Showing papers by "M Maarten Steinbuch published in 2011"
01 Oct 2011-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: The NANOMEFOS as discussed by the authors was developed to provide suitable metrology (high accuracy, universal, noncontact, large measurement volume and short measurement time) for use during manufacturing of these surfaces.
Abstract: Aspherical and freeform optics are applied to reduce geometrical aberrations as well as to reduce the required number of components, the size and the weight of the system. To measure these optical components with nanometre level uncertainty is a challenge. The NANOMEFOS machine was developed to provide suitable metrology (high accuracy, universal, non-contact, large measurement volume and short measurement time) for use during manufacturing of these surfaces. This paper describes the design, realization and testing of this machine. In particular it describes the design and testing of the air-bearing motion system with parallel stage configuration, and the separate metrology system with Silicon Carbide metrology frame and an interferometry system for direct displacement measurement of the optical probe. Preliminary validation measurements demonstrate the nanometer level repeatability for freeform surface measurement. © 2011 Elsevier Inc.
62 citations
TL;DR: In this paper, a model of the stage and motor is developed incorporating the switching behavior of the drive legs, the contact deformation, and stick-slip effects between the legs and the stage.
Abstract: Piezo actuators are used in high-precision systems that require nanometer accuracy. In this paper, we consider a nano-motion stage driven by a walking piezo actuator, which contains four bimorph piezo legs. We propose a (model-based) optimization method to derive waveforms that result in optimal driving properties of the walking piezo motor. A model of the stage and motor is developed incorporating the switching behavior of the drive legs, the contact deformation, and stick-slip effects between the legs and the stage. The friction-based driving principle of the motor is modeled using a set-valued friction model, resulting in a model in terms of differential-algebraic inclusions. For this model, we developed a dedicated numerical time-stepping solver. Experiments show a good model accuracy in both the drive direction and the perpendicular direction. The validated model is used in an optimization, resulting in waveforms with optimal driving properties of the stage at constant velocity. Besides the model-based optimization, also a direct experimental data-based waveform optimization is performed. Experiments with the optimized waveforms show that compared to existing sinusoidal and asymmetric waveforms in literature the driving properties can be significantly improved by the model-based waveforms and even further by the data-based waveforms.
57 citations
13 Oct 2011
TL;DR: In this article, a non-predictive controller based on a combination of Dynamic Programming (DP) and Pontryagin's Minimum Principle (PMP) is described and taken as a benchmark control solution for optimizing the gear shift problem of the parallel HEV in terms of computational efficiency.
Abstract: In this paper, Model Predictive Control (MPC) framework is exploited to synthesize a predictive controller for a parallel Hybrid Electric Vehicle (HEV) equipped with an Automated Manual Transmission. The algorithm also controls the gear shift command, together with the power split between the engine and electric machine and the engine on-off state using the route information ahead. A non-predictive controller based on a combination of Dynamic Programming (DP) and Pontryagin's Minimum Principle (PMP) is described and taken as a benchmark control solution for optimizing the gear shift problem of the parallel HEV in terms of computational efficiency. This so-called DP-PMP control approach is then utilized in the MPC framework to realize the predictive controller for a gear shift problem in a receding horizon mode. Simulation results show that the non-predictive controller improves the fuel economy up to 35.9% and 43.5% on NEDC and FTP75 respectively when compared with a conventional vehicle. Even with a short horizon, fuel saving of the predictive controller is very close to that of the non-predictive controller with a relative difference of 0.3%. Moreover, the predictive controller can be seen as a suitable realtime implementable control candidate with a fast computation property.
39 citations
TL;DR: An H"~ norm-based criterion is derived that guarantees stability of the time-varying delay system for a given range of variations of the repetitive delay in the repetitive controller that is continuously adjusted based on the repetitive variable.
29 citations
TL;DR: A mapping from the parameters defining the nonlinear and LTI dynamics to the output spectrum is derived, which allows analytic description and analysis of the corresponding higher order sinusoidal input describing functions.
