Characterisation of ultrasonic sensors for vehicle occupancy detection

Abstract

Automotive companies are constantly evolving and adapting new technologies to offer better services and solutions. Methode Electronics is a leading company in this area, designing and manufacturing thousands of switches each year. In such an industry, a company like Methode must offer innovative products to keep up with the competition. This project serves as a proof of concept for such an innovative system. The proposed system is a seat belt reminder that uses one type of sensor, and can also function as a vehicle intrusion detector. This system is to be implemented in an overhead panel. The aim of this project is to correctly detect the occupant of the passenger seat, be it a person or an object, and implement an algorithm that would monitor the passenger seat area for any intrusions. Several different proximity sensors were compared to identify the best sensor for the application. Ultrasonic sensors were chosen and several ultrasonic sensors on the market were considered, ultimately choosing the HRLV-Maxsonar-EZ2. This sensor was tested to evaluate its detection zone for targets of different sizes, to analyse the error in the reported readings and to verify the sensor’s performance as the temperature varies. Two algorithms were implemented, one for vehicle intrusion detection and one for occupancy detection. Both algorithms were tested for different scenarios and under different conditions, to test their ability to correctly detect an occupant or intrusion. From the tests, it was concluded that the proposed system is able to correctly detect an occupant on the passenger seat and detect intrusion in the vehicle. There were some limitations of the system, and these were discussed in detail to find ways how to improve the system.