# Wireless Home Assistive System for Severely Disabled People
## 3 Results and Discussions
### The Experimental Results of MCT
#### 3.1.2 The Efficiency of MCT used as a Keyboard  
In order to verify the efficiency of the fuzzy algorithm and keyboard mode performance of MCT, eight severely disabled subjects were asked to type 26 English alphabets ('a' to 'z', sequentially) with the help of a pacifier with a limit switch inside that is regarded as the input accessory connected with  
Figure 8: A mouse test interface for evaluating the efficiency of MCT (**a**) before the test and (**b**) after the test. Figure 9: The test data of the mouse mode of MCT for 8 severely disabled subjects (3 times per subject). MCT. An example of the tone and silence intervals of the Morse codes of each corresponding alphabet letter in the sequence is shown in Figure 10. For instance, the corresponding Morse codes of characters 'a' and 'b' are shown in Table 2. The analysis of tone and silence intervals in Figure 10 is shown in Table 3.  
In Figure 10, \"*', '\(\Delta\)', and dash line (_...) are used to represent the short tone/short silence, the long tone/long silence, and the variable threshold, respectively. The variable threshold adjusted by the fuzzy algorithm can separate the long and short tone/silence interval clearly. It proves that the fuzzy algorithm of Morse codes can effectively trace the typing speeds of different subjects whether the subject is a green hand or a specialist of Morse code typing. In tone sequences, the mean values of the short tone intervals and long tone intervals of Morse codes typing are \(134.4\pm 60.4\) and \(748.6\pm 207.6\) milliseconds (ms), respectively. In silence sequences, the mean values of the short silence intervals and long silence intervals of Morse codes typing are \(337.3\pm 91.7\) and \(1755.2\pm 771.9.6\) ms, respectively. The results indicate that the maximum short tone and minimum long tone are \(194.8\) ms and \(541\) ms, respectively. The long-to-short ratio of Morse code is about \(2.78\) smaller than \(3\); i.e., the standard ratio of long to short Morse code. Thus, the fuzzy algorithm can adjust the threshold value and follow the \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{4}{c}{\({}^{\prime}\)a\({}^{\prime}\)} & \multicolumn{8}{c}{\({}^{\prime}\)b\({}^{\prime}\)} \\ \hline
**No.** & **a1** & **a2** & **a3** & **a4** & **b1** & **b2** & **b3** & **b4** & **b5** & **b6** & **b7** & **b8** \\ \hline Morse code & \({}^{*}\) & & \(\triangle\) & & \(\triangle\) & & \({}^{*}\) & & \({}^{*}\) & & \({}^{*}\) & \\ \hline Tone interval (ms) & 76 & & 1149 & & 535 & & 108 & & 119 & & 93 & \\ \hline Silence interval (ms) & & 444 & & 1642 & & 386 & & 331 & & 398 & & 2641 \\ \hline \hline \end{tabular} (*: short tone, \(\Delta\): long tone).  
\end{table} 
Table 2: The input order and corresponding Morse codes of characters ’a’ and ’b’. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{_Tone_} & \multicolumn{2}{c}{_Silence_} \\ \hline  & _Long_ & _Short_ & _Long_ & _Short_ \\ \hline _Mean_ & 748.6 & 134.4 & 1755.2 & 337.3 \\ _Standard deviation_ & 207.6 & 60.4 & 771.9 & 91.7 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Statistical analysis of Morse codes typing (ms). Figure 10: The intervals of corresponding Morse codes relating to (**a**) tone sequence of Morse code and (**b**) silence sequence of Morse code. (*: short tone, \(\Delta\): long tone). typing speed variation of the subject to successfully recognize the corresponding Morse codes of the English alphabet. According to the test results of eight severely disabled subjects, the average typing speed is about 13.63 characters/minute, the fastest typing speed is 16.17 characters/minute, and the slowest typing speed is about 11.23 characters/minute. The accuracy of the Morse codes typing test with MCT is about 92%, and the errors include insertion errors (1.71%), deletion errors (2.99%), and substitution errors (5.13%).