Robust Fault Diagnosis by Optimal Input Design for Self-sensing Systems

This paper presents a methodology for model based robust fault diagnosis and a methodology for input design to obtain optimal diagnosis of faults. The proposed algorithm is suitable for real time implementation. Issues of robustness are addressed for the input design and fault diagnosis methodologies. The proposed technique allows robust fault diagnosis under suitable conditions on the system uncertainty. The designed input and fault diagnosis techniques are illustrated by numerical simulation.Comment: Accepted in IFAC World Congress 201

Method for accurate fault diagnosis in an inkjet print head

\u3cp\u3eIn a method for identifying of and distinguishing between at least two different predetermined disturbance states in an inkjet print head, the method comprises providing a disturbance identification input signal; applying the disturbance identification input signal to an actuator, the actuator being part of an ejection unit of an inkjet print head; receiving a residual pressure wave output signal; and analyzing the residual pressure wave output signal. The step of analyzing comprises designing and providing a respective mathematical analysis operator for each identifiable disturbance state; executing each respective mathematical analysis operator using the received residual pressure wave output signal as an input for each respective mathematical analysis operator; comparing an output of each respective mathematical analysis operator to a respective predetermined output reference; deciding for each predetermined disturbance state whether the disturbance state is present, wherein it is decided that a corresponding disturbance state is present, if an output of a respective mathematical analysis operator corresponds to the respective predetermined output reference; and it is decided that a corresponding disturbance is not present, if an output of a respective mathematical analysis operator does not correspond to the respective predetermined output reference\u3c/p\u3

Contrôle Discret Robuste en boucle ouverte : une approche LMI

International audienceLe filtrage et la pré-compensation sont des cas particuliers d'une classe plus générale de problèmes: les problèmes de contrôle en boucle ouverte. Ce papier aborde une classe de problèmes de contrôle robuste en boucle ouverte pour des systèmes discrets incertains. L'incertitude est représentée au moyen de transformations linéaires fractionnelles (LFT) et peut être composée de différentes incertitudes (paramétriques, dynamiques, non-linéarités,etc...). Il est démontré que la synthèse d'un filtre garantissant un certain niveau de performance pour le système Boucle Ouverte peut se mettre sous la forme d'un problème d'optimisation convexe sous contraintes inégalité matricielles linéaires, qui peut être résolu efficacement

Drop-on-Demand Inkjet Printhead Performance Improvement Using Robust Feedforward Control

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Drop-on-Demand Inkjet Printhead Performance Improvement Using Robust Feedforward Control

Abstract-The printing quality delivered by a Drop-onDemand (DoD) inkjet printhead is mainly limited due to the residual oscillations in the ink channel. The maximal jetting frequency of a DoD inkjet printhead can be increased by quickly damping the residual oscillations and by bringing in this way the ink-channel to rest after jetting the ink drop. The inkjet channel model obtained is generally subjected to parametric uncertainty. This paper proposes a robust optimization-based method to design the input actuation waveform for the piezo actuator in order to improve the damping of the residual oscillations in the presence of parametric uncertainties in the ink-channel model. Simulation results are presented to show the efficacy of the proposed method

Robust feedforward control for a drop-on-demand inkjet printhead

International audienceThe printing quality delivered by a Drop-on-Demand (DoD) inkjet printhead is mainly limited due to operational issues of the residual oscillations in the ink channel. The maximal jetting frequency of a DoD inkjet printhead can be increased by quickly damping the residual oscillations and by bringing in this way the ink-channel to rest after jetting the ink drop. The inkjet channel model obtained is generally subjected to parametric uncertainty. This paper proposes a robust optimization-based method to design the input actuation waveform for the piezo actuator in order to improve the damping of the residual oscillations in presence of the parametric uncertainties in the ink-channel model. Experimental results are presented to show the efficacy of the proposed method

Minimization of cross-talk in a piezo inkjet printhead based on system identification and feedforward control

The printing quality delivered by a drop-on-demand inkjet printhead is severely affected by the residual oscillations in an ink channel and the cross-talk between neighboring ink channels. For a single ink channel, our earlier contribution shows that the actuation pulse can be designed, using a physical model, to effectively damp the residual oscillations. It is not always possible to obtain a good physical model for a single ink channel. A physical model for a multi-input multi-output (MIMO) inkjet printhead is made even more sophisticated by the presence of the cross-talk effect. This paper proposes a system identification-based approach to build a MIMO model for an inkjet printhead. Additionally, the identified MIMO model is used to design new actuation pulses to effectively minimize the residual oscillations and the cross-talk. Using simulation and experimental results, we demonstrate the efficacy of the proposed method

Soft Sensing-Based In Situ Control of Thermofluidic Processes in DoD Inkjet Printing

This article introduces a closed-loop control strategy for maintaining consistency of liquid temperature in commercial drop-on-demand (DoD) inkjet printing. No additional sensors or additional actuators are installed in the printhead while achieving consistency in liquid temperature. To this end, this article presents a novel in situ sensing-actuation policy at every individual liquid nozzle, where the jetting mechanism has three distinct roles. It is used for jetting liquid droplet onto the print media based on the print job. It is used as a soft sensor to estimate the real-time liquid temperature of the jetting nozzle. While not jetting liquid, it is used as a heating actuator to minimize the gradient of liquid temperature among nozzles. The soft sensing-based in situ controller is implemented in an experimentally validated digital twin that models the thermofluidic processes of the printhead. The digital twin is scalable and flexible to incorporate an arbitrary number of liquid nozzles, making the control strategy applicable for future designs of the printhead

Minimization of cross-talk in a piezo inkjet printhead based on system identification and feedforward control

\u3cp\u3eThe printing quality delivered by a drop-on-demand inkjet printhead is severely affected by the residual oscillations in an ink channel and the cross-talk between neighboring ink channels. For a single ink channel, our earlier contribution shows that the actuation pulse can be designed, using a physical model, to effectively damp the residual oscillations. It is not always possible to obtain a good physical model for a single ink channel. A physical model for a multi-input multi-output (MIMO) inkjet printhead is made even more sophisticated by the presence of the cross-talk effect. This paper proposes a system identification-based approach to build a MIMO model for an inkjet printhead. Additionally, the identified MIMO model is used to design new actuation pulses to effectively minimize the residual oscillations and the cross-talk. Using simulation and experimental results, we demonstrate the efficacy of the proposed method.\u3c/p\u3