## 5 Conclusions  
A method has been introduced in order to enhance the effectiveness of interpretation of verbal instructions with uncertain information such as \"move far forward\" by identifying the actual intention of the user. The ability for effectively interpreting such voice instructions by a service robot is useful in accomplishing typical daily activities and human-robot collaborative tasks that involve navigation of the robot. Therefore, the proposed method will improve the abilities of human-friendly service robots.  
The main improvement of the proposed method over the existing approaches is that the system is capable of switching the intention of the robot by identifying the actual intention of the user. The actual intention of the user is identified by analyzing the information conveyed from pointing gestures that can be accompanied with voice instructions. Moreover, the interaction ability has been improved by integrating multimodal interaction ability in order to guess the intention of the user for improved interpretation of uncertain information in user instructions.  
The intention of the robot is switched by the proposed motion intention switcher (MIS) by altering the perceptive distance from the default to an alternative. The position referred from the pointing gesture and the arrangement of the environment in that scenario are analyzed by the MIS in order to decide the alternative perceptive distance. Moreover the MIS shifts the perception of the robot between the default and the alternative hypotheses based on a set of predefined rules. It would be interesting for future work to consider a probabilistic approach instead of this rule-based approach for intention switching.  
Experiments have been carried out in an artificially-created domestic environment in order to analyze the behavior of the the proposed MIS. The behavior of the MIS has been found to be effective according to the experimental results. Furthermore, experiments have been carried out in order to evaluate the performance gain of the proposed concept. The experimental results validates the potential of the proposed concept in enhancing the human-friendliness of service robots by effective interpretation of ambiguous voice instructions.  
Supplementary materials can be found at www.mdpi.com/2076-3417/7/8/821/s1.  
**Acknowledgments: This work was supported by University of Moratuwa Senate Research Grant Number SRC/CAP/16/03.**  
**Author Contributions: [PERSON] and [PERSON] conceived and designed the proposed concept and experiments; [PERSON] and [PERSON] performed the experiments; [PERSON] and [PERSON] analyzed the data; [PERSON] contributed to designing and implementing the gesture evaluation module; [PERSON] and [PERSON] wrote the paper.**  
**Conflicts of Interest: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.**  
Figure 11: This graph shows the mean values of the user rating for the effectiveness of uncertain information evaluation of the systems in the two cases: system with MIS and without MIS. The error bars represent the standard error.