29 citations
TL;DR: In this article, a combined Kadomtsev-Porcelli model of a sawtoothing plasma actuated by an electron cyclotron current drive system has been set-up.
Abstract: A systematic methodology for structured design of feedback controllers for the sawtooth period is presented, based on dedicated identification of the sawtooth dynamics. Therefore, a combined Kadomtsev-Porcelli model of a sawtoothing plasma actuated by an electron cyclotron current drive system has been set-up. This is used to derive the linearized input-output relations (transfer functions) from the varying deposition location of the electron cyclotron waves (ECW) to the sawtooth period. These transfer functions are derived around a large collection of operating points. Assessment of these control-relevant transfer functions shows that a sawtooth period controller requires an integral (I) action to guarantee closed-loop stability with zero steady-state error. Additional proportional-integral (PI) action can be applied to further increase the closed-loop performance. The parameters of both the I and PII controllers have been optimized in terms of stability, performance and robustness. Moreover, the effect of the mechanical ECW launcher on the closed-loop performance is studied for realistic cases. It is shown that the launcher dynamics seriously affects the achievable closed-loop performance in present-day experiments. © 2011 IAEA, Vienna.
25 citations
TL;DR: In this article, the hardware design and control design of a novel ball handling mechanism in the RoboCup Middle Size League used by team Tech United Eindhoven is presented.
25 citations
TL;DR: In this article, the authors focus on the combined optimization of hybrid system use, gearbox and vehicle velocity with a novel cost function description which describes the influence of the automated manual transmission, the potential of brake energy recovery, and vehicle velocities with one control signal.
21 citations
TL;DR: In this paper, the authors investigated the sawtooth period behavior under periodic forcing by electron cyclotron waves and proposed an open-loop locking controller based on injection locking, which is a well-known technique to control limit cycles of nonlinear dynamic oscillators.
Abstract: In this paper the sawtooth period behaviour under periodic forcing by electron cyclotron waves is investigated. The deposition location is kept constant while the gyrotron power is modulated with a certain period and duty cycle. Extensive simulations on a representative dynamic sawtooth model show that when this modulation is properly chosen, the sawtooth period quickly synchronizes to the same period and remains locked at this value. It is shown that the range of modulation periods and duty cycles over which sawtooth period locking occurs, depends on the deposition location, but is particularly large for depositions near the q = 1 surface. The simulation results reveal a novel approach to control the sawtooth period in open loop, based on injection locking, which is a well-known technique to control limit cycles of non-linear dynamic oscillators. The locking and convergence results are therefore used in a simple open-loop locking controller design, with which accurate sawtooth period tracking to any desired value is indeed demonstrated. Injection locking appears to let the sawtooth period converge to the modulation period quickly, partly because it does not suffer from slow EC mirror launcher dynamics. Moreover, imulations show that the method has a relatively large robustness against general uncertainties and disturbances. Hence, injection locking is expected to outperform conventional sawtooth control methods using a variable deposition location and constant gyrotron power. Finally, the recent result with sawtooth pacing is shown to be a special case of the general locking effect.
19 citations
TL;DR: This paper presents an algorithm for optimized (low latency, robust and high fidelity) real-time sensing of the crashes, based on time-scale wavelet theory and edge-detection, which is robust and accurate.
18 citations
TL;DR: In this paper, a metrological AFM using a three-degree-of-freedom (DOF) stage to move the sample with respect to the probe of the AFM is considered.
Abstract: Atomic force microscopes (AFMs) are used for sample imaging and characterization at nanometer scale. In this work, we consider a metrological AFM, which is used for the calibration of transfer standards for commercial AFMs. The metrological AFM uses a three-degree-of-freedom (DOF) stage to move the sample with respect to the probe of the AFM. The repetitive sample topography introduces repetitive disturbances in the system. To suppress these disturbances, repetitive control (RC) is applied to the imaging axis. A rotated sample orientation with respect to the actuation axes introduces a nonrepetitiveness in the originally fully repetitive errors and yields a deteriorated performance of RC. Directional repetitive control (DRC) is introduced to align the axes of the scanning movement with the sample orientation under the microscope. Experiments show that the proposed directional repetitive controller significantly reduces the tracking error as compared to standard repetitive control.
