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TSU-CHIN TSAO

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Papers by TSU-CHIN TSAO

Two-Parameter Robust Repetitive Control With Application to a Novel Dual-Stage Actuator for Noncircular Machining

IEEE/ASME Transactions on Mechatronics, 2004

This paper presents a robust repetitive controller design for a novel dual-stage actuator system.... more This paper presents a robust repetitive controller design for a novel dual-stage actuator system. The dual-stage actuator, which consists of an electrohydraulic actuator for 25-mmgross motion and a piezoelectric actuator for 40-m fine motion, is designed for noncircular machining application. The controller is designed through a sequence of two single-input-single-output (SISO) designs by exploiting the triangular structure of the two by two actuator system dynamics. The tracking error from the first stage electrohydraulic actuator is used as reference for the second stage piezoelectric actuator. In this master-slave control arrangement, the overall sensitivity function is the product of two sensitivity functions from each actuator's servo loop. Thus, performance is improved at the frequencies where the sensitivity values are already well less than one. In the real-time control implementation, the effects of finite word length are analyzed and addressed via controller order reduction and realization. In an experiment of tracking an automotive cam profile at the rate of 10 cycles per second (600 rpm), the proposed dual-stage servo system generated tracking error of 4m peak-to-valley and 0.80-m root-meansquare (RMS) value, showing a substantial improvement over the 16 micron peak-to-valley and 2.64-m RMS errors generated by the electrohydraulic servo system alone.

Electrohydraulic Valve-trains for Direct Injection Compression Ignition Camless Engine Operations - Phase I Project Final Report

Robust performance control of electrohydraulic actuators for electronic cam motion generation

IEEE Transactions on Control Systems Technology, 2000

AbstractThis paper addresses digital control design and implementation for an electrohydraulic s... more

Rejection of repeatable and non-repeatable disturbances for disk drive actuators

Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999

This paper presents an application of two-parameter robust repetitive control (TPRRC) in disk dri... more This paper presents an application of two-parameter robust repetitive control (TPRRC) in disk drive servo control, where the repeatable rrmout (RRO) and non-repeatable runout (NRRO) are rejected simultaneously. The repeatable disturbances are rejected by tbe internal model structure of TPRRC, while the nonrepeatable disturbances are attenuated by the robust performance specification. The design procedure of TPRRC is given. A simple structure of tbe robust performance weighting function WP(j@ is proposed and the relationship between the coefficients of WP@iS) and the performance specification over the non-repeatable disturbance is discussed too. The simulation results using the measured position error signals (PES) of a disk drive as output disturbance are presented to show the effectiveness of the disturbance rejection of disk drive servo control and demonstrate that it is a cost effective way to improve the track density of disk drives.

1992ACC/TM12 Active andPassive DampingofEuler-Bernoulli Beams andTheirInteractions

Active andpassive ding ofEuler-Bernoulli beams andtheir interactions arcstudiusinm thebeam's ... more Active andpassive ding ofEuler-Bernoulli beams andtheir interactions arcstudiusinm thebeam's exact transfer function model. Viscous and oigt damping are showntoma theopenlooppoles andzeros the imaginary axinthe ampedcaseinto acircle intheleft half plane andinto thenegative real axis. While atv P-D collocated control using sky-hooked actuators isknownto sabilize thebeanitisson stheDeiaDvaction using proof-mas atIE candestabdmbm. 1. Itroduction Thereisoften a snugtemptation torelyon computationally iMtensive methods like thefinite element rmetod whenstudying thedynamics ofdistributed stms, neglecting those methods that maybemoreanalytically based. Thesuperiority oftheformer overthelatter is unquestionable fthegeometry ofthectural system is complicated. Howev,this maynotbeuefor'simple' syst Hkeunifom Eue-Bruoul orTimoshenko beams, where theanalytical approachyields exact solutions andthe finite element resuts arapproximate. Inanaly'large space structumes wherebeamsarabu...

A description of the dynamic behavior of fuzzy systems

IEEE Transactions on Systems, Man, and Cybernetics

A Description of the Dynamical Behavior of Fuzzy Systems Abslmcf-A new approach for analyzing the... more A Description of the Dynamical Behavior of Fuzzy Systems Abslmcf-A new approach for analyzing the global behavior of a fuzzy dynamical system is presented. It applies the concept and method of cell-to-cell mapping to obtain the evolving trend of the states of a fuzzy dynamical system. The behavior of the fuzzy dynamical system is characterized by equilibria, periodic motions, and their domain of attractions. "Be min-max operation rcumulates the fuzziness of a fuzzy system in every step of iterations and makes the state evolution obscure. I l w proposed method transforms a given fuzzy mapping to a Z-tWZ mapping and docs not accumulate fuzziness. Both the red and fuzzy initial state response analyses are discussed. An inverted pendulum controlled by a fuzzy controller is analyzed to illustrate the validity of the method.

