CN-122028018-A - Fall detection system based on BLE back scattering technology and implementation method thereof

CN122028018ACN 122028018 ACN122028018 ACN 122028018ACN-122028018-A

Abstract

The invention discloses a fall detection system based on BLE back scattering technology, and relates to the technical field of wireless communication. The system comprises an acceleration sensing module, a baseband signal generating module, a back scattering modulation module, an energy collection and power supply management module and a terminal information processing system. The system comprises an acceleration sensing module, a baseband signal generating module, a backscattering modulation module, a terminal processing system and a fall detection algorithm, wherein the acceleration sensing module acquires triaxial acceleration data, the baseband signal generating module packages the data into a broadcast protocol data unit which accords with BLE standard, the signal is subjected to smoothing processing through GFSK, symbols are mapped into subcarriers with different frequencies through MFSK, the backscattering modulation module switches an impedance unit according to the received subcarriers with different frequencies, the baseband signal is modulated onto an environment radio frequency carrier, and the terminal processing system receives and analyzes the BLE broadcast signal to execute the fall detection algorithm. The invention also discloses a realization method of the fall detection system based on the BLE backscattering technology, and the fall detection system has the advantages of low power consumption, high compatibility and miniaturization.

Inventors

FENG MAN
ZHANG LIFAN
XU CHENYU
LI JIANING
LU WEIBING

Assignees

东南大学

Dates

Publication Date: 20260512
Application Date: 20260126

Claims (10)

