the right from the
center will light up. If you continue
to the left, the second LED to the right from the center will light up, and
so on. This indicates you should move
back to the right, and the further out the light is, the further right you
have to move to be back in the center of the lane. When switching lanes, the system can be
turned off by the switch located on the transmitter. When the center light is on, you are in the
center of the lane. Acceptance Tests: The performance test will be done at five levels 1. Ensure that the sensors can find the tracking line. 2. Ensure that the Virtual Rumble Strip can be toggled on/off. 3. Ensure that the RC car be driven by a microprocessor chip with pre-programmed instructions. 4. Make certain that the chip can drive the RC car down the tracking line. 5. Ensure that the RC car functions properly under real world conditions. Tracking Line 1)
During the tracking process, we will test the sensors
to make certain that they detect a line or lines on the road. At this phase we will be using an
oscilloscope to test the voltage output by our sensors to ensure they are
working properly. Toggle the Virtual Rumble Strip 2) The system will be created so that the user can turn the system on and off. The sensors should be able to sense the tracking strip within a short time of initiation. RC car Driven by Microprocessor 3) A microprocessor chip will be hard coded to drive the RC car over a pre-designated course. The chip will need to control speed and the steering of the vehicle. Using variable outputs on the microprocessor, this should be achievable. Microprocessor follows Tracking Line 4) For this portion, the microprocessor must be programmed to keep the car directly above the tracking line. Feedback control systems will need to be designed to monitor the degree of deviation. Real World Testing 5) The Virtual Rumble Strip RC Car will be observed to be functional while driving on real concrete. Product Cost: The end-product is approximately proportional to the cost of the parts. To achieve the target of not exceeding our Departmental $500 budget, we will only build one prototype of our design using this allocated money. The parts include the electronic components, and the RC car. Dispute Resolution: Any disagreements that can not be resolved between the team members will be discussed first with the Project Advisor. If further problems ensue, then the Course Coordinators will be brought in to help solve the situation. Work Cited (1)J.-S.Wang and R. Knipling, “Single vehicle roadway departure crashes: Problem size and statistical description,” USDOT NHTSA,Washington, DC, DOT HS 808, Mar. 1994.
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