What is the Fall Detection Bracelet?

Seniors who live independently often have a concern. If something goes wrong, can I still call for help? Wearable home emergency call system for added peace of mind. An important part of the system is fall detection. This functionality can be easily integrated into the corresponding device by incorporating suitable sensors.

Fall Detection Bracelet

Micro-Electro-Mechanical Systems (MEMS) motion sensors are ubiquitous and function differently in different devices. The signal generated by the MEMS must be parsed before it can be used by the fall detection bracelet.

Fall Detection Bracelet System

A fall detection sensor in a home emergency call system can automatically detect a person falling and standing still. Assuming that the emergency caller cannot manually trigger the emergency call switch, the emergency call must be made automatically.

How does a triaxial accelerometer detect a fall? A fall means a brief loss of weight, i.e. a certain acceleration is measured, followed by a high negative acceleration (a sharp deceleration). If no change in acceleration is measured for a period of time, it means that the person wearing the sensor is stationary.

To develop a fall detection system, the pulses generated by the MEMS must be properly interpreted. Another challenge is having to get very accurate values. Therefore, disturbances such as temperature fluctuations must be compensated for. In conclusion, a lot of effort has to be made before the fall detection algorithm function can be developed. Fortunately, today’s sensor modules are very developer friendly.

Preset functions for Fall Detection Bracelet

Some “smart” functions are integrated into the sensor. The 3-axis accelerometer uses MEMS technology based on the capacitive measurement principle. It integrates a temperature sensor, and the output data is compensated and calibrated. Four measurement ranges are available: ±2 g, ±4 g, ±8 g and ±16 g. Specific functions such as free fall, wake-up, activity, motion, and orientation detection can be selected through register settings. The status of specific functions can be known through two programmable interrupt pins. This application-oriented measurement value processing and output greatly simplifies application development.

This is also the case with fall detection. Developers can easily implement fall detection functions thanks to built-in preset functions and optional parameters. A big advantage of this sensor is that built-in functionality minimizes the uninterrupted but unnecessary transmission of sensor acceleration data, as well as complex calculations on this data.

Advantages of fall detection

The 3-axis accelerometer has two programmable interrupt pins, INT_0 and INT_1. These two pins can be activated or deactivated independently. Interrupt signals from sensor functions are routed to these two pins.

Three functions are required for fall detection: “Free Fall”, “Wake Up” and “Stationary/Motion”. By combining these sensor functions, reliable information such as whether the wearer has fallen and can move afterward can be determined. The sensor sends the interrupt signal generated by these events to pins INT_0 and INT_1 to notify the monitoring system to issue an alarm.

Fall detection bracelet setting threshold

In free fall, the acceleration values ​​for all three axes tend to approach one value. In the sensor module’s registers, two application-specific values ​​must be defined that generate an interrupt reporting a fall when these two values ​​occur simultaneously: the threshold at the time of free fall, and the duration of the free fall.

In order to use sensor data to interpret a fall event, the sensor wake-up condition must also be defined, by setting a threshold for acceleration changes and a minimum duration for this pulse. To exclude the effects of gravity vectors and very low frequency noise when detecting wake events, a high pass filter output should be used.

The “Station/Motion” algorithm feature informs the alarm system whether the wearer of the sensor remains motionless or still able to move after a fall. The stillness function combines two detection events: “sleep” and “wake up” to record stillness events. The sensor does not have a separate sleep interrupt signal. It does this by monitoring sleep and wake up interrupt signals.

Parameters such as wake-up threshold and duration can be defined according to the application. A sleep interrupt signal will be generated if the X-axis, Y-axis, and Z-axis output acceleration values ​​are less than the wake-up threshold and the output value remains within this range for the specified duration.

If the data value from either axis is above the defined wakeup threshold and the data remains within this range for a period of time, a wakeup interrupt signal is generated.

Four Stages of Fall Detection bracelet

  1. Before the fall, the vector sum of the acceleration values ​​from the three axes approaches g. By simultaneously monitoring the direction of acceleration before and after a fall, more information about the fall event can be obtained.
  2. In free fall conditions, weightlessness always occurs at the onset of the fall. By defining an appropriate free-fall duration and threshold, a fall can be detected by interrupting the signal. During the free fall, the acceleration tends to a value, but after the free fall, the person hits the ground with a higher acceleration peak.
  3. Immediately after a fall, the wearer will try to move. If the fall is too severe, you cannot move immediately after the fall. The duration of this event is configurable through the inactivity detection feature.
  4. If the person becomes unable to move due to unconsciousness after a certain time (configured in the still function), an interrupt signal is generated. The fall detection system generates an alert by comparing the direction of the sensor’s acceleration before and after the fall instructs the fall detection system. If the person moves within a certain time, a wake-up signal is generated without generating an interrupt signal. In this case, the fall detection system will not generate automatic alerts.
GPS navigation remote ECG and fall detection-monitor for the elderly

The ECG drop detection system uses the MXTOS2-200 module and the PSoC CY8C38 module that provide high-precision three-dimensional positions to design a small and exquisite remote elderly monitor

.ECG Solutions Healthcare Highfive

ECG Solutions Healthcare Highfive

Using unique over-sampling technology and low-power, low-component sensor modules, through the real-time acquisition and measurement of physiological state parameters such as the elderly’s ECG, respiratory rate, walking status (falls), and comparison with the normal physiological parameter range, Early warning action. The effect is good.

When the elderly carrying this monitor is abnormal outside, the upper computer of the centralized control center receives the position information and physiological parameters transmitted by the GSM/GPRS wireless module in the monitor, so as to realize rapid positioning and attendance and first aid to protect the elderly Human life and health.

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