Abstract In order to effectively evaluate the capability of large-scale blackout emergency handli... more Abstract In order to effectively evaluate the capability of large-scale blackout emergency handling, and find out the weak links for power grid enterprises in regard to large-scale blackout emergency handling, the evaluation indices system for the emergency handling ...
Based on the dynamic model, a novel nonlinear tracking controller is developed to overcome the no... more Based on the dynamic model, a novel nonlinear tracking controller is developed to overcome the nonlinear dynamics and friction of a planar parallel manipulator. The dynamic model is formulated in the active joint space, and the active joint friction is described with the Coulomb + viscous friction model. A nonlinear tracking controller is designed to eliminate the tracking error by using the power function. The nonlinear tracking controller is proven to guarantee asymptotic convergence to zero of both the tracking error and error rate with the Barbalat’s lemma. The trajectory tracking experiment of the proposed controller is implemented on an actual five-bar planar parallel manipulator both at the low-speed and high-speed motion. Moreover, the control performances of the proposed controller are compared with the results of the augmented PD (APD) controller.
When a pumped storage plant is used for black-start in system restoration, some capacity in the u... more When a pumped storage plant is used for black-start in system restoration, some capacity in the upper reservoir must be reserved. However, this capacity cannot be used for load-balancing in daily operation. Obviously, the economy of pumped storage plant would be influenced. So it is significant to make reasonable evaluation of black-start capacity of the upper reservoir. In order to address this problem, a methodology from the perspective of energy conservation is first proposed in this paper. Furthermore, according to a specific black-start plan, this paper gives an algorithm to obtain the electricity energy consumed in the black-start procedure. Accordingly, the black-start capacity can be attained by the relation between the potential energy and the electricity energy. An example from a practical black-start test can be used to verify the feasibility of this algorithm.
In order to improve trajectory tracking accuracy for a redundantly actuated parallel manipulator,... more In order to improve trajectory tracking accuracy for a redundantly actuated parallel manipulator, a so-called augmented nonlinear PD (ANPD) controller based on the conventional dynamic controller is proposed in this paper. The ANPD controller is designed by replacing the linear PD in the augmented PD controller with a nonlinear PD algorithm. The stability of the parallel manipulator system with the proposed ANPD controller is proven using the Lyapunov stability theorem, and the ANPD controller is further proven to guarantee asymptotic convergence to zero of both the tracking error and error rate. The superiority of the ANPD controller is verified through trajectory tracking experiments of an actual 2-d.o.f. redundantly actuated parallel manipulator.
A coordination controller is proposed to improve the coordination relation of multiple kinematic ... more A coordination controller is proposed to improve the coordination relation of multiple kinematic chains in the parallel manipulators with actuation redundancy. The coordination errors are defined using the tracking errors of the neighboring active joints, and the coordination controller is designed in the task space. And the coordination controller is proved to guarantee asymptotic convergence to zero of both tracking and coordination errors by the Barbalat's Lemma. The trajectory tracking experiments of an actual parallel manipulator with actuation redundancy are carried out, and then the control performances between the coordination controller and the augmented PD (APD) controller are compared.
In this paper, the characteristics and harm of the impact that natural disasters could make on po... more In this paper, the characteristics and harm of the impact that natural disasters could make on power system were analyzed. Furthermore, the natural disaster early warning system for power system is proposed, and details of the four parts of the system are introduced respectively. The authors focused on the information sources of early warning monitor, the three steps of risk assessment, the determination of warning grade and five facets of early warning response. This paper will provide theoretical support for the future construction of a natural disaster early warning system for power system.
The necessity of super grid operation at different layer and zone together with relevant technica... more The necessity of super grid operation at different layer and zone together with relevant technical principles are discussed in this paper. The proposed methodology deals with two questions: whether electromagnetic loops should exist or not in power system and how to put in practice. Corresponding indices are established to assess the system performance. An example is demonstrated and a software program, BPA, is used to implement the calculating and analysis.