1. A fall detection system based on BLE back scattering technology is characterized by comprising an acceleration sensing module, a baseband signal generation module, a back scattering modulation module, an energy collection and power supply management module and a terminal information processing system, The acceleration sensing module is used for collecting triaxial acceleration data and inputting the triaxial acceleration data into the baseband signal generating module; The baseband signal generating module is used for packaging the triaxial acceleration data into a BLE data packet payload, adding a device name identifier and a power consumption information identifier, performing cyclic redundancy check and whitening on the triaxial acceleration data added with the device name identifier and the power consumption information identifier, assembling the triaxial acceleration data into a broadcast packet protocol data unit conforming to the BLE standard, and sending a baseband signal to the back scattering modulation module in a modulation signal form; The back scattering modulation module is used for modulating the baseband signal onto an environment radio frequency carrier wave to generate a reflected signal; The energy collection and power supply management module is connected with the acceleration sensing module, the baseband signal generation module and the back scattering modulation module and is used for collecting energy from the environment radio frequency carrier wave and supplying power to the acceleration sensing module, the baseband signal generation module and the back scattering modulation module; And the terminal information processing system is used for receiving and analyzing the reflected signals transmitted by the back scattering modulation module, extracting acceleration data from the reflected signals and executing a fall detection algorithm according to the acceleration data.
2. The fall detection system based on BLE back-scattering technology as claimed in claim 1, wherein the back-scattering modulation module adopts a quadrature IQ modulator structure, and the back-scattering modulation module is configured to receive the baseband signal from the baseband signal generation module, switch the impedance unit in the back-scattering modulation module according to the received baseband signal, and modulate the baseband signal onto an ambient radio frequency carrier to generate the reflected signal.
3. The fall detection system based on BLE back scattering technology according to claim 1, wherein the back scattering modulation module adopts an IQ modulator structure, and comprises a power divider, a 90-degree phase shifter, two radio frequency switches controlled by baseband signals, and a combiner, wherein an input end of the power divider is used for receiving an environmental radio frequency carrier signal, an output end of the power divider is divided into two paths, one path is directly output to one radio frequency switch, the other path is output to the other radio frequency switch through the 90-degree phase shifter, output ends of the two radio frequency switches are respectively connected to an input end of the combiner, and an output end of the combiner is connected to an antenna port for synthesizing the modulated reflected signals into a single radio frequency output signal and radiating the single radio frequency output signal to space so as to realize modulation of the back scattering signal based on IQ quadrature modulation.
4. The fall detection system based on BLE back scattering technology according to claim 1, wherein the acceleration sensing module uses an MPU6050 sensor, communicates with the baseband signal generating module through an I2C protocol, only enables an MPU6050 sensor accelerometer function, and disables a gyroscope function; the baseband signal generation module is used for finally mapping symbols in the broadcast packet protocol data unit to subcarriers with corresponding frequencies through Gaussian Frequency Shift Keying (GFSK) and multi-system frequency shift keying (MFSK) after the broadcast packet protocol data unit is assembled and generated to form a baseband signal; The terminal information processing system is a smart phone or special wireless receiving equipment, and the built-in application program is configured to scan and receive the reflected signal transmitted by the back scattering modulation module, execute Cyclic Redundancy Check (CRC), analyze the triaxial acceleration data in the broadcast packet protocol data unit, and judge whether a falling event occurs by analyzing the acceleration vector and the amplitude characteristic.
5. The fall detection system based on BLE backscatter technology of claim 1, wherein the baseband signal generation module is implemented by a low power field programmable gate array FPGA, the internal program corresponding to the baseband signal generation module includes a top layer function, an MPU6050 sensor driving module, an uplink control module, and a baseband modulation module, wherein the MPU6050 sensor driving module controls the sensor to collect three-axis acceleration data and transmit the three-axis acceleration data to the uplink control module, the uplink control module performs clock frequency division, CRC check, and whitening operations, and the processed three-axis acceleration data is transmitted to the baseband modulation module, and the baseband modulation module performs GFSK and MFSK operations.
6. A fall detection system based on BLE back scattering technology as claimed in claim 5, wherein the MPU6050 sensor driver module communicates with the MPU6050 sensor via the I2C protocol, collects three-axis acceleration data, and outputs the three-axis acceleration data to the uplink control module in a 16-bit format.
7. A fall detection system based on BLE back scattering techniques as claimed in claim 5, wherein the uplink control module incorporates a finite state machine FSM for performing clock division, CRC checksum whitening operations, generating broadcast packet protocol data units conforming to a prescribed format and transmitting to the baseband modulation module.
8. The fall detection system based on BLE back scattering technology according to claim 5, wherein the baseband modulation module comprises a clock frequency division sub-module, a data shifter sub-module, a Gao Silv wave sub-module, and an FSK modulation sub-module, wherein the clock frequency division sub-module provides an operating clock for the whole baseband modulation module, the data shift sub-module transmits the broadcast packet protocol data unit transmitted by the uplink module to the Gao Silv wave sub-module in a serial form, the gaussian filter sub-module performs GFSK operation on the received data and then transmits the data to the FSK modulation sub-module, and the FSK modulation sub-module performs MFSK operation on the received data and outputs a baseband signal.
9. A fall detection system based on BLE back scattering techniques as claimed in claim 8, wherein the FSK modulation submodule comprises a numerically controlled oscillator NCO, and wherein the frequency hopping is based on the principle of phase accumulation to obtain the 4 different frequency sub-carriers required to perform MFSK operation based on the set base frequency and frequency hopping size.
10. A method for implementing a fall detection system based on BLE back scattering technology as claimed in claim 1, comprising: Step 1, after the FPGA is electrified, an energy collection and power supply management module provides an initial working voltage for each module; step 2, starting an acceleration sensing module by the FPGA, acquiring X, Y, Z triaxial acceleration data, and transmitting the triaxial acceleration data to a baseband signal processing module; The method comprises the steps of (3) encapsulating acceleration data into broadcast packet protocol data units conforming to BLE 5.0 standard by a baseband signal processing module, wherein the encapsulation process comprises the steps of generating a broadcast packet protocol data unit header according to the BLE 5.0 standard, including a protocol data unit PDU type, a transmitting address and a length field; Step 4, performing CRC check on the broadcast packet protocol data unit after framing to generate a 24-bit cyclic redundancy check code and attaching the 24-bit cyclic redundancy check code to the tail part of the broadcast packet protocol data unit; step 5, oversampling and edge detection are carried out on the broadcast packet protocol data unit signal, and a stepped transition symbol is output according to a signal jump stage; Step 6, mapping corresponding frequency offset according to the stepped transition symbol output by the Gaussian filtering submodule and inputting the frequency offset to the NCO module, wherein the NCO module refers to the input frequency offset, accumulates phase increment in real time by using a phase accumulator, generates in-phase and quadrature square wave signals by extracting high bits of the accumulator, and finally generates a baseband signal for controlling antenna impedance in a combined mode; Step 7, the back scattering modulation module adjusts the impedance unit setting in the back scattering modulation module according to the baseband signals with different frequencies generated by the NCO module, so as to change the reflection coefficient of the antenna, modulate the baseband signals onto the environmental radio frequency carrier signal and carry out frequency shifting, generate a reflection signal conforming to the BLE broadcasting protocol and radiate outwards; and 8, the terminal information processing system receives the reflected signal, demodulates, decodes and verifies the CRC, extracts triaxial acceleration data in the reflected signal, processes and analyzes the triaxial acceleration data by adopting a falling detection algorithm, and triggers a local alarm or remote notification if the falling event is judged.

