Robust active fault-tolerant control for internal combustion gas engine for air–fuel ratio control with statistical regression-based observer model

Arslan Ahmed Amin,Khalid Mahmood-Ul-Hasan

doi:10.1177/0020294018823031

Arslan Ahmed Amin, Khalid Mahmood-Ul-Hasan

Open Access

https://doi.org/10.1177/0020294018823031

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Abstract

Fault-tolerant control systems are utilized in safety and critical applications to achieve greater reliability and availability for continued operation despite faults in the system components. These systems can be utilized in the process plants to avoid costly production loss due to abnormal and unscheduled tripping of the machines. In this paper, advanced fault-tolerant control systems of active type are proposed for air–fuel ratio control of internal combustion gas engine in a process plant to achieve greater reliability and availability to avoid a shutdown of the gas engine. Gas engines are extensively used equipment in the process industry and proper air–fuel ratio control in the fuel system of these engines is quite important to achieve greater engine efficiency, fuel energy savings and environmental protection. Active fault-tolerant control system is proposed in this paper in which linear regression–based observer model is used in the fault detection and isolation unit for fault detection, isolation and reconfiguration. Fuel actuator is introduced in the fuel supply line and proportional feedback controller is implemented to maintain the air–fuel ratio in faulty conditions. Redundancy in the sensors and fuel actuator is proposed to avoid engine shutdown in case of simultaneous faults in more than one sensor and to avoid a single point of failure due to fault in the single actuator. Noise is introduced in the sensor measurements to determine the robustness of proposed active fault-tolerant control system in noisy and faulty conditions. Results show that the proposed system remains stable, maintaining air–fuel ratio well in faulty conditions and is robust to noise.

Highlights

In the active fault-tolerant control systems (AFTCS), faults are identified and isolated by a separate dedicated unit called as fault detection and isolation (FDI)
FDI is the main component in AFTCS in which observer model is implemented to generate estimated values of various parameters of the system to compare with actual sensor values
The fault estimation unit is designed using the statistical linear regression technique on the data obtained from lookup tables of the model

Summary

Introduction

Fault-tolerant control is an advanced approach to obtain greater reliability and availability in safety and critical applications such as unmanned air vehicles (UAVs), airplanes and nuclear facilities where system failure can cause human and environmental damages. Fault-tolerant fuel control system is implemented in Simulink that has analytical redundancy for sensors to provide estimated values from lookup tables during faults in the sensors.[42] This model is used in this research study for implementation of our proposed AFTCS In this model, four sensors play a vital role in AFR control as described as follows: Throttle position sensor. Our contribution is the design of FTC for AFR control of SI IC gas engines using linear regression–based observer in the FDI unit with redundant sensors and actuators to achieve greater reliability due to both analytical and hardware redundancies. Such type of AFR control is not found in the literature so far up to our best knowledge. The conclusion of the study is presented in the last section

Research methodology

Results and discussions

Conclusion