The optimal kinematics configuration of planar parallel manipulator is presented using analysis o... more The optimal kinematics configuration of planar parallel manipulator is presented using analysis of the relation between inverse kinematics and force transmission. First, direct kinematics and inverse kinematics of the 2-dof redundantly actuated planar parallel manipulator are solved, and eight configurations of the eight inverse kinematics solutions are gained. Then, workspace on the x-y plane of the manipulator is confirmed. Finally, based on the reciprocal of the Jacobian matrix index, plots of the force transmission performance on the efficient workspace of the eight kinematics configurations are calculated, and the two equivalent optimal kinematics configuration are pointed out at the same time
A nonlinear adaptive (NA) controller in the task space is developed for the trajectory tracking o... more A nonlinear adaptive (NA) controller in the task space is developed for the trajectory tracking of a 2-DOF redundantly actuated parallel manipulator. The dynamic model with nonlinear friction is established in the task space for the parallel manipulator, and the linear parameterization expression of the dynamic model is formulated. Based on the dynamic model, a new control law including adaptive dynamics compensation, adaptive friction compensation and error elimination items is designed. After defining a quadratic performance index, the parameter update law is derived with the gradient descent algorithm. The stability of the parallel manipulator system is proved by the Lyapunov theorem, and the convergence of the tracking error and the error rate is proved by the Barbalat’s lemma. The NA controller is implemented in the trajectory tracking experiments of an actual 2-DOF redundantly actuated parallel manipulator, and the experiment results are compared with the APD controller.
The singularity of a five-bar parallel manipulator is analyzed and a nonlinear tracking controlle... more The singularity of a five-bar parallel manipulator is analyzed and a nonlinear tracking controller is designed in this paper. Three types of the singularity are analyzed and the singularity curve equations are formulated by using the Jacobian matrix of the parallel manipulator. The dynamic model is established in the active joint space, and the active joint friction is described with the Coulomb + viscous friction model. Based on the dynamic model, a nonlinear tracking controller eliminating the tracking error with the power function is proposed. The trajectory tracking experiment of an actual five-bar parallel manipulator is carried out. The performances between the proposed controller and the traditional augmented PD (APD) controller are compared.
In order to improve the actual tracking accuracy of a planar parallel manipulator with redundant ... more In order to improve the actual tracking accuracy of a planar parallel manipulator with redundant actuation, a new adaptive compensation of dynamics and friction is developed. Firstly, the dynamic model is established in the task space for the parallel manipulator, and a linear parametrization expression with respect to the model parameters is formulated. Then, based on the dynamic model, a new adaptive control law which contains dynamics compensation, friction compensation and tracking error elimination items is designed. The parameter adaptation law is derived by the Lyapunov method, and the convergence of the tracking error and the error rate is proved by the Barbalat's lemma. At last, the proposed controller is implemented in the trajectory tracking experiments of an actual planar parallel manipulator with redundant actuation.
Continuous path (CP) control was researched on an Internet-based two degrees-of-freedom robot arm... more Continuous path (CP) control was researched on an Internet-based two degrees-of-freedom robot arm in this paper. First, the condition needed to realize the continuous path control was analyzed. The important parameter “the highest resultant speed” was calculated considering the existence of network-delay. Then the relation between the linear interpolation numbers and errors of the four-leaf rose curve was derived. The remote control experiment in the actual robot arm system was carried out, and the effects of the interpolation point number to control precision and drawing time were also discussed. At last, a constant compensation method was applied to eliminate the mechanical effects existed in the system and improve the precision of the path-tracking further.
The self-identification of a redundantly actuated parallel manipulator is transformed into an opt... more The self-identification of a redundantly actuated parallel manipulator is transformed into an optimization problem, and then differential evolution algorithm is used to obtain a globally optimal solution of the kinematic parameters. Based on the kinematic equations of the parallel manipulator, a new optimization function is formulated by eliminating the passive joint angles and decoupling the kinematic parameters. In order to obtain the global optimum, differential evolution algorithm is applied to minimize the optimization function. The proposed self-identification method is realized on an actual parallel manipulator, and the comparison on the actuated joint errors indicates that the identified kinematic parameters are much more accurate than the nominal parameters. Finally, the kinematic control experiments are carried out, and then the tracking accuracy of the end-effector based on the identified kinematic model is compared with the results by using the nominal kinematic model.