Description

Fall detection system based on BLE back scattering technology and implementation method thereof Technical Field The invention relates to the technical field of wireless communication, in particular to a fall detection system based on BLE backscattering technology and an implementation method thereof. Background Falls are common and highly dangerous accidents among the elderly population, which tend to occur suddenly, with serious consequences, and are difficult to find in time in a particular environment. Therefore, the real-time detection and alarm system for the old people falling event has important practical application value. Currently, fall detection systems on the market mainly comprise three types, namely a user-initiated alarm system, a fall detection system based on visual perception and a fall detection system based on a wearable sensor. The first mode relies on the user to actively send out an alarm signal after falling down, and the user cannot effectively respond when losing consciousness or mobility, the second mode is generally limited to an indoor fixed monitoring scene, lacks adaptability to outdoor environment, and is limited in application range, and the third mode has good applicability and instantaneity, but has obvious limitations in long-term use due to factors such as equipment volume, battery endurance, wearing comfort and the like. Disclosure of Invention The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a fall detection system based on BLE (Bluetooth low energy) back scattering technology and an implementation method thereof. The invention adopts the following technical scheme for solving the technical problems: The fall detection system based on BLE backscattering technology comprises an acceleration sensing module, a baseband signal generation module, a backscattering modulation module, an energy collection and power supply management module and a terminal information processing system, The acceleration sensing module is used for collecting triaxial acceleration data and inputting the triaxial acceleration data into the baseband signal generating module; The baseband signal generating module is used for packaging the triaxial acceleration data into a BLE data packet payload, adding a device name identifier and a power consumption information identifier, performing cyclic redundancy check and whitening on the triaxial acceleration data added with the device name identifier and the power consumption information identifier, assembling the triaxial acceleration data into a broadcast packet protocol data unit conforming to the BLE standard, and sending a baseband signal to the back scattering modulation module in a modulation signal form; The back scattering modulation module is used for modulating the baseband signal onto an environment radio frequency carrier wave to generate a reflected signal; The energy collection and power supply management module is connected with the acceleration sensing module, the baseband signal generation module and the back scattering modulation module and is used for collecting energy from the environment radio frequency carrier wave and supplying power to the acceleration sensing module, the baseband signal generation module and the back scattering modulation module; And the terminal information processing system is used for receiving and analyzing the reflected signals transmitted by the back scattering modulation module, extracting acceleration data from the reflected signals and executing a fall detection algorithm according to the acceleration data. As a further optimization scheme of the fall detection system based on the BLE backscattering technology, the backscattering modulation module adopts a quadrature IQ modulator structure, and is used for receiving the baseband signal from the baseband signal generation module, switching the impedance unit in the backscattering modulation module according to the received baseband signal, and modulating the baseband signal onto an environmental radio frequency carrier wave to generate a reflected signal. As a further optimization scheme of the fall detection system based on the BLE backscattering technology, the backscattering modulation module adopts an IQ modulator structure and comprises a power divider, a 90-degree phase shifter, two radio frequency switches controlled by baseband signals and a combiner, wherein the input end of the power divider is used for receiving an environment radio frequency carrier signal, the output end of the power divider is divided into two paths, one path is directly output to one radio frequency switch, the other path is output to the other radio frequency switch through the 90-degree phase shifter, the output ends of the two radio frequency switches are respectively connected to the input end of the combiner, and the output end of the combiner is connected to an antenna port and used for combining the modulated re