## 2 Materials and Methods
### Structure of the Collected Data  
Utilizing the idea of sensor fusion, our proposed apparatus is capable of collecting various data types. In contrast to conventional paper-based writing, the focus of this research pertains to a much greater volume of biometric data. All information gathered by a specific device remains stored on that particular device. Furthermore, each written trace made by a user, whether it is a signature, phrase, word, or letter, produces a sequence of data points. Every unique point comprises information derived from the MotionEvent object [39], such as the pressure level, orientation, touch coordinates, action type, and so on. A distinct file is used for storing the data, including all the pertinent sensor information. In addition, the files represent a connection between the data collected from a variety of different sensors located on multiple devices. For instance, it provides a link to a video file or to piezo outputs acquired using the smartphone device. Figure 5 depicts the mentioned data structure, listing both internal and external sensors and devices utilized in the proposed apparatus. The data are organized to ensure that each unique recorded point in the handwriting corresponds to a particular set of values. The aforementioned MotionEvent object is used for the purpose of reporting events related to movement, such as those using a mouse, stylus, finger, or trackball. It offers a substantial amount of useful data pertaining to the touch event. Action codes and axis values are used to characterize movements in motion events. The action code denotes the change in state, such as the movement of a pointer either downwards or upwards. Position and the other movement features are defined by the axis values. To provide the reader with a comprehensive understanding of the acquired parameters in Figure 4, a more elaborate explanation follows. In the context of utilizing pointing  
Figure 5: The data structure consists of the measurements obtained from a variety of sensors while writing signatures, sentences, words, and letters on the tablet. The handwriting has a collection of unique recorded points, each of which is associated with various data obtained from both the internal and external sensors of different devices. devices such as touchscreens, the terms _Axis Value X_ and _Axis Value Y_ refer to the precise X and Y coordinates, respectively. The values represent the absolute location of the center of the touch surface on the screen. _DownTime_ refers to the duration, measured in milliseconds, during which the user first initiates a sequence of position events. In this context, the parameter _Elapsed Real Time_ refers to the nanoseconds since system initialization for each touch event. The value also includes periods of inactivity. Regardless of the system decorations or multi-window mode, _Event Raw X_ and _Event Raw Y_ indicate the coordinates within the coordinate space of the device's display. In multiple-screen contexts, the coordinate space comprises all spanning screens. In contrast to the preceding, the _Event X_ and _Event Y_ parameters provide the view's X and Y coordinates in response to the corresponding movement event. The employed unit of measurement is pixels. _Orientation_ refers to the orientation of the touch region and tool area, which was measured in radians in a clockwise direction from the vertical axis. A zero-radian angle indicates that the main axis of contact is directed upwards, is ideally circular, or has an indeterminate orientation. A positive angle implies the main axis of contact is right-oriented, whereas a negative angle denotes a left-oriented one. The complete range spans from \(-\pi/2\) radians, denoting a finger pointing completely to the left, to \(\pi/2\) radians, signifying an entirely right-pointing finger. A series of motion events containing actions is used to represent each entire gesture. The transitions and motions of the pointer state are determined by these actions.