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1) System background
The main service targets of nursing homes are the elderly, and the problem of aging is more prominent. Because of their older age, the elderly are more or less physically inconvenient, and the degree of self-care is not as good as that of the young, and they are more prone to accidents. The infrastructure construction in nursing homes is becoming more advanced, and they are generally equipped with gardens, fitness venues, entertainment venues, and leisure venues. These facilities first enrich the lives of the elderly and add luster to the lives of the elderly; at the same time, they also bring potential inconveniences to the elderly. Because the site involves a large area, it is impossible for the management personnel to take care of every elderly person in each location. When an elderly person has a problem, it is necessary for the service personnel to find the location of the elderly person and provide corresponding assistance as quickly as possible. Therefore, it is necessary to adopt an effective way to take care of the elderly, and to determine the location of the elderly in the nursing home in real time and provide timely services to them. “Positioning” is even more important.
Based on the actual situation of nursing homes, Shanghai Ti Bigao developed the zigbee nursing home positioning system to provide higher quality care and care to the elderly.
Two) Zigbee introduction
Zigbee is an emerging short-distance, low-rate, low-power wireless network technology. It is a technical proposal between wireless tag technology and Bluetooth. It was previously known as “HomeRF Lite” or “FireFly” wireless technology, mainly used for short-range wireless connections. It has its own radio standard, which coordinates communication among thousands of tiny sensors. These sensors only require very low power consumption and transmit data from one sensor to another through radio waves in a relay manner, so their communication efficiency is very high. Finally, these data can be entered into a computer for analysis or collected by another wireless technology such as WiMax. The basis of Zigbee is IEEE802.15.4, which is a standard of the IEEE Wireless Personal Area Network (PAN) working group and is called the IEEE802.15.4 (Zigbee) technical standard.
Zigbee is not just the name of 802.15.4. IEEE only deals with low-level MAC layer and physical layer protocols, so the Zigbee Alliance standardizes its network layer protocols and APIs. The full protocol is used for 4K bytes that can be directly connected to the basic node of a device at a time or 32K bytes as a hub or router coordinator. Each coordinator can connect up to 255 nodes, and several coordinators can form a network, and there is no limit to the number of routing transmissions. The Zigbee Alliance has also developed a security layer to ensure that this portable device will not accidentally leak its identification, and that this long-distance transmission using the network will not be obtained by other nodes.
ZigBee can use three frequency bands, namely the 2.4 GHz ISM frequency band, the European 868 MHz frequency band, and the US 915 MHz frequency band. The channels available for different frequency bands are 16, 1, and 10. China adopts the 2.4 GHz frequency band, which is a frequency band that is free of application and royalty-free; adopts direct sequence spread spectrum technology DSSS (Direct Sequence Spread Spectrum), and the transmission distance is between 10 and 75 m (increased RF transmission power, up to 500 m) ; The transmission rate is 20~250 kb/s, suitable for sensor data acquisition and control data transmission. ZigBee technology has powerful networking capabilities and can form star, tree and MESH mesh networks.
1) RSSI positioning technology
RSSI[2](Received Signal Strength Indicator) refers to the strength of the wireless signal received by the base station. In the positioning based on the received signal strength indicator RSSI, the transmitting signal strength of the transmitting base station is known, and the receiving base station calculates the propagation loss of the signal based on the strength of the received signal. Some algorithms calculate the position of the node. This technology has low hardware requirements and relatively simple algorithms, and shows good characteristics in a laboratory environment. However, due to changes in environmental factors, it often needs to be improved in practical applications. The received signal strength is a function of the transmit power and the distance between the transmitter and receiver.
RSSI=-(10n•lgd+A)(1)
Among them, n represents the signal propagation constant, also called the propagation index; d represents the distance from the transmitter; A represents the received signal strength at a distance of 1 m.
