Stage 4. *Analysis.*

Let *G* = [

44 Biofeedback

*y*′ - and *z*′

*Gx*′ *Gy*′ *Gz*′ ] *T*

by the following equation:

*ρ* = cos−1

tilt angle of the sensor with respect to the earth.

be an acceleration vector, where *Gx*′

**Figure 3.** Posture training devices (left: head/neck training headset, right: lumbar training belt).

earhook in both sides of the ears. **Figure 3** shows the wearable training headset.

**3. Collaborative, social-networked posture training**

(

√

With the accelerations measured and provided by the accelerometer, Eq. (1) can calculate the

The calculated tilt angle needs to be further transformed into the coordinate system (*x*, *y*, *z*) of the head, with its origin at the center of the head in **Figure 1**. The sensor tilt angle is then converted into the head/neck posture angle. The lumbar angle can be determined along similar calculations. The stream of the posture angles forms a set of time-series data, which are processed by the meta-heuristic based on Kalman filter and fuzzy logics algorithms [44]. Rather than placing an accelerometer in the C7 vertebral only such as in [11], our innovative design puts the posture angle sensor along with the C7-tragus line. The posture angle sensor is fixed with a fine plastic enclosure that is attached to a lanyard and connects to a creatively designed

This research adopts the direct biofeedback learning mechanism that the individual gains control of the head and neck posture after receiving the biofeedback. Our biofeedback sensing and

, *Gy*′

*Gz* \_\_\_\_\_\_\_\_\_ ′

\_\_\_\_\_\_\_\_\_\_ *Gx*′ 2 + *Gy*′ 2 + *Gz*′ 2

and *Gz*′

represent the acceleration in *x*′

) (1)

Posture data are compiled, transferred and stored in the cloud for further analysis. The subject can query and review their own historical behaviors and analytic information in their smartphone or smartwatch.

#### Stage 5. *Sharing.*

Notifications of posture alerts and analytic data can be shared to subject's parents, guardian, or friends. Without violating privacy and security considerations, the data and analytics stored in the cloud can be shared to doctors, researchers, or public health workers to improve healthcare and welfare.

The collaborative, social-networked posture training (CSPT) framework is designed and based on three fundamental technologies of (1) real-time posture measuring, (2) biofeedback control and (3) social networks and collaboration. Monitoring and measuring of head/neck and lower back postures require techniques of sensing the movement and measuring the displacement of head/neck and lumbar positions in real time, with respect to their neural positions. Transformation among many coordinate systems is needed to reflect head/neck and lower back postures.

There have been some researches attempting to define the normal and correct posture of head, neck and shoulder, from various different points of view [45–47]. The idea along the neutral spine position—ears aligned with the shoulders and the shoulder blades retracted—is mostly used by many researchers and practitioners. This research defines the head/neck posture by the head-and-neck angle—the angle between true vertical (or horizontal) and a line connecting C7 vertebra and tragus (the cartilaginous protrusion in front of the ear hole). This research also defines the lumbar posture by the lumbar angle—the angle between true vertical and a line connecting L3, the middle of the five lumbar vertebrae and S2 at the level of posterior superior lilac spine. Both the head-and-neck and lumbar angles are measurable (or *observable* in the control theory context). We use both the head-and-neck angle and the lumbar angle to model the upper-body posture. The determination of a good posture depends on a series of sophisticated transformation and computation with the fuzzy logic combination of head-andneck and lumbar angles. When a bad posture is detected and lasts for a short period of time, the biofeedback mechanism starts to send alerts and notifications to the wearing kid to adjust and restore to a good posture.

Biofeedback technology is based on the idea that people can get more control over those normally involuntary functions by harnessing the power of the mind and becoming aware of what is going on inside the body. Biofeedback facilitates relaxation. It can help relieve several mental and physical conditions that are related to stress. The posture training CSPT App provides biofeedbacks via sound, music, voice and vibration to remind teenagers of their poor posture.

Social connections—both quantity and quality—are crucial to mental and physical health. The reasons that we adopt social networks and collaboration technology to encourage posture training of teens have three folds: first, Internet users, especially *i*-*Generation*, are now spending several hours per day with their peers on social media platforms. Second, information sharing has become an indispensable part and is more dynamic and more connected in social media revolution. Social networks platforms make it easy for teens to share their experience and performance of their maintaining good posture to their peers. Third, teens interact with their peers and receive appraisals and encouragement from their friends through social networks so that positive social support and competition are timely and reinforced. Posture training and collaboration among the teens is thus achieved.

