- freely available
Electronics 2016, 5(2), 19; https://doi.org/10.3390/electronics5020019
2. Materials and Methods
2.1. Defining the Functional Requirements and Conceptual Design
- The device has to be able to measure the distance from the rear end of the host vehicle with sufficient range and sufficient accuracy to be able to operate at motorway speed limits (130 km/h).
- The device has to be able to measure the instant velocity of the host vehicle with sufficient accuracy to calculate the required safety distance.
- The device has to visually alert the driver(s) of the trailing vehicle(s) whenever their safety distance to the host vehicle is too short.
- The device has to alert the driver of the host vehicle of a possible or inevitable rear-end collision.
- The device has to be able to record all of the ride parameters (time, location, velocity, acceleration) for the last 1000 km of travel.
- The concept of the device must be such that a realization of a working prototype with the basic subset of functions will be possible by integrating components that are either readily available or can be made using the existing workshop equipment.
- The device must be installable into any motor vehicle with on-board electrical power without requiring any permanent changes to the vehicle or its systems.
- The previous seven requirements shall be fully fulfilled while minimizing the cost of the components.
- C-1 = a2 + b1 + c2 + d1 + e1 + e2 + f1 + g1 + h2 + i1 + j2 + k2 + l3
- C-2 = a3 + b1 + c2 + d1 + e1 + e2 + f1 + g1 + h2 + i1 + j2 + k2 + l3
- C-3 = a2 + b3 + c2 + d2 + e1 + e2 + f1 + g1 + h2 + i1 + j2 + k2 + l3
- C-4 = a4 + b1 + c2 + d4 + e1 + e2 + f1 + g1 + h4 + i1 + j2 + k2 + l1 + l5
- C-5 = a2 + b2 + c2 + d5 + e1 + f3 + f4 + g1 + h2 + i1 + j1 + k1 + l1 + l3
2.2. Design and Adaptation of the Selected Concept
2.3. Selection of the Components
2.4. Prototype Assembly
2.5. Software Setup and Development
2.6. Testing the Finished Prototype
- The allowed relative measurement error of the host vehicle velocity (from the GPS module) in the 30–200-km/h range is below 5%.
- The allowed relative measurement error of the host vehicle velocity (from the radar sensor) in the 30–200-km/h range is below 10%.
- The allowed relative measurement error of the trailing vehicle velocity (from the radar sensor) in the 30–200-km/h range is below 10%.
- The measurement range of the radar sensor when measuring the distance to target is within the 5–70-m range.
- The allowed relative measurement error of the measured distance from the rear-most point of the host vehicle to the front-most point of the trailing vehicle on the same traffic lane within the 5–110-m range is below 10%.
- The reliability of the alert activation when the measured safety distance of the trailing vehicle is too short must not be below 95%; in other words, the alert shall activate in at least 19 of 20 cases of safety distance rules violations.
- The radar sensor must always provide reliable distance-to-target measurement without any disturbances in the form of unexplained values or significant oscillations.
- The radar sensor must be able to sense a vehicle abruptly cutting in onto the traffic lane on which the host vehicle is driving.
- The radar sensor must not sense objects outside the roadway or vehicles driving on other traffic lanes as a trailing vehicle.
Conflicts of Interest
Global Positioning System
|RADAR (also “radar”)|
RAdio Detection And Ranging
LIght Detection And Ranging
Light Amplification by Stimulated Emission of Radiation
Liquid Crystal Display
Global System for Mobile Communications
Universal Serial Bus
Digital Signal Processor
Universal Asynchronous Receiver and Transmitter
Secure Digital High-Capacity
National Marine Electronics Association
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|a||Distance measurement||LIDAR||RADAR||LASER||image analysis||ultrasound||active infrared||passive infrared|
|b||Host vehicle velocity measurement||GPS||vehicle Hall sensor||optical sensor|
|c||Data processing||microcontroller||embedded computer||desktop computer||laptop computer|
|d||Alerting the other vehicle’s driver||LED matrix display||transparent LED net||projection on glass||strobe flash||vehicle rear lights||LCD screen|
|e||Power supply||vehicle on-board power||independent battery||solar cells||dynamo|
|f||Attachment to any vehicle||suction cups||adhesive||bolts||snap-in joints|
|g||Acceleration measurement||digital 3-axial accmtr.||analogue 3-axial accmtr.|
|h||Automatic distress alert||GSM voice call||GSM text message||GSM data||Wi-Fi to mobile phone||Bluetooth|
|i||Alerting the host vehicle driver||audible: beep||audible: speech||visible: light||tactile: vibration|
|j||Parameter recording||hard disk||memory card||tachograph|
|k||Recording locations with frequent violations||hard disk||memory card||tachograph|
|l||Data transfer from the device for analysis||wired USB||wired serial||wired Ethernet||wireless Bluetooth||wireless Wi-Fi|
|Component||Manufacturer and Type||Cost Estimate (€)|
|Radar sensor with DSP board||RFbeam Microwave GmbH K-MC3||560|
|Single-board computer||Raspberry Pi Foundation Model B||30|
|SDHC memory card||SanDisk Ultra (8 GB Class 10)||8|
|GPS module||u-blox AG Antaris 4 AEK-4T||200|
|Power supply voltage regulator + accessories (capacitors and heat sink)||Generic 7805-TO 220||4|
|LED-matrix display (including a driver MC)||Olimex Shield-LOL-10 mm-Green||25|
|polypropylene (PP) enclosure||TRACON Electric Co. 200 × 150 × 75 mm||6|
|Suction cup mount||Bohle AG Veribor||35|
|Cables, connectors, adapters||various||18|
|Measuring Wheel Distance (m)||Average Radar Measurement (m)||Average Absolute Error (m)||Average Relative Error (%)|
|1||GPS host vehicle velocity measurement error under 5%||-||-||not checked, GPS used as the reference|
|2||Radar host vehicle velocity measurement error under 10%||√|
|3||Radar trailing vehicle velocity measurement error under 10%||-||-||not checked, assumed OK due to fulfilled Criterion 2|
|4||Radar measuring range 5–70 m||√|
|5||Radar distance measurement error under 10%||√|
|6||Alert activation rate over 95%||√|
|7||Radar provides reliable, disturbance-free distance measurement||x||false targets due to electrical interference|
|8||Radar senses trailing vehicle cutting in onto the host vehicle lane||√|
|9||Radar must not sense objects outside the roadway or vehicles on other lanes||x||false alerts in tight curves|
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