Showing papers by "M Maarten Steinbuch published in 2003"

Model-based feedforward for motion systems

Abstract: This paper considers model-based feedforward for motion systems The proposed feedforward controller consists of an acceleration feedforward part and an inverse dynamics model of flexible modes Based on analysis and H/sub /spl infin// model-based feedforward design, the inverse dynamics can be restricted to a second order filter in the form of a skew notch even if the motion system has more parasitic modes The benefit of this is an on-line tuning possibility Tracking errors and settling times can be reduced significantly compared to acceleration feedforward

Experimental modelling and LPV control of a motion system

Abstract: The objective of this paper is to show how experimentally based modelling can be used for designing Linear Parametrically Varying (LPV) controllers. As a test system we use an industrial pick and place unit with one linear X-drive and two independent linear Ydrives. The dynamics of the Y-axes depend on the Xposition. An LPV model is derived by using measured Frequency Response Functions at different positions, fitting a parametric model on each measurement and combining these models by linking parameters via a fit as a function of operating point. Rewriting the LPV model into a LFT structure and applying model reduction in the space of the scheduling variable finalizes the modelling phase. With this model an LPV controller is calculated and shows robust performance for the whole operating range, in contrast to local H∞ controllers.

Analysis of Slip in a Continuously Variable Transmission

Abstract: High clamping force levels reduce the efficiency of the Continuously Variable Transmission (CVT). However, high clamping force level are necessary to prevent slip between the belt and the pulleys. If a small amount of slip is allowed, the clamping force level can be reduced. To achieve this, slip in a CVT is investigated. From measurements on an experimental setup, Traction curve data and efficiency measurements are derived. A model describing slip in a CVT is verified using measurements with a belt with increased play. It is found that small amounts of slip can be controlled in a stable way on the setup. The traction curve was mostly dependent on the CVT ratio. Efficiency is found to be highest for 1 to 2% slip depending on the ratio. The model is in reasonable agreement with the measurements.Copyright © 2003 by ASME

Time-frequency analysis of a motion system with learning control

Abstract: Iterative learning control (ILC) is a known technique for improving the performance of systems or processes that operate repetitively over a fixed time interval. ILC generates a feed-forward signal effective for providing good tracking control. Experience with ILC algorithm applied to the wafer stage of a wafer scanner motion system has shown that ILC has liability to deal with limited performance in the face of position dependent dynamics, with the fact that ILC does not account for setpoint trajectory changes and with stochastic effects. The goal of the research presented in this paper is to integrate ILC applied to the wafer stage motion system with time-frequency analysis. This provides insight into the above mentioned ILC shortcomings when the learning control technique is applied on the considered motion system. We examine the suitability of a time-frequency adaptive filtering design for the learned feed-forward when applied to the wafer stage setup.

Iterative learning control for variable setpoints, applied to a motion system

Abstract: Iterative Learning Control (ILC) is a known technique for improving the performance of systems or processes that operate repetitively over a fixed time interval. ILC generates a feedforward signal effective for providing good tracking control. However, there still exist a number of problems which hinder extensions of ILC schemes. The major obstacle is perhaps the requirement that the trajectory (or repetitive disturbance) must be strictly repeatable over operations. ILC has also liability to deal with stochastic effects. This paper presents the design and the implementation of a time-frequency adaptive ILC that is applicable for motion systems which execute the same kind of repetitive tasks. For the motion system, we show that the adaptive algorithm we propose leads to design one (learned) feed-forward signal suitable for different setpoints. We demonstrate that, when implementing time-frequency adaptive ILC, very good time performance (tracking errors) is obtained. The proposed algorithm converges faster than standard ILC. With time-frequency adaptive ILC noise amplification is reduced.

Introduction to an integrated design for motion systems using over-actuation

Abstract: In this paper an introduction and motivation is given towards an integrated design approach for motion systems using overactuation. Looking to motion systems and their history, the current status of mechatronic motion systems is discussed. One of the main aspects that limit performance in mechanical systems is the presence of vibrations. An overview is presented of several passive and active methods to solve vibration problems. Active vibration control can be regarded as a form of overactuation to improve system performance. It is expected that an integrated overactuated design approach will be advantageous over traditional vibration control solutions, which often make use of adaptations after the mechanical design has been completed. Before a framework for an integrated design approach can be posed, different strategies of overactuation must be investigated. To study the closed-loop characteristics of resonances in mechanical systems with more actuators more closely, some first explorations of a dual-input single-output motion system are made.

