Posture Pulse

Problem statement

With people working hours behind a desk and smartphones being indispensable in our daily lives, remaining good posture is becoming a difficult task. Prolonged sitting with bad posture can lead to muscular and skeletal imbalance, causing pain and discomfort in the long run [1]. When using a smartphone people tend to tilt their head to their screen. With our head being the heaviest part of the body, this is causing significant strain to the neck muscles. Even being more problematic with children where the weight ratio of the head is even bigger [2]. Research shows that 40 percent of children in the Netherlands between the ages of 8 to 18 struggles with neck and back problems [3]. Furthermore, uninterrupted sitting for more than an hour increases the risks of cardiovascular problems, due to bad circulation [3]. Haptic technology can help us develop a device for remaining good posture.

State of the art

To be able to correct posture, it is important to define what good posture is. Ensuring the correct position of the spine is essential for good posture. The spine can be split in three sections each with their own natural curvature. These three sections are the neck, mid-back and lower-back and should all be in the natural position for good posture. Moreover, the head, shoulders and hips should be aligned to prevent strain in the neck muscles [4]. Possible effects of bad posture are: neck pain, upper and lower back pain, shoulder pain, deformed spine curvatures, constructed nerves, lower lung capacity and poor blood circulation [5][6].

Different approaches have been taken since the relevance of good posture on the work floor was clear to the general public. The first method was raising awareness. Commonly the desk workers were given a seminar or a folder about the relevance of posture and the downsides of bad postures [1]. This worked for a decent amount of people but not everyone could be motivated. Soon another or supplementary approach surfaced, where the focus wasn’t on the desk workers themselves but their working environment. Attention was given to how the monitor and keyboard should be placed with regard to the worker. Ergonomic mouses, chairs and keyboards became more common. Furthermore, desks and chairs were measured to have the perfect hight for the specific person. Additionally, an expert could be assigned to improve the workspace [7]. 

An ergonomic chair can offer great help with regard to workspace ergonomics. These chairs have spinal support which helps to keep a good posture. Another advantage is that they drastically improve the performance of the worker. The disadvantages of ergonomic chairs lie within their high cost and the fact that they are only useful when one sits behind the same desk daily, which is not always the case in current working environments [8].

Braces are a widely used posture corrector. They pull the shoulders back and address muscle imbalance. Due to the chest muscles often being tight, the back muscles can become overstretched. Correctors can help activating those back muscles, but it is important to not permanently wear the brace [9]. Wearing back braces for too long can weaken the back muscles and cause dependency of the brace. [10]

Another approach is by using wearables. Wearables have already shown promising results with regard to posture analysis and correction [11]. Currently there are some wearable posture devices on the market. Often used sensors are accelerometers, gyroscopes and magnetometers. These sensors are used in combination with software to analyse the posture of the individual wearing the device. Many currently available wearable devices only measure a part of the important indicators of bad posture. For example, often only the neck strain is measured, while also the position of the back and shoulders is important to analyse good posture. These devices are able to collect and store data [12]. The collected data is personal and sensitive, meaning it should be stored safely or not be stored at all if possible.

References

[1]  RxWellness, “Your desk job causes bad posture – Here’s how to fix it,” Chiropractor Near Me – RxWellness Spine & Health, Feb. 23, 2024. https://www.rxwellness.net/your-desk-job-causes-bad-posture-heres-how-to-fix-it/ (accessed May 20, 2024)

[2] “Fysiotherapeute Frédérique Neys: "Bij kinderen die voorovergebogen zitten op hun gsm, zien we een versneld verouderingsproces” | radio2,” Radio2. https://radio2.be/lees/fysiotherapeute-frederique-neys-bij-kinderen-die-voorovergebogen-zitten-op-hun-gsm-zien-we-een-versneld-verouderingsproces?view=web (accessed May 20, 2024)

[3] V. Nws, “‘Ban smartphones van de speelplaats,’” vrtnws.be, May 19, 2016. [Online]. Available: https://www.vrt.be/vrtnws/nl/2016/05/19/_ban_smartphonesvandespeelplaats-1-2659484/ (accessed May 20, 2024)

[4] E. J. Pekas, M. F. Allen, and S.-Y. Park, “Prolonged sitting and peripheral vascular function: potential mechanisms and methodological considerations,” Journal of Applied Physiology, vol. 134, no. 4, pp. 810–822, Apr. 2023, doi: 10.1152/japplphysiol.00730.2022. (accessed May 30, 2024)

[5] Z. Wine and Z. Wine, “7 Detrimental effects of bad posture,” BackFit Health + Spine, May 15, 2023. https://www.backfithealth.com/blogs/7-detrimental-effects-of-bad-posture (accessed May 10, 2024)

