## 3 Simulated Intraoral Magnetic Localization Setup  
The closure of the inside mouth space makes it difficult to monitor the tongue movement vividly and precisely, which lays the foundation for evaluation of the magnetic localization method. To validate the feasibility of the proposed TCI system utilizing aLMA and \(T\)-type PM in inverse magnetic localization and focus on its performance in localization accuracy and efficiency, experiments were carried out on simulated intraoral setup with controllable high positioning resolution, which is almost impossible in human body experiments. The experimental setup in Figure 4 consists of a 3D translation platform with high positioning resolution (including a GUI, a controller, and a motorized positioning system), the proposed TCI system (including a custom-made GUI, a \(T\)-type PM, a sensor array, and an I\({}^{2}\)C-USB adapter (Viewtool, Shenzhen, China)), and an oral model of a general adult. Detailed information of the experimental setup is presented in Table 1.  
The combined \(T\)-type PM was mounted on the end of an aluminum pole and made up of two cylindrical NdFe-B magnets (MISUMI, Tokyo, Japan), which were axially magnetized and formed a letter \(T\) shape. The motion of the combined \(T\)-type PM was automatically driven by a 3D translation platform (MITSUBISHI, Tokyo, Japan) with a 10-\(\upmu\)m translation resolution. An array of eight three-axis AMR sensors (Honeywell, Plymouth, MN, USA) detected the magnetic field distribution related to the combined \(T\)-type PM, and delivered the digitized signals to the PC (Dell, Round Rock, TX, USA) through a 12-bit I\({}^{2}\)C-USB adapter (Viewtool, Shenzhen, China). The sensor array was fixed on the slider of the 3D translation platform (MITSUBISHI, Tokyo, Japan), which was positioned on the _xy_-plane. The freedom of the relative movement between the combined \(T\)-type PM and the sensor array was three. An oral model of general adult made by non-ferromagnetic material was employed to simulate the space environment inside the mouth.  
A custom-made GUI in Figure 5 was loaded on PC (Dell, Round Rock, TX, USA) based on Labview (NI, Austin, TX, USA) and MATLAB (Mathworks, Natick, MA, USA) for signal process and information display. The interface was developed in Labview (NI, Austin, TX, USA), and the inverse localization algorithm was programmed in MATLAB (Mathworks, Natick, MA, USA), whose results are displayed on the GUI. On the GUI, the _Noise Calibration_ section displayed the averaged noise level on each sensor channel, based on the assumption that the noise level at the sensor observation point was constant. The _Calibrated Sensor Measurements_ section indicated the sampling information, including  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Components** & **Property** & **Manufacture** \\ \hline \multirow{4}{*}{\(T\)-type PM} & Two NdFe-B magnet; & \\  & Axially magnetized; & \\  & \(\Phi\) = 1.56 mm, \(2l\) = 6.48 mm; & \\  & \(B_{r}\) = 0.1430 T & \\ \hline \multirow{4}{*}{AMR sensor} & Eight three-axis HMC5983; & \\  & Resolution: 0.227 \(\upmu\)T, & \\  & Maximum output rate: 220 Hz & \\  & Range: \(\pm\)0.4 mT & \\ \hline I\({}^{2}\)C–USB adapter & VTG200A; 12-bit; & Viewtool, Shenzhen, China \\ \hline \multirow{2}{*}{Gauss meter} & Model-421; & \\  & resolution: 0.1 \(\upmu\)T & \\ \hline
3D translation platform & Resolution: 10 \(\upmu\)m & MITSUBISHI, Tokyo, Japan \\ \hline \hline \end{tabular}
\end{table}
Table 1: Experimental setups. AMR: anisotropic magnetoresistive.  
Figure 4: Experimental setup.  
real-time measurements with the exclusion of noises on each sensor channel, preset sample number, and sample frequency. The _PM Localization_ section provided the localization results computed by the proposed aLMA, which is processed in MATLAB (Mathworks, Natick, MA, USA). The _Parameter Settings_ section indicated the magnitude \(m\) of the magnetic moment for the PM marker precalibrated by the Gauss meter (Lakeshore, Westerville, OH, USA).