S. Krishnamani ¹, T. Mohanraj ¹

Affiliations
1 Department of Instrumentation and Control Engineering, SRM University, Kattankulathur - 603203, Tamil Nadu, IN

Abstract

Objective: This paper aims at designing a fault tolerant controller for a launch vehicle electro-mechanical actuator using model reference adaptive controller. Fault detection and diagnosis is a crucial topic in spacecraft operations and an important aspect of on board software with respect to safety, performance and reliability. Method/Statistical Analysis: This paper commences by the mathematical modeling of an electro-mechanical actuator based on a BLDC torque motor. The system is then subjected to a servo design and it is used as the model system for a model reference adaptive controller. MIT Rule is used as the control law for model based controller. The residuals for fault detection are generated by model reference adaptive control technique and it has the capability to detect and isolate the errors. The continuous operation of the system is obtained using a real time reconfiguration achieved using the model based approach. The entire system was simulated in MATLAB/SIMULINK software. Findings: The servo design of the launch vehicle electromechanical actuator system was developed using the mathematical model and the compensated system was used as the model system in the fault tolerant scheme using the model reference adaptive controller. The fault tolerant controller scheme was able to detect, isolate the faulty conditions and switch over the system output to the model output during the fault condition. The system is driven by the model output when fault occurs. The application of MIT rule is mainly for low frequency signals. Applications/Improvements: The system could be used in the launch vehicle applications, in order to make the system give ideal response during system failure. The control law used for the model reference adaptive controller can be improved and the Lyapnov method or theory of augmentation can be utilized instead of MIT Rule.

Keywords

Electro-Mechanical Actuator, Fault Tolerant Controller (FTC), Launch Vehicle, Model Reference Adaptive Controller (MRAC), MIT Rule.

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S. Krishnamani ¹, T. Mohanraj ¹, K. Murugumohan Kumar ¹

Affiliations
1 Department of Mechanical Engineering, SASTRA University, Thirumalaisamudram, Thanjavur - 613401, Tamil Nadu, IN

Abstract

vBackground/objectives: Today, as a result of limited fuel resources and stringent emission standards, the methyl ester fuel has been focused on alternative fuels for I.C engine. Methyl ester fuels can be effectively used in low heat rejection engines (LHR), in which the surface temperature of the combustion temperature is increased by providing a thermal barrier coating. The main objective of our work is to reduce the engine exhaust emissions like HC and CO using diethyl ether in low heat rejection engine. Methods/Statistical Analysis: In this work, engine components like piston crown, cylinder head, and liner, inlet and exhaust valves of a diesel engine were coated with the ceramic material lanthanum zirconate by plasma spray technique. The effects of rapeseed methyl ester (biodiesel) produced by transesterification method and its blends with Diethyl ether (10% and 20% by volume) were studied in the low heat rejection engine. Findings: The thermal efficiency is found to be higher for diesel and biodiesel in the LHR engine. The results indicate that, B10 (10% Diethyl ether & 90% Biodiesel) and B20 (20% Diethyl ether & 80% Biodiesel) shows lower thermal efficiency compared with that straight biodiesel in low heat rejection engine. Applications/Improvements: Significant improvements were observed in engine exhaust emissions like CO and HC (except NOx) for all the diethyl ether blended biodiesel fuel in LHR engine. The higher oxygen content in the blended fuel reduces CO and HC emissions by 10% and 18% respectively compared to biodiesel in LHR engine.

Keywords

Brake Thermal Efficiency, Combustion Characteristics, Lanthanum Zirconate, Low Heat Rejection Engine, Rapeseed Methyl Ester, Transesterification

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S. Krishnamani ¹, T. Mohanraj ¹

Affiliations
1 Department of Mechanical Engineering, SASTRA University, Thanjavur - 613401, Tamil Nadu, IN

Abstract

The objective of this paper is to establish the temperature distributions in plasma sprayed Yttria Stabilized Zirconia (YSZ) and magnesia stabilized zirconia (MgZrO₃) thermal barrier coating on an aluminum alloy piston crown to raise the potential of a diesel engine. The influence of ceramic coating thickness on temperature variations are studied by finite element method using ANSYS. The temperature distribution analyses were conducted for the ceramic coating thickness of 0.3 mm over the piston crown surface. The results of the piston coated with two different coatings were analyzed. It is observed that, the peak exterior surface temperature of the ceramic piston with the material MgZrO₃ is increased by 32% and 20% for the piston coated with yttria stabilized zirconia compared with conventional aluminum alloy piston. It is concluded that the substrate temperature of the piston coated with MgZrO₃ and yttria stabilized zirconia is reduced by 25% and 17% compared with uncoated aluminum alloy piston. The lower substrate surface temperature by coating results in improved heat to work conversion efficiency of the engine.

Keywords

ANSYS, Finite Element Method, MgZrO₃, Thermal Analysis, Yttria Stabilized Zirconia (YSZ).

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S. Amrutha ¹, T. Mohanraj ¹, N. Chakrapani Ramapriya ¹, M. Sujatha ¹, R. Ezhilarasie ¹, A. Umamakeswari ¹

Affiliations
1 School of Computing, SASTRA University, Thanjavur - 613401, Tamil Nadu, IN

Abstract

Objective: There is a need for a distributed data storage mechanism to reduce the probability of data loss and cope with node failure as well. The increase in amount of data generated in the wireless sensor network necessitates an innetwork data aggregation protocol that creates summaries of data as information is disseminated in the network. Methods: An effervescent aggregation technique has been formulated that makes use of the existing data redundancy in the dissemination-based network and combines it with consistency checks to filter false aggregate information. A greedy approach is formulated to keep the copies of the data in the nearby neighbour who has greater capacity. Findings: Architecture designed for in-network aggregation helps in dealing with a large amount of data by eliminating redundant information and at the same time distributes the aggregate information in the nearby node since dissemination deals with memory shortage and node failure. Applications: The benefits of the system include that the redundant copies are maintained in some other nodes which has higher memory and power this may, in turn, increase the reliability of the data in nodes of sensor networks and the availability is ensured during the communication with sinks.

Keywords

Data Dissemination, Data Replication, Wireless Sensor Networks.

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