Abstract In order to effectively evaluate the capability of large-scale blackout emergency handli... more Abstract In order to effectively evaluate the capability of large-scale blackout emergency handling, and find out the weak links for power grid enterprises in regard to large-scale blackout emergency handling, the evaluation indices system for the emergency handling ...
Based on the dynamic model, a novel nonlinear tracking controller is developed to overcome the no... more Based on the dynamic model, a novel nonlinear tracking controller is developed to overcome the nonlinear dynamics and friction of a planar parallel manipulator. The dynamic model is formulated in the active joint space, and the active joint friction is described with the Coulomb + viscous friction model. A nonlinear tracking controller is designed to eliminate the tracking error by using the power function. The nonlinear tracking controller is proven to guarantee asymptotic convergence to zero of both the tracking error and error rate with the Barbalat’s lemma. The trajectory tracking experiment of the proposed controller is implemented on an actual five-bar planar parallel manipulator both at the low-speed and high-speed motion. Moreover, the control performances of the proposed controller are compared with the results of the augmented PD (APD) controller.
When a pumped storage plant is used for black-start in system restoration, some capacity in the u... more When a pumped storage plant is used for black-start in system restoration, some capacity in the upper reservoir must be reserved. However, this capacity cannot be used for load-balancing in daily operation. Obviously, the economy of pumped storage plant would be influenced. So it is significant to make reasonable evaluation of black-start capacity of the upper reservoir. In order to address this problem, a methodology from the perspective of energy conservation is first proposed in this paper. Furthermore, according to a specific black-start plan, this paper gives an algorithm to obtain the electricity energy consumed in the black-start procedure. Accordingly, the black-start capacity can be attained by the relation between the potential energy and the electricity energy. An example from a practical black-start test can be used to verify the feasibility of this algorithm.
In order to improve trajectory tracking accuracy for a redundantly actuated parallel manipulator,... more In order to improve trajectory tracking accuracy for a redundantly actuated parallel manipulator, a so-called augmented nonlinear PD (ANPD) controller based on the conventional dynamic controller is proposed in this paper. The ANPD controller is designed by replacing the linear PD in the augmented PD controller with a nonlinear PD algorithm. The stability of the parallel manipulator system with the proposed ANPD controller is proven using the Lyapunov stability theorem, and the ANPD controller is further proven to guarantee asymptotic convergence to zero of both the tracking error and error rate. The superiority of the ANPD controller is verified through trajectory tracking experiments of an actual 2-d.o.f. redundantly actuated parallel manipulator.
A coordination controller is proposed to improve the coordination relation of multiple kinematic ... more A coordination controller is proposed to improve the coordination relation of multiple kinematic chains in the parallel manipulators with actuation redundancy. The coordination errors are defined using the tracking errors of the neighboring active joints, and the coordination controller is designed in the task space. And the coordination controller is proved to guarantee asymptotic convergence to zero of both tracking and coordination errors by the Barbalat's Lemma. The trajectory tracking experiments of an actual parallel manipulator with actuation redundancy are carried out, and then the control performances between the coordination controller and the augmented PD (APD) controller are compared.
In this paper, the characteristics and harm of the impact that natural disasters could make on po... more In this paper, the characteristics and harm of the impact that natural disasters could make on power system were analyzed. Furthermore, the natural disaster early warning system for power system is proposed, and details of the four parts of the system are introduced respectively. The authors focused on the information sources of early warning monitor, the three steps of risk assessment, the determination of warning grade and five facets of early warning response. This paper will provide theoretical support for the future construction of a natural disaster early warning system for power system.
The necessity of super grid operation at different layer and zone together with relevant technica... more The necessity of super grid operation at different layer and zone together with relevant technical principles are discussed in this paper. The proposed methodology deals with two questions: whether electromagnetic loops should exist or not in power system and how to put in practice. Corresponding indices are established to assess the system performance. An example is demonstrated and a software program, BPA, is used to implement the calculating and analysis.