<title>Smart suspension systems for bridge-friendly vehicles</title>

Smart Structures and Materials 2002: Smart Systems for Bridges, Structures, and Highways, 2002

ABSTRACT In this paper, the effects of using semi-active control strategy (such as MR dampers) in... more ABSTRACT In this paper, the effects of using semi-active control strategy (such as MR dampers) in vehicle suspensions on the coupled vibrations of a vehicle traversing a bridge are examined in order to develop various designs of smart suspension systems for bridge-friendly vehicles. The bridge-vehicle coupled system is modeled as a simply supported beam traversed by a two-degree-of-freedom quarter-car model. The surface unevenness on the bridge deck is modeled as a deterministic profile of a sinusoidal wave. As the vehicle travels along the bridge, the system is excited as a result of the surface unevenness and this excitation is characterized by a frequency defined by the speed of travel and the wavelength of the profile. The dynamic interactions between the bridge and the vehicle due to surface deck irregularities are obtained by solving the coupled equations of motion. Numerical results of a passive control strategy show that, when the lower natural frequency of the vehicle matches with a natural frequency (usually the first frequency) of the bridge and the excitation frequency, the maximum response of the bridge is large while the response of the vehicle is relatively smaller, meaning that the bridge behaves like a vibration absorber. This is undesirable from a bridge design viewpoint. Comparative studies of passive and semi-active controls for the vehicle suspension are performed. It is demonstrated that skyhook control can significantly mitigate the response of the bridge, while ground-hook control reduces the tire force impacted onto the bridge.

A semi-automated vascular access system for preclinical models

Physics in Medicine and Biology, 2013

Murine models are used extensively in biological and translational research. For many of these st... more Murine models are used extensively in biological and translational research. For many of these studies it is necessary to access the vasculature for the injection of biologically active agents. Among the possible methods for accessing the mouse vasculature, tail vein injections are a routine but critical step for many experimental protocols. To perform successful tail vein injections, a high skill set and experience is required, leaving most scientists ill-suited to perform this task. This can lead to a high variability between injections, which can impact experimental results. To allow more scientists to perform tail vein injections and to decrease the variability between injections, a vascular access system (VAS) that semi-automatically inserts a needle into the tail vein of a mouse was developed. The VAS uses near infrared light, image processing techniques, computer controlled motors, and a pressure feedback system to insert the needle and to validate its proper placement within the vein. The VAS was tested by injecting a commonly used radiolabeled probe (FDG) into the tail veins of five mice. These mice were then imaged using micro-positron emission tomography to measure the percentage of the injected probe remaining in the tail. These studies showed that, on average, the VAS leaves 3.4% of the injected probe in the tail. With these preliminary results, the VAS system demonstrates the potential for improving the accuracy of tail vein injections in mice.

Application of Repetitive Control to Vibration Attenuation in Certain Engineering Structures

Journal of Vibration and Control, 1999

The application of repetitive control to the problem ofattenuation of vibration in a class of eng... more The application of repetitive control to the problem ofattenuation of vibration in a class of engineer ing structures excited by periodic disturbances occurring at a fundamental frequency and its integer multiples is examined. The internal model principle is employed to design controllers for a single degree of freedom structure as well as for a Euler-Bernoulli beam. The beam system is examined experimentally.

On asymptotics of the solution of the moving oscillator problem

Journal of Sound and Vibration, 2003

Asymptotic behavior of the solution of the moving oscillator problem is examined for large and sm... more Asymptotic behavior of the solution of the moving oscillator problem is examined for large and small values of the spring stiffness for the general case of non-zero beam initial conditions. In the limiting case of infinite spring stiffness, it is shown that the moving oscillator problem for a simply supported beam is not equivalent, in a strict sense, to the moving mass problem. The two problems are shown to be equivalent in terms of the beam displacements but are not equivalent in terms of stresses (the higher order derivatives of the two solutions differ). In the general case, the force acting on the beam from the oscillator is shown to contain a high-frequency component , which does not vanish and can even grow when the spring coefficient tends to infinity. The magnitude of this force and its dependence on the oscillator parameters can be estimated by considering the asymptotics of the solution for the initial stage of the oscillator motion. It is shown that, for the case of a simply supported beam, the magnitude of the high-frequency force depends linearly on the oscillator eigenfrequency and velocity. The deficiency of the moving mass model is principally that it fails to predict stresses in the supporting structure. For small values of the spring stiffness, the moving oscillator problem is shown to be equivalent to the moving force problem. The discussion is amply illustrated by results of numerical experiments.