The relationship between the attenuation of the signal and the logarithmic attenuation of the distance. The shorter the distance between the base station and the positioning tag, the smaller the absolute distance error caused by the deviation of the RSSI value; and when the distance is greater than a certain value, the absolute distance error caused by the RSSI fluctuation will be very large. An unknown base station may receive signals from n positioning tags, so several base stations with a larger RSSI value should be used for positioning calculations, so as to avoid expansion of positioning errors.
2) ZigBee technology realizes the advantages of positioning
1. Low power consumption
Due to the low transmission rate of ZigBee, the transmit power is only 1 mW, and the sleep mode is adopted, so ZigBee devices are very power-saving. ZigBee devices can last up to 6 months to 2 years with only two AA batteries, and their power consumption is much lower than other wireless devices.
2. Low cost
Compared with GPS, the positioning engine is integrated with the MCU in a single-chip ZigBee RF transceiver. The cost is less than 1/10 of the GPS hardware, and the power consumption is only a small part of the GPS hardware, and the ZigBee protocol is royalty-free.
3. Short time delay
The communication delay and the delay of activation from the dormant state are both very short. The typical search device delay is 30 ms, the dormant activation delay is 15 ms, and the active device channel access delay is 15 ms. Therefore, ZigBee technology is suitable for applications that require high real-time positioning.
4. Large network capacity
A star-shaped ZigBee network can accommodate up to 254 slave devices and one master device, and the networking mode is flexible. With the maturity of ZigBee technology, the number of ZigBee devices will continue to increase in the future. ZigBee RF equipment or infrastructure can be used to easily build a ZigBee network, which reduces the cost of ZigBee node design and networking, and uses more ZigBee devices to achieve higher The positioning accuracy.
Three) Program introduction
Every elderly person is equipped with a wristband. The wristband has a built-in zigbee radio frequency card. The card is based on zigbee wireless technology and uses the international 2.4~2.5GHz frequency band. The wristband can actively send information to the outside world. It can transmit the distance from 0 to 1500 meters. After the wristband information is received by the base station, the base station can interpret the information in the card, and then know which old man’s wristband number is? Where is it? The base station then sends the read information to the computer. When the elderly moves to other locations, the computer can monitor the specific location in real time. When an elderly person encounters difficulties anywhere in the community, press the button on the portable wristband, and the computer screen of the supervisor of the monitoring center will immediately display the location of the elderly person, as well as the elderly person’s personal health status, previous diseases, etc. Relevant information provides guidance for medical staff’s quick response and emergency help.
Four) Product introduction
1. Wristband technology
The products in this system all use the 2.4GHz zigbee wireless technology. This technology is very suitable for use in nursing homes because it actively sends data out, has a long transmission distance, very small radiation, and high positioning accuracy.
1) The composition of the wristband
Shell: Made of special medical materials, it will not irritate the skin or feel uncomfortable. It consists of a watchband and a watch head. The watchband can freely adjust the tightness of the strap to the wrist. The watch head has a built-in core chip device.
Chip device: zigbee, single chip control, SOS alarm module, battery module. The zigbee wireless module is responsible for external and internal data transmission and reception; the single chip is responsible for data analysis, processing and control; the SOS module is the button input for alarm and help; the battery powers the circuit. :
2) The function of the wristband
The distance of the wristband’s outward transmission can be up to 1500 meters, and the distance can be adjusted by software to meet the use distance and positioning accuracy of the site.
There is an SOS button on the side of the wristband. When the elderly need help, they can press SOS to ask the service staff for help.
Each wristband stores an ID number, which can be used as an electronic identity for the elderly. This ID number is composed of dozens of letters and numbers, and will never be repeated.
Each wristband can also store the personal information of the elderly, such as: elderly management: elderly information, outing registration, elderly situation list, check-in registration, elderly health files, period health file query, check-in information
The above information can be stored in the wristband before wearing the wristband to the elderly. The data in the wristband can be synchronized with the data in the computer.