09 May 2011
TL;DR: A two level algorithm is proposed of particular use for teams of cooperating robots and the algorithm is based on a multiple hypotheses filter in order to reduce the sensitivity to track loss in case of temporary occlusions of objects or false measurements.
Abstract: Robots increasingly operate in dynamic environments and in order to operate safely, reliable world models are indispensable. A world model is the robot's view of the world and contains information about obstacle locations and velocities. A two level algorithm is proposed. It is of particular use for teams of cooperating robots and the algorithm is based on a multiple hypotheses filter. Each robot features a low level world model with a fast update rate which can be used for obstacle avoidance. The local world models are combined to one global view of the world that is shared between all robots and can be used for the implementation of team strategies. Labeling and tracking is added to the multiple hypotheses filter in order to reduce the sensitivity to track loss in case of temporary occlusions of objects or false measurements. The algorithm was extensively tested during the 2010 RoboCup Middle Size League world championships in Singapore, the results of which are presented.
01 Dec 2011
TL;DR: In this article, an approach to estimate the maximum friction between the pushbelt and pulley set in a mass-produced Continuously Variable Transmission (CVT) is described, which is useful to accurately determine the maximum transmittable torque and to monitor the variator condition.
Abstract: This study describes an approach to estimate the maximum friction between the pushbelt and pulley set in a mass-produced Continuously Variable Transmission. Up-to-date friction knowledge is useful to accurately determine the maximum transmittable torque and to monitor the variator condition. Besides standard sensors, torque signals are assumed to be available. An adaptive estimator is presented based on the Kalman filter, which estimates friction-related parameters to find the maximum friction. The filter requires no a priori knowledge of the maximum friction and needs no detailed friction model. Experiments show that this method can be used for both an undamaged and damaged pushbelt.
18 Aug 2011
TL;DR: In this paper, a method of objectively analyzing the performance index for the optimal control problem of a parallel hybrid electric vehicle is introduced by using the Singular Value Decomposition method.
Abstract: The definition of a performance index for the optimization design and optimal control problem of a Hybrid Electric Vehicle is not often considered and analyzed explicitly. In literature, there is no study about proposing a method of building or evaluating whether a performance index is appropriate. In this paper a method of objectively analyzing the performance index for the optimal control problem of a parallel Hybrid Electric Vehicle is introduced. The correlations and interdependencies among the objectives of the performance index are addressed by using the Singular Value Decomposition method. It is found that a simplified performance index consisting of fuel consumption and comfort can be obtained without sacrificing the vehicle performance compared to the case with the original one including fuel consumption, comfort and driveability.
13 Oct 2011
TL;DR: A hierarchical control framework where at the lower levels the authors use local and independent PID controllers for adjusting the stage and the beam deflectors and these controllers are coordinated by a supervisory controller such that maximum performance is achieved.
Abstract: Electron microscopes are important tools for material science research since they can reveal accurate images (down to the atomic level) for a wide range of specimens. Moreover, a sample can be visualized while thermal processes are induced to the specimen. Such processes involve the contraction or the expansion of the specimen holder, and hence image movement. In current practice one has to wait until the image stabilizes and then analyze the sample. In this paper we propose a hierarchical control framework where at the lower levels we use local and independent PID controllers for adjusting the stage and the beam deflectors. These controllers are then coordinated by a supervisory controller such that maximum performance is achieved. The coordinating controller will solve a nonlinear optimization problem for linear stage models in the model-based predictive control (MPC) setting. Typically, this problem is NP hard and therefore difficult to solve. In this paper we propose to further improve the performance of the system by recasting the optimization problem into a mixed-integer linear programming (MILP) one. The advantage is that for MILP optimization problems solvers are available which guarantee to find the global optimum. Then the MILP solution can be used as good initial point when solving optimization problems for nonlinear stage models.