Experimental Study of Non-Linear Transient Motion Confinement in a System of Coupled Beams

Journal of Sound and Vibration, 1996

An experimental study of non-linear confinement of transient motions in a flexible structure cons... more An experimental study of non-linear confinement of transient motions in a flexible structure consisting of two weakly coupled cantilever beams with active grounding non-linearities has been carried out. The experimental fixture and the control methodology used for implementing the active non-linearities are discussed in detail. It has been found that the system with active non-linearities possesses motion confinement properties, that is, transient motions originating at one of the beams become spatially confined mainly to the directly excited beam, with small amounts of vibrational energy ''leaking'' to the unexcited one. As the damped motion decays the non-linear effects diminish and the motion confinement phenomenon becomes less evident. The experimental results are in agreement with analytical predictions. The implementation of non-linear motion confinement in vibration and shock isolation designs of repetitive systems is discussed.

Tool Positioning for Noncircular Cutting With Lathe

Journal of Dynamic Systems, Measurement, and Control, 1987

This paper presents the design and implementation of a digital controller for a lathe to machine ... more This paper presents the design and implementation of a digital controller for a lathe to machine workpieces with noncircular cross sections. Noncircular cutting is accomplished by controlling the radial tool position in the direction normal to the surface of workpiece. A discrete time model for the tool carriage in the radial direction is obtained by a least squares method applied to input and output data. The model is used for designing digital feedback and feedforward controllers. The zero phase error tracking control algorithm is applied as a feedforward control law for positioning of the tool along desired time varying signals. The effectiveness of the proposed controller is demonstrated by experiment and simulation.

003 Hexapod Surgical System : système d’aide robotisée

Journal Français d'Ophtalmologie, 2009

Cellules souches mésenchymateuses et cicatrisation cornéenne. Therapeutic potential of bone marro... more

Dynamic variable depth of cut machining using piezoelectric actuators

International Journal of Machine Tools and Manufacture, 1994

ABSTRACT

Robot-assisted intraocular surgery: development of the IRISS and feasibility studies in an animal model

Eye, 2013

The aim of this study is to develop a novel robotic surgical platform, the IRISS (Intraocular Rob... more The aim of this study is to develop a novel robotic surgical platform, the IRISS (Intraocular Robotic Interventional and Surgical System), capable of performing both anterior and posterior segment intraocular surgery, and assess its performance in terms of range of motion, speed of motion, accuracy, and overall capacities. To test the feasibility of performing &#39;bimanual&#39; intraocular surgical tasks using the IRISS, we defined four steps out of typical anterior (phacoemulsification) and posterior (pars plana vitrectomy (PPV)) segment surgery. Selected phacoemulsification steps included construction of a continuous curvilinear capsulorhexis and cortex removal in infusion-aspiration (I/A) mode. Vitrectomy steps consisted of performing a core PPV, followed by aspiration of the posterior hyaloid with the vitreous cutter to induce a posterior vitreous detachment (PVD) assisted with triamcinolone, and simulation of the microcannulation of a temporal retinal vein. For each evaluation, the duration and the successful completion of the task with or without complications or involuntary events was assessed. Intraocular procedures were successfully performed on 16 porcine eyes. Four eyes underwent creation of a round, curvilinear anterior capsulorhexis without radialization. Four eyes had I/A of lens cortical material completed without posterior capsular tear. Four eyes completed 23-gauge PPV followed by successful PVD induction without any complications. Finally, simulation of microcannulation of a temporal retinal vein was successfully achieved in four eyes without any retinal tears/perforations noted. Robotic-assisted intraocular surgery with the IRISS may be technically feasible in humans. Further studies are pending to improve this particular surgical platform.

