# NOVA Mobility Assistive System: Developed and Remotely Controlled with IOPT-Tools
## 1 Introduction
In this sense, we argue that road signs, information panels, and other infrastructures should collect data from the environment, with information about the state of a street or a road (such as road traffic, flow of people on the street, mobility scooters on the road, wheelchairs leaving or entering transport, etc. ), and provide it to wheelchairs and other vehicles. As such, we propose a novel Mobility Assistive System (MAS), named NOVA-MAS, which supports the acquisition of data from the environment, its control, and the dissemination of information between infrastructures and between infrastructures and their users. The infrastructures will be able to exchange data with users and it will also allow for the dissemination of information along public roads, ensuring updated and reliable information to support appropriate/safe decisions by their users. This will make road signs and information panels naturally dynamic, updating their information based on the data received from other infrastructures and vehicles, such as smart wheelchairs with multiple sensors. NOVA-MAS can be a complement to crowdsourcing platforms, supporting the dissemination of local and volatile information. By local and volatile information, we mean information that only matters in that location and at that moment. The development and management of such systems is a challenging task. They require an architecture that supports (1) data collection, processing, and transmission; (2) specific controllers that change their behavior according to real-time information; and, (3) remote operation capabilities to allow their monitoring, execution control, and reprogramming. To support these functionalities, we also propose a suited model-driven development approach, combined with the use of a specific Petri net class (the Input-Output Place-Transition Petri net class--IOPT-nets) [22] and its associated tool framework (IOPT-Tools) [23]. Petri nets [24] are a graphical and intuitive modeling formalism, with well-defined execution semantics, that has been widely proposed (1) to model and analyze road traffic, at macroscopic or microscopic level [25; 26; 27; 28; 29; 30]; (2) to model, analyze, implement, and optimize, traffic sign controllers [30]; and, (3) to model and validate an interactive road sign system [31]. However, none of these Petri net classes and associated tools support the complete development flow of such systems, as IOPT-Tools framework does. IOPT-nets have a formal definition and a well-defined execution semantics, enabling simulations and model-checking techniques, for verification purposes, and automatic code generation, for implementation purposes. This make IOPT-nets suited for safety critical systems development, such as connected and dynamic infrastructures, where a failure may cause or not prevent a road accident. IOPT-net models can be created in the IOPT editor [23]. IOPT simulation tools support token player animations and timing diagrams [23]. IOPT model-checking tools [32] include a state-space generator and a query engine, which are used to define queries and apply them to the generated state-spaces, to check the controller's proprieties, such as the occurrence of deadlocks, live-locks, or other undesired situations. IOPT automatic code generators support code generation in C [33] (used in this work), VHDL, Instruction List, and Simulink System block, ensuring that the systems will be free from manual codification errors. Because the IOPT C code generator, automatically generates controllers with run-time monitoring capabilities, and an IOPT debugger tool [34; 35] is available, the infrastructures can be remotely monitored and controlled without any effort from the system developers. Therefore, as illustrated in Figure 1, with the use of IOPT-nets and IOPT-Tools it is possible develop infrastructure controllers, supporting: (1) the control of dynamic/variable road signs, and their remote monitoring and control; (2) infrastructures interaction; and, (3) infrastructures interaction with users/vehicles.