In this doctoral dissertation, we present a compansion system that transforms the telegraphic language (utterances with only uninflected content words) that comes from the use of pictogram-based Augmentative and Alternative Communication (AAC) into natural language in Catalan and Spanish. The system has been designed to improve the communication of people who rely on AAC, who usually have severe speech or motor impairments and use pictogram-based communication methods in their daily life. The compansion system has two main components: a syntactic-semantic dependency parser and a generator that constructs the final sentence. The system has been technically evaluated and results show that 99,66% of the sentences generated by it, taking into account the restrictions of a constrained grammar, were considered correct by three independent annotators. Furthermore, a user interface with a pictogram prediction system has also been researched and implemented during the thesis in order to test it with end-users. The system as a whole was tested with 4 participants with severe cerebral palsy and ranging degrees of linguistic competence and intellectual disabilities. During tests, participants were able to learn new linguistic skills while using the compansion system, which proved a source of motivation. The system can also be adapted to the linguistic competence of each person and required no learning curve during tests when none of its special features were used. Finally, qualitative and quantitative results showed a mean communication rate increase of 41,59%, compared to the same communication device without the compansion system, and an overall improvement in the communication experience when the output is in natural language.