003 Hexapod Surgical System: système d’aide robotisée

Cellules souches mésenchymateuses et cicatrisation cornéenne. Therapeutic potential of bone marro... more

Some recent results in moving load problems with application to highway bridges

In this paper, some recent results obtained for various aspects of the moving load problem are di... more In this paper, some recent results obtained for various aspects of the moving load problem are discussed. While encompassing a range of problems involving discrete subsystems traversing a primary distributed parameter system, a simple vehicle crossing a bridge is used herein to demonstrate various effects and their relative importance.

On Equivalence of the Moving Mass and Moving Oscillator Problems

Asymptotic behavior of the solution of the moving oscillator problem is examined for large values... more Asymptotic behavior of the solution of the moving oscillator problem is examined for large values of the spring stiffness for the general case of nonzero beam initial conditions. In the limit of infinite spring stiffness, the moving oscillator problem for a simply supported beam is shown to be not equivalent in a strict sense to the moving mass problem; i.e., beam displacements obtained by solving the two problems are the same, but the higher-order derivatives of the two solutions are different. In the general case, the force acting on the beam from the oscillator is shown to contain a high-frequency component, which does not vanish, or even grows, when the spring coefficient tends to infinity. The magnitude of this force and its dependence on the oscillator parameters can be estimated by considering the asymptotics of the solution for the initial stage of the oscillator motion. For the case of a simply supported beam, the magnitude of the high-frequency force linearly depends on the oscillator eigenfrequency and velocity. The deficiency of the moving mass model is noted in that it fails to predict stresses in the bridge structure. Results of numerical experiments are presented.

Dynamic variable depth of cut machining using piezoelectric actuators

ABSTRACT

Tool positioning for noncircular cutting with lathe

This paper presents the design and implementation of a digital controller for a lathe to machine ... more This paper presents the design and implementation of a digital controller for a lathe to machine workpieces with noncircular cross sections. Noncircular cutting is accomplished by controlling the radial tool position in the direction normal to the surface of workpiece. A discrete time model for the tool carriage in the radial direction is obtained by a least squares method applied to input and output data. The model is used for designing digital feedback and feedforward controllers. The zero phase error tracking control algorithm is applied as a feedforward control law for positioning of the tool along desired time varying signals. The effectiveness of the proposed controller is demonstrated by experiment and simulation.

Two-Parameter Robust Repetitive Control With Application to a Novel Dual-Stage Actuator for Noncircular Machining

IEEE/ASME Transactions on Mechatronics, 2004

This paper presents a robust repetitive controller design for a novel dual-stage actuator system.... more This paper presents a robust repetitive controller design for a novel dual-stage actuator system. The dual-stage actuator, which consists of an electrohydraulic actuator for 25-mmgross motion and a piezoelectric actuator for 40-m fine motion, is designed for noncircular machining application. The controller is designed through a sequence of two single-input-single-output (SISO) designs by exploiting the triangular structure of the two by two actuator system dynamics. The tracking error from the first stage electrohydraulic actuator is used as reference for the second stage piezoelectric actuator. In this master-slave control arrangement, the overall sensitivity function is the product of two sensitivity functions from each actuator's servo loop. Thus, performance is improved at the frequencies where the sensitivity values are already well less than one. In the real-time control implementation, the effects of finite word length are analyzed and addressed via controller order reduction and realization. In an experiment of tracking an automotive cam profile at the rate of 10 cycles per second (600 rpm), the proposed dual-stage servo system generated tracking error of 4m peak-to-valley and 0.80-m root-meansquare (RMS) value, showing a substantial improvement over the 16 micron peak-to-valley and 2.64-m RMS errors generated by the electrohydraulic servo system alone.

Electrohydraulic Valve-trains for Direct Injection Compression Ignition Camless Engine Operations - Phase I Project Final Report

Robust performance control of electrohydraulic actuators for electronic cam motion generation

IEEE Transactions on Control Systems Technology, 2000

AbstractThis paper addresses digital control design and implementation for an electrohydraulic s... more

Rejection of repeatable and non-repeatable disturbances for disk drive actuators

Proceedings of the 1999 American Control Conference (Cat. No. 99CH36251), 1999

This paper presents an application of two-parameter robust repetitive control (TPRRC) in disk dri... more This paper presents an application of two-parameter robust repetitive control (TPRRC) in disk drive servo control, where the repeatable rrmout (RRO) and non-repeatable runout (NRRO) are rejected simultaneously. The repeatable disturbances are rejected by tbe internal model structure of TPRRC, while the nonrepeatable disturbances are attenuated by the robust performance specification. The design procedure of TPRRC is given. A simple structure of tbe robust performance weighting function WP(j@ is proposed and the relationship between the coefficients of WP@iS) and the performance specification over the non-repeatable disturbance is discussed too. The simulation results using the measured position error signals (PES) of a disk drive as output disturbance are presented to show the effectiveness of the disturbance rejection of disk drive servo control and demonstrate that it is a cost effective way to improve the track density of disk drives.

