Showing papers by "M Maarten Steinbuch published in 2007"

Rule-based energy management strategies for hybrid vehicles

Abstract: The highest control layer of a (hybrid) vehicular drive train is termed the Energy Management Strategy (EMS). In this paper an overview of different control methods is given and a new rule-based EMS is introduced, based on the combination of Rule-Based and Equivalent Consumption Minimization Strategies (RB-ECMS). The RB-ECMS uses only one decision variable and requires no tuning of many threshold control values and parameters. This decision variable represents the maximum propulsion power of the secondary power source (i.e. electric machine/battery) during pure electric driving. The RB-ECMS is compared with the strategy based on Dynamic Programming (DP), which is inherently optimal for a given cycle. The RB-ECMS proposed in this paper requires significantly less computation time with a similar result to DP (within 1% accuracy).

Error modeling and improved position estimation for optical incremental encoders by means of time stamping

Abstract: Optical incremental encoders are extensively used for position measurements in motion systems. The number of slits on the encoder disk defines the resolution of the encoder and bounds the accuracy of the position measurement. The encoder position measurements suffer from quantization errors. Moreover, encoder imperfections occur due to manufacturing tolerances. In this paper a method, which is based on time stamping, is proposed to obtain more accurate position and velocity estimations. Time stamping makes use of stored events, consisting of the encoder counts and their time instants, which are captured at a high resolution clock. Low order polynomial fitting through these encoder events is combined with active compensation of the encoder errors. The proposed method is applied in real-time experiments to a motion system. The results show an improvement in the position accuracy of up to 87% in terms of the maximum error. The estimated velocity is also much more accurate than the differentiated quantized encoder output signal.

H 2 performance analysis of reset control systems

Abstract: To overcome fundamental limitations of linear controllers, reset controllers were proposed in literature. Since the closed loop system including such a reset controller is of a hybrid nature, it is difficult to determine its performance. The focus in this paper is to determine the performance of a SISO reset control system in H2 sense. The method is generally applicable in the sense that it is valid for any proper LTI plant and linear-based reset controller. We derive convex optimization problems in terms of LMIs to compute an upperbound on the H2 norm, using dissipativity theory with piecewise quadratic Lyapunov functions. Finally, by means of a simple multiobjective tracking example, we show that reset control can outperform a linear controller obtained via a standard multiobjective control design method.

Laboratory study on needle-tissue interaction: towards the development of an instrument for automatic venipuncture

Abstract: Although venipuncture is one of the most common clinical procedures and is performed by trained medical staff, difficulties arise in 5% of insertion procedures. An instrument that guarantees the insertion of a needle into a vein in a single approach is expected to be beneficial to both medical staff and patients. The next step towards automatic venipuncture is to determine if insertion force feedback can be used, irrespective of insertion speed, insertion angle, or vein depth and diameter. Needle insertion experiments are performed on phantom and porcine tissues to study the interaction between the needle and tissue. A prototype instrument is developed to perform automatic venipuncture on the phantom. From the experiments, we conclude that an increased insertion speed of the needle leads to an increase in insertion force and tissue deformation. Furthermore, distinct force peaks are observed at the penetration of phantom skin and vein, thus enabling automatic detection of phantom vein puncture.

Cogging Compensating Piecewise Iterative Learning Control with application to a motion system

Abstract: Iterative learning control (ILC) is an effective control technique for motion systems that perform repetitively the same trajectory (setpoint). The result of the learning procedure is a feedforward signal that perfectly compensates all deterministic dynamics in the system for the learned setpoint performed at a specific start position. For other setpoints and start positions, the learned feedforward signal will not be perfect, because the learned deterministic dynamics are setpoint- and position-dependent. In this paper cogging compensating piecewise ILC (CCPILC) is proposed that enables to use one learned feedforward signal for different setpoints and start positions without losing performance. The learned feedforward signal will therefore be decomposed into a setpoint- and a position-dependent part, such that both parts can be adapted individually according to the desired change in setpoint and/or start position.

Control of a high precision stage using a walking piezo actuator

Abstract: Piezoelectric actuators are commonly used for positioning high precision stages. The need for new actuators and drive principles are being invoked by the increasing demands regarding speed and accuracy. The used walking piezo actuator is a non-resonant piezoelectric actuator that can drive a stage through four piezoelectric drive legs. In this paper, the piezo actuator is used to drive a stage with one degree-of-freedom. A model of the stage and the piezo actuator was made to develop and test a feedback control strategy. A new drive principle was developed, which results in overlapping tip trajectories of the drive legs and a continuous and smooth motion of the stage. Feedforward control and gain scheduling further improve the performance. Constant motion up to 2 mm/s is performed with a tracking error below 400 nm. Point-to-point movements of 5 nm up to the complete stroke of the stage are performed with a final static error below the encoder resolution.

