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Mechatronics, IEEE/ASME Transactions on

Issue 2 • Date June 2003

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Displaying Results 1 - 18 of 18
  • Guest editorial

    Page(s): 149 - 150
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    Freely Available from IEEE
  • Observer-corrector control design for robots with destabilizing unmodeled dynamics

    Page(s): 151 - 164
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (786 KB) |  | HTML iconHTML  

    Industrial robotic manipulators and other mechatronic systems often possess undesirable higher order dynamics exhibited in the form of resonance conditions which affect closed-loop stability when feedback control is applied. In this study, an alternative reduced-complexity control design strategy is presented. The fundamental idea of the proposed approach is to synthesize a substitute feedback signal which reflects the dominant dynamics essential for operation of the system subject to control but does not include the undesirable higher order dynamic effects. A unique arrangement of a band-limited state observer and a low-pass filter corrector is employed for this purpose, providing a mechanism to extract the dominant dynamics from the output of the system with minimal amplitude and phase distortion. The resulting synthetic signal is used as a controller input, effectively eliminating destabilizing effects of the undesirable higher order dynamics. As a result, the controller can be designed practically without taking the higher order dynamic effects into account, which allows for use of conventional control techniques, and translates into reduced modeling requirements, simplified controller design and shorter development time when compared to a complete dynamic analysis. The effectiveness of the proposed concept is demonstrated experimentally on motion control of a four-axis direct-drive robotic manipulator for automated pick-place operations in semiconductor manufacturing applications. It is concluded that the proposed control design strategy provides improved control performance, increased stability margin, and added robustness against variations in system parameters in comparison to common methods adopted currently in the engineering practice. View full abstract»

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  • Dynamics modeling and simulation of constrained robotic systems

    Page(s): 165 - 177
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    Dynamic analysis is the basic element of mechanical design and control of mechanisms. This work intends to address dynamic methods relevant to constrained robots and mechanisms from a unified analytical point of view, which is based on differential variational principles. A constrained robotic system is a mechanical system, where we need to consider kinematic constraint conditions explicitly in dynamic modeling and analysis. Important classes of constrained robotic systems include, for example, parallel robots and closed-chain mechanisms where the loop closure conditions can be generally expressed by nonlinear holonomic constraint equations, and mobile robots where the system is subjected to linear nonholonomic constraints. Our primary focus is on systems with nonlinear holonomic constraint equations (e.g., parallel robots, robotic systems with closed kinematic chains). However, the approach and formulation discussed are also applicable for nonholonomic systems. In the framework presented, many approaches can be discussed, and new directions can be highlighted that can contribute to the better understanding of dynamic behavior. Two new approaches for the dynamic analysis and for the simulation of constrained robotic systems are introduced and discussed. The paper also points out some areas and methods where further exploration is necessary to shed light on problems and applications related to constrained robotic systems. View full abstract»

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  • On modeling, identification, and control of a heavy-duty electrohydraulic harvester manipulator

    Page(s): 178 - 187
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (981 KB) |  | HTML iconHTML  

    Focuses on modeling, parameter estimation, and control for a heavy-duty electrohydraulic manipulator of a harvester machine. The linear-graph method is implemented in deriving mathematical models for the swing, boom and stick subsystems. Actuation dynamics are subsequently integrated with manipulator dynamics to result in a complete machine model. Identification procedures employed in estimating physical parameters are discussed in detail and key parameter results supplied. Model validation studies show good agreement between model predictions and experiments. A Cartesian controller for the motion of the manipulator end-point is described and response results are presented. It is shown that the obtained response is very good for the purposes of this harvester machine, resulting in very small relative tracking errors. View full abstract»

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  • Dynamic modeling and control of a conveyance microrobotic system using active friction drive

