# Airbag Protection and Alerting System for Elderly People
## 4 Results and Discussion  
This part represents the experimental findings and engages in a comprehensive discussion of their implications. Figure 16 shows the final design of the proposed system. All experiments were conducted related to the standing position. Environmental conditions were all assumed to be within the specifications and ambient conditions provided in the sensor's datasheet. Also, the pipe was made of plastic, so it was resistant to corrosion. The electrical components were covered with silicon and placed in a plastic box. This makes the system relatively water and dust proof. The electrical components have a relatively high resistance to heat based on their data sheets and our tests. Figure 14: Sending SMS canceled interface. Figure 15: Received SMS content. When designing the system, we calibrated our ADXL345 accelerometer to read on a sensitivity of 16 G (which corresponds to the acceleration unit of gravity). The ADXL345 accelerometer can read through a sensitivity of 2 G, 4 G, 8 G, and 16 G (the higher the number the higher the sensitivity to motion, the lower the number the higher the accuracy of the acceleration readings). All results were measured by experiments and trials, so some trials already included some faults (false falls). The testing process was as follows, we simulated 10 free-fall tests for different G's and thresholds. The system would open at the right time, too late, too early, or not open at all. Considering all the cases as failures except for when it opened at the right desired time (not too late, too early, or not at all), the number of right times divided by 10 (total number of falls) represents the accuracy of the system at the certain configuration of G and threshold. For a threshold of 10 and 15, the system would be too sensitive to motion, and it would result in the airbag inflating when no fall had occurred (by normal movements). For a threshold of 30, the system would be unresponsive and would result in a fall without the airbag inflating (most of the time it only responded to very sudden actions, and it would open after the fall had occurred). For a threshold of 25, the system would mostly be unresponsive for the lower G's but was 70% accurate on 16 G. For a threshold of 20, the results were better than a threshold of 25 but the airbag would sometimes inflate on sudden movements such as sudden changes in direction and fast complete stops. After testing thresholds between 20 and 25, we found an optimum threshold of 22 for the ADXL345 accelerometer sensitivity of 16 G.  
The 2 G only reads within a range of \(\pm\)2 gravitational units (g). This means it can accurately measure accelerations from \(-\) 2 g to \(+\)2 g. This range is suitable for applications that involve relatively low accelerations, which is not suitable for the system's application. The 4 G and 8 G only read within a range of \(\pm\)4 and \(\pm\)8 gravitational units (g), respectively, which means they can accurately measure accelerations from \(-\)4 g to \(+\)4 g and \(-\)8 to \(+\)8, respectively. These ranges are useful for applications where moderate accelerations need to be measured. The 16 G is a suitable range for our system because it is sensitive to high changes in acceleration with an accuracy of readings that is suitable for providing the right results for our application (hitting the threshold or not). Through testing, it yielded the best results. The accuracy through various G's and thresholds is shown in Figure 17.  
Figure 16: Final system design. Comparing our design to others in the literature, our system can provide waist fall protection as opposed to [3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 18; 19] which do not provide any protection against falls. Our system is also capable of sending notification alerts when a fall occurs via SMS including the location information, whereas this feature is not provided by [3; 4; 5; 6; 7; 8; 9; 10; 11; 12; 13; 14; 15; 16; 17].