Time filter

Source Type

Lourens E.,Catholic University of Leuven | Papadimitriou C.,Catholic University of Leuven | Papadimitriou C.,University of Thessaly | Gillijns S.,Flanders Mechatronics Technology Center | And 3 more authors.
Mechanical Systems and Signal Processing | Year: 2012

An algorithm is presented for jointly estimating the input and state of a structure from a limited number of acceleration measurements. The algorithm extends an existing joint input-state estimation filter, derived using linear minimum-variance unbiased estimation, to applications in structural dynamics. The filter has the structure of a Kalman filter, except that the true value of the input is replaced by an optimal estimate. No prior information on the dynamic evolution of the input forces is assumed and no regularization is required, permitting online application. The effectiveness and accuracy of the proposed algorithm are demonstrated using data from a numerical cantilever beam example as well as a laboratory experiment on an instrumented steel beam and an in situ experiment on a footbridge. © 2012 Elsevier Ltd.


Vo-Minh T.,Catholic University of Leuven | Tjahjowidodo T.,Flanders Mechatronics Technology Center | Ramon H.,Biosensors | Van Brussel H.,Catholic University of Leuven
IEEE/ASME Transactions on Mechatronics | Year: 2011

Two main challenges in using a pneumatic artificial muscle (PAM) actuator are the nonlinearity of pneumatic system and the nonlinearity of the PAM dynamics. The latter is complicated to characterize. In this paper, a Maxwell-slip model used as a lumped-parametric quasi-static model is proposed to capture the force/length hysteresis of a PAM. The intuitive selection of elements in this model interprets the unclear, but blended contributing causes of the hysteresis very well, which are assumed to originate from the dry friction of the double helix weaving of the PAM braided shell, the friction of the weaving and the bladder, the elasticity of the bladder and/or the deformation of the conical parts of a PAM close to the end caps. The obtained model is simple, but physically meaningful and easy to handle in terms of control. © 2006 IEEE.


Wang X.,Catholic University of Leuven | Stoev J.,Flanders Mechatronics Technology Center | Pinte G.,Flanders Mechatronics Technology Center | Swevers J.,Catholic University of Leuven
Mechatronics | Year: 2013

Two control approaches are presented to improve the energy efficiency of a robot which has to perform point-to-point motions during a fixed time interval. One is called Proximate Energy Optimal Servo (PEOS) and the other is called Energy-Optimal Model Predictive Control (EOMPC). The PEOS approach is based on the Proximate Time Optimal Servo (PTOS) control algorithm whose parameters are optimized in order to achieve energy efficient behavior. The EOMPC approach developed based on the Time-Optimal Model Predictive Control (TOMPC) approach achieves energy optimal performance by minimizing the energy losses in the object function. The two developed approaches are applied to a robot playing badminton and compared to two existing control approaches: the Proximate Time Optimal Servo (PTOS) and the Time-Optimal Model Predictive Control (TOMPC). The robot is still able to intercept most of the opponent shuttles on time, while a significant reduction of the energy consumption is demonstrated in both cases. © 2013 Elsevier Ltd. All rights reserved.


Ompusunggu A.P.,Flanders Mechatronics Technology Center | Ompusunggu A.P.,Catholic University of Leuven | Papy J.-M.,Flanders Mechatronics Technology Center | Vandenplas S.,Flanders Mechatronics Technology Center | And 2 more authors.
Mechanical Systems and Signal Processing | Year: 2013

Wet friction clutches play a critical role in vehicles equipped with automatic transmissions, power shift transmissions and limited slip differentials. An unexpected failure occurring in these components can therefore lead to an unexpected total breakdown of the vehicle. This undesirable situation can put human safety at risk, possibly cause long-term vehicle down times, and result in high maintenance costs. In order to minimize the negative impacts caused by the unexpected breakdown, an optimal maintenance scheme driven by accurate condition monitoring and prognostics therefore needs to be developed and implemented for wet friction clutches. In this paper, the development of a condition monitoring system that can serve as a basis for health prognostics of wet friction clutches with a focus in heavy duty vehicle applications is presented. The developed method is based on monitoring the dominant modal parameters extracted from the torsional vibration response occurring in the post-lockup phase, i.e. just after the clutch is fully engaged. These modal parameters, namely the damped torsional natural frequency f d and the decay factor σ, are computed based on the pre-filtered Hankel Total Least Squares (HTLS) method which has an excellent performance in estimating the parameters of transient signals with a relatively short duration. In order to experimentally validate the proposed monitoring method, accelerated life tests were carried out on five different paper-based wet friction clutches using a fully instrumented SAE#2 test setup. The dominant modal parameters extracted from the post-lockup velocity signals are then plotted in function of the service life (duty cycle) of the tested clutches. All the plots exhibit distinct trends that can be associated with the progression of the clutch degradation. Therefore, the proposed quantities can be seen as relevant features that may enable us to monitor and assess the condition of wet friction clutches. Since velocity sensor(s) is typically available in a transmission, the proposed monitoring method allows for the practical implementation. © 2012 Elsevier Ltd. All rights reserved.