    Page(s): 188 - 202
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    Presents a new generation of compliant multidegree of freedom piezoelectric microconveyer for microobjects based on the cooperation of arrayed direct-drive micro standing-wave ultrasonic actuators (microSWUMs). Their operating driving principles based on active frictional contact forces offer direct-drive and low-speed characteristics at the microscale. The tradeoff, however, is the complexity of dynamic modeling and control to cope with the optimization of the intermittent friction drive mechanism. A method using an equivalent electromechanical circuit is proposed for estimating and analyzing the optimum driving force, including the dynamic electrical and the mechanical energy conversions. On the basis of the proposed method, the friction drive optimization of the microrobot is performed through the implementation of different controllers: 1) an electromagnetic-field-based preload controller ensuring optimal preload; 2) an open-loop piecewise-modulated controller for self locking and driving force control; and 3) a resonant frequency compensation. Finally, an experimental investigation has been performed on a prototype of ultrasonic microconveyer incorporating 48 arrayed microSWUMs whose overall dimensions are 47 × 29 mm2 in order to demonstrate the proposed optimized friction drive. View full abstract»

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  • Full-state tracking and internal dynamics of nonholonomic wheeled mobile robots

    Page(s): 203 - 214
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (863 KB) |  | HTML iconHTML  

    In the paper, the stable full-state tracking problem is investigated for nonholonomic wheeled mobile robots under output-tracking control laws. Dynamics of such wheeled mobile robots are nonholonomic and pose challenging problems for control design and stability analysis. The dynamics formulated in terms of full-state tracking errors offer some properties that allow better understanding of the internal and zero dynamics of the tracking-error system and more insights to the trajectory tracking stability. Output functions are chosen as virtual reference points for various types of wheeled mobile robots in aid of output controller designs. Sufficient conditions are derived to ensure the stable full-state trajectory tracking under output-tracking control laws. A type (1,1) mobile robot of car-like configuration is studied in detail and further numerical analysis provides more results which are beyond the reach of analytical means. An example and simulation results are presented to confirm the theory and observations. View full abstract»

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  • An optimal information method for mobile manipulator dynamic parameter identification

    Page(s): 215 - 225
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    High-performance robot-control algorithms often rely on system-dynamic models. For field robots, the dynamic parameters of these models may not be well known. The paper presents a mutual-information-based observability metric for the online dynamic parameter identification of a multibody system. The metric is used in an algorithm to optimally select the external excitation required by the dynamic system parameter identification process. The excitation is controlled so that the identification favors parameters that have the greatest uncertainty at any given time. This algorithm is applied to identify the vehicle and suspension parameters of a mobile-field manipulator, and is found to be computationally more efficient and robust to noise than conventional methods. Issues addressed include the development of appropriate vehicle models, compatible with the onboard sensors. Simulations and experimental results show the effectiveness of this algorithm. View full abstract»

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  • Hybrid fault adaptive control of a wheeled mobile robot

    Page(s): 226 - 233
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    A fault adaptive control methodology for mobile robots is presented. The robot is modeled as a continuous system with a supervisory controller. The physical processes of the robot are modeled using bond graphs, and this forms the basis of a combined qualitative reasoning and quantitative model-based estimation scheme for online fault detection and isolation during robot operation. A hierarchical-control accommodation framework is developed for the supervisory controller that determines a suitable control strategy to accommodate the isolated fault. It is shown that for small degradations in actuation effort, a robust controller achieves fault accommodation without significant loss of performance. However, for larger faults, the supervisor needs to switch among several controllers to maintain acceptable performance. The switching stability among a set of trajectory tracking controllers is presented. Simulation results verify the proposed fault adaptive control technique for a mobile robot. View full abstract»

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  • Mathematical models of binary spherical-motion encoders

    Page(s): 234 - 244
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    This paper presents several algorithms that solve the problem of determining the orientation of a freely rotating ball that is partially enclosed in a housing. The ball is painted in two colors (black and white) and the housing has a number of sensors that detect these colors. The question which we attempt to answer is: knowing how the ball is painted, knowing the location of the sensors, and given a complete set of sensor measurements, how does one determine the orientation of the ball to within an acceptable error threshold? The algorithms we present to solve this problem are based on methods and terminology from geometric control theory. Essentially, we generate dynamical systems that evolve on the group SO(3). These dynamical systems are constructed so as to attract the computed orientation of the ball to the actual one being detected by the sensors. Solving this spherical decoding problem is important in applications where the spherical motion must be detected. One such application is the feedback control of spherical motors. View full abstract»