2. Base Station
The base station receives the information from the wristband, converts the data into digital signals through demodulation, and connects to the computer through the gateway. The wristband must be used in conjunction with the base station.
The base station can be installed arbitrarily, no data line connection is required, as long as the power supply is provided, so no construction is required, and the installation is extremely simple.
3. Gateway
The gateway is a terminal device that reads the signal of the base station. It is connected to the computer through the USB interface, and the data of the base station is connected to the computer through the USB to read the relevant data.
5) Introduction to system modules
1. System Overview
Wear a wristband for each elderly in the nursing home, and adjust the tightness of the wristband when wearing it to avoid discomfort to the elderly (you can also choose to take it off and wear it freely). Each elderly wristband stores the ID number and elderly information. The ID number is the electronic identification number of the elderly. The elderly information includes: name, age, gender, room number, family information (family, affection number, home address, etc.), medical history file.
A certain number of base stations are installed in rooms, corridors, stairs, toilets, and mobile homes. When a base station is installed in a certain location, the address number of the base station is bound to the location, for example, base station 1 is installed to Room 302, when base station No. 1 sends information to the computer, the computer knows that it is the information sent by the old man in room 302.
When the old man is within the recognition range of a certain base station, the base station transmits the old man’s wristband number to the computer, and the computer can immediately determine:
The computer will pop up an information box on the screen according to the settings, prompting the manager to deal with it quickly.
2. System function module
1) Automatic reporting of the location of the elderly
The wristband can be set to send information to the base station intermittently and report its location to the system. The system can monitor and manage all elderly people. When an elderly person’s information is not uploaded to the computer, the computer will pop up an alarm dialog box. Prompt the manager to view. The system will automatically draw the action trajectory diagram of the elderly in a certain period of time.
2) The system queries the location of the elderly
When the manager wants to check the location of an old man, he can enter the old man’s name or electronic ID number in the system. If you want to find the 123 number, the system will give all base stations instructions to retrieve the 123 number information; Then all base stations send out information. When the corresponding ID number is retrieved, the base station that reads the number 123 (such as number 11) will reply to the computer, and the computer can determine that the number 123 is in the *** place (11 The place where the base station is installed)
3) SOS call for the elderly
When the elderly encounter difficulties anywhere in the community, when they press the emergency rescue button on the wristband, an emergency message will be sent to the base station, which will be uploaded to the computer from time to time, and the computer will immediately display the elderly’s place on the computer screen of the manager. The location of the medical staff, as well as the personal health status of the elderly, the diseases they have suffered and other related information, provide guidance for the rapid response and emergency help of medical staff. At the same time, it can also monitor the real-time location of the staff for standardized management and reasonable scheduling.
4) Automatic alarm in dangerous areas
Due to the insufficient self-care ability of the elderly, certain areas in the activity center or building are recorded as dangerous areas. Install base stations at the edge of these areas. When an elderly person approaches, it will be read by the base station. The base station will be reported to the computer, and the computer will prompt the manager to deal with it. At the same time, it will control the sound and light alarm in the dangerous area to remind the elderly to pay attention to safety.
5) Video linkage function
Video surveillance can help managers understand the actual scene of the scene. When there is an SOS alarm, the system controls the camera in the corresponding area, switches to a designated fixed point, and monitors the scene.
6) Rules are individually set
This function is set for some special elderly people, and some elderly people who need special care need to be limited to a certain range of activities or behaviors.
7) Time setting rules
Nursing homes often require more elderly people to take care of, and the hospital will have specific management regulations, such as meal time and rest time. For example, when the break time comes, the system will instruct the base station in each room to read the wristband information to determine whether each elderly person is resting in his room. If there are not enough people or people in other rooms are in this room, the system will After judging it, the manager was then prompted to persuade the elderly to return to the room.
The management system for nursing homes based on zigbee is of practical significance. The application of zigbee nursing home management system is an important strategy to deal with the aging problem. It is the inevitable trend of future world development.
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