Cyber-physical systems design for runtime trustworthiness maintenance supported by tools

The trustworthiness of cyber-physical systems is a critical factor for establishing wide-spread adoption of these systems. Hence, especially the behavior of safety-critical software components needs to be monitored and managed during system operation. Runtime trustworthiness maintenance should be planned and prepared in early requirements and design phases. This involves the identification of threats that may occur and affect user’s trust at runtime, as well as related controls that can be executed to mitigate the threats. Furthermore, observable and measureable system quality properties have to be identified as indicators of threats, and interfaces for reporting these properties as well as for executing controls have to be designed and implemented. This paper presents a process model for preparing and designing systems for runtime trustworthiness maintenance, which is supported by several tools that facilitate the tasks to be performed by requirements engineers and system designer

A tool for monitoring and maintaining system trustworthiness at runtime

Trustworthiness of software systems is a key factor in their acceptance and effectiveness. This is especially the case for cyber-physical systems, where incorrect or even sub-optimal functioning of the system may have detrimental effects. In addition to designing systems with trustworthiness in mind, monitoring and maintaining trustworthiness at runtime is critical to identify issues that could negatively affect a system's trustworthiness. In this paper, we present a fully operational tool for system trustworthiness maintenance, covering a comprehensive set of quality attributes. It automatically detects, and in some cases mitigates, trustworthiness threatening events. The use of such a tool can enable complex software systems to support runtime adaptation and self-healing, thus reducing the overall upkeep cost and complexity

Design, Construction and Evaluation of a Row Crop Thinning Machine

Equipment availability is necessary in the development of Agriculture mechanization. Crop thinning is one of the most important stages in row crop production which is laborious and costly. The objective of this project is design and construction of a row crop thinning machine. Four main system units are plant sensors, ground sensors, control and thinning platforms. In this machine the unwanted plants on the rows are randomly removed by employing a pneumatically system. A blade on a vertical arm with pendulum motion removes the plant from the rows. The machine control system consists of an arm and a blade which is activated by a double acting cylinder and equipped with a relay and a timer. The pneumatic cylinder is controlled via a solenoid valve. Laboratory tests were conducted to validate the machine performance. Some other preliminary tests also were performed for optimization of parameters such as cinematic index and cutting length of blades. The laboratory tests (totally 9 tests) were performed with a constant forward speed and three levels of plant density, using artificial plants. The data were analyzed using SPSS software. The results show that satisfactory performance of the machine is achieved when the plant density is moderate i.e. the thinning performance reduces with higher plant distance in the row. The other effective variable on machine performance is the adjustment of sensor sensitivity, which is used to distinguish between week and strong plants. In general the machine performance is sensitive to plant shape and morphology, plant distribution pattern in the field, growing stage of the plants, time of thinning and the effectiveness of previous weeding operation

Combining risk-management and computational approaches for trustworthiness evaluation of socio-technical systems

The analysis of existing software evaluation techniques reveals the need for evidence-based evaluation of systems’ trustworthiness. This paper aims at evaluating trustworthiness of socio-technical systems during design-time. Our approach combines two existing evaluation techniques: a computational approach and a risk management approach. The risk-based approach identifies threats to trustworthiness on an abstract level. Computational approaches are applied to evaluate the expected end-to-end system trustworthiness in terms of different trustworthiness metrics on a concrete asset instance level. Our hybrid approach, along with a complementary tool prototype, support the assessment of risks related to trustworthiness as well as the evaluation of a system with regard to trustworthiness requirements. The result of the evaluation can be used as evidence when comparing different system configurations