## 6 Conclusions  
The findings of this study are summarized as follows:  
By establishing a relative position and attitude measurement model based on PSDs and eddy current, as well as a six-DOF relative position and attitude measurement system, compared with four-bar and eight-bar sensor configuration schemes, we find that the layout of an eight-bar position sensor has a higher system redundancy, allowing for the arbitrary failure of one out of four sets in the longitudinal and transverse directions. When there is only a one-way failure in the actuator, it does not affect the payload module's motion of six DOF (degrees of freedom). Meanwhile, by analyzing the failure modes under the measurement models, it can be concluded that the position and attitude measurement system has high redundancy. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Design Value**} & \multicolumn{4}{c}{**Actual Measurement Value**} & \multirow{2}{*}{\
\begin{tabular}{c} **Linear Fitting** \\ **Current** \\ **(mA)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Current** \\ **Error** \\ **(mA)** \\ \end{tabular} } \\ \hline \(-\)5 & 100 & 20 & \(-\)99.756 & \(-\)20.097 & \(-\)9.9615 & \(-\)99.7085 & \(-\)0.0475 \\ \(-\)4 & 80 & 20 & \(-\)79.659 & \(-\)19.994 & \(-\)7.9587 & \(-\)79.7228 & 0.0638 \\ \(-\)3 & 60 & 20 & \(-\)59.665 & \(-\)19.948 & \(-\)5.9615 & \(-\)59.7372 & 0.0722 \\ \(-\)2 & 40 & 20 & \(-\)39.717 & \(-\)19.914 & \(-\)3.9682 & \(-\)39.7515 & 0.0345 \\ \(-\)1 & 20 & 20 & \(-\)19.803 & \(-\)19.944 & \(-\)1.97738 & \(-\)19.7658 & \(-\)0.0372 \\ \(0\) & 0 & 20 & 0.141 & \(-\)19.99 & 18.422 mV & 0.2198 & \(-\)0.0788 \\ \(1\) & 20 & 20 & 20.131 & \(-\)20.005 & 2.0152 & 20.2055 & \(-\)0.0745 \\ \(2\) & 40 & 20 & 40.136 & \(-\)20.075 & 4.0178 & 40.1911 & \(-\)0.0551 \\ \(3\) & 60 & 20 & 60.211 & \(-\)20.045 & 6.0225 & 60.1768 & 0.0342 \\ \(4\) & 80 & 20 & 80.256 & \(-\)19.887 & 8.0258 & 80.1625 & 0.0935 \\ \(5\) & 100 & 20 & 100.143 & / & 10.0219 & 100.1481 & \(-\)0.0051 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Small current (high-precision) test data. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Design Value**} & \multicolumn{4}{c}{**Actual Measurement Value**} & \multirow{2}{*}{\
\begin{tabular}{c} **Linear Fitting** \\ **Current** \\ **(mA)** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Current** \\ **Error** \\ **(mA)** \\ \end{tabular} } \\ \hline \(-\)5 & 3.5 & / & \(-\)3310.4 & / & \(-\)9.441 & \(-\)3311.5314 & 1.1314 \\ \(-\)4 & 2.8 & \(-\)700 & \(-\)2647.8 & 662.6 & \(-\)7.5504 & \(-\)2648.4593 & 0.6593 \\ \(-\)3 & 2.1 & \(-\)700 & \(-\)1984.32 & 663.48 & \(-\)5.6606 & \(-\)1985.3872 & 1.0672 \\ \(-\)2 & 1.4 & \(-\)700 & \(-\)1322.9 & 661.42 & \(-\)3.7698 & \(-\)1322.3151 & \(-\)0.5849 \\ \(-\)1 & 0.7 & \(-\)700 & \(-\)660.58 & 662.32 & \(-\)1.8803 & \(-\)659.2430 & \(-\)1.3370 \\ \(0\) & 0 & \(-\)700 & 2.88 & 663.46 & 11.021 mV & 3.8291 & \(-\)0.9491 \\ \(1\) & 0.7 & \(-\)700 & 665.29 & 662.41 & 1.9066 & 666.9012 & \(-\)1.6112 \\ \(2\) & 1.4 & \(-\)700 & 1328.85 & 663.56 & 3.8027 & 1329.9733 & \(-\)1.1233 \\ \(3\) & 2.1 & \(-\)700 & 1993.1 & 664.25 & 5.6983 & 1993.0454 & 0.0546 \\ \(4\) & 2.8 & \(-\)700 & 2656.9 & 663.8 & 7.5943 & 2656.1175 & 0.7825 \\ \(5\) & 3.5 & \(-\)700 & 3321.1 & 664.2 & 9.4899 & 3319.1895 & 1.9105 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: High-current (high-force value) test data. Based on a self-designed testing and calibration system that adopts an eight-bar Maglev layout, the actuator has unidirectional dual-mode output. Separately, small-current (high-precision) and high-current (high-force value) conditions were tested, and the least-squares method was applied to fit the current output curve and calculate the relative output error. It can be concluded that the system has strong linearity in both low- and high-current ranges.