# A Novel Approach to Wearable Image Recognition Systems to Aid Visually Impaired People
## 4 Evaluation
### Discussion  
After all participants completed the task, we conducted a post-test debrief interview with users about the experience during the testing. In addition to the issues mentioned above, the main goal of testing was to gather information related to the following aspects: Is the device easy to learn? Which type of device do you prefer to use? Is the real-time capability of the device meeting your daily needs? What is your impression of the device? Do you have any suggestions for this device? After discussions with them, the following conclusions can be highlighted:  
1. The visually impaired people who participated in the experiment expressed their willingness to experience this device and felt that the modular design was cool. In addition, they think the system is easy to learn because of vibrations, ring tones, and audio information. Therefore, they only need to make a corresponding judgment according to the prompt.
2. A participant said that he preferred hand-held type device instead of wearing his head, especially when reading text. Because he only needs to control the vertical distance between the device and the book by hand, instead of moving the head. Six participants expressed their support for his views.
3. Most participants suggested that we should choose a thinner mobile power source so that the hand-held device can be easily placed in the pocket. The weight of the head-mounted device also needs to be further reduced.
4. When asked if the recognition speed can meet the daily needs, they said that the recognition time of 2-3 s is completely acceptable. Furthermore, they pay more attention to accuracy than time. They are willing to use the device at a party or at home to find their acquaintances.  
Figure 17: Experimental results (left) and duration of the experiment (right).  
Two participants indicated that the number of vibrations was frequent when an object was detected, which affected the wearing comfort. They suggested reducing the frequency of detecting obstacles or pausing vibrations while identifying objects.  
All participants indicated that the price of $250 is acceptable. They have always believed that the price of smart assistive equipment is very high and cannot be afforded at all.  
It is worth mentioning that during the experiment, we did not design an obstacle avoidance test. Because the ultrasonic module of the device mainly plays a role in scanning the interest points with the infrared sensor, reliable obstacle detection cannot be achieved. But we have considered three solutions. The first is to add the SLAM algorithm to achieve camera-based navigation, but it also has high requirements for hardware devices. Therefore, our future research direction is to put the online SLAM algorithm and image recognition algorithm in the cloud server for processing.  
The second option is to increase the number of ultrasonic modules or other distance-measuring sensors. As [PERSON] et al. proposed [33], using a smart phone belt for obstacle detection, there are four ultrasonic modules that detect the left side of the user. Right, center left, center right. But this will increase the weight and energy consumption of our device.  
The third solution is to combine our system with a white cane. Because the white cane is the most familiar obstacle avoidance device for most visually impaired people, it has the advantages of simplicity and reliability. We believe that smart assistive devices should not completely replace white canes, at least in the current transition period, because the novel smart devices are not mature enough.