An investigation on the neural networks based active vibration control of flexible redundant manipulators was conducted. The smart links of the manipulator were synthesized with the flexible links to which were attach...An investigation on the neural networks based active vibration control of flexible redundant manipulators was conducted. The smart links of the manipulator were synthesized with the flexible links to which were attached piezoceramic actuators and strain gauge sensors. A nonlinear adaptive control strategy named neural networks based indirect adaptive control (NNIAC) was employed to improve the dynamic performance of the manipulator. The mathematical model of the 4-layered dynamic recurrent neural networks (DRNN) was introduced. The neuro-identifier and the neuro-controller featuring the DRNN topology were designed off line so as to enhance the initial robustness of the NNIAC. By adjusting the neuro-identifier and the neuro-controller alternatively, the manipulator was controlled on line for achieving the desired dynamic performance. Finally, a planar 3R redundant manipulator with one smart link was utilized as an illustrative example. The simulation results proved the validity of the control strategy.展开更多
For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasing...For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasingly difficult to obtain the analytic solution of its self-motion manifold in the traditional way for solving matrix equation.In this paper,we take the pose of end manipulator as the result of the joint sequential motion based on the mentality of motion equivalence,the structure and the reference velocity which correspond precisely to the points in self-motion manifold as self-motion variable.Thus an analytical solution for the self-motion manifold of the 8 degree of freedom wheeled mobile manipulator is presented by taking vector algebra as a tool,which facilitates deriving the closed solution of its self-motion manifold.In the closing part of this paper,calculating examples of self-motion manifold and mechanism self-motion simulation are proposed,which proves the validity of solution algorithm for self-motion manifold.展开更多
This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cab...This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cable-driven exoskeleton robot to execute the task smoothly and safely, it is necessary to consider the tracking motion performance as well as passivity when interacting with the environment under the conditions of the actuation cables＇ redundancy and the pulling limitation. With the additional consideration of the maximum limitation of the cable tension, cable-driven robot actually can only apply a certain range of feasible wrench on the external environment, which makes the task executed by robot be restricted. In order to make designed wrench be feasible and keep the desired trajectory tracking ability, we present a new control method by extending PVFC （passive velocity field control） method considering tracking stability and passivity. The approach augmented a higher dimensional virtual flywheel dynamics in a specific orthogonal complement space of the cable＇s actuation space. After the final adjustment of the designed wrench with respect to the cable＇s constraint, this method is capable of driving the cable robot to complete the trajectory tracking task and realize the passivity.展开更多
基金Supported by National Natural Science Foundation of China(No.59975001 and 50205019).
文摘An investigation on the neural networks based active vibration control of flexible redundant manipulators was conducted. The smart links of the manipulator were synthesized with the flexible links to which were attached piezoceramic actuators and strain gauge sensors. A nonlinear adaptive control strategy named neural networks based indirect adaptive control (NNIAC) was employed to improve the dynamic performance of the manipulator. The mathematical model of the 4-layered dynamic recurrent neural networks (DRNN) was introduced. The neuro-identifier and the neuro-controller featuring the DRNN topology were designed off line so as to enhance the initial robustness of the NNIAC. By adjusting the neuro-identifier and the neuro-controller alternatively, the manipulator was controlled on line for achieving the desired dynamic performance. Finally, a planar 3R redundant manipulator with one smart link was utilized as an illustrative example. The simulation results proved the validity of the control strategy.
文摘For the non-holonomic constraint robot,determining the pose of its end-effector will rely on its joints' displacement and the velocity of its non-holonomic constraint joints as well.Therefore,it becomes increasingly difficult to obtain the analytic solution of its self-motion manifold in the traditional way for solving matrix equation.In this paper,we take the pose of end manipulator as the result of the joint sequential motion based on the mentality of motion equivalence,the structure and the reference velocity which correspond precisely to the points in self-motion manifold as self-motion variable.Thus an analytical solution for the self-motion manifold of the 8 degree of freedom wheeled mobile manipulator is presented by taking vector algebra as a tool,which facilitates deriving the closed solution of its self-motion manifold.In the closing part of this paper,calculating examples of self-motion manifold and mechanism self-motion simulation are proposed,which proves the validity of solution algorithm for self-motion manifold.
基金This research has been partially supported by National Natural Science Foundation of China under Grant No. 61472117.
文摘This paper proposes a novel dynamic control approach for a cable-driven robot with high redundant actuation and cable tension limitations to perform tracking task while interacting with environment. In order for a cable-driven exoskeleton robot to execute the task smoothly and safely, it is necessary to consider the tracking motion performance as well as passivity when interacting with the environment under the conditions of the actuation cables＇ redundancy and the pulling limitation. With the additional consideration of the maximum limitation of the cable tension, cable-driven robot actually can only apply a certain range of feasible wrench on the external environment, which makes the task executed by robot be restricted. In order to make designed wrench be feasible and keep the desired trajectory tracking ability, we present a new control method by extending PVFC （passive velocity field control） method considering tracking stability and passivity. The approach augmented a higher dimensional virtual flywheel dynamics in a specific orthogonal complement space of the cable＇s actuation space. After the final adjustment of the designed wrench with respect to the cable＇s constraint, this method is capable of driving the cable robot to complete the trajectory tracking task and realize the passivity.