**4. CSPT system design**

**Figure 4.** The CSPT framework.

**4.1. Wearable posture training subsystem**

ory and 4kB of SRAM with AES 128-bit encryption.

as follows:

The CSPT system consists of three subsystems: wearable posture training headset, socialnetworked posture training App and cloud services subsystems. Each subsystem is described

Collaborative, Social-Networked Posture Training with Posturing Monitoring and Biofeedback

http://dx.doi.org/10.5772/intechopen.74791

47

The wearable posture training headset subsystem is a sophisticatedly designed, earhook headset that is equipped with a real-time sensory system to monitor head and neck posture. The sensory system is an embedded system with dedicated hardware of accelerometer functions to detect and transmit the three-axis acceleration values of the device continuously. We adopt a 32-bit ARM Cortex M0 microprocessor [48] as the core of the embedded system. The microprocessor operates at CPU frequencies of 30 MHz and equips with 16kB of flash mem-

A three-axis accelerometer is used in the embedded system to detect the attitude of the posture monitoring hardware, that is, its pitch, roll and yaw. The accelerometer is featured by its ultra-low power, high performance, micro-electro mechanical system (MEMS) motion sensor for lightweight and long-lasting applications and wearable devices. The accelerometer is used to measure the accelerations of three axes of pitch, roll and yaw and generate 16-bit data streams with output rates in hundreds Hertz. The analog readings measured by the accelerometer are first digitalized and then sent to the 32-bit microprocessor through serial

As depicted in **Figure 4**, the CSPT framework consists of four building modules—posture monitoring wearables of posture training headset and lumbar belt, a smartphone, a social network CSPT App and CSPT cloud services. A posture monitoring device implemented with an embedded posture-sensing system is devised to monitor the neck-and-head posture in real time. A smartphone is used to provide interface to the device. A special-design lumbar belt is used to hold the smartphone so that the low back posture can be properly measured. While the subject wears the posture monitoring wearables, the corresponding posture data are filtered, streamed and sent to the CSPT App for posture estimation and determination. Once a bad posture is determined, the CSPT App sends biofeedback signals of sound, music, flashing light, or vibrations to notify the wearing kids to adjust and improve their posture timely. User's posture data are sent to the CSPT cloud for storage and further processing. The statistics and analytics of posture behaviors by individuals and groups are provided by CSPT cloud computing. Teens as well as their parents, teachers and friends can overview these posture behaviors in the CSPT App, including peers' appraisals and encouragements. Strong and interesting engagement to posture training activities can be established and continue via good peer support and positive peer competition.

Collaborative, Social-Networked Posture Training with Posturing Monitoring and Biofeedback http://dx.doi.org/10.5772/intechopen.74791 47

**Figure 4.** The CSPT framework.

the head-and-neck angle—the angle between true vertical (or horizontal) and a line connecting C7 vertebra and tragus (the cartilaginous protrusion in front of the ear hole). This research also defines the lumbar posture by the lumbar angle—the angle between true vertical and a line connecting L3, the middle of the five lumbar vertebrae and S2 at the level of posterior superior lilac spine. Both the head-and-neck and lumbar angles are measurable (or *observable* in the control theory context). We use both the head-and-neck angle and the lumbar angle to model the upper-body posture. The determination of a good posture depends on a series of sophisticated transformation and computation with the fuzzy logic combination of head-andneck and lumbar angles. When a bad posture is detected and lasts for a short period of time, the biofeedback mechanism starts to send alerts and notifications to the wearing kid to adjust

Biofeedback technology is based on the idea that people can get more control over those normally involuntary functions by harnessing the power of the mind and becoming aware of what is going on inside the body. Biofeedback facilitates relaxation. It can help relieve several mental and physical conditions that are related to stress. The posture training CSPT App provides biofeedbacks via sound, music, voice and vibration to remind teenagers of their poor

Social connections—both quantity and quality—are crucial to mental and physical health. The reasons that we adopt social networks and collaboration technology to encourage posture training of teens have three folds: first, Internet users, especially *i*-*Generation*, are now spending several hours per day with their peers on social media platforms. Second, information sharing has become an indispensable part and is more dynamic and more connected in social media revolution. Social networks platforms make it easy for teens to share their experience and performance of their maintaining good posture to their peers. Third, teens interact with their peers and receive appraisals and encouragement from their friends through social networks so that positive social support and competition are timely and reinforced. Posture

As depicted in **Figure 4**, the CSPT framework consists of four building modules—posture monitoring wearables of posture training headset and lumbar belt, a smartphone, a social network CSPT App and CSPT cloud services. A posture monitoring device implemented with an embedded posture-sensing system is devised to monitor the neck-and-head posture in real time. A smartphone is used to provide interface to the device. A special-design lumbar belt is used to hold the smartphone so that the low back posture can be properly measured. While the subject wears the posture monitoring wearables, the corresponding posture data are filtered, streamed and sent to the CSPT App for posture estimation and determination. Once a bad posture is determined, the CSPT App sends biofeedback signals of sound, music, flashing light, or vibrations to notify the wearing kids to adjust and improve their posture timely. User's posture data are sent to the CSPT cloud for storage and further processing. The statistics and analytics of posture behaviors by individuals and groups are provided by CSPT cloud computing. Teens as well as their parents, teachers and friends can overview these posture behaviors in the CSPT App, including peers' appraisals and encouragements. Strong and interesting engagement to posture training activities can be established and continue via

training and collaboration among the teens is thus achieved.

good peer support and positive peer competition.

and restore to a good posture.

posture.

46 Biofeedback