EXPERIENCE IN METRICS AND MEASUREMENTS FOR N-VERSION PROGRAMMING

1994 ◽  
Vol 01 (01) ◽  
pp. 41-62 ◽  
Author(s):  
MICHAEL R. LYU ◽  
JIA-HONG CHEN ◽  
ALGIRDAS AVIŽIENIS
Keyword(s):  
Life Cycle ◽  
Flight Control ◽  
Fault Tolerant ◽  
Structural Diversity ◽  
Control Software ◽  
Baseline Design ◽  
Software Diversity ◽  
Points Of View ◽  
Design Diversity ◽  
Diversity Measurement

The N-Version Programming (NVP) approach applies the idea of design diversity to obtain fault-tolerant software units, called N-Version Software (NVS) units. The effectiveness of this approach is examined by the software diversity achieved in the member versions of an NVS unit. We define and formalize the concept of design diversity and software diversity in this paper. Design diversity is a property naturally applicable to the NVP process to increase its fault-tolerance attributes. The baseline design diversity is characterized by the employment of independent programming teams in the NVP. More design diversity investigations could be enforced in the NVP design process, including different languages, different tools, different algorithms, and different methodologies. Software diversity is the resulting dissimilarities appearing in the NVS member versions. We characterize it from four different points of view that are designated as: structural diversity, fault diversity, tough-spot diversity, and failure diversity. Our goals are to find a way to quantify software diversity and to investigate the measurements which can be applied during the life cycle of NVS to gain confidence that operation will be dependable when NVS is actually employed. The versions from a six-language N-Version Programming project for fault-tolerant flight control software were used in the software diversity measurement.

Robust fault-tolerant flight control of quadrotor against faults in multiple motors

2021 ◽  
pp. 095441002199954
Author(s):  
Dinesh D Dhadekar ◽  
S E Talole
Keyword(s):  
Flight Control ◽  
Tracking Control ◽  
Fault Tolerant ◽  
External Disturbances ◽  
Detection And Identification ◽  
Attitude Tracking ◽  
Fault Detection And Identification ◽  
Attitude Tracking Control ◽  
Disturbance Estimator

In this article, position and attitude tracking control of the quadrotor subject to complex nonlinearities, input couplings, aerodynamic uncertainties, and external disturbances coupled with faults in multiple motors is investigated. A robustified nonlinear dynamic inversion (NDI)-based fault-tolerant control (FTC) scheme is proposed for the purpose. The proposed scheme is not only robust against aforementioned nonlinearities, disturbances, and uncertainties but also tolerant to unexpected occurrence of faults in multiple motors. The proposed scheme employs uncertainty and disturbance estimator (UDE) technique to robustify the NDI-based controller by providing estimate of the lumped disturbance, thereby enabling rejection of the same. In addition, the UDE also plays the role of fault detection and identification module. The effectiveness and benefits of the proposed design are confirmed through 6-DOF simulations and experimentation on a 3-DOF Hover platform.

Dynamic Sensor Allocation Framework for Fault Tolerant Flight Control

2014 ◽  
Vol 47 (3) ◽  
pp. 3477-3482 ◽  
Author(s):  
Tamás Peni ◽  
Bálint Vanek ◽  
Zoltán Szabó ◽  
József Bokor
Keyword(s):  
Flight Control ◽  
Fault Tolerant

scholarly journals FADEC Computer Systems for Safety Critical Application

1998 ◽  
Author(s):  
Friedrich Schwamm
Keyword(s):  
Fault Tolerant ◽  
Parallel Execution ◽  
Computer Design ◽  
Control Software ◽  
Computing Power ◽  
Safety Requirements ◽  
Engine Control System ◽  
Complex Functions ◽  
Hardware Overhead ◽  
Safety Features

One of the main requirements for modern FADEC systems is to implement great computing power with many interfaces and to keep the FADEC hardware effort to a minimum. On the other side the criticality potential of computer failures is considered as ‘hazardous’. The trend in FADEC development is to implement even more complex functions into the control software which consequently increases the authority and therefore the criticality potential of computer failures. In the mid 80’s a double computer system was used to performed a parallel execution of the control software with identical input parameters to output identical results. A difference in any one of these computer results causes the comparator hardware to output a failure indication. This was considered to have a 100% coverage of computer failures. The problem with this system was certainly the relatively large hardware overhead and the limited intelligence of the comparator logic. Some other FADEC systems have implemented only a Watch Dog Timer and Bus Access Supervisory hardware to detect computer malfunctions. With this method the proof for the achievements of the safety requirements have become almost impossible since adequate fault models of the computer components are difficult to establish due to their increasing functional complexity. This paper describes how to develop the safety features for the Computer Design from the Engine Control System Safety Requirements to achieve a full coverage of the potentially critical failure effects with fault tolerant failure recovery functions and a minimum of hardware overhead.

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