## 3 System Architecture for Hand Therapy
### Wearable and Multiple Control Methods  
The device supports three control methods for the users and the therapist: (1) Smartphone-based speech, (2) Smartphone-based touch, and (3) Internet of Things (IoT)-based dashboard. Considering the ease of use and comfort of the users, multiple control methods are provided. In addition, they are provided considering the financial background and affordability of users in under-developed and developing nations. The smartphone-based speech and touch control methods are cheaper and simpler for users from low-income countries. The IoT-based dashboard control is an option provided to the therapist to remotely control the wearable device. The user can set the speed and number of cycles through the mobile app or the IoT framework as per the instructions from the doctor. The goal of each control method is to open/close the wearable thumb part when attached to the user's hand, so that the user can perform hand exercises and hold an object to perform useful tasks such as eating, drinking water, writing, etc. 1. Smartphone-based Speech Control: The user can use the speech/voice commands and control the wearable via a smartphone app which is exclusively designed and developed for this purpose, as shown in Figure 4. The speech commands are sent from the smartphone using the Bluetooth wireless interface. Only two simple voice commands are used: OPEN and CLOSE. In the beginning of therapy, the therapists can use the voice commands to operate the wearable. The user, along with the therapy, can easily learn how to use the wearable with simple voice commands. Refer to Video S1: HOD_1;
2. Smartphone-based Touch Control: This is similar to the speech-based app except that it uses a touch-based app of the smartphone. Using the touch-based app, the therapist or the user can choose the angle control parameters and touch the OPEN/CLOSE (control command) button as shown in Figure 3c to operate the wearable. In the initial phase of the therapy, the therapist can use this option to carry out the therapy slowly and steadily and train the users. Once the therapy reaches a stage where the users can operate the wearable themselves, then they can begin the operation with the touch control and gradually move to voice control or custom control which is similar to autonomous control. 3. The smartphone app can track the three control parameters including count, angle, and speed when open and close commands are used. The therapist/user has the option to set all these three parameters in the custom control mode. The count tracks the number of times that the wearable opens and closes. This can be compared with auto mode. The angle parameter is set to specify how many degrees (width of open/close) the wearable can open or close. The angle can be set in the range of 0 to 90\({}^{\circ}\). Initially, the therapy starts with a low angle and the angle can increase as the therapy progresses. Similarly, the speed parameter can be set to specify the speed with which the wearable can open/close. The count is user-programmable with a maximum value of 30 and hence, can be changed according to the progress in the therapy of the user. The speed change is in terms of the number of steps to reach the chosen angle as the servo doesn't have any speed control. 4. IoT Dashboard Control: Figure 5 shows the IoT dashboard which can send control signals to NodeMCU via IoT cloud to open and close the wearable device. The dashboard contains OPEN/CLOSE switches used for opening and closing the wearable device when the user is undergoing therapy. This is particularly useful when the therapist is remotely monitoring the user. If the user has any issues in controlling the wearable device and wants some assistance from the therapist, IoT dashboard control can be used. It is a very simple interface and has only two switches which makes it easier for the therapist to use without the need to spend a lengthy amount of time getting trained.