State Estimator Design for Real-time Controlled Restraint Systems

Abstract: In this paper, a method is presented to estimate the motion of a vehicle occupant in frontal impact. Knowledge of the occupant's motion during a crash can significantly reduce the risk of injury, as restraint systems could be real-time adapted to the optimal settings. It is shown that the chest acceleration of the occupant, an important measure of injury, is accurately estimated by filtering of the belt displacement at the retractor side. Low order, nonlinear models are constructed from complex models, and a state estimator filter is designed using a linearization of these low order models.

Parametric Modeling of Components for Selection and Specification of Hybrid Vehicle Drivetrains

Abstract: Drivetrain hybridization implies adding a secondary powe rs ource (electric machine/battery) to a primary power source (engine/fille df u e lt ank) in ord e rt o improv e: fuel economy, emissions, drivability (performance), comfort and safety. Designing a hybrid vehicle drivetrain fulfilling the require dv ehicle driving functions is therefore a comple xt ask. Many r esearchers have put effort formulating and developing overall hybrid drivetrain analysis, design and optimization models including top-leve lv ehicle control strategy for optimal fuel economy. This paper seeks to investigate the possibility of overall model simplification for the hybrid drivetrain system including the control strate gy. This is p erforme db y d escribing the component efficiencies and control rule sw ith only af ew characteristic parameters that capture the total systems fuel efficie ncy with suffici ent accuracy (~1%). Using these parameters the modeling and simulation process can be done very quickly. The method has bee nd emonstrate do n a serie s- , ap arall e l-a nd as eries-parallel hybrid drivetrain with specified component technologies, vehicle parameters and drive cycle .T he fuel economy and control strategy results are compared with Simulink/Advisor and Dynamic Programming.

Data-driven multivariable controller design using Ellipsoidal Unfalsified Control

Abstract: Ellipsoidal unfalsified control is a data-driven, plant-model-free control design method. In this work, this framework is extended to cover full-block multivariable controllers. A new controller structure and a sequential update procedure are proposed. A simulation example shows the effectiveness of the method.

Time-frequency analysis of position-dependent dynamics in a Motion System with ILC

Abstract: This paper exploits high-resolution time-frequency analysis of servo error signals in the investigation of position-dependent dynamics in a motion system with iterative learning control. Based on the matching pursuit algorithm signals are decomposed with respect to a multiple complex dictionary of atoms. A high-resolution signal energy distribution is derived in the time-frequency plane, which does not include cross-terms, like Wigner distribution. The proposed method, applied for analysis of servo errors of a real system, provides insights in the appearance and propagation of certain low energetic system features, which can be related to position-dependent dynamics.

Control oriented modeling of vehicular occupants and restraint systems

Abstract: This paper presents manageable models of an occupant and restraint system. Low-order design models are essential in the development of active restraint systems, which aim at lowering certain injury criteria by real-time control of the occupant motion with a restraint actuator. The design models are constructed from first principles, using knowledge obtained from a sensitivity analysis of a reference occupant model. The models can easily be employed for controller and observer design, and can be used in real-time injury prediction. The design model is validated in a variety of frontal impact simulations, and the most important biomechanical responses are compared to the responses of the reference model. For the covering abstract see ITRD E141762.

Experimental investigation of macro-slip in a pushbelt CVT variator

Abstract: One way to further reduce the fuel consumption of passenger cars that are equipped with a pushbelt continuously variable transmission (CVT) is to improve the CVT efficiency by lowering the clamping forces in the variator. This approach requires the application of active control of the slip between the belt and the conical sheaves, which demands for a reliable and accurate dynamic variator model that describes the variator characteristics in the applicable slip range. In this paper, the dynamic variator model is investigated in detail, with emphasis on the torque transmission. As a first step, the torque transmission in stationary situations is investigated, in which it is generally assumed that macro-slip occurs on the pair of conical sheaves with the smallest wrapped angle. In this paper, it is experimentally shown that macro-slip only occurs on the pair of conical sheaves with the smallest wrapped angle for the extreme ratios Low and OverDrive in stationary situations.

