S1E12: How Smart Posture trainer device works?
Introduction
A good posture depends on both the orientation of the person’s back as well as its curvature. I use a lumbar support pillow with my rolling chair to make sure I’m not slouching and it has worked pretty well for me. But if you’re traveling or using different spaces, you cannot carry a support pillow with you. Or the chair may not have a backrest and you need other methods to make sure you’re not slouching. And this is where smart posture trainer devices come in.
Upright Go is a gadget that you can stick to your upper back directly on the skin, and it vibrates or can send an alert to your phone when you’re spine posture isn’t acceptable. It’s a smart Posture correction alerting device. The design is patented by Upright Technologies but their actual product differs a bit in terms of mechanical design. I’ll explain the Tech using the model in the patent file as it is easier to visualize. Here is how it works!
Hardware
Carrying member - A flexible sheet, constituting a leaf spring that is convex in the direction of the user when wearing the device. This flexibility allows this member to bend when you slouch or curve your spine due to different activities.
Strain gauge - A traditional strain gauge that uses a Wheatstone bridge to determine the change in electrical resistance, thereby determining the strain. It is placed lengthwise on top of the carrying member attached to it.
Terminal caps of carrying member - Terminal caps are provided at either end of the carrying member. These are used to facilitate the sliding of the ends of the carrying member with respect to the caps. It is made of a smooth material so you can feel comfortable while wearing the device. Adhesives on the terminal caps are used for the device to stick to your upper back body.
Tilt Sensor - A 3-axis accelerometer that can measure the acceleration in X, Y, and Z axis with respect to the device. This is used as a tilt sensor to determine the orientation of the device.
Housing - Printed Circuit Board, Battery, Vibrator, and all the other electronics are placed within the housing. This module is basically attached to the center of the carrying member. Thus, the carrying member is not disturbed.
Note: When the gadget is correctly aligned to our spine, the X-axis is along the length of the spine.
Figure 1: Upright Go mechanical assembly
How does it work?
Figure: How Strain Gauge works?
As you go about your day, and when you bend your spine through slouching, etc., the carrying member changes its shape due to bending. As the strain gauge is attached to the carrying member, it can measure the bending as a measure of the change in its electrical resistance.
In parallel, the changes in the orientation of your back are detected and measured by the tilt sensor (accelerometer). When your body is not vertically straight and is angled, the tilt sensor detects this change.
The controller uses the readings from both the strain gauge and the tilt sensor to determine whether or not an unacceptable deviation has occurred. Combining data increases the accuracy of the device, thereby reducing the incidents of false positives.
Once the device detects that your spine & posture isn’t in the correct shape, it’ll vibrate using the vibrator in the housing or you can set the device to send you an alert to your phone, etc.
What if the user bends down intentionally?
In this case, the strain gauge indicates that the curvature of the user has undergone a deviation from what is acceptable as they are bending their spine. But if the tilt sensor indicates that the orientation of the user’s back changed rapidly, the controller may determine that an acceptable deviation has occurred as the user bent down intentionally. Hence, the user needn’t be alerted.
Conclusion
Upright Go can be paired with your phone through their app and you can track the statistics on a real-time and daily basis. On a different note, I’ve been observing that accelerometers, gyroscopes, or sensor fusion are used in almost every gadget. So a strong fundamental in understanding how they work and what they are will help you go a long way in understanding any gadget.
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