Contact Force Estimation for an Elastic Beam Using Optimal High-Gain Disturbance Observer

2010 ◽  
Author(s):  
Yan Liu ◽  
Dirk So¨ffker
Keyword(s):  
Contact Force ◽  
Disturbance Observer ◽  
Elastic Beam ◽  
High Gain ◽  
Contact Forces ◽  
Force Estimation ◽  
Input Estimation ◽  
System States ◽  
Unknown Input Estimation ◽  
Noisy Measurements

This contribution presents a contact force estimation approach based on an optimal high-gain disturbance observer for an elastic beam using noisy measurements. The reconstruction of contact forces as an example for unknown input estimation represents a class of typical mechanical engineering problems related to the estimation of unknown effects for disturbance rejection or accommodation or fault diagnosis and isolation. The high-gain disturbance observers applied here is able to estimate estimate unknown external inputs together with system states. But choosing observer gains is a difficult task because of the influence of measurement noise. The important advantage of the proposed approach in comparison with classical high-gain disturbance observer is the self adjustment of the observer gains according to the actual estimation situation. Estimation results based on real measurements from known high-gain disturbance observer and the proposed optimal one are compared. It can be shown that the proposed algorithm allows optimized disturbance observer gains calculation, being able to be situatively adapted.

scholarly journals Stator-Rotor Contact Force Estimation of Rotating Machine

Automation ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 83-97
Author(s):  
Mark Spiller ◽  
Dirk Söffker
Keyword(s):  
Contact Force ◽  
Dry Friction ◽  
Nonlinear Filtering ◽  
Friction Model ◽  
Contact Forces ◽  
Elastic Behavior ◽  
Force Estimation ◽  
Severe Problem ◽  
Suggested Approach ◽  
System States

In turbomachines, dry friction resulting from stator–rotor contacts is a severe problem that may degrade lifetime of the machine or even lead to complete failure. Knowledge about the system states and contact forces is beneficial for system monitoring or to prevent contacts through, e.g., active magnetic bearings. In this paper, a nonlinear model is derived that describes the lateral rotor vibrations in the case of contact and no contact. The elastic behavior of the shaft is modeled based on the finite-element method. The contact is described by a dry friction model. An augmented system description is formulated that allows estimation of rotor displacements and contact forces by means of nonlinear filtering approaches like an extended Kalman filter. A simulation study was conducted that explicitly considered the hazardous backward whirl. The suggested approach shows suitable estimation performance related to both state and contact force estimation.

Reconstruction of the Dynamic Rail-Wheel Contact Forces

2003 ◽  
Author(s):  
Svenja Kirchenkamp ◽  
Dirk So¨ffker
Keyword(s):  
Contact Force ◽  
Normal Force ◽  
Elastic Beam ◽  
Contact Forces ◽  
Force Estimation ◽  
Measurement Device ◽  
Tangential Contact ◽  
Proportional Integral ◽  
First Time ◽  
Displacement Measurements

This contribution introduces a virtual measurement device for the reconstruction of the in practice unmeasureable railwheel contact forces. For this aim the Proportional-Integral (PI)-Observer is used. Then, the concept of a measurement sleeve at the axle bearing is shown. With the displacement measurements resulting from the sleeve using the PI-Observer, an estimation of the tangential contact force and the dynamic normal force is possible. Using the simulation of the rail-wheel contact, the feasibility of the estimation of the contact force behavior is shown. As an outlook for further applications of the PI-Observer in the context of rail-wheel contact force estimation, the reconstruction of contact forces by using acceleration measurements is demonstrated by an example of an elastic beam for the first time.