Identification and control for future restraint systems

Abstract: In this paper, an approach to design an ideal restraint system is discussed. The problem, normally solved by optimization approaches, is translated to a tracking problem, where a given reference trajectory has to be tracked. Before a controller can be designed, identification of the local dynamic input-output behavior is performed in several operating points using stepwise perturbations added to the input. Using the obtained model, a stabilizing controller is designed with loop shaping for performance. Results are shown for the design of the belt force, such that the maximum chest deceleration of the driver in a frontal crash test with 56 km/h crash velocity, is minimized. A reduction of 60% of the maximum chest acceleration is achieved.

Control design for robust performance of a direct-drive robot

Abstract: An experimental approach to achieve robust performance of direct-drive robot motion control is presented in this paper. It consists of: (i) decoupling the robot dynamics via feedback linearisation; (ii) frequency domain identification of the decoupled dynamics; (iii) compensation of these decoupled dynamics using feedback controllers designed via /spl mu/-synthesis. The designed controllers ensure robust performance, i.e., guaranteed accuracy of robot motions despite uncertainty in its dynamics and disturbances affecting the robot operation. Theoretical aspects of the control design are formulated. Its practical implementation on a direct-drive robotic arm is demonstrated in detail. Experimental investigation confirms the quality of the design: specifications on performance and robustness are practically realized.

Modeling the 3-DOF dynamics of an electrodynamic Maglev suspension system with a passive sled

Abstract: A model that describes the 3-DOF dynamics of a passively levitated electro-dynamic maglevsystem is presented. The model is based on the flux-current-force interactions and the geometricrelationships between the levitation coils and the permanent magnets on the sled. The model ispresented in a parametric state-space formulation, suitable to extract model parameters frominput-output measurements in a minimum mean square error sense, and model predictions arecompared with measured trajectories in height, pitch and roll. The proposed structure is very wellsuited to later develop robust feedback control of the sled dynamics.

Frequency domain iterative learning control for direct-drive robots

Abstract: This paper presents an Iterative Learning Control algorithm for direct-drive robots. The learning algorithm assumes linear dynamics, which is created using a nonlinear model-based compensator. The convergence criterion of the learning controller is derived in the frequency domain. Rules for designing the filters, used in the update law, are explained. The effectiveness of the algorithm is demonstrated in experiments on a spatial direct-drive robot. The root-mean-square values of the tracking errors in a demanding writing task are over 10 times smaller after just eight iterations of the learning algorithm, compared with the errors before learning.

Compensation of mode shapes with a piezo electric actuator for an optical drive

Abstract: In miniaturized systems (e.g. optical disk drives) much effort is made to design a structure in such a way that the demands on dimensions (height, width) and desired bandwidth are satisfied. Easier, and often cheaper designs can not be used, because they suffer from lower resonance frequencies, which limit the bandwidth. A method is presented for mechatronic structures that compensates unwanted bandwidth limiting resonance frequencies with an additional piezo electric actuator. Advantage of this method is that no extra sensor is used and that the contribution of the piezo is much easier to tune (when compared to a notch filter), since it is part of the structure. Disadvantage is that the piezo influences the dynamics of the original system, which complicates the choice of a suitable piezo actuator.

Compensation of mode shapes with a piezo electric actuator

Abstract: In miniaturized systems (e.g. optical disk drives) much effort is made to design a structure in such a way that the demands on dimensions (height, width) and desired bandwidth are satisfied. Easier, and often cheaper designs can not be used, because they suffer from lower resonance frequencies, which limit the bandwidth. A method is presented for mechatronic structures that compensates unwanted bandwidth limiting resonance frequencies with an additional piezo electric actuator. Advantage of this method is that no extra sensor is used and that the contribution of the piezo is much easier to tune (when compared to a notch filter), since it is part of the structure. Disadvantage is that the piezo influences the dynamics of the original system, which complicates the choice of a suitable piezo actuator.

Robust controller design for a teleoperated forceps

Abstract: s presented at the Medical Physics and Engineering 2003 - VIII EFOMP Congress - 30th NVKF Annual Scientific Meeting (May 20-23, 2003, Eindhoven, The Netherlands)

The Smart Powertrain, Clean, Efficient and Safe Utilization of Existing Infrastructure

Abstract: In this paper a new project that is to be launched at the end of 2003 is described. The project is entitled "The Smart Powertrain" and is defined in the Netherlands where it is pending for governmental subsidy. The Smart Powertrain fuses Hybrid Powertrain Technology (HPT) with Advanced Driver Assist (ADA) Systems for improving both the efficiency of the powertrain and traffic. Break-through technologies on active and passive safety are an integral part of the project definition. The integration of HPT and ADA in one context will result in currently unforeseeable benefits on emissions and congestion, particularly since they are mutually enforcing mechanisms. The paper describes the Smart Powertrain definition, motivation for this definition and preliminary results on fuel economy benefits. Highly specialized R&D that is currently performed in The Netherlands and runs ahead on the SPT program is briefly addressed throughout the paper.