Abstract-In this paper, a human-machine shared control strategy is proposed for the navigation control of a wheelchair, employing both brain-machine control mode and autonomous control mode. In the brain-machine control mode, contrary to the traditional four-direction control signals, a novel brain-machine interface using steadystate visual evoked potentials is presented, which utilizes two brain signals to produce a polar polynomial trajectory. The produced trajectory is continuous in curvature without violating dynamic constraints of the wheelchair. In the autonomous control mode, the synthesis of angle-based potential field and vision-based simultaneous localization and mapping technique is proposed to guide the robot navigating among the obstacles. Extensive experiments have been conducted to test the developed shared control wheelchair in several scenarios with a number of volunteers, and the results have verified the effectiveness of the proposed shared control scheme.Index Terms-Angle potential field, brain-machine interface (BMI), shared control, vision-based simultaneous localization and mapping (SLAM).

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Assurance cases are used to demonstrate confidence in system properties of interest (e.g. safety and/or security). A number of system assurance approaches are adopted by industries in the safety-critical domain. However, the task of constructing assurance cases remains a manual, trivial and informal process. The Structured Assurance Case Metamodel (SACM) is a standard specified by the Object Management Group (OMG). SACM provides a richer set of features than existing system assurance languages/approaches. SACM provides a foundation for model-based system assurance, which has great potentials in growing technology domains such as Open Adaptive Systems. However, the intended usage of SACM has not been sufficiently explained. In addition, there has been no support to interoperate between existing assurance case (models) and SACM models.In this article, we explain the intended usage of SACM based on our involvement in the OMG specification process of SACM. In addition, to promote a model-based approach, we provide SACM compliant metamodels for existing system assurance approaches (the Goal Structuring Notation and Claims-Arguments-Evidence), and the transformations from these models to SACM. We also briefly discuss the tool support for model-based system assurance which helps practitioners to make the transition from existing system assurance approaches to model-based system assurance using SACM.

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The original MrsP proposal presented a new multiprocessor resource sharing protocol based on the properties and behaviour of the Priority Ceiling Protocol, supported by a novel helping mechanism. While this approach proved to be as simple and elegant as the single processor protocol, the implications with regard to nested resources was identified as requiring further clarification. In this work we present a complete approach to nested resources behaviour and analysis for the MrsP protocol. 3