1992ACC/TM12 Active andPassive DampingofEuler-Bernoulli Beams andTheirInteractions

Active andpassive ding ofEuler-Bernoulli beams andtheir interactions arcstudiusinm thebeam's ... more Active andpassive ding ofEuler-Bernoulli beams andtheir interactions arcstudiusinm thebeam's exact transfer function model. Viscous and oigt damping are showntoma theopenlooppoles andzeros the imaginary axinthe ampedcaseinto acircle intheleft half plane andinto thenegative real axis. While atv P-D collocated control using sky-hooked actuators isknownto sabilize thebeanitisson stheDeiaDvaction using proof-mas atIE candestabdmbm. 1. Itroduction Thereisoften a snugtemptation torelyon computationally iMtensive methods like thefinite element rmetod whenstudying thedynamics ofdistributed stms, neglecting those methods that maybemoreanalytically based. Thesuperiority oftheformer overthelatter is unquestionable fthegeometry ofthectural system is complicated. Howev,this maynotbeuefor'simple' syst Hkeunifom Eue-Bruoul orTimoshenko beams, where theanalytical approachyields exact solutions andthe finite element resuts arapproximate. Inanaly'large space structumes wherebeamsarabu...

A description of the dynamic behavior of fuzzy systems

IEEE Transactions on Systems, Man, and Cybernetics

A Description of the Dynamical Behavior of Fuzzy Systems Abslmcf-A new approach for analyzing the... more A Description of the Dynamical Behavior of Fuzzy Systems Abslmcf-A new approach for analyzing the global behavior of a fuzzy dynamical system is presented. It applies the concept and method of cell-to-cell mapping to obtain the evolving trend of the states of a fuzzy dynamical system. The behavior of the fuzzy dynamical system is characterized by equilibria, periodic motions, and their domain of attractions. "Be min-max operation rcumulates the fuzziness of a fuzzy system in every step of iterations and makes the state evolution obscure. I l w proposed method transforms a given fuzzy mapping to a Z-tWZ mapping and docs not accumulate fuzziness. Both the red and fuzzy initial state response analyses are discussed. An inverted pendulum controlled by a fuzzy controller is analyzed to illustrate the validity of the method.

<title>Smart suspension systems for bridge-friendly vehicles</title>

Smart Structures and Materials 2002: Smart Systems for Bridges, Structures, and Highways, 2002

ABSTRACT In this paper, the effects of using semi-active control strategy (such as MR dampers) in... more ABSTRACT In this paper, the effects of using semi-active control strategy (such as MR dampers) in vehicle suspensions on the coupled vibrations of a vehicle traversing a bridge are examined in order to develop various designs of smart suspension systems for bridge-friendly vehicles. The bridge-vehicle coupled system is modeled as a simply supported beam traversed by a two-degree-of-freedom quarter-car model. The surface unevenness on the bridge deck is modeled as a deterministic profile of a sinusoidal wave. As the vehicle travels along the bridge, the system is excited as a result of the surface unevenness and this excitation is characterized by a frequency defined by the speed of travel and the wavelength of the profile. The dynamic interactions between the bridge and the vehicle due to surface deck irregularities are obtained by solving the coupled equations of motion. Numerical results of a passive control strategy show that, when the lower natural frequency of the vehicle matches with a natural frequency (usually the first frequency) of the bridge and the excitation frequency, the maximum response of the bridge is large while the response of the vehicle is relatively smaller, meaning that the bridge behaves like a vibration absorber. This is undesirable from a bridge design viewpoint. Comparative studies of passive and semi-active controls for the vehicle suspension are performed. It is demonstrated that skyhook control can significantly mitigate the response of the bridge, while ground-hook control reduces the tire force impacted onto the bridge.