TL;DR: In this article, three different modelling and simulation methods (forward dynamic, quasi-static backwards, and inverse dynamic) were compared and the simulation results using these methods were analyzed and the difference in simulation results for the vehicle used on representative driving cycles was discussed.
Abstract: In this paper, three different modelling and simulation methods (forward dynamic, quasi-static backwards, and inverse dynamic) will be compared and the simulation results using these methods will be analysed. From a Forward Dynamic (FDM) model, a Forward Quasi-static (FQM) and a Backward Quasi-static Model (BQM) for the engine will be derived. The difference in simulation results for the vehicle used on representative driving cycles will be discussed. The forward dynamic model contains a scalable engine model based on physical laws. The accuracy of this model will be investigated by comparing simulation results with measured quasi-static efficiency data of actual engines.
18 Aug 2011
TL;DR: In this paper, the authors present the modeling and design of an optimal Energy Management Strategy (EMS) for a flywheel-based hybrid vehicle, that does not use any electrical motor/generator, or a battery, for its hybrid functionalities.
Abstract: This paper presents the modeling and design of an optimal Energy Management Strategy (EMS) for a flywheel-based hybrid vehicle, that does not use any electrical motor/generator, or a battery, for its hybrid functionalities. The hybrid drive train consists of only low-cost components, such as a flywheel module and a continuously variable transmission. This hybrid drive train is characterized by a relatively small energy capacity (flywheel) and discrete shifts between operation modes, due to the use of clutches. The main design criterion of the optimized EMS is the minimization of the overall fuel consumption, over a pre-defined driving cycle. In addition, comfort criteria are formulated as constraints, e.g., to avoid high-frequent shifting between driving modes. The criteria are used to find the optimal sequence of driving modes and the generated engine torque. Simulations show a fuel saving potential of 20% to 39%, dependent on the chosen driving cycle.
Posted Content•
TL;DR: It is shown indeed that time-domain constraints on closed-loop signals of linear systems can be incorporated as linear matrix inequalities, even when complex conjugate poles are assigned.
Abstract: This paper presents a general framework for the design of linear controllers for linear systems subject to time-domain constraints. The design framework exploits sums-of-squares techniques to incorporate the time-domain constraints on closed-loop signals and leads to conditions in terms of linear matrix inequalities (LMIs). This control design framework offers, in addition to constraint satisfaction, also the possibility of including an optimization objective that can be used to minimize steady state (tracking) errors, to decrease the settling time, to reduce overshoot and so on. The effectiveness of the framework is shown via a numerical example.
TL;DR: In this article, a modular model for the hydraulic actuation system on the basis of first principles is constructed and validated, which is characterized by a relatively low complexity and a reasonably high accuracy.
Abstract: A reduction in the fuel consumption of a passenger car with a pushbelt continuously variable transmission (CVT) can be established via optimization of the hydraulic actuation system. This requires a model of the dynamic characteristics with low complexity and high accuracy, e.g., for closed-loop control design, for closed-loop simulation, and for optimization of design parameters. The hydraulic actuation system includes a large number of hydraulic components and a model of the dynamic characteristics is scarce, which is caused by the complexity, the nonlinearity, and the necessity of a large number of physical parameters that are uncertain or unknown. In this paper, a modular model for the hydraulic actuation system on the basis of first principles is constructed and validated, which is characterized by a relatively low complexity and a reasonably high accuracy. A modular approach is pursued with respect to the first principles models of the hydraulic components, i.e., a hydraulic pump, spool valves, proportional solenoid valves, channels, and hydraulic cylinders, which reduces complexity and improves transparency. The model parameters are either directly provided, directly measured, or identified. The model of the hydraulic actuation system is composed of the models of the hydraulic components and is experimentally validated by means of measurements that are obtained from a production pushbelt CVT. Several experiment types are considered. The correspondence between the measured and simulated responses is fairly good.
