Group 9 - Final Project Report
“Round Back Away Bra” by Group 9
Kan Tsz Ling 54425996
Wong Hoi Ho 54392715
Lee Sze Ying 54430331
What is it?
“Round Back Away Bra” is a posture correcting wearables that notifies the user when they slouch, help them maintain correct and beautiful posture all day long. It is specially designed for women to wear in everyday situations.
User will be notified with subtle vibrations from the sensor when their shoulder and back hunch forward. By using our product, we want the user is able to practice the mindfulness to correct slouching, develop good habit and get rid of back, shoulder or neck pain.
Our Inspiration
As Hong Kong is an urban city, many people depends on electronic gadgets such as mobiles and laptops. This leads to occurence of round back (寒背) problem. As continuous round-back will lead to serious irreversible negative health impacts, we decided to develop a product to improve existing problem and prevent the any deterioration.
Demonstration Video of “Round Back Away Bra”:
Prototyping Process:
Testing Video
Testing Pressure Sensor
During the early testing period, we try to use two flex sensors to detect whether the user is slouching. These two flex sensors are placed inside the bra strays, as drawn in the following image:
However, the values returned from the sensor are not very obvious. It may not provide reliable data for people with different slouching posture and different body shape. Ken suggested that we can try with pressure sensor, so we purchased two small pressure sensor from the web to see the effect:
The testing result is not very ideal, pressure created by round back is insufficient, so it did not return any changed value from the sensor. We decided to give up using the pressure sensor. Instead, we tried to figure out a new location, in which the flex sensor can provide a more reliable data.
Since the flex sensor is not sensitive for original designated location (i.e. shoulder/backbone, previous testing video: https://www.youtube.com/watch?v=UVMP207cLSI ), we moved the location to the middle of the breast and it helps us better detect the posture of the user. In our case, the Reading of normal posture is around 480-510. When the user is slouching, the value will change to around 430-450. Therefore, we decided to use only one flex sensor to detect the slouching posture.
Here is the updated circuit diagram:
Updated Material list:
LilyPad Arduino USB (ATmega32U4)
Flex Sensor
Lithium Ion Battery 2Ah
Stainless conductive thread
10Ω resistor
Lilypad Vibe Board (DEV -11008)
How does it work?
While we were testing the vibe motor, we found it annoying when we got vibrating notification frequently. So we set 8 seconds detecting time for the posture checking sensor. It the posture does not get any improvement for the next 8 seconds, the vibe motor will vibrate twice times to notify user again. It could help reduce the chance of wrong detection.
Detection will start anytime when users wore up Round-back Away bra. Vibration will generated if round-back is detected for 8 seconds or more. If round-back posture keep goes on and no improvement is made, vibration will start again after 8 seconds. A loop of vibration will occur if users do not make any changes since their round-back condition is detected. Once the posture is corrected, no more vibraion will occur again.
On the other hand, if no abnormal readings are detected, (i.e. users keep having good posture), no vibration will occur and Round-Back away bra will only act the role of a normal bra.
Our Work Process:
Sensor Locations
We tested flex sensor on breadboard before actually sewing on the bra. Specific curvature is adopted to the sensor during the process. Readings shown on computer screen is the indicator. However, we forgot the problem that it is difficult to sew it onto the bra directly. As a result, we solder the tip of flex sensor with conductive materials for easy sewing. However, it is still a big challenge for the connection. We also adjust the shape of resistor to enhance stability of the soft circuit.
We sew an extra pocket between the bra pads of the bra. This is to hide the sensor well and ensure it will not dispatched from the bra.
Assembling of sensor
The testing in Arduino Uno board is not that similar to Lilypad.. Crocodile clips are used to fix and allow conduction during the testing period. Difficulties discovered as they are loose and easy to disconnect.
Attachment of conductive thread
The conductive thread we bought from Taobao is a bit thicker and harder than normal sewing thread, we need to be extra careful to prevent any breakage. It improved the difficulties while sewing. Besides, the loose threads caused short circuit, the thread from the positive side accidentally touches the negative side and cause a short circuit. To ensure it is sticked tightly, we use use sellotape and hot glue to glue the tip of the thread.
Making some decorations for the bra..
We used old clothes created new shapes and forms such as sakura and hearts by reassembling. This is to hide the vibration sensor in a secret way and act as decorations on our product.
Hiding the Stitches on the Bra..
Difficulties and failures:
Due to unexpected elasticity of the cloth texture, inelastic thread used lead to failure of 1st trial. Bra used is unable to expand and it broke at the end.
Solution:
We tried again with a new bra and widen the distance between each stitches.
Future Improvements:
(1) More sizes can be developed for different breast sizes
(i.e. Cup A - G). This is facilitates women with different cups and avoid discrimination.
(2) Vest with similar function can be designated for male. So, not only female can escape from round-back, but also male.