Proportional-Integral-Observer With Adaptive High-Gain Design Using Funnel Adjustment Concept

2017 ◽  
Author(s):  
Fateme Bakhshande ◽  
Dirk Söffker
Keyword(s):  
Feedback Linearization ◽  
Dynamical Behavior ◽  
High Gain ◽  
Present Contribution ◽  
Input Estimation ◽  
Proportional Integral ◽  
Spring System ◽  
Unknown Input Estimation ◽  
Mass Spring ◽  
Funnel Control

This paper focuses on a novel gain design approach of Proportional-Integral-Observer (known as PI-Observer) for unknown input estimation such as disturbances. Whereas estimation of the fast dynamical behavior requires large observer gains, the effect of measurement noise is not negligible. To adjust the PIO gain adaptively, in this contribution the idea of funnel control is taken into consideration. The advantage of the proposed approach compared to previously published PIO gain design is the self adjustment of the observer gains according to the actual estimation situation. To improve the control performance and robustness, in the present contribution the proposed approach is combined with exact feedback linearization (EFL) method. The effectiveness of the proposed approach is verified by simulation results of a MIMO mass-spring system.

Robust contact force estimation for robot manipulators in three-dimensional space

2006 ◽  
Vol 220 (9) ◽  
pp. 1317-1327 ◽  
Author(s):  
J Jung ◽  
J Lee ◽  
K Huh
Keyword(s):  
Contact Force ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Contact Forces ◽  
Robust Estimator ◽  
Force Sensors ◽  
Force Estimation ◽  
Estimation Algorithms

Information on contact forces in robot manipulators is indispensable for fast and accurate force control. Instead of expensive force sensors, estimation algorithms for contact forces have been widely developed. However, it is not easy to obtain the accurate values due to uncertainties. In this article, a new robust estimator is proposed to estimate three-dimensional contact forces acting on a three-link robot manipulator. The estimator is based on the extended Kalman filter (EKF) structure combined with a Lyapunov-based adaptation law for estimating the contact force. In contrast to the conventional EKF the new estimator is designed such that it is robust to the deterministic uncertainties such as the modelling error and the sensing bias. The performance of the proposed estimator is evaluated through simulations of a robot manipulator and demonstrates robustness in estimating the contact force. The estimation results show that it can be potentially used to replace the expensive force sensors in robot applications.

Nonintrusive Measurement of Contact Forces During Vibration Dominated Impacts

2004 ◽  
Vol 126 (3) ◽  
pp. 489-497 ◽  
Author(s):  
Satwinder Jit Singh ◽  
Anindya Chatterjee
Keyword(s):  
Contact Force ◽  
Tikhonov Regularization ◽  
Strain Gauge ◽  
Initial Conditions ◽  
Contact Point ◽  
Electrical Contact ◽  
Contact Forces ◽  
Force Estimation ◽  
Contact Duration ◽  
Gauge Data

Impact force estimation is done indirectly through, e.g., strain measurements away from the contact point, because inserting a force transducer between the contacting objects changes the force. Most prior contact force measurements involved a single contact interval. Here we study transverse impacts of a slender beam and a clamped-free plate; contact occurs more than once within one impact. Strain gauge data, electrical contact detection, and a dynamic model of the beam are used to estimate the contact force. The problem of force estimation from strain gauge data is ill-posed, and Tikhonov regularization fails initially. A reduced-order model is then developed using symmetry, and better initial conditions are estimated using a Kalman filter. Subsequently, Tikhonov regularization gives excellent force estimates, empirically supported by the contact duration measurements. Two other methods that explicitly use the contact duration measurements are also given. The first uses Tikhonov regularization within each contact interval, followed by Kalman filtering during noncontact to get initial conditions for the next contact. The second uses truncated Fourier sine series in each contact interval and is, computationally, the simplest. All three methods provide consistent force estimates. Our work complements recent work by Inoue and coworkers where the impulse response of the colliding object was measured separately using a Hopkinson bar, and electrical contact was not monitored.

scholarly journals A Discrete-Time Extended Kalman Filter Approach Tailored for Multibody Models: State-Input Estimation

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4495
Author(s):  
Rocco Adduci ◽  
Martijn Vermaut ◽  
Frank Naets ◽  
Jan Croes ◽  
Wim Desmet
Keyword(s):  
Kalman Filter ◽  
High Fidelity ◽  
Force Estimation ◽  
Computationally Efficient ◽  
Input Estimation ◽  
Multibody Model ◽  
System States ◽  
Filter Approach ◽  
The Stability ◽  
Stability And Accuracy

