Active fault detection in linear controller hardware with sine signal

Linear controller is used commonly to control dynamic system. In case of any failure in controller hardware, dynamic system could be misdirect. This case would be risky for human and work safety. The failure could occur in controller hardware due to over heating, power source malfunction, radiation and other effects. There are currently fault detection methods for controller hardware. This fault detection methods are passive and based on comparison approach. Active fault detection methods are used in dynamic system already. Active fault detection has two main advantage such as reliability and high speed. In this thesis, active fault detection is used in linear controller hardware and auxiliary signal is selected as sine signal. Active fault detection in controller hardware has challenge. The challenge is that controller output which goes dynamic system must not been affected by fault detection process. Because any small change in controller output could mislead dynamic system and cause risky for work safety. This thesis propose duplicated controller in the same hardware design. The design aim to separate controller output and auxiliary output signal without losing any signal data. In dublicated controller design, there are two duplicated controller. First controller use positive sine signal and second controller use negative sine signal for fault detection. Controller output is obtained by adding two duplicated controller output and auxiliary output signal is obtained by subtracting controller outputs. After constructing duplicated control design, auxiliary signal selections criteria are declared. Frequency of auxiliary signal is selected according to bode plot of linear controller. The criteria for frequency is that magnitude of linear controller response at selected frequency must be observable. The magnitude of auxiliary signal is chosen according to controller hardware restriction. Controller hardware has digital&analog input-output limit such as 5 volt. Thus magnitude of auxiliary signal and auxiliary output signal must be proper to hardware input-output limit. After declaring auxiliary signal selection criteria, active fault detection method is constructed in simulation. Active fault detection method is applied on magnetic levitation system and its predesigned linear controller in simulation. Simulation result show that active fault detection process does not affect predesigned controller performance. Also active fault detection is tested in simulation with external factor, loop cycle time and bit change faults scenarios. After saving simulation result, active fault detection methods is embed into Atmega328P microcontroller. Embedded fault detection software is also tested with external factor , loop cycle time, bit change fault scenarios. After saving experimental test results, thesis aim to make fault masking based on active fault detection. Hot standby dynamic redundancy design is proposed to fault masking process. Fault detection mechanism use rms value of auxiliary output signal. Mechanism check rms value. If rms value exceed faulty boundary values, mechanism activate fault indicator signal. After activating fault indicator, simple switch mechanism isolate faulty controller and drive dynamic system by redundant controller. Fault masking design is constructed in simulation. The fault masking design is tested with external factor fault, loop cycle time fault and bit change fault scenarios