Depraetere B.,Catholic University of Leuven | Pinte G.,Flanders Mechatronics Technology Center | Swevers J.,Catholic University of Leuven
Proceedings of the American Control Conference | Year: 2011

This paper presents a new iterative learning strategy to control wet clutches. These are complex hydraulic systems that are commonly used in automatic transmissions of heavy duty vehicles, and their control aims at performing fast and smooth engagements. Learning is used to overcome the need for complex models and to maintain performance despite large variations in the system behavior. Classical iterative learning control techniques can however not be employed directly since reference trajectories corresponding to the performance requirements are unavailable. Instead, the presented iterative learning strategy translates the performance requirements directly into an objective function and constraints, hence constituting a numerical optimization problem. After each engagement, this problem is solved in order to find the control signal for the next engagement, using a piecewise linear model for the clutch. Learning is included by using the measured response data to update the models and constraints used by the optimization problem. The presented strategy is successfully validated on an experimental test bench containing wet clutches. The learning process is shown to converge towards the desired engagement quality, and a demonstration is given of the robustness with respect to changes in the operating conditions. © 2011 AACC American Automatic Control Council.


Ompusunggu A.P.,Flanders Mechatronics Technology Center | Sas P.,Catholic University of Leuven | Van Brussel H.,Catholic University of Leuven
Mechatronics | Year: 2013

In this paper, a friction model appropriate for wet friction clutches based on the extension of the Generalized Maxwell Slip (GMS) friction model is integrated to a four-DOF lumped-mass-spring-damper system which represents a typical SAE#2 test setup. Degradation models expressing the evolutions of the friction model parameters are also proposed, where the structure of the degradation models is inspired from experimental results obtained in the earlier work. This way, the engagement dynamics of the clutch system during the useful lifetime can be simulated. It appears that the previously developed pre-and post-lockup features extracted from the simulated signals obtained in this study are qualitatively in agreement with the experimental results. Those features show their predictive behaviors that confirm their feasibility to be used for clutch monitoring and prognostics. Furthermore, the models and simulation procedure discussed in this paper can be employed for developing and evaluating prognostics algorithms for wet friction clutch applications. © 2013 Elsevier Ltd. All rights reserved.


Alujevic N.,Catholic University of Leuven | Zhao G.,Catholic University of Leuven | Depraetere B.,Flanders Mechatronics Technology Center | Sas P.,Catholic University of Leuven | And 2 more authors.
Journal of Sound and Vibration | Year: 2014

The optimum resonance frequency and the damping coefficient for passive Tuned Mass Dampers (TMD) have been determined using various optimality criteria in the past. In this study an active damping method using Inertial Actuators (IAs) is considered. Closed form expressions for the H2 optimal control parameters that minimise the kinetic energy of the primary structure are derived. It is shown that the resonance frequency of the IA should be as low as practically possible. However, for a given resonance frequency, an optimal pair exists of the passive damping coefficient of the IA and the feedback gain. Closed form expressions for these are provided in the paper. It is noted that the amount by which the described active approach outperforms an optimally tuned TMD having the same mass depends on the squared ratio of resonance frequencies of the IA and the primary structure. © 2014 Elsevier Ltd.


Depraetere B.,Catholic University of Leuven | Pinte G.,Flanders Mechatronics Technology Center | Swevers J.,Catholic University of Leuven
International Workshop on Advanced Motion Control, AMC | Year: 2010

This paper considers the control of wet clutches, and presents a two-level control strategy to learn and adapt the control signals during normal machine operation. With this approach it is possible to avoid the current practise of experimental calibrations, where regular recalibrations are needed to compensate for time-varying dynamics, e.g. due to wear and changes in oil temperature. On a low level, the developed controller determines the actuator signal by solving an optimal control problem before each engagement of the clutch. The models and constraints for this optimization problem are iteratively updated by a high-level controller, which consists of a recursive identification algorithm to model the system dynamics, and of an ILC-type algorithm to learn appropriate values for the constraints. The performance and robustness of this control scheme are validated on an experimental test setup. © 2010 IEEE.


Ompusunggu A.P.,Flanders Mechatronics Technology Center
Mechanical Systems and Signal Processing | Year: 2014

This paper discusses how a qualitative understanding on the physics of failure can lead to a theoretical derivation of effective features that are useful for condition monitoring of wet friction clutches. The physical relationships between the features and the mean coefficient of friction (COF) which can be seen as the representation of the degradation level of a wet friction clutch are theoretically derived. In order to assess the accuracy of the theoretical relationships, Pearson's correlation coefficient is applied to experimental data obtained from accelerated life tests on some commercial paper-based wet friction clutches using a fully instrumented SAE#2 setup. The analyses on the experimental data reveal that the theoretical predictions are plausible. © 2014 Elsevier Ltd. All rights reserved.


Gadeyne K.,Flanders Mechatronics Technology Center | Pinte G.,Flanders Mechatronics Technology Center | Berx K.,Flanders Mechatronics Technology Center
Advanced Engineering Informatics | Year: 2014

An important challenge in mechatronic system design is to select a feasible system architecture that satisfies all requirements. This article describes (i) the necessary concepts that a system architect needs to be able to formally and declaratively describe the design space of mechanical design synthesis problems, thereby minimizing accidental complexity; (ii) how a Domain Specific Language based on the SysML modeling language and the Object Constraint Language (OCL) can be used to create this model of the design space; and (iii) an iterative process to come up with a formal model of the design space. This model describes the design space independent of any (knowledge of a) particular solving technology for the Design Space Exploration. Furthermore, the information in the model allows to select the most appropriate solving strategy for a particular design synthesis problem. The different concepts are illustrated on the example of automated synthesis of a gearbox. © 2014 Elsevier Ltd. All rights reserved.

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