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  • Control of ionic polymer metal composites

    Page(s): 245 - 253
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    Robotic devices are traditionally actuated by hydraulic systems or electric motors. However, with the desire to make robotic systems more compact and versatile, new actuator technologies are required. In this paper, the control of ionic polymer metal composite actuators is investigated from a practical perspective. The actuator characteristics are examined through the unblocked maximum displacement and blocked force output. An open-loop position control and closed-loop position proportional-integral-derivative (PID) control are then applied to a strip of actuators. Finally, the performance of the polymer is investigated when implementing an impedance controller (force/position control). View full abstract»

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  • Design and energetic characterization of a liquid-propellant-powered actuator for self-powered robots

    Page(s): 254 - 262
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (520 KB) |  | HTML iconHTML  

    This paper describes the design of a power supply and actuation system appropriate for position or force controlled human-scale robots. The proposed approach utilizes a liquid monopropellant to generate hot gas, which is utilized to power a pneumatic-type actuation system. A prototype of the actuation system is described, and closed-loop tracking data are shown, which demonstrate good motion control. Experiments to characterize the energetic performance of a six-degree-of-freedom actuation system indicate that the proposed system with a diluted propellant offers an energetic figure of merit five times greater than battery-powered DC motors. Projections based on these experiments indicate that the same system powered by undiluted propellant would offer an energetic figure of merit in an order of magnitude greater than a comparable battery-powered DC motor actuated system. View full abstract»

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  • The Tricept robot: dynamics and impedance control

    Page(s): 263 - 268
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    The Tricept is a novel industrial robot characterized by a hybrid kinematic design featuring a three-degrees-of-freedom (3-DOF) structure of parallel type and a 3-DOF spherical wrist. In this work the authors focus on the derivation of a dynamic model to be used for both simulation and control purposes. Two different approaches are discussed and compared in terms of inverse dynamics computation. Then, a model-based control is derived aimed at enforcing a 6-DOF impedance behavior at the end effector to manage interaction with the environment. Simulation results are presented to evaluate the accuracy of an approximate dynamic model computation as well as to test the effectiveness of the proposed impedance control strategy. View full abstract»

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  • Inertial vibration damping control of a flexible base manipulator

    Page(s): 268 - 271
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (439 KB) |  | HTML iconHTML  

    A rigid (micro) robot mounted serially to the tip of a long flexible (macro) robot is often used to increase the reach capability, but flexibility in the macro-manipulator can make it susceptible to vibration. A rigid manipulator attached to a flexible but unactuated base was considered as an analogous problem. The interaction forces and torques acting at the base of the robot are used to damp the vibration. Appropriate control gain limits are established to ensure the inertia effects, or those directly due to accelerating the links of the rigid robot, have the greatest influence on the interactions. By commanding the link accelerations out of phase with the base velocity, vibrational energy will be removed from the system. This signal is then added to the rigid robot position controller, providing combined rigid robot position and vibration control of the base. View full abstract»

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  • Bang-bang impact control using hybrid impedance/time-delay control

    Page(s): 272 - 277
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    For stabilization of a robot manipulator upon collision with a stiff environment, a nonlinear bang-bang impact controller is developed. Under this control, a robot can successfully achieve contact tasks without changing the control algorithm or controller gains throughout all three modes: free space, transition and constrained motion. It uses a robust hybrid impedance/time-delay control algorithm to first absorb impact forces and stabilize the system. This control input alternates with zero when no environment force is sensed due to loss of contact. This alternation of control action repeats until the impact transient subsides and steady state is attained. After impact transient, the hybrid impedance/time-delay control algorithm is again utilized. This bang-bang control method provides stable interaction between a robot with severe nonlinear joint friction and a stiff environment, and achieves rapid response while minimizing force overshoots. During contact transition, we employ one simple control algorithm that switches only to zero and maintains the same gains, while other controllers use more than one control algorithm or different control gains. It is shown via experiments that overall performance is superior or comparable to more complicated existing impact force control techniques. View full abstract»

