A Wearable Mobile Sensor Platform to Assist Fruit Grading - Embedded.com

A Wearable Mobile Sensor Platform to Assist Fruit Grading

Measurement systems and devices are present everywhere in the current world, but frequently based on computers and interfaces that need explicit user interactions. Several devices are not portable or user friendly, so they can be only used in structured laboratory environments by trained people.

As we use hands for most of our daily tasks, one interesting solution is to integrate sensors in our hands to build a wearable mobile sensing platform in the form of a glove. The advantage of such platform is that the hands of the user and his attention become free for his task while the glove acts as an intuitive supporting device that provides and collects information about the task being done.

We propose a novel mobile sensing platform mounted on a glove that integrates several sensors, such as touch pressure, imaging, inertial measurements, localization and a Radio Frequency Identification (RFID) reader.

The glove operation is standalone, without the need of any of these external hardwares, but if any is available, the glove can use them as auxiliary devices. There are two types of sensors mounted on the fingers: finger bending sensors to measure finger flexion angle and pressure sensors mounted on each fingertip.

External devices communicate with the glove via the ARM board inside the box in forearm of the user. The ARM board is based on a Gumstix Overo FireSTORM module, which runs the main algorithms of the system on a 800 MHz ARM Cortex-A8 processor with 512 MB of RAM and 8 GB SD Card. This box also contains WiFi, Bluetooth and 8 AAA standard batteries. The processor runs Linux with the OpenCV computer vision library.

The system we have implemented allows evaluation of fruit quality by simply pointing the glove to a fruit and then touching this fruit. It uses distance information and one of the cameras to compute fruit's area and then approximates its volume by a spherical model.

Finally, when the user touches the fruit, the volume is also computed based on the finger bending sensors, its turgor pressure is measured and an overall quality parameter is computed according to weights for each of these parameters that can be provided by the user. If the result is below a certain customizable threshold, the tactile feedback system warns the user by vibrating the glove during a specified time.

As a platform, the system is suitable for several applications, but this work focuses on a fruit classification and grading system. One interesting usage of this system is help workers during manual harvesting.

To read this external content in full, download the complete paper from the MDPI online archives.

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