With the next evolution of assistive care products on the rise, your grandma’s next cane may rival your smart phone in terms of the technology that is going into it. Smart canes are capable of monitoring health vitals and integrating GPS and sensors, so it will immediately know when and where a user falls or sense an irregular heartbeat. Cellular, Wi-Fi or Bluetooth® wireless connectivity features can also alert paramedics during medical emergencies. Even simple location-based services that alert family when someone wanders too far from home, or aiding lost individuals with directions back home, are just a few of the services being offered through the latest generation of smart canes.
These smart canes are not just for seniors. Hikers and walkers are enjoying many of these features as well, especially in locations where carrying a smart phone is not ideal, like rocky or uneven surfaces where dropping a phone is more likely. This is also driving demand for these devices.
Renesas’ smart crutch reference design incorporates many of these features. It monitors the health of the user through biometrics, as well as the environment for heat or freeze warnings and acceleration and inclination to detect falls by user. It also provides GPS positioning and IoT connectivity for tracking the user when necessary. It could also be used for Alzheimer’s patients that have wandered off from their homes. Finally, the smart crutch also has a built-in LED flashlight for navigating through dark areas. The entire smart crutch is powered by a rechargeable Li-ion battery.
The “heart” of this unit is the RA4M1. This series of MCUs balances the needs for low power with the demand for connectivity and performance. These MCUs deliver up to 48MHz of CPU performance using an Arm® CortexⓇ-M4 core with up to 512kB of embedded flash memory. The series offers a wide set of peripherals, including USB, CAN, ADC, Bluetooth Low Energy 5.0, capacitive touch, a segment LCD controller, and security IP integration, making it suitable for IoT, industrial equipment, home appliances, office equipment, healthcare products, and meters. It has plenty of compute power to manage all the sensor data and the communications used in this design, including analysis of the 6-axis G-Sensor data.
The sensors on this smart crutch reference design are critical. The OB1203 is a fully integrated optical sensing module for pulse oximetry (photoplethysmography, or PPG), multi-channel color sensing (CS), ambient light sensing (LS) and proximity sensing (PS). With the appropriate algorithm, it can determine human heart rate, blood oxygen saturation (SpO2), respiration rate and heart rate variability. The HS3003 is a highly accurate, fully-calibrated relative humidity and temperature sensor with fast measurement response time, allowing users to monitor the environment. These features, along with the small package size, makes the HS3003 ideal for applications that require portability and harsh environments. The ISL29035 is an integrated ambient and infrared light-to-digital converter and its advanced self-calibrated photodiode array emulates human eye response with excellent IR rejection.
On the battery charging side, the ISL9205D is an integrated single-cell Li-ion charger capable of operating at an input voltage as low as 2.5V. The low operating voltage allows the charger to work with a variety of AC adapters. The ISL91127IR is a high current (4.5A) high efficiency buck-boost regulator that uses a proprietary buck-boost algorithm to maintain a voltage regulation while providing excellent efficiency and very low output voltage ripple when the input voltage is close to the output voltage.
With this reference design, Renesas is showing engineers a compact and robust design for a smart cane/crutch that is easy to scale and incorporate other features that may be required in these types of applications.
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