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  • Intelligent feedforward control and payload estimation for a two-link robotic manipulator

    Page(s): 277 - 282
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    Conventional model-based computed torque control fails to produce a good trajectory tracking performance in the presence of payload uncertainty and modeling error. The challenge is to provide accurate dynamics information to the controller. A new control architecture that incorporates a neural-network, fuzzy logic and a simple proportional-derivative (PD) controller is proposed to control an articulated robot carrying a variable payload. An off-line trained feedforward (multilayer) neural network takes payload mass estimates from a fuzzy-logic mass estimator as one of the inputs to represent the inverse dynamics of the articulated robot. The effectiveness of the proposed architecture is demonstrated by experiment on a two-link planar manipulator with changing payload mass. Experimental results show that this control architecture achieves excellent tracking performance in the presence of payload uncertainty. View full abstract»

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  • Grasping control of rolling manipulations with deformable fingertips

    Page(s): 283 - 286
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    This paper deals with the problem of stable grasping in rolling manipulations with soft deformable fingertips in two-dimensional space and without the effect of gravity. Two rolling distance models for the soft-area contact motion and their effect on contact kinematics are considered. The modeling of contact forces in soft-area contacts is discussed and an analysis of a stable grasp is made. A simple feedback controller for stabilizing the grasp is proposed and tested in simulation. The control law is based on the object's equilibrium conditions and is designed so that it drives the system at rest by achieving a desired value for the normal contact forces and appropriate tangential forces to balance the moments created by the contact offset. View full abstract»

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  • Teleoperated touch feedback from the surfaces at the nanoscale: modeling and experiments

    Page(s): 287 - 298
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1785 KB) |  | HTML iconHTML  

    In this paper, a teleoperated nanoscale touching system is proposed, and continuum nanoscale contact mechanics models are introduced. The tele-nanorobotic system consists of a piezoresistive nanoprobe with a sharp tip as the nanorobot and force-topology sensor, a custom-made 1-degree-of-freedom haptic device for force-feedback, three-dimensional (3D) virtual reality (VR) graphics display of the nano world for visual feedback, and a force-reflecting servo type scaled teleoperation controller. Using this system, one-dimensional and 3D touching experiments and VR simulations are realized. Scaling of nano-forces is one of the major issues of the scaled teleoperation system since nanometer scale forces are dominated by surface forces instead of inertial forces as in the macro world. As the force scaling approach, a heuristic rule is introduced where nano-forces are linearly scaled with an experimentally determined scaling parameter. Simulation results and preliminary experiments of touching silicon and InAs quantum dot nanostructures show that adhesion forces at the nanoscale can be felt repeatedly at the operator's hand, and the proposed system enables the nanoscale surface topography and contact/noncontact nano-force feedback. View full abstract»

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  • Large deflection dynamics and control for planar continuum robots

    Page(s): 299 - 307
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (750 KB) |  | HTML iconHTML  

    This paper focuses on a class of robot manipulators termed "continuum" robots - robots that exhibit behavior similar to tentacles, trunks, and snakes. In previous work, we studied details of the mechanical design, kinematics, path-planning and small-deflection dynamics for continuum robots such as the Clemson "tentacle manipulator". In this paper, we discuss the dynamics of a planar continuum backbone section, incorporating a large-deflection dynamic model. Based on these dynamics, we formulate a vibration-damping setpoint controller, and include experimental results to illustrate the efficacy of the proposed controller. View full abstract»

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Aims & Scope

IEEE/ASME Transactions on Mechatronics encompasses all practical aspects of the theory and methods of mechatronics, the synergetic integration of mechanical engineering with electronic and intelligent computer control in the design and manufacture of industrial products and processes.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Okyay Kaynak
Department of Electrical and Electronic Engineering
Bogazici University
34342 Istanbul, Turkey
okyay.kaynak@boun.edu.tr