【Running posture training shoes】No.009-Work submission

sipower

【Running posture training shoes】No.009-Work submission [Copy link]

Running posture training shoes

Author: sipower

1. Introduction

Nowadays, many people exercise by running, but not many people pay attention to what kind of running posture is healthy and what intensity is reasonable. Long-term unhealthy running will cause many adverse consequences. For example, if we land on the sole of the foot or the heel first when running, it will cause a great impact on our bones and joints; if we run with our feet splayed, the knees and toes will not be in the same direction, which will increase the burden on the knee joints; this design is designed for foot posture, and the wrong running posture can be corrected through real-time prompts on the mobile phone APP, thereby solving various adverse consequences caused by wrong running posture.

The finished work is as follows:

Figure 1, the entire work

The mobile APP interface is as follows:

Figure 2, APP interface

2. System Block Diagram

This work uses four pressure sensors to collect the pressure of the soles of the feet, analyzes the pressure changes at the four points, identifies the current running posture, and sends the results to the mobile phone via Bluetooth. The trainer can use the real-time data to compare and correct his running posture to achieve a correct and healthy running training effect. The specific system block diagram is as follows:

Figure 3, System Block Diagram

3. Functional description of each part

The main control part uses the RSL10-002GEVB development board, which has 4 ADC input IO ports for connecting 4 thin-film pressure sensors. The sensors are distributed in 4 directions under the insole to detect the force of the entire sole, front, back, left, and right. The microcontroller program recognizes the running posture through different force distributions. It can also calculate the step frequency through the pressure changes of the sensor .

Figure 4, Connection between sensor and AD

This work uses a self-made pressure sensor to collect the pressure of the sole of the foot. The basic idea is to use a paper shell with a layer of carbon powder as an insole as the base common electrode. The other electrode of the sensor is cut into small pieces of copper foil and attached to the carbon powder. The greater the pressure, the closer the contact between the copper foil and the carbon powder, the smaller the resistance, and vice versa, the resistance becomes larger, thus realizing the function of the pressure sensor. The finished sample is shown in the figure below. For the detailed production process, please refer to my fourth post "Sensor Production and Primary Data Processing".

Figure 5: Homemade sensor

Considering that the circuit inside the shoe is not convenient to charge, and the power consumption of RSL10 is extremely low, the power supply is designed as a battery-free system. The power generation device is a push-type micro generator, which comes from a self-generating doorbell. I kept the rectification, voltage regulation, and energy storage parts above, and the output is connected to the development board. When pressing quickly, the measured voltage can basically stabilize above 4V, and can generate about 0.4mA current. Using LDO to reduce the voltage to 3.3V, about 1mW of power can be obtained. Sending a packet about once a second is barely enough. In practical applications, at least one generator should be installed on the sole and heel to ensure stable power supply. The connected sample is shown in the figure below. For detailed test process, please refer to my seventh post "Research on Self-generating Function".

Figure 6: Connection between the pressure generator and the evaluation board

Here is a brief introduction to the design ideas of the analysis algorithm . I set up 4 pressure sensors on the soles of the feet, numbered as 0, 1, 2, and 3, as shown in the figure below. When walking or running, the order in which these four points reach the maximum pressure point is different, and this order represents different foot postures. For example, when walking with your toes inward, points 0 and 1 reach the maximum pressure earlier than points 2 and 3; when running, if the forefoot touches the ground first, points 1 and 3 will reach the maximum value first, and if the heel touches the ground first, points 0 and 2 will reach the maximum value first. As long as this order is calculated, the posture can be identified. Then the amplitude and duration of the maximum value of each point can be used to further analyze the rationality of the posture. The step frequency can be calculated by calculating the change cycle. For detailed processing, please refer to my fifth post "Posture Recognition and Step Frequency Calculation".

Figure 7. Sensor location on the sole of the foot

For the Bluetooth communication part, the original plan was to use broadcast packets to transmit data. After multiple debugging, the program integration was not successful. Finally, I changed to use the "peripheral_server" routine as the basis, transplanted the ADC program I wrote, and realized the final function by adding analysis algorithm and other codes. After the program is actually running, the data can be read correctly from the Bluetooth debugging APP, as shown in the figure below. For the detailed processing process, please refer to my sixth post " Bluetooth Communication Program Design ".

Figure 8, Bluetooth communication is successful

Finally, it is Android mobile phone APP design. Since I have been engaged in hardware-related work, I am not very good at PC and mobile phone software development. I use App Inventor, a tool designed by Google that does not require too much professional programming knowledge, but only requires logical thinking to design Android mobile phone APP. Although it cannot design a very gorgeous interface, it has no problem in realizing various commonly used functions. At present, the second version, App Inventor2, is commonly used. It is recommended to use the WxBit Chinese enhanced version in China, which has expanded many functions and provides an example exhibition hall, which is more convenient to use. The code block design and interface design are shown in the figure below. For the detailed design process, please refer to my eighth post " Android APP Design ".

Figure 9, APP design

4. Source Code

The source code package includes: the entire RSL10 project, the source files of the Android APP based on App Inventor2 , and the APK installation file. The links are as follows:

https://download.eeworld.com.cn/detail/sipower/620028

code.zip (3.99 MB, downloads: 8)

5. Demonstration video of the work’s functions

The first video is a test demonstration of the micro push-type generator, which can meet the power requirements of BLE communication by pressing quickly. The computer screen shows the voltage change waveform tested by the oscilloscope, and the mobile phone is running the BLE test APP. The green characters displayed on the screen scroll to the end indicate that the Bluetooth connection is successful and the data sent by the evaluation board is received.

https://training.eeworld.com.cn/course/6092/lesson/30522/media

The second video is a demonstration of the entire work, which first introduces the composition of the work and then demonstrates the actual use process. In order to achieve a better demonstration effect, the power supply is powered by a power bank, and there is no crazy pressing of the generator like in the previous video.

https://training.eeworld.com.cn/course/6092/lesson/30523/media

6. Project Summary

Through this competition, I became familiar with the RSL10 low-power Bluetooth chip, and also learned to use ON Semiconductor's integrated IDE. In particular, I learned a lot of knowledge about BLE Bluetooth, which laid a good foundation for more and more Bluetooth-related development in the future. The various experiments in this competition also proved the power of the RSL10 chip. At the same time, I also realized that if you really want to make a good product, you need to make very careful choices, precise adjustments, and rigorous verifications in device selection, circuit optimization, and program design to achieve an excellent user experience. This time, my work has realized basic functions, but it is still relatively simple, and there are still many points that can be optimized. I hope that my work can serve as a starting point for more users to be inspired and make functional and easy-to-use products.

Finally, I would like to thank all the moderators and experts in the forum for their help, and thank ON Semiconductor and Avnet for giving me this opportunity to showcase my work. I hope everyone can learn something from this event and receive a satisfactory award.

Posting link:

No001. The long-awaited release - received the first post of the development board

https://bbs.eeworld.com.cn/thread-1162661-1-1.html

【Running posture training shoes】 No.002-Establishment of software development environment

https://bbs.eeworld.com.cn/thread-1163108-1-1.html

【Running posture training shoes】 No.003-Data collection and real-time display

https://bbs.eeworld.com.cn/thread-1166929-1-1.html

【Running posture training shoes】 No.004-Sensor production and primary data processing

https://bbs.eeworld.com.cn/thread-1168929-1-1.html

【Running posture training shoes】 No.005-Posture recognition and step frequency calculation

https://bbs.eeworld.com.cn/thread-1169560-1-1.html

【Running posture training shoes】 No.006-Bluetooth communication program design