18 Aug 2011
TL;DR: A frequency domain method is introduced that allows fast and high accuracy tuning of controller parameters when the closed loop system is subject to nonlinear influences and this methodology is applied to optimally compensate friction in a high precision motion stage of a transmission electron microscope.
Abstract: Friction is a performance limiting factor in many industrial motion systems. Correct compensation or control of friction and other nonlinearities is generally difficult. Apart from the complex nature of friction, compensation of even the most basic type of friction, Coulomb friction, is non trivial.Most available tuning methods rely on time domain data and are often unable to distinguish between nonlinear effects of friction and that of for example linear viscous damping. Furthermore, the sensitivity of time domain data to the influence of friction is too low for correct tuning in many of the high precision motion applications currently used in industry. In this paper a frequency domain method is introduced that allows fast and high accuracy tuning of controller parameters when the closed loop system is subject to nonlinear influences. This methodology is applied to optimally compensate friction in a high precision motion stage of a transmission electron microscope. Theoretical and experimental results are presented and related to time domain performance to illustrate the advantage of frequency domain tuning over time domain tuning.
TL;DR: In this article, the tubular guide (TG) is proposed, a semi-permanent 3.5 m long tube which is an extension of the Upper Port, to reduce the cross-talk between lift and rotation motion.
01 Jan 2011
TL;DR: In this article, three different modeling and simulation methods (forward dynamic, quasi-static backwards, and inverse dynamic) are compared and the simulation results using these methods will be analyzed and the base line vehicle used in this paper consists of a conventional drive train with a natural aspirated engine.
Abstract: In this paper, three different modeling and simulation methods (forward dynamic, quasi-static backwards, and inverse dynamic) will be compared and the simulation results using these methods will be analyzed. The base line vehicle used in this paper consists of a conventional drive train with a natural aspirated engine. From a Forward Dynamic (FDM) model, a Forward Quasi-static (FQM) and a Backward Quasi-static Model (BQM) for the engine will be derived. The difference in simulation results for the base line vehicle used on representative driving cycles (NEDC, FTP75) will be discussed. The forward dynamic model contains a scalable engine model based on physical laws. The accuracy of this model will be investigated by comparing simulation results with measured quasi-static efficiency data of actual engines. The work presented in this paper will form the basis to develop a modeling, simulation and design method which can be used for quick (alternative, or hybrid) drive train specification, or (supervisory) control calibration with sufficient accuracy.
TL;DR: A model-based predictive (MPC) approach to control the image drift by actively moving the specimen holder and by shifting the beam deflectors present in these microscopes is proposed.
Journal Article•
13 Oct 2011
TL;DR: An algorithm based on time-scale wavelet theory and edge detection for accurate real-time sawtooth period estimation has been developed and the realized accuracy of the detection algorithm is well below the uncertainty of the crash period for most crashes.
Abstract: Resistive magneto-hydrodynamic instabilities are expected to limit the performance of nuclear fusion reactors. Prime examples are the sawtooth instability and the neoclassical tearing modes. The sawtooth instability will affect the refueling of the plasma core and the fast particle concentration. In reactor relevant conditions, the sawtooth can also trigger secondary instabilities. These are the neo-classical tearing modes, which can deteriorate the plasma performance or even disrupt the discharge. These modes (sawteeth and tearing modes) appear at specific locations in the tokamak plasma, associated with the distribution of the current density and the toroidal magnetic field. Localized current drive from electron cyclotron waves is foreseen as a possible actuator for the width of the tearing modes and the period of the sawteeth. Magnetic pick-up coils, electron cyclotron emission (ECE) and soft X-ray emission are the most likely sensors. A system approach for real-time detection, localisation and control of resistive magneto-hydrodynamic modes in tokamaks is presented. The system combines an ECE diagnostic for sensing of the instabilities in the same sight-line with a steerable Electron Cyclotron Resonant Heating and Current Drive (ECRH/CD) antenna. A model for the sawtooth is used to derive the linearized input-output relations (transfer functions) from the varying deposition location of high power Electron Cyclotron waves to the sawtooth period. The transfer functions are derived around a large collection of operating points. Proportional-integral-integral (PII) action can be applied to achieve fast and perfect tracking, while satisfying robustness constraints. The launcher dynamics seriously affects the closed loop performance in present-day experiments. Special emphasis is put on the issue of real-time sawtooth period detection. An algorithm based on time-scale wavelet theory and edge detection for accurate real-time sawtooth period estimation has been developed. The period is estimated by detecting subsequent crashes. The realized accuracy of the detection algorithm is well below the uncertainty of the crash period for most crashes. Multi-resolution analysis enables distinction between different sizes of sawtooth crashes due to the different sizes of wavelets (scales), resulting in an algorithm, which is robust and accurate. A methodology for fast detection of q = m/n = 2/1 tearing modes and retrieval of their location, rotation frequency and phase is presented. Set-points to establish alignment of the ECRH/CD deposition location with the centre of the tearing mode are generated in real-time and forwarded in closed-loop to the steerable launcher and as a modulation pulse train to the gyrotron.