A semi-automated vascular access system for preclinical models

Physics in Medicine and Biology, 2013

Murine models are used extensively in biological and translational research. For many of these st... more Murine models are used extensively in biological and translational research. For many of these studies it is necessary to access the vasculature for the injection of biologically active agents. Among the possible methods for accessing the mouse vasculature, tail vein injections are a routine but critical step for many experimental protocols. To perform successful tail vein injections, a high skill set and experience is required, leaving most scientists ill-suited to perform this task. This can lead to a high variability between injections, which can impact experimental results. To allow more scientists to perform tail vein injections and to decrease the variability between injections, a vascular access system (VAS) that semi-automatically inserts a needle into the tail vein of a mouse was developed. The VAS uses near infrared light, image processing techniques, computer controlled motors, and a pressure feedback system to insert the needle and to validate its proper placement within the vein. The VAS was tested by injecting a commonly used radiolabeled probe (FDG) into the tail veins of five mice. These mice were then imaged using micro-positron emission tomography to measure the percentage of the injected probe remaining in the tail. These studies showed that, on average, the VAS leaves 3.4% of the injected probe in the tail. With these preliminary results, the VAS system demonstrates the potential for improving the accuracy of tail vein injections in mice.

Application of Repetitive Control to Vibration Attenuation in Certain Engineering Structures

Journal of Vibration and Control, 1999

The application of repetitive control to the problem ofattenuation of vibration in a class of eng... more The application of repetitive control to the problem ofattenuation of vibration in a class of engineer ing structures excited by periodic disturbances occurring at a fundamental frequency and its integer multiples is examined. The internal model principle is employed to design controllers for a single degree of freedom structure as well as for a Euler-Bernoulli beam. The beam system is examined experimentally.

On asymptotics of the solution of the moving oscillator problem

Journal of Sound and Vibration, 2003

Asymptotic behavior of the solution of the moving oscillator problem is examined for large and sm... more Asymptotic behavior of the solution of the moving oscillator problem is examined for large and small values of the spring stiffness for the general case of non-zero beam initial conditions. In the limiting case of infinite spring stiffness, it is shown that the moving oscillator problem for a simply supported beam is not equivalent, in a strict sense, to the moving mass problem. The two problems are shown to be equivalent in terms of the beam displacements but are not equivalent in terms of stresses (the higher order derivatives of the two solutions differ). In the general case, the force acting on the beam from the oscillator is shown to contain a high-frequency component , which does not vanish and can even grow when the spring coefficient tends to infinity. The magnitude of this force and its dependence on the oscillator parameters can be estimated by considering the asymptotics of the solution for the initial stage of the oscillator motion. It is shown that, for the case of a simply supported beam, the magnitude of the high-frequency force depends linearly on the oscillator eigenfrequency and velocity. The deficiency of the moving mass model is principally that it fails to predict stresses in the supporting structure. For small values of the spring stiffness, the moving oscillator problem is shown to be equivalent to the moving force problem. The discussion is amply illustrated by results of numerical experiments.

Experimental Study of Non-Linear Transient Motion Confinement in a System of Coupled Beams

Journal of Sound and Vibration, 1996

An experimental study of non-linear confinement of transient motions in a flexible structure cons... more An experimental study of non-linear confinement of transient motions in a flexible structure consisting of two weakly coupled cantilever beams with active grounding non-linearities has been carried out. The experimental fixture and the control methodology used for implementing the active non-linearities are discussed in detail. It has been found that the system with active non-linearities possesses motion confinement properties, that is, transient motions originating at one of the beams become spatially confined mainly to the directly excited beam, with small amounts of vibrational energy ''leaking'' to the unexcited one. As the damped motion decays the non-linear effects diminish and the motion confinement phenomenon becomes less evident. The experimental results are in agreement with analytical predictions. The implementation of non-linear motion confinement in vibration and shock isolation designs of repetitive systems is discussed.

Tool Positioning for Noncircular Cutting With Lathe

Journal of Dynamic Systems, Measurement, and Control, 1987

This paper presents the design and implementation of a digital controller for a lathe to machine ... more This paper presents the design and implementation of a digital controller for a lathe to machine workpieces with noncircular cross sections. Noncircular cutting is accomplished by controlling the radial tool position in the direction normal to the surface of workpiece. A discrete time model for the tool carriage in the radial direction is obtained by a least squares method applied to input and output data. The model is used for designing digital feedback and feedforward controllers. The zero phase error tracking control algorithm is applied as a feedforward control law for positioning of the tool along desired time varying signals. The effectiveness of the proposed controller is demonstrated by experiment and simulation.

