## 4 Results and Discussion
### Evaluation of Performance Gain of the Proposed Method
Then, the robot was placed on the same initial position (i.e., '\(I_{1}\)') after disabling the MIS (i.e., system similar to [20]) and again the user was asked to navigate the robot to the goal. In this event, if the user had commanded the robot \"move medium forward\" similar to the earlier event, the robot would have moved to a point between the obstacle and the robot (due to the limitation of the system without MIS discussed in Section 3.3.1). However, that movement would be a waste since the user cannot navigate the robot beyond the obstacle without changing the moving direction. Therefore, with this in mind, the user first issued the command \"move little left\" in order to take away the robot from the barrier. The robot quantified the distance meant by \"little\" as 86 cm by considering the default perceptive distance and moved to position '\(a_{1}\)'. Then the robot was commanded \"move far right\" and robot moved to position '\(b_{1}\)' in order to fulfill the request of the user. Then, the robot was commanded \"move medium right\" and the robot moved to position '\(c_{1}\)' which was inside the goal area. Therefore, the task was completed. In order to complete the task with the system with the MIS, the user had to issue only two user instructions while with the system without the MIS, the user had to issues three instructions in order to complete the tasks. Moreover, the work overhead of the user is comparative less when the MIS is deployed into the robot. In case 2, the initial position of the robot was '\(I_{2}\)' and the goal is annotated as 'goal 2' in the map. In the system with the MIS event, the user first issued the command \"move little forward\" accompanied with a pointing gesture that express the requirement for the intention switching. If such a gesture had not been issued, the robot would have moved to a location that is well past the nearby table. Therefore, the robot moved to position '\(A_{2}\)' by switching the perception to the alternative perception. Then the robot was commanded, \"move medium right\" without giving a pointing gesture. Therefore, the robot moved to position '\(B_{2}\)' considering the default intention. Therefore, the task was completed with 2 user instructions. In the event of the system without the MIS, first the command, \"move medium left\" was issued by the user and the robot moved to location '\(a_{2}\)'. If the command \"move little forward\" had been issued in this case, the robot would have moved to a location that is well past the intended moving position due to the limitation of the system (without MIS) and the user already knew this from his past experience. That is the reason for issuing the command \"move medium right\" instead of \"move little forward\" similar to the system with the MIS case. Then with the next voice instruction, the robot moved to position '\(b_{2}\)'. After the next instruction, the robot moved to '\(c_{2}\)' that is inside the goal area. Therefore, in order to navigate the robot in this situation, three user instructions were required which is higher than for the event with the MIS. Similarly, the experiments have been carried out in all the layout arrangements by all the participants. The average number of steps required for fulfilling the navigation task in each layout arrangement for the system with the MIS and without the MIS is given in the graph shown in Figure 10.  
In all the layout arrangements except 6 and 9, the robot with the MIS was able to be navigated to the goal positions with a fewer number of voice instructions compared to the robot without the MIS and the difference is statistically significant (\(p<0.05\)) according to the results of two sample \(t\) tests. Moreover, the system with MIS has better abilities in understanding the intention of the user over the system without the MIS. Therefore, the deployment of the MIS enhances the evaluating ability of the ambiguous language instructions by the robot. However, in layout arrangements 6 and 9, the number of steps taken by both the system are the same.