Precise dynamic models of processes are required for many applications, ranging from control engineering to the natural sciences and economics. Frequently, such precise models cannot be derived using theoretical considerations alone. Therefore, they must be determined experimentally. This book treats the determination of dynamic models based on measurements taken at the process, which is known as system identification or process identification. Both offline and online methods are presented, i.e. methods that post-process the measured data as well as methods that provide models during the measurement. The book is theory-oriented and application-oriented and most methods covered have been used successfully in practical applications for many different processes. Illustrative examples in this book with real measured data range from hydraulic and electric actuators up to combustion engines. Real experimental data is also provided on the Springer webpage, allowing readers to gather their first experience with the methods presented in this book. Among others, the book covers the following subjects: determination of the non-parametric frequency response, (fast) Fourier transform, correlation analysis, parameter estimation with a focus on the method of Least Squares and modifications, identification of time-variant processes, identification in closed-loop, identification of continuous time processes, and subspace methods. Some methods for nonlinear system identification are also considered, such as the Extended Kalman filter and neural networks. The different methods are compared by using a real three-mass oscillator process, a model of a drive train. For many identification methods, hints for the practical implementation and application are provided. The book is intended to meet the needs of students and practicing engineers working in research and development, design and manufacturing.

Identification of Dynamic Systems: An Introduction with Applications

This paper presents a fault-tolerant control approach for four-wheel independently driven (4WID) electric vehicles. An adaptive control-based passive fault-tolerant controller is designed to ensure vehicle system stability and to track the desired vehicle motion when an in-wheel motor/motor driver fault happens. Due to the system actuation redundancy, it is challenging to isolate the faulty wheel and to accurately estimate the control gain of the faulty in-wheel motor/motor driver for 4WID electric vehicles. An active fault diagnosis (FD) approach is thus proposed to explicitly isolate and evaluate the fault. Based on the estimated control gain of the faulty wheel, the control efforts of all the wheels are redistributed to relieve the torque demand on the faulty wheel. Simulations using a high-fidelity CarSim full-vehicle model show the effectiveness of the proposed in-wheel motor/motor driver active fault diagnosis and fault-tolerant control approaches in various driving scenarios.

Fault-Tolerant Control With Active Fault Diagnosis for Four-Wheel Independently Driven Electric Ground Vehicles

A survey of fault-tolerant controllers based on safety-related issues

This paper presents an in-wheel motor fault diagnosis and fault-tolerant control method for four-wheel independently actuated (4WIA) electric vehicles. The 4WIA electric vehicle is one of the promising architectures for electric vehicles. While such a vehicle architecture greatly increases the flexibility for vehicle control, it also elevates the requirements on system reliability, safety, and fault tolerance due to the increased number of actuators. A fault diagnosis approach for finding the faulty in-wheel motor=motor driver pair is developed. The proposed diagnosis approach does not need an accurate knowledge on tire-road friction coefficient (TRFC) and is robust to tire force modeling inaccuracies. Based on the in-wheel motor=motor driver fault diagnosis mechanism, a control-allocation based vehicle fault-tolerant control system is designed to accommodate the in-wheel motor=motor driver fault by automatically allocating the control effort among other healthy wheels. Simulations using a high-fidelity, CarSimVR , full-vehicle model show the effectiveness of the proposed in-wheel motor=motor driver fault diagnosis and fault-tolerant control approaches. [DOI: 10.1115/1.4005050]

Fault-Tolerant Control for Electric Ground Vehicles With Independently-Actuated In-Wheel Motors

Fault-tolerant actuators and drives—Structures, fault detection principles and applications

This paper deals with the design of jerk-limited time-optimal control sequences for rest-to-rest maneuvers of flexible structures. The resulting jerk profiles will be either bang-bang or bang-off-bang. To ensure quiescent states at the end of the maneuver, a pole cancellation technique will be used. Further constraints account for the geometric boundary conditions. This paper will also investigate the development of the control profile upon variation of the maximum allowable amount of jerk. The last section presents numerical results. The proposed control algorithm is implemented for the Floating Oscillator benchmark problem.

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Jerk limited time optimal control of flexible structures

The problem of designing jerk limited-time optimal control proe les for rest-to-rest maneuvers of e exible structures with multiple actuators is addressed. The problem formulation includes constraints to cancel the poles corresponding to the rigid-body mode and e exible modes of the system and to satisfy the boundary conditions of the rest-to-rest maneuver. Further constraints can be added to increase robustness to parametric uncertainties of the plant. The technique proposed is applied to a three-mass/two-spring system and the evolution of the shape of the control proe le as a function of jerk is illustrated. I. Introduction T HERE has been extensive research in the e eld of vibration control of slewing e exible structures. The knowledge obtained throughoutthisresearchhasbeenappliedtoawidevarietyofcontrol problems, including, but not limited to, maneuvering of large space structures, 1 e exiblearmrobots, 2 computerdiskdrives, 3 andcranes. 4 In most of these applications, the objective of the controller is to minimize the maneuver time with quiescent e nal states. Robustness tomodelingerrors,limitsonfuelconsumed,maximumdeformation permitted,andso on,havebeenincludedintheproblemformulation as additional constraints. Research in the e eld of input shaping was motivated by Smith’ s development of the Posicast Control. 5 The sensitivity of these controllers to uncertainties in damping and frequencies of the modes was addressed by Singer and Seering, 6 and the resulting pree lter was referred to as an input shaper. Singh and Vadali 7 illustrated that a time-delay pree lter that cancels the underdamped poles of the system results in the same control proe le as the input shaped controller. They also illustrated that the use of a series of time-delay e lters results in increased robustness to modeling errors. Various other approaches, which include forcing the derivative of the sensitivity curve at the nominal values of the model parameters to zero and designing input shapers that maximize the uncertain region where the residual vibration is less than a prespecie ed quantity, 8 have been investigated in the interest of desensitizing the pree lter with respect to modeling errors. Techniques to desensitize the timeoptimal control proe le have been developed by Liu and Wie 9 and Singh and Vadali. 10 A very recent approach to the design of desensitized time-delay e lters is a minimax formulation proposed by Singh. 11 All of the aforementioned approaches assume that the actuator can track step inputs, which is equivalent to requiring ine nite jerk control proe les. Jerk is indicative of the time rate of change of the inertia forces and is a measure of the impact levels that can excite unmodeled dynamics, which is of concern in the control of e exible structures. Bhat and Miu 3 study the problem of designing control proe les, minimizing a cost function that is the time integral

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Desensitized Jerk Limited-Time Optimal Control of Multi-Input Systems

http://www.nt.ntnu.no/users/skoge/prost/proceedings/ifac2008/data/papers/1479.pdf

Marco Muenchhof

Papers

Fault-tolerant actuators and drives—Structures, fault detection principles and applications

Jerk limited time optimal control of flexible structures

Desensitized Jerk Limited-Time Optimal Control of Multi-Input Systems

Displacement Sensor Fault Tolerance for Hydraulic Servo Axis

Comparison of change detection methods for a residual of a hydraulic servo-axis