Design and realization of a measurement machine for the universal non-contact measurement of large freeform optics with 30 nm uncertainty

Abstract: A new measurement machine is being developed capable of universal, non-contact and fast measurement of freeform optics with a measurement uncertainty of 30 nm (2s). The detailed design is now almost complete and realization is progressing rapidly. The ambitious requirements are still expected to be met and completion is expected in the 3rd quarter of 2007.

Haptic manipulation of virtual linkages with kinematic loops

Abstract: This paper proposes an approach to providing realistic force feedback to users manipulating virtual linkages with kinematic loops. In the proposed approach, users feel the effect of the effect of the virtual kinematic loops: (a) on the inertia of the virtual linkage at the user-selected operational point (OP); and (b) on their freedom of motion. The approach introduces a method for computing the inertia of linkages with kinematic loops at arbitrarily selected OPs. It uses this inertia to select the directions of motion resisted by the virtual joints. Users feel the apparent inertia via impedance control, and the motion restrictions via stiffness control. Controlled experiments within a planar haptic interaction system validate that the proposed approach successfully renders the kinematic loop closure constraints to users.

Multivariable control design for fixed direction disturbances

Abstract: In this paper, a blind identification method is employed to model multivariable disturbances with fixed direction. The multivariable disturbance model is used to design non- diagonal weighting filters for Hinfin control. It is demonstrated that in this way, intuitive shaping of the directions of closed loop transfer functions is facilitated, maximally exploiting design freedom that has no analogue for scalar systems.

Low latency 2D position estimation with a line scan camera for visual servoing

Abstract: This paper describes the implementation of a visual position estimation algorithm, using a line-scan sensor positioned at an angle over a 2D repetitive pattern. An FFT is used with direct interpretation of the phase information at the fundamental frequencies of the pattern. The algorithm is implemented in a FPGA. The goal is to provide fast position estimation on visual data, to be used as feedback information in a dynamic control system. Traditional implementations of these systems are often hampered by low update rates ( 10 msec). These limit the obtainable bandwidths of the control system. Presented here is an implementation of an algorithm with a high update rate (30kHz) and low latency (100 µsec). This system can be used for a range of repetitive structures and has a high robustness. Resolutions of less than 0.1 µm have been demonstrated on real products with 210×70 µm feature size.

Blind identification and allocation of multivariate disturbances

Abstract: A second order statistics based blind identification technique is used to recover the physical sources from disturbances acting on a multivariable system. The results are then used to find the physical location of disturbance sources in an active vibration isolation platform. Furthermore, implications for multivariable controller design are discussed.

Active printhead alignment for Wide Format Printing Systems

Abstract: In this work, an active printhead alignment method for wide format printing systems is proposed. Instead of tightening manufacturing tolerances, the misalignment of each printhead is measured with respect to the printer frame and is regulated using a voice coil actuator. This dramatically increases performance where costs of the alignment mechanism can be compensated by loosening the manufacturing tolerances which would otherwise be necessary. An experimental setup has been build for proof-of-concept. The experiments show promising results. Printheads can be aligned with an accuracy of 2 mum. The higher print accuracy results in a better print quality and enables additional features such as higher resolution printing (> 600 dpi) and adding redundant printheads for covering temporary nozzle disfunctioning.

Time domain performance based nonlinear state feedback control of constrained linear systems

Abstract: This paper describes a method to design a nonlinear state feedback controller that meets a set of time-domain specifications not attainable by linear state feedback. Using a constrained polynomial interpolation technique, an input signal is computed that satisfies the desired time-domain constraints on the input and state-trajectories. The computed input is constructed by nonlinear combinations of the states, such that a nonlinear state feedback law is obtained. Stability of the resulting closed-loop polynomial system is analyzed using sum-of-squares techniques. An illustrative example is presented, showing that the proposed nonlinear controller outperforms its linear counterpart. To validate the proposed method, experiments on a fourth-order motion system have been carried out.

Piecewise linear sheet control in an H ∞ framework

Abstract: This paper presents a control design approach for sheet control in a printer paper path. By splitting up the control problem in two levels, i.e. low level motor control loops and a high level sheet control loop, a hierarchical control structure is obtained. The high level sheet dynamics are formulated in the piecewise linear modeling formalism. Given this model, together with models of the controlled low level motor dynamics, a high level feedback controller is designed with guaranteed H∞ performance. The designed controller is implemented on a experimental paper path setup to show the effectiveness of the control design in practice.