[6] Form Recovery and Wellness, “10 Surprising effects of poor posture on your body,” Form Recovery and Wellness, Jul. 19, 2023. https://formrecovery.com/10-surprising-effects-of-poor-posture-on-your-body/ (accessed May 10, 2024)

[7] N. Corbett and N. Corbett, “How to improve ergonomics in the workplace | McClure Ergonomics,” McClure Ergonomics, Sep. 10, 2021. https://mcclureergonomics.com/5-big-strategies-to-improve-ergonomics-in-the-workplace/ (accessed May 10, 2024)

[8] “The Importance of Ergonomic Office Chairs: A comprehensive guide to Comfort, Productivity, and Long-Term Health,” No More Pain Ergonomics. https://www.nomorepainergonomics.com.au/blogs/no-more-pain-ergonomics/the-importance-of-ergonomic-office-chairs-a-comprehensive-guide-to-comfort-productivity-and-long-term-health (accessed May 10, 2024)

[9] C. R. P. Mdt Dpt, Ocs, Cert., “Do posture correctors work? plus expert tips on how to use them,” Hospital for Special Surgery. https://www.hss.edu/article_do-posture-correctors-work.asp (accessed May 30, 2024)

[10] S. Dang MD, “When to consider a back brace,” Spine-health. https://www.spine-health.com/treatment/alternative-care/when-consider-back-brace (accessed May 30, 2024)

[11] J. Campbell and M. Fraser, “CartRight: Maintaining Good Posture in the Presence of Adaptive Haptics,” ResearchGate, Sep. 2019. https://www.researchgate.net/publication/335673145_CartRight_Maintaining_Good_Posture_in_the_Presence_of_Adaptive_Haptics (accessed May 10, 2024)

[12] N. K. M. Yoong, J. Perring, R.J. Mobbs. “Commercial Postural Devices: A Review,” National Library of Medicine, Nov. 23, 2019. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6929158/ (accessed May 10, 2024)

1.     Arduino micro

2.     Supply cable for Arduino (micro-USB to USB-A)

3.     Breadboard

4.     Electric cables suited for breadboard

5.     Multiplexer

6.     2x Adafruit DRV2605L (motor drives)

7.     Tachammer: 1x Drake LFI; 1x Drake LF

8.     T-shirt

9.     Conductive rubber cord stretch sensor

10.  4k7 Ohm resistor 

To detect bad posture, a conductive rubber cord stretch sensor is attached to the fabric along the spine. The fabric should be fit tightly around the body. It is important that the two ends of the cord are well attached and the cord is not lose, to make sure that the cord will stretch when the back is hunched.  

This circuit is based on a common multiplexer circuit with an Arduino.

Firstly, all the necessary supplies are connected (Vin and GND).

Secondly, the data line from D2 on the Arduino is connected with the SDA port on the multiplexer. Similarly, the clock line is connected from D3 to SCL.

Then the A0, A1 and A2 need to be wired directly to the ground. After that the multiplexer can be connected to the motor drives. SD1 and SC1 need to be connected to their respective ports (SDA and SCL) of the first motor drive, and similarly SD2 and SC2 to the second drive. Then the motors should be connected to the positive and negative port of their drive. Finally, the INT port of both motor drives should be connected to the D13 pin on the Arduino. This pin provides the PWM signal that is useful when using these motors.  

Lastly, the stretch band resistor is connected. To be able to do an analogue reading, a resistor bridge is necessary. place the 4K7 Ohm resistor to the 5V supply on one side, and a free breadboard line on the other, connect one wire of the stretch band to this line and the other to the ground. Ultimately, place one end of a wire on the same line on the breadboard and the other and at port A5.     

The conductive rubber cord stretch sensor did not arrive on time while doing this project, so it was simulated by using a potentiometer. Both have a similar working principle as they measure a voltage due to change in resistance. The code is written for a potentiometer, but is almost the same as for the conductive rubber cord stretch sensor.

When a voltage above the threshold value of 1.25V is detected (bad posture), the code will do the following:

1.      The system waits for 3.5 secods specified by function delaytime.

2.      During this waiting period, if the voltage drops below the threshold (user corrects posture), the loop breaks and resets the delaytime to 3.5 seconds for the next cycle.

3.      If the voltage remains above the threshold value after the waiting period, the system enters a loop where it continuously sent out pulses that will actuate both tachammers.

4.      If the voltage drops below the threshold again, the pulses stop, and the code exits the loop, resetting the delaytime.

If all went well, you now have a posture corrector that will alert you when your back is hunched through vibration. It is important to note that all people are different, so the threshold value is different for everyone.