For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receivi...For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receiving errors of GNSS signal in the environment of HEO space are analyzed,and related compensating scheme is also proposed.Acquisition of GNSS signal is implemented by using weak signal acquisition technology based on Duffing.Precise tracking of weak GNSS signal is also realized by adopting dynamic detection and compensation technology based on Duffing chaotic oscillator.Simulation results show that,certain acquisition sensitivity and navigation precision can be reached,and the acquisition and tracking of weak GNSS signal can be realized by using the proposed technology,which provides good technology support for autonomous navigation of HEO and large elliptical spacecrafts.展开更多
A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The i...A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The initial amplitude of yoyo could be mapped to the desired final amplitude by adjusting the virtual control. First,the yoyo motion was formulated into a nonlinear optimal control problem which contained the virtual control. The reference trajectory of robot could be obtained by solving the optimal problem with analytic method or more general numerical approach. Then,both PI and deadbeat control methods were used to control the yoyo system. The simulation results show that the analytic solution of the reference trajectory is identical to the numerical solution,which mutually validates the correctness of the two solution methods. In simulation,the initial amplitude of yoyo is set to be 0.22 m which is 10% higher than the desired final amplitude of 0.2 m. It can be seen that the amplitude achieves the desired value asymptotically in about five periods when using PI control,while it needs only one period with deadbeat control. The reference trajectory of robot is generated by optimizing a certain performance index; therefore,it is globally optimal. This is essentially different from those traditional control methods,in which the reference trajectories are empirically imposed on robot. What's more,by choosing the height of the robot arm when the yoyo arrives at the bottom as the virtual control,the motion of the robot arm may not be out of its stroke limitation. The proposed approach may also be used in the control of other similar periodical dynamic systems.展开更多
The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinearcontrol system.Its mathematical model is established,and nonlinear factors are analyzed.Due to the existenceof dea...The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinearcontrol system.Its mathematical model is established,and nonlinear factors are analyzed.Due to the existenceof deadlock zone and the small damp of the pneumatic oscillating cylinder,it is likely to result inovershoot,and there is also certain steady-state error,so online modifying of proportion-integration-differentiation(PID) parameters is needed so as to achieve better control performance.Meanwhile considering thestability demand for long-term run,a fuzzy adaptive PID controller is designed.The result of hardware-inloop(HIL) test and real-time control experiment shows that the adaptive PID controller has desirable selfadaptabilityand robustness to external disturbance and to change of system parameters,and its control performanceis better than that of traditional PID controllers.展开更多
基金the National Key Research and Development Program of China(No.2016YFB0501000)the Major Program of National Natural Science Foundation of China(No.61690214)the Project of D020214.
文摘For global navigation satellite system(GNSS)in the application of high earth orbit(HEO)determination,there are problems such as small number of visible satellites and weak signal magnitude.The transmitting and receiving errors of GNSS signal in the environment of HEO space are analyzed,and related compensating scheme is also proposed.Acquisition of GNSS signal is implemented by using weak signal acquisition technology based on Duffing.Precise tracking of weak GNSS signal is also realized by adopting dynamic detection and compensation technology based on Duffing chaotic oscillator.Simulation results show that,certain acquisition sensitivity and navigation precision can be reached,and the acquisition and tracking of weak GNSS signal can be realized by using the proposed technology,which provides good technology support for autonomous navigation of HEO and large elliptical spacecrafts.
基金Project(50475025) supported by the National Natural Science Foundation of China
文摘A general approach for controlling of periodical dynamic systems was presented by taking robotic yoyo as an example. The height of the robot arm when the yoyo arrives at the bottom was chosen as virtual control. The initial amplitude of yoyo could be mapped to the desired final amplitude by adjusting the virtual control. First,the yoyo motion was formulated into a nonlinear optimal control problem which contained the virtual control. The reference trajectory of robot could be obtained by solving the optimal problem with analytic method or more general numerical approach. Then,both PI and deadbeat control methods were used to control the yoyo system. The simulation results show that the analytic solution of the reference trajectory is identical to the numerical solution,which mutually validates the correctness of the two solution methods. In simulation,the initial amplitude of yoyo is set to be 0.22 m which is 10% higher than the desired final amplitude of 0.2 m. It can be seen that the amplitude achieves the desired value asymptotically in about five periods when using PI control,while it needs only one period with deadbeat control. The reference trajectory of robot is generated by optimizing a certain performance index; therefore,it is globally optimal. This is essentially different from those traditional control methods,in which the reference trajectories are empirically imposed on robot. What's more,by choosing the height of the robot arm when the yoyo arrives at the bottom as the virtual control,the motion of the robot arm may not be out of its stroke limitation. The proposed approach may also be used in the control of other similar periodical dynamic systems.
基金Supported by Japanese SMC Corporation with contract (No. 05-07)
文摘The servo system actuated by oscillating pneumatic cylinder for X-Y plate is a multi-variable nonlinearcontrol system.Its mathematical model is established,and nonlinear factors are analyzed.Due to the existenceof deadlock zone and the small damp of the pneumatic oscillating cylinder,it is likely to result inovershoot,and there is also certain steady-state error,so online modifying of proportion-integration-differentiation(PID) parameters is needed so as to achieve better control performance.Meanwhile considering thestability demand for long-term run,a fuzzy adaptive PID controller is designed.The result of hardware-inloop(HIL) test and real-time control experiment shows that the adaptive PID controller has desirable selfadaptabilityand robustness to external disturbance and to change of system parameters,and its control performanceis better than that of traditional PID controllers.
