Xiaotian Dai

The University of York · Department of Computer Science

Conventional mixed-criticality systems (MCS)s are designed to terminate the execution of less critical tasks in exceptional situations so that the timing properties of more critical tasks can be preserved. Such a strategy can be controversial and has proven difficult to implement in practice, as it can lead to hazards and reduced functionality due...

All systems rely on inputs and outputs (I/Os) to perceive and interact with their surroundings. In safety-critical systems, it is important to guarantee both the performance and time-predictability of I/O operations. However, with the continued growth of architectural complexity in modern safety-critical systems, satisfying such real-time requireme...

Autonomous systems are of high complexity and often regarded as mixed-criticality systems (MCS) in which functions are allocated criticality levels according to risk assessment based on safety standards. Typically, tasks have different realtime requirements across criticality levels, and the estimated worst-case execution times (WCETs) are distinct...

Fully- and semi-autonomous systems are complex and safety-critical with strict timing and resource constraints, and have a deep processing pipeline with strong dependencies between different functions. Furthermore, tasks with different criticalities share the same hardware, and the scheduling strategy has to guarantee high criticality tasks' execut...

Modelling execution times in complex real-time embedded systems is vital for understanding and predicting tasks’ temporal behaviour, and to improve the system scheduling performance. Previous research mainly relied on worst-case execution time estimations based on formal static analyses that are often pessimistic. The models that resulted are hard...

Modelling execution times in complex real-time embedded systems is vital for understanding and predicting tasks’ temporal behaviour, and to improve the system scheduling performance. Previous research mainly relied on worst-case execution time estimations based on formal static analyses that are often pessimistic. The models that resulted are hard...

Emerging advanced control applications, with increased complexity in software but limited computing resources, suggest that real-time controllers should have adaptable designs. These control strategies also should be designed with consideration of the run-time behavior of the system. One of such research attempts is to design the controller along w...

With ever more complex functionalities being implemented in emerging real-time applications, multi-core systems are demanded for high performance, with directed acyclic graphs (DAG) being used to model functional dependencies. For a single DAG task, our previous work presented a concurrent provider and consumer (CPC) model that captures the node-le...

Time-Sensitive Networking (TSN) is being widely investigated to provide Ethernet capabilities for in-vehicle backbone communication. However, the gate control list (GCL), as a simple mechanism for achieving timing determinism for safety-critical traffic (ST) frames with hard deadlines, is too rigid to handle the intrinsic timing uncertainty of auto...

This paper presents a state-of-the-art filter that reduces the complexity in object detection, tracking and mapping applications. Existing edge detection and tracking methods are proposed to create suitable autonomy for mobile robots, however, many of them face overconfidence and large computations at the entrance to scenarios with an immense numbe...

In Mixed-Criticality Systems (MCSs), timely handling of I/O operations is a key for the system being successfully implemented and appropriately functioned. The I/O system for a MCS must simultaneously enable different features, including isolation/separation, timing-predictability, performance, scalability and energy-efficiency. Moreover, such I/O...

This paper presents a state-of-the-art filter that reduces the complexity in object detection, tracking and mapping applications. Existing edge detection and tracking methods are proposed to create suitable autonomy for mobile robots, however many of them face overconfidence and large computations at the entrance to scenarios with an immense number...

Long-lived, non-stop cyber-physical systems (CPS) are subject to evolutionary changes that can undermine the guarantees of schedulability that were verified at the time of deployment. At the same time, knowledge gleamed from extended periods of execution can be exploited to reduce the uncertainties that were inevitably presented in the system model...

The emerging scenarios of cyber-physical systems (CPS), such as autonomous vehicles, require implementing complex functionality with limited resources, as well as high performances. This paper considers a common setup in which multiple control and non-control tasks share one processor, and proposes a dual-mode strategy. The control task switches be...

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...

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, lenghty and informal process. The Structured Assurance Case Metamodel...

In a Cyber-Physical Control System (CPCS), there is often a hybrid of hard real-time tasks which have stringent timing requirements and soft real-time tasks that are computationally intensive. The task scheduling of such systems is challenging and requires flexible schemes that can meet the timing requirements without being over-conservative. Fixed...

In some long-lived real-time systems, it is not uncommon to see that the execution times of some tasks may exhibit trends. For hard and firm real-time systems, it is important to ensure these trends will not jeopardize the system. In this paper, we first introduce the notion of dynamic worst-case execution time (dWCET), which forms a new perspectiv...