The optimal kinematics configuration of planar parallel manipulator is presented using analysis o... more The optimal kinematics configuration of planar parallel manipulator is presented using analysis of the relation between inverse kinematics and force transmission. First, direct kinematics and inverse kinematics of the 2-dof redundantly actuated planar parallel manipulator are solved, and eight configurations of the eight inverse kinematics solutions are gained. Then, workspace on the x-y plane of the manipulator is confirmed. Finally, based on the reciprocal of the Jacobian matrix index, plots of the force transmission performance on the efficient workspace of the eight kinematics configurations are calculated, and the two equivalent optimal kinematics configuration are pointed out at the same time
A nonlinear adaptive (NA) controller in the task space is developed for the trajectory tracking o... more A nonlinear adaptive (NA) controller in the task space is developed for the trajectory tracking of a 2-DOF redundantly actuated parallel manipulator. The dynamic model with nonlinear friction is established in the task space for the parallel manipulator, and the linear parameterization expression of the dynamic model is formulated. Based on the dynamic model, a new control law including adaptive dynamics compensation, adaptive friction compensation and error elimination items is designed. After defining a quadratic performance index, the parameter update law is derived with the gradient descent algorithm. The stability of the parallel manipulator system is proved by the Lyapunov theorem, and the convergence of the tracking error and the error rate is proved by the Barbalat’s lemma. The NA controller is implemented in the trajectory tracking experiments of an actual 2-DOF redundantly actuated parallel manipulator, and the experiment results are compared with the APD controller.
The singularity of a five-bar parallel manipulator is analyzed and a nonlinear tracking controlle... more The singularity of a five-bar parallel manipulator is analyzed and a nonlinear tracking controller is designed in this paper. Three types of the singularity are analyzed and the singularity curve equations are formulated by using the Jacobian matrix of the parallel manipulator. The dynamic model is established in the active joint space, and the active joint friction is described with the Coulomb + viscous friction model. Based on the dynamic model, a nonlinear tracking controller eliminating the tracking error with the power function is proposed. The trajectory tracking experiment of an actual five-bar parallel manipulator is carried out. The performances between the proposed controller and the traditional augmented PD (APD) controller are compared.
In order to improve the actual tracking accuracy of a planar parallel manipulator with redundant ... more In order to improve the actual tracking accuracy of a planar parallel manipulator with redundant actuation, a new adaptive compensation of dynamics and friction is developed. Firstly, the dynamic model is established in the task space for the parallel manipulator, and a linear parametrization expression with respect to the model parameters is formulated. Then, based on the dynamic model, a new adaptive control law which contains dynamics compensation, friction compensation and tracking error elimination items is designed. The parameter adaptation law is derived by the Lyapunov method, and the convergence of the tracking error and the error rate is proved by the Barbalat's lemma. At last, the proposed controller is implemented in the trajectory tracking experiments of an actual planar parallel manipulator with redundant actuation.
Continuous path (CP) control was researched on an Internet-based two degrees-of-freedom robot arm... more Continuous path (CP) control was researched on an Internet-based two degrees-of-freedom robot arm in this paper. First, the condition needed to realize the continuous path control was analyzed. The important parameter “the highest resultant speed” was calculated considering the existence of network-delay. Then the relation between the linear interpolation numbers and errors of the four-leaf rose curve was derived. The remote control experiment in the actual robot arm system was carried out, and the effects of the interpolation point number to control precision and drawing time were also discussed. At last, a constant compensation method was applied to eliminate the mechanical effects existed in the system and improve the precision of the path-tracking further.
The self-identification of a redundantly actuated parallel manipulator is transformed into an opt... more The self-identification of a redundantly actuated parallel manipulator is transformed into an optimization problem, and then differential evolution algorithm is used to obtain a globally optimal solution of the kinematic parameters. Based on the kinematic equations of the parallel manipulator, a new optimization function is formulated by eliminating the passive joint angles and decoupling the kinematic parameters. In order to obtain the global optimum, differential evolution algorithm is applied to minimize the optimization function. The proposed self-identification method is realized on an actual parallel manipulator, and the comparison on the actuated joint errors indicates that the identified kinematic parameters are much more accurate than the nominal parameters. Finally, the kinematic control experiments are carried out, and then the tracking accuracy of the end-effector based on the identified kinematic model is compared with the results by using the nominal kinematic model.
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