A cantilever rubber beam with laminated piezoelectric actuators and sensors is initially tested to determine the properties governing the dynamic behavior of the beam. Various techniques are employed to estimate beam ...
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A cantilever rubber beam with laminated piezoelectric actuators and sensors is initially tested to determine the properties governing the dynamic behavior of the beam. Various techniques are employed to estimate beam properties such as elastic stiffness, damping coefficient and natural frequencies, as well as piezoelectric actuator capabilities for vibration control purposes. A simplified Euler-Bernoulli model is proposed, which is validated using the properties previously discovered. A passive electric shunt circuit is then proposed for the beam vibration suppression, when subjected to external excitation forces. Simulation of a series resistor-inductor shunt circuit is used to demonstrate the capability of altering the beam's dynamic behavior. Various methods for tuning the shunt circuit are explored in an effort to achieve optimal vibration suppression characteristics. Furthermore, experimental testing is conducted for validation of simulation results, which also yields similar information about passive shunting techniques for vibration damping.
GVG has been effectively used as a sensor based navigation tool using 360° sensor data. For mobile guide robot applications, however, we can only use 180° sensor data and the robustness of the navigation alg...
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GVG has been effectively used as a sensor based navigation tool using 360° sensor data. For mobile guide robot applications, however, we can only use 180° sensor data and the robustness of the navigation algorithm is critical for successful applications. For that purpose, the robot should be equipped with three capabilities. Those are 1) incremental GVG construction, 2) robust GVG navigation and 3) navigation strategy that just uses half of the sensor scan, i.e. 180°. In this paper, we propose a GVG navigation algorithm that has above 3 capabilities. We firstly propose a method that can estimate the invisible 180° range from previous range data. Moreover, we suggest a way of robust GVG navigation algorithm by using a sensor data matching technique. The simulation result validates that the proposed algorithm can incrementally and robustly navigate the semi-unstructured map by using 180° sensor scan.
This paper deals with the sequential inverse kinematics for the high speed tracking of flexible robots. As a continuation of the implicit expansion method in [1], the explicit version of the sequential inverse kinemat...
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This paper deals with the sequential inverse kinematics for the high speed tracking of flexible robots. As a continuation of the implicit expansion method in [1], the explicit version of the sequential inverse kinematics is presented which is easier to be understood conceptually. The accuracy and stability of the two algorithms are compared and proved. Numerical study verifies the validity of the theoretical results.
A recently proposed method for stabilizing haptic interfaces and teleoperation systems was tested with a "PHANToM" commercial haptic device. The "Passivity Observer" (PO) and "Passivity Contro...
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A recently proposed method for stabilizing haptic interfaces and teleoperation systems was tested with a "PHANToM" commercial haptic device. The "Passivity Observer" (PO) and "Passivity Controller" (PC) stabilization method was formed to stabilize the system but also excite high frequency mode in the device. To solve this problem, we propose a method to use a time-varying desired energy threshold instead of fixed zero energy threshold for the PO, and make the actual energy input follow the time-varying energy threshold. With the time-varying energy threshold, we make the PC control action smooth without sudden impulsive behavior by distributing the dissipation. The proposed new PO/PC approach is applied to PHANToM with high stiffness (K = 500N/m), and stable and smooth contact is guarantee. Resetting and active environment display problems also can be solved with the reference energy following idea.
This paper deals with optimum force balancing of a planar parallel manipulator, articulated with revolute joints, by properly distributing link masses, and connecting only one spring between its two coupler links. Aft...
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This paper deals with optimum force balancing of a planar parallel manipulator, articulated with revolute joints, by properly distributing link masses, and connecting only one spring between its two coupler links. After conducting the static force analysis of the mechanism, the force balancing is formulated as an optimisation problem such that a sum-squared values of bearing forces is minimized throughout an operation range of the manipulator, provided that a set of balancing constraints consisting of balancing conditions, the sizes of some inertial and geometric parameters are satisfied. Optimisation results indicate that the proposed optimisation approach is systematic, versatile and easy to implement for the optimum balancing of the parallel manipulator and other more general parallel manipulators. This work contributes to previously published work from the point of view of being a step towards optimum design of parallel manipulators, which is currently lacking in the literature.
This paper presents the development of a proportional-integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the d...
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This paper presents the development of a proportional-integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory as closely as possible despite the highly non-linear and coupled dynamics. The proportional-integral sliding mode is chosen to ensure the stability of the overall dynamics during the entire period i.e. the reaching phase and the sliding phase. Application to a two-link planar robot manipulator is presented.
This paper presents the development of a proportional-integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the d...
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This paper presents the development of a proportional-integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory as closely as possible despite the highly nonlinear and coupled dynamics. The proposed controller is designed using the centralized and decentralized approaches. The proportional-integral sliding mode is chosen to ensure the stability of overall dynamics during the entire period, i.e., the reaching phase and the sliding phase. Application to a two-link planar robot manipulator is considered.
In this paper, we present the results and implications of our experimental study into the parameter identification and the position error modelling of a Motoman SK 120 robot manipulator for kinematic calibration. The ...
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In this paper, we present the results and implications of our experimental study into the parameter identification and the position error modelling of a Motoman SK 120 robot manipulator for kinematic calibration. The true values of the parameters and the coefficients of the error model are estimated, in the least-squares sense, from the position data of 85 identification configurations of the manipulator measured by a high precision laser tracking system. The proposed error model is utilised to calculate the expected position errors for an exemplary Cartesian space trajectory. These errors are then corrected using a first order approximation of the inverse kinematic model. The results prove that the established model is accurate enough to represent position error of the manipulator without needing further experimental position data. This work contributes to previously published work from the point of view of being a simple and systematic approach to the self-calibration of robotics systems with minimum experimental data.
This paper aims (i) to introduce a new monolithic micromanipulation system for applications requiring micro/nano scale planar motion, and (ii) to model its stiffness consisting of the inherent stiffness of its joints,...
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This paper aims (i) to introduce a new monolithic micromanipulation system for applications requiring micro/nano scale planar motion, and (ii) to model its stiffness consisting of the inherent stiffness of its joints, and the artificial stiffness due to its joint space position controller in order to obtain a decoupled compliant motion for the manipulator end point while a Cartesian force vector is acting upon it. The micromanipulation system is an in-parallel actuated planar manipulator based on five single DOF flexure joints connecting five supposedly rigid links to each other. Numerical results provided show that there exist practical operation ranges of the manipulator yielding both a suitable set of joint serve gains as well as a diagonal Cartesian stiffness matrix. The stiffness model can be used to predict the reaction forces arising from part misalignment and the task forces during the execution of micro tasks, such as micromanufacturing and microassembly. The determination of the forces is also useful for many applications such as designing micro fixtures and micro end effectors sustainable to task forces.
This paper addresses kinematic analysis and constrained structural optimisation of a five-bar planar parallel manipulator articulated with revolute joints only. The kinematics of the manipulator is investigated, and i...
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This paper addresses kinematic analysis and constrained structural optimisation of a five-bar planar parallel manipulator articulated with revolute joints only. The kinematics of the manipulator is investigated, and its Jacobian matrix as a function of the input joint positions has been formulated. An objective function based on minimizing the overall deviation of the condition number of the manipulator Jacobian matrix from the ideal condition number throughout the workspace of the manipulator has been employed to determine the link lengths subjected to a set of optimisation constraints. Optimisation results indicate that the proposed optimisation method is systematic, versatile and easy to implement for the optimal synthesis of the five-bar parallel manipulator and other kinematic chains.
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