The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC con...The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC content on friction coefficient and wear volume of the composites were studied.The hardness and scratch resistance of the composites are greatly improved by the addition of WC.The penetrate depth and residual depth increase near-linearly with normal load increasing and decrease with WC content increasing,and the friction coefficient of the composites also shows the same variation trend.The valid material removal mechanism is found to transform from micro-plowing to micro-cutting as the normal load increases.展开更多
The problem of linear systems subject to actuator faults（outage,loss of efectiveness and stuck）,parameter uncertainties and external disturbances is considered.An active fault compensation control law is designed wh...The problem of linear systems subject to actuator faults（outage,loss of efectiveness and stuck）,parameter uncertainties and external disturbances is considered.An active fault compensation control law is designed which utilizes compensation in such a way that uncertainties,disturbances and the occurrence of actuator faults are account for.The main idea is designing a robust adaptive output feedback controller by automatically compensating the fault dynamics to render the close-loop stability.According to the information from the adaptive mechanism,the updating control law is derived such that all the parameters of the unknown input signal are bounded.Furthermore,a disturbance decoupled fault reconstruction scheme is presented to evaluate the severity of the fault and to indicate how fault accommodation should be implemented.The advantage of fault compensation is that the dynamics caused by faults can be accommodated online.The proposed design method is illustrated on a rocket fairing structural-acoustic model.展开更多
This paper proposes a relative attitude and distance estimation algorithm based on pairwise range measurements between vehicles as well as inertial measurement of each platform. The solution of Wahba＇s Problem is int...This paper proposes a relative attitude and distance estimation algorithm based on pairwise range measurements between vehicles as well as inertial measurement of each platform. The solution of Wahba＇s Problem is introduced to compute the relative attitude between multi-platforms with the sampled pairwise ranges, in which the relative distance estimation is derived and the estimation error distributions are analyzed. An extended Kalman filter is designed to fuse the estimated attitude and distance with the inertial measurement of each platform. The relative poses between platforms are determined without any external aided measurement. To show this novelty, a real testbed is constructed by our research lab. And the experiment results are positive.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 21175157 and 21375151)
文摘The WC particle-reinforced copper matrix composites with WC content in the range of 5 vol%-30 vol%were prepared and investigated by micro-scratch tests under the loads of 1-4 N.The influences of normal load and WC content on friction coefficient and wear volume of the composites were studied.The hardness and scratch resistance of the composites are greatly improved by the addition of WC.The penetrate depth and residual depth increase near-linearly with normal load increasing and decrease with WC content increasing,and the friction coefficient of the composites also shows the same variation trend.The valid material removal mechanism is found to transform from micro-plowing to micro-cutting as the normal load increases.
基金supported by National Natural Science Foundation of China (No.61174053)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20100172110023
文摘The problem of linear systems subject to actuator faults（outage,loss of efectiveness and stuck）,parameter uncertainties and external disturbances is considered.An active fault compensation control law is designed which utilizes compensation in such a way that uncertainties,disturbances and the occurrence of actuator faults are account for.The main idea is designing a robust adaptive output feedback controller by automatically compensating the fault dynamics to render the close-loop stability.According to the information from the adaptive mechanism,the updating control law is derived such that all the parameters of the unknown input signal are bounded.Furthermore,a disturbance decoupled fault reconstruction scheme is presented to evaluate the severity of the fault and to indicate how fault accommodation should be implemented.The advantage of fault compensation is that the dynamics caused by faults can be accommodated online.The proposed design method is illustrated on a rocket fairing structural-acoustic model.
基金This work was supported in part by the Major State Basic Research Development Program of China （No. 2014CB845303）, the National Natural Science Foundation （NNSF） of China （No. 61527810） and the Science and Technology Planning Project of Guangdong, China （No. 2013B020200006）.
文摘This paper proposes a relative attitude and distance estimation algorithm based on pairwise range measurements between vehicles as well as inertial measurement of each platform. The solution of Wahba＇s Problem is introduced to compute the relative attitude between multi-platforms with the sampled pairwise ranges, in which the relative distance estimation is derived and the estimation error distributions are analyzed. An extended Kalman filter is designed to fuse the estimated attitude and distance with the inertial measurement of each platform. The relative poses between platforms are determined without any external aided measurement. To show this novelty, a real testbed is constructed by our research lab. And the experiment results are positive.