01 Jan 2011
TL;DR: The aim was to design and build a microrobotic system adapted to the needs of vitreoretinal surgeons that allows 5 degrees of freedom through a kinematically defined rotation point at the entry site into the sclera.
Abstract: Purpose:Robotics have enhanced and refined microinvasive surgery in several disciplines. Its applicability in eye surgery has been limited by ergonomic and scaling issues. Our aim was to design and build a microrobotic system adapted to the needs of vitreoretinal surgeons. Methods:Constraints regarding head positioning and size, ocular access, surgical execution, and procedural requirements were defined by observations at live surgeries, discussions with surgeons, operation room teams, and computer simulations. Additional design parameters for the robotic slave (RS) included a low weight, high stiffness, low friction and play-free design. For the control module (CM), intuitiveness of the controller, body posture of the operator and patient proximity were considered. Results:The RS consists of at least two instrument manipulators (IMs).The IM’s design allows 5 degrees of freedom through a kinematically defined rotation point at the entry site into the sclera. Force measurement down to 10mN is possible and manipulation with an accuracy of
01 Jan 2011
TL;DR: The goal of this project is the development of design methods for autonomous robot systems, using standardized architectures, which can safely work in a care situation, which will be used as a research platform to investigate standards in mechanical and electric interfaces and software architectures.
Abstract: Due to ageing of the population, providing care to acceptable will standards become increasingly difficult. Thanks to recent advances in robotics and mechatronics, it is now starting to become possible to develop robots that can provide assistance in daily living, e.g., fetching objects, opening and closing of doors and drawers and operating switches. However, these technologies have not been brought together into an economically viable service robot. The goal of this project is the development of design methods for autonomous robot systems, using standardized architectures, which can safely work in a care situation. As a first step, the AMIGO robot has been designed, which will be used as a research platform to investigate standards in mechanical and electric interfaces and software architectures. Furthermore, it will be used in related activities such as the RoboEarth project and the RoboCup@Home competition.
01 Jan 2011
TL;DR: In this report a traction controller is developed for an omni-directional robot, named Turtle, and the explanation of the relevant software for the motion of the Turtles is spread over three chapters.
Abstract: In this report a traction controller is developed for an omni-directional robot, named Turtle. At first traction and slip are defined and the geometry of the Turtle is discussed. Then the explanation of the relevant software for the motion of the Turtles is spread over three chapters. The motion schemes of the Turtle in Simulink are simplified and discussed. The trajectory planner that creates the driving path for a Turtle is explained in detail and simulations are performed to show what kind of signals the trajectory planner creates and how these signals are alternated as inputs to the motors. After this some research has been done into control systems of other vehicles and some initial ideas are sketched for traction control in the Turtles. Finally the actual traction controller is developed and explained using flowcharts, the implementation (in C-code) of the traction controller and some simulations to give a quick look for how it works. Afterwards a general conclusion is drawn and some future work is suggested.
01 Feb 2011