Conference Paper

A Closed-Loop Perspective on Fault Detection for Precision Motion Control: With Application to an Overactuated System

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... The main idea in [27] and [31] is to use identified models of subsystems in real-time, to detect and isolate faults, as illustrated in Figure 1. This automatic diagnostics provides major opportunities to improve fault tolerance through system reconfiguration, e.g, temporarily redistribute the forces in the overactuated motion control setting in case of a damaged actuator, as well as move towards predictive maintenance to maximize system availability. ...
... In [27] and [31] an approach is proposed, which relies on identified models of submodules of complex systems. After measuring frequency response functions, parameterized models are used for fault diagnosis system synthesis. ...
... As a case study, see [31] for details, we consider the prototype experimental system in Figure 2. This case study is specifically designed to exhibit dominant flexible dynamical behavior, expected to arise in next generation positioning systems as the wafer stage and reticle stage depicted in Figure 1. ...
... A method to detect additive faults is using residual generators. This method has been applied in the context of mechatronic systems, see Classens et al. (2021a). For multiplicative faults, other approaches are more suitable, e.g., originating from the domain of system identification such as the recursive least squares (RLS) algorithms, see Ljung (1987); Söderström and Stoica (2001). ...
... To manipulate the effective resonances of the system, an input and output transformation is applied to isolate the flexible mode. An additional internal feedback loop is created for the flexible mode of the system with timevarying constants k 2 (t) and d 2 (t) which allow to vary the internal stiffness and damping of the beam over time, see Fig. 4. For details regarding the implementation, see Classens et al. (2021a). ...
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... The actuators are current-driven voice-coil actuators, whereas the sensors are contactless fiberoptic displacement sensors with an approximate accuracy of 1 µm. Since the system has more actuators than DOFs, it is said to be over-actuated [29]. However, over-actuation is not considered in this work; in fact, only the middle sensor-actuator pair is exploited. ...
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Linearising the dynamics of nonlinear mechanical systems is an important and open research area. In this paper, we adopt a data-driven and feedback control approach to tackle this problem. A model predictive control architecture is developed that builds upon data-driven dynamic models obtained using nonlinear system identification. The overall methodology shows a high degree of performance combined with significant robustness against imperfect modelling and extrapolation. These findings are demonstrated using large set of synthetic experiments conducted on a asymmetric Duffing oscillator and using an experimental prototype of a high-precision motion system.
... Indeed, in traditional model-based control applications (59) , the model is only used to design a feedback controller, and after the controller is implemented, the identified model is being disposed of. The main idea in (60) and (61) is to use the identified model in real-time, to detect and isolate faults, as illustrated in Figure 13. This automatic diagnostics provides major opportunities for system reconfiguration, e.g, temporarily redistribute the forces in the overactuated motion control setting in Section 3.2 in case of a damaged actuator, as well as move towards predictive maintenance to maximize system availability. ...
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Technology in a broad sense is driven by developments in semiconductor technology, particularly with respect to the computational power of devices and systems, as well as sensor technology. The progress of semiconductor technology has demonstrated an exponential curve since the middle of the previous century, representing Moore's Law. Consequently, it is of utmost importance to bridge the gaps between disciplines in the fields of control, automation, and robotics. Moreover, data-driven approaches need to be combined with model-based design. This will lead to new digital twinning and automated design approaches that provide major opportunities. Furthermore, this necessitates the redefinition of our university system.
... The relevance of this framework is highlighted through the investigation of closed-loop operators as well as an illustrative case study. An experimental case study, using an overactuated motion system, is described in [17]. ...
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Chapter
The sections in this article are1The Problem2Background and Literature3Outline4Displaying the Basic Ideas: Arx Models and the Linear Least Squares Method5Model Structures I: Linear Models6Model Structures Ii: Nonlinear Black-Box Models7General Parameter Estimation Techniques8Special Estimation Techniques for Linear Black-Box Models9Data Quality10Model Validation and Model Selection11Back to Data: The Practical Side of Identification