003 Hexapod Surgical System : système d’aide robotisée

Journal Français d'Ophtalmologie, 2009

Cellules souches mésenchymateuses et cicatrisation cornéenne. Therapeutic potential of bone marro... more

Dynamic variable depth of cut machining using piezoelectric actuators

International Journal of Machine Tools and Manufacture, 1994

ABSTRACT

Robot-assisted intraocular surgery: development of the IRISS and feasibility studies in an animal model

Eye, 2013

The aim of this study is to develop a novel robotic surgical platform, the IRISS (Intraocular Rob... more The aim of this study is to develop a novel robotic surgical platform, the IRISS (Intraocular Robotic Interventional and Surgical System), capable of performing both anterior and posterior segment intraocular surgery, and assess its performance in terms of range of motion, speed of motion, accuracy, and overall capacities. To test the feasibility of performing &#39;bimanual&#39; intraocular surgical tasks using the IRISS, we defined four steps out of typical anterior (phacoemulsification) and posterior (pars plana vitrectomy (PPV)) segment surgery. Selected phacoemulsification steps included construction of a continuous curvilinear capsulorhexis and cortex removal in infusion-aspiration (I/A) mode. Vitrectomy steps consisted of performing a core PPV, followed by aspiration of the posterior hyaloid with the vitreous cutter to induce a posterior vitreous detachment (PVD) assisted with triamcinolone, and simulation of the microcannulation of a temporal retinal vein. For each evaluation, the duration and the successful completion of the task with or without complications or involuntary events was assessed. Intraocular procedures were successfully performed on 16 porcine eyes. Four eyes underwent creation of a round, curvilinear anterior capsulorhexis without radialization. Four eyes had I/A of lens cortical material completed without posterior capsular tear. Four eyes completed 23-gauge PPV followed by successful PVD induction without any complications. Finally, simulation of microcannulation of a temporal retinal vein was successfully achieved in four eyes without any retinal tears/perforations noted. Robotic-assisted intraocular surgery with the IRISS may be technically feasible in humans. Further studies are pending to improve this particular surgical platform.

003 Hexapod Surgical System: système d’aide robotisée

Cellules souches mésenchymateuses et cicatrisation cornéenne. Therapeutic potential of bone marro... more

Some recent results in moving load problems with application to highway bridges

In this paper, some recent results obtained for various aspects of the moving load problem are di... more In this paper, some recent results obtained for various aspects of the moving load problem are discussed. While encompassing a range of problems involving discrete subsystems traversing a primary distributed parameter system, a simple vehicle crossing a bridge is used herein to demonstrate various effects and their relative importance.

On Equivalence of the Moving Mass and Moving Oscillator Problems

Asymptotic behavior of the solution of the moving oscillator problem is examined for large values... more Asymptotic behavior of the solution of the moving oscillator problem is examined for large values of the spring stiffness for the general case of nonzero beam initial conditions. In the limit of infinite spring stiffness, the moving oscillator problem for a simply supported beam is shown to be not equivalent in a strict sense to the moving mass problem; i.e., beam displacements obtained by solving the two problems are the same, but the higher-order derivatives of the two solutions are different. In the general case, the force acting on the beam from the oscillator is shown to contain a high-frequency component, which does not vanish, or even grows, when the spring coefficient tends to infinity. The magnitude of this force and its dependence on the oscillator parameters can be estimated by considering the asymptotics of the solution for the initial stage of the oscillator motion. For the case of a simply supported beam, the magnitude of the high-frequency force linearly depends on the oscillator eigenfrequency and velocity. The deficiency of the moving mass model is noted in that it fails to predict stresses in the bridge structure. Results of numerical experiments are presented.

Dynamic variable depth of cut machining using piezoelectric actuators

ABSTRACT

Tool positioning for noncircular cutting with lathe

This paper presents the design and implementation of a digital controller for a lathe to machine ... more This paper presents the design and implementation of a digital controller for a lathe to machine workpieces with noncircular cross sections. Noncircular cutting is accomplished by controlling the radial tool position in the direction normal to the surface of workpiece. A discrete time model for the tool carriage in the radial direction is obtained by a least squares method applied to input and output data. The model is used for designing digital feedback and feedforward controllers. The zero phase error tracking control algorithm is applied as a feedforward control law for positioning of the tool along desired time varying signals. The effectiveness of the proposed controller is demonstrated by experiment and simulation.