Model-based force estimation is an emerging methodology in the mechatronic community given the possibility to exploit physically inspired high-fidelity models in tandem with ready-to-use cheap sensors. In this work, an inverse input load identification methodology is presented combining high-fidelity multibody models with a Kalman filter-based estimator and providing the means for an accurate and computationally efficient state-input estimation strategy. A particular challenge addressed in this work is the handling of the redundant state-description encountered in common multibody model descriptions. A novel linearization framework is proposed on the time-discretized equations in order to extract the required system model matrices for the Kalman filter. The presented framework is experimentally validated on a slider-crank mechanism. The nonlinear kinematics and dynamics are well represented through a rigid multibody model with lumped flexibilities to account for localized interaction phenomena among bodies. The proposed methodology is validated estimating the input torque delivered by a driver electro-motor together with the system states and comparing the experimental data with the estimated quantities. The results show the stability and accuracy of the estimation framework by only employing the angular motor velocity, measured by the motor encoder sensor and available in most of the commercial electro-motors.

Modified PIO Design for Robust Unknown Input Estimation

2003 ◽  
Author(s):  
Idriz Krajcin ◽  
Dirk So¨ffker
Keyword(s):  
Practical Importance ◽  
Elastic Beam ◽  
Observer Design ◽  
Measurement Noise ◽  
Unknown Input ◽  
Friction Forces ◽  
Input Estimation ◽  
Sensitivity Problem ◽  
Unknown Input Estimation ◽  
First Time

In this contribution, an extension for the Proportional-integral-Observer (PIO) is presented. The observer can estimate unknown forces with impact character or e.g. friction forces acting on a system. Therefore, the observer does not use any information about the contact. The classical PIO is in the case of relevant measurement noise not able to achieve satisfactory performance. The new formulated observer design permits to estimate unknown input forces acting on a system while measurement noise is present. The main focus of the paper is a new extension of the PIO for general applications and an experimental improvement of the performance, given for the first time with this paper. The introduced extension is especially to improve the observer robustness to measurement noise. This is an issue of high practical importance due to the fact that the PIO-scheme works with high gains, getting sensitive to measurement noise. With the introduced extension, the sensitivity problem is attenuated. The estimation of impact forces acting on a fixed elastic beam is used as a principle example. The introduced method works generally and can be applied to different tasks for elastic structures.

Disturbance-Observer-Based Force Estimation for Haptic Feedback

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Abhishek Gupta ◽  
Marcia K. O’Malley
Keyword(s):  
Force Control ◽  
Disturbance Observer ◽  
Closed Loop ◽  
Haptic Feedback ◽  
Open Loop ◽  
Contact Forces ◽  
Haptic Interface ◽  
Force Sensing ◽  
Force Estimation ◽  
Control Approach

In this paper, we propose the use of a nonlinear disturbance-observer for estimation of contact forces during haptic interactions. Most commonly used impedance-type haptic interfaces employ open-loop force control under the assumption of pseudostatic interactions. Advanced force control in such interfaces can increase simulation fidelity through improvement of the transparency of the device. However, closed-loop force feedback is limited both due to the bandwidth limitations of force sensing and the associated cost of force sensors required for its implementation. Using a disturbance-observer, we estimate contact forces at the tool tip, then use these estimates for closed-loop control of the haptic interface. Simulation and experimental results, utilizing a custom single degree-of-freedom haptic interface, are presented to demonstrate the efficacy of the proposed disturbance-observer (DO)-based control approach. This approach circumvents the traditional drawbacks of force sensing while exhibiting the advantages of closed-loop force control in haptic devices. Results show that the proposed disturbance-observer can reliably estimate contact forces at the human-robot interface. The DO-based control approach is experimentally shown to improve haptic interface fidelity over a purely open-loop display while maintaining stable and vibration-free interactions between the human user and virtual environment.

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