Robot Flow Control - Development of a Modular, Graphical User Interface

Kurzfassung

At DLR, the Robotics and Mechatronics Center is developing a new software for robot flow control programming called RAFCON. It is built up from scratch and includes a lot of features coming directly from the people using the software after its completion. Therefore, a lot of requests regarding usability and functionality have to be taken into account. RAFCON uses hierarchical state machines, similar to Harel state machines, to implement the flow control, as this provides a good overview over the task and its parts and supports the step-by-step execution of encapsulated subtasks. This work focuses on the development of a graphical, modular user interface simplifying the workflow and meeting the requirements. These are for instance the integration of RAFCON into the institutes corporate design, an intuitive user interface and fast state machine development. In order to create a consistent and matching design and color theme, the design of the GUI has been developed in collaboration with an external designer. The initial, bright color schema is replaced by a dark one, which reduces the stress on the human eye during work. According to design theory, some important factors need to be considered when creating a user interface. The coloring and contrasts or ''gestalt'' principles are part of this. The colors of the controls (e.g. buttons, text outputs) need to be carefully chosen. Bright signal colors like red or orange guide the user focus on the important elements, whereas decent colors as blue or green are used to show uncritical information. Combining colors accurately, different contrasts can be created to further emphasize the importance of crucial events. Following ''gestalt'' principles, it is possible to arrange the elements in the GUI beneficial for the work flow and use them to generate a coherent look. The created design orders and groups control-elements to improve the utilization of the available space and build a consistent user interface. New icons round out the appearance and help keeping the corporate design. Furthermore, a new feature to rearrange single elements was implemented. It increases the possibility for the user to organize the control elements according to their needs. To gain more flexibility, this is used in the left and right side bars, providing additional information about the selected state and general information (e.g. state machine libraries, history). The logging view has been extended with a feature to choose which information (debug, info, warning and error) should be logged, which helps to improve finding important logging outputs. Additionally, a new toolbar is added next to the graphical editor, containing the execution control buttons (start, pause, stop). Python is the chosen programming language for the entire project. Due to the predefined programming language, GTK is used for the window design and display. For the implementation of the main part of the GUI, the graphical editor, another library (Gaphas) has been used to gain more flexibility in customization. Gaphas is especially designed for the development and display of state machines. It is highly customizable regarding functionality and look. All in all, the new design of the GUI could be realized successfully. The wanted effects of integrating RAFCON into the corporate design and improve the work flow could be achieved using the dark colored theme and the modular design. Furthermore, a lot of additional features have been implemented which work according to their needs. The new design and features turn RAFCON into a reliably working and intuitive software for the creation of robot flow controls.