Actuator grid design for an adaptive deformable mirror

Abstract: In a collaboration of the Technische Universiteit Eindhoven, Delft University of Technology and TNO Science and Industry a new adaptive deformable mirror (DM) is being developed. The deformable mirror will be used in large telescope systems to correct both the temporal and spatial high frequent distortions in the optical wavefront caused by atmospheric turbulence.The DM consists of a thin continuous membrane which acts as the correcting element. A grid of low voltage electro-magnetical push-pull actuators, - located in an actuator plate -, impose out-of-plane displacements in the mirror’s membrane. In the design variable reluctance actuators are used. These consist of a closed magnetic circuit in which a strong permanent magnet provides a static magnetic force on a ferromagnetic core which is suspended in a membrane. By applying a current through the coil which is situated around the magnet, this force is influenced, providing movement of the core. This movement is transferred via a rod imposing the out-of-plane displacements in the reflective deformable membrane. In the actuator design a match is made between the negative stiffness of the magnet and the positive stiffness of the membrane suspension. If the locality of the influence functions, mirror modes, force and power dissipation are taken into account, a resonance frequency of 1500 Hz and an overall stiffness of 1000 N/m for the actuators is needed. The dynamic response of the first actuators is tested in a dedicated setup. It shows an eigen frequency of 950 Hz. This is due to a lower magnetic force than expected. With a Helmholtz coil test setup the 2nd quadrant of the B-H curve is reconstructed by stacking of the magnets and using the demagnetization factor. It is shown that the values for Hc and Br of the magnets are indeed lower than the values used for the initial design. New actuators, with increased magnet thickness, are designed, fabricated and tested.Transfer functions are made with different dc offsets of the actuator. From these transfer functions, characteristics as resonance frequencies, force, stiffness, motor constant, current and dissipation and efficiency all as function of the stroke of the actuator have been adopted. These experimental results are compared with the theoretic predictions. The results are in good agreement.Grids with 61 actuators are made including the dedicated drive electronics. The module is the standard building block from which large arrays are assembled.

A high-speed valve for surge control in a centrifugal compression system

Abstract: This paper deals with the critical problem of actuator limitations for the successful implementation of active surge control. We specify the capacity, bandwidth and allowable time delay for a control valve that can be used to actively suppress surge in a specific full-scale centrifugal compression system. The actuator requirements are obtained from closed-loop simulations with a nonlinear simulation model of the compressor test rig. In order to meet the requirements, a new high-speed valve actuator had to be developed. We present the resulting actuator design and provide test results to illustrate that the control valve meets our design specifications.

Mechatronic Design of an Efficient Drive for Wide Format Printing Systems

Abstract: In this paper, a new design of a carriage drive for wide format printing systems (WFPS) is proposed. The new drive design reverses the carriage by buffering the kinetic energy of the carriage resulting in a fast reversal and a high energy efficiency for higher productive WFPS. A mechanical spring is used as an energy buffer and a clutch is designed which engages smoothly enabling reversal at arbitrary moments. This way, only a small conventional carriage drive motor is needed to overcome the friction forces acting on the carriage. A prototype has been built and experiments have been conducted showing promising results. The first experiments show that the power of the drive motor can be reduced at least by a factor of 30 while keeping the reversal time equal. This power reduction should compensate the extra costs needed for the drive-aid. Because this drive-aid can be easily scaled for higher productive WFPS, it has the potential to become an attractive alternative in the future.

Data-based velocity observer using encoder time stamping

Abstract: In motion systems, position measurements are often obtained using optical incremental encoders. The position accuracy is limited by the quantized position measurement of the encoder. Velocity and acceleration signals obtained by numerical differentiation are dominated by high-frequency content due to the quantization. In literature, several methods have been proposed to improve the position and velocity estimations using position measurements at irregular time instants [1, 2]. These methods often require a system model to be available or are not applicable in real-time experiments.

Hydraulic CVT Slip Control: New Challenges

Abstract: A pushbelt continuously variable transmission (CVT) is a stepless power transmission device with infinitely many transmission ratios within a certain range. This is enabled by the variator, which consists of a segmented steel V-belt that is clamped in between two pairs of conical sheaves, see Figure 1. High clamping forces are exerted by a hydraulic actuation system to prevent global slip of the belt at all times, which leads to increased hydraulic pump losses and increased friction losses.