A new non-decoupling three-dimensional guidance law is proposed for bank-to-turn （BTT） missiles with the motion coupling problem. In this method, the different geometry is taken for theoretically modeling on B-IT mi...A new non-decoupling three-dimensional guidance law is proposed for bank-to-turn （BTT） missiles with the motion coupling problem. In this method, the different geometry is taken for theoretically modeling on B-IT missiles＇ motion within the threedimensional style without information loss, and meanwhile, Liegroup is utilized to describe the line-of-sight （LOS） azimuth when the terminal angular constraints are considered. Under these cir- cumstances, a guidance kinematics model is established based on differential geometry. Then, corresponding to no terminal angular constraint and terminal angular constraints, guidance laws are re- spectively designed by using proportional control and generalized proportional-derivative （PD） control in SO（3） group. Eventually, simulation results validate that this developed method can effectively avoid the complexity of pure Lie-group method and the information loss of the traditional decoupling method as well.展开更多
It is comment that unmanned aerial vehicles （UAVs） have limitation on information cap- turing in reality applications. Therefore, online method of motion planning is necessary for such UA- Vs. Gyroscopic force （GF...It is comment that unmanned aerial vehicles （UAVs） have limitation on information cap- turing in reality applications. Therefore, online method of motion planning is necessary for such UA- Vs. Gyroscopic force （GF） is used for obstacle avoidance as an online method. However, classical GF has shortcoming in generating orbit for UAV with high velocity because the GF results in a time- varying turning radius. Modified gyroscopic force （MGF） given by function of velocity can overcome this shortcoming and help get a more practical control law for avoidance. MGF can also be used to implement the guidance of UAV by designing particular active conditions. Interactions in forms of stress function and damping force are introduced so that an UAV group can have coordinated motion. By combining controls of MGF and interactions, motion planning of UAV group in obstacle environ- ment can be implemented.展开更多
Although the channel-decoupling assumption is often used in design of three-dimensional guidance laws, it loses its rationality for aircrafts with strong kinematics coupling because body rotation arises. To overcome t...Although the channel-decoupling assumption is often used in design of three-dimensional guidance laws, it loses its rationality for aircrafts with strong kinematics coupling because body rotation arises. To overcome this trouble, a novel guiding method was proposed based on Lie-group. After a model of 3D guidance is formulated using vectors, the precision guidance with ending angular constraints can be transformed into a problem involving the relation between directional angles and rotational angular velocities of certain vectors. When the guidance model is imposed a SO(3)-based description, a novel 3D sliding mode guidance law with ending angular constraints can be developed via Lie-group control method and variable structure control theory. Finally, the feasibility and performance of the guidance law were shown by simulating the examples.展开更多
"We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initi..."We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initiatives and activities are delivering positive results,and we are able to take advantage of the growth momentum and opportunities in our end markets.Consequently,we are in a position to increase our full-year expectations for the second time this year."展开更多
This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two p...This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two points of view pedagogic and psycholinguistic, which is followed by a brief guideline for organizing group work in class.展开更多
The present paper reports on a small-scale project that investigates two main questions： （1） whether EFL （English as a Foreign Language） learners prefer working in pairs or small groups; and （2） what factors th...The present paper reports on a small-scale project that investigates two main questions： （1） whether EFL （English as a Foreign Language） learners prefer working in pairs or small groups; and （2） what factors they take into consideration when they are free to choose their partners in pair work activities. To investigate the research questions, a questionnaire was developed and distributed among 96 Iranian intermediate EFL students who participated in the study on a voluntary basis. The findings showed that 45% of the participants preferred pair work, 26% preferred group work, and 29% reported it made no difference to them. The results also indicated that learners select their partners based on four factors： age, proficiency, familiarity and language learning motivation. Gender and popularity with the whole class were among the factors that the participants did not pay attention to when opting for a partner.展开更多
基金supported by the National University of Defense Technology Innovation Support Project for Outstanding Graduate Student(B100303)
文摘A new non-decoupling three-dimensional guidance law is proposed for bank-to-turn （BTT） missiles with the motion coupling problem. In this method, the different geometry is taken for theoretically modeling on B-IT missiles＇ motion within the threedimensional style without information loss, and meanwhile, Liegroup is utilized to describe the line-of-sight （LOS） azimuth when the terminal angular constraints are considered. Under these cir- cumstances, a guidance kinematics model is established based on differential geometry. Then, corresponding to no terminal angular constraint and terminal angular constraints, guidance laws are re- spectively designed by using proportional control and generalized proportional-derivative （PD） control in SO（3） group. Eventually, simulation results validate that this developed method can effectively avoid the complexity of pure Lie-group method and the information loss of the traditional decoupling method as well.
基金Supported by the National Natural Science Foundation of China(61350010)
文摘It is comment that unmanned aerial vehicles （UAVs） have limitation on information cap- turing in reality applications. Therefore, online method of motion planning is necessary for such UA- Vs. Gyroscopic force （GF） is used for obstacle avoidance as an online method. However, classical GF has shortcoming in generating orbit for UAV with high velocity because the GF results in a time- varying turning radius. Modified gyroscopic force （MGF） given by function of velocity can overcome this shortcoming and help get a more practical control law for avoidance. MGF can also be used to implement the guidance of UAV by designing particular active conditions. Interactions in forms of stress function and damping force are introduced so that an UAV group can have coordinated motion. By combining controls of MGF and interactions, motion planning of UAV group in obstacle environ- ment can be implemented.
基金Sponsored by the National Natural Science Foundation of China (60374006)
文摘Although the channel-decoupling assumption is often used in design of three-dimensional guidance laws, it loses its rationality for aircrafts with strong kinematics coupling because body rotation arises. To overcome this trouble, a novel guiding method was proposed based on Lie-group. After a model of 3D guidance is formulated using vectors, the precision guidance with ending angular constraints can be transformed into a problem involving the relation between directional angles and rotational angular velocities of certain vectors. When the guidance model is imposed a SO(3)-based description, a novel 3D sliding mode guidance law with ending angular constraints can be developed via Lie-group control method and variable structure control theory. Finally, the feasibility and performance of the guidance law were shown by simulating the examples.
文摘"We are pleased to announce another quarter of profitable growth,"said Dr.Roland Fischer,CEO of Oerlikon Group."Our positive performance confirms that our strategy addresses attractive markets,our initiatives and activities are delivering positive results,and we are able to take advantage of the growth momentum and opportunities in our end markets.Consequently,we are in a position to increase our full-year expectations for the second time this year."
文摘This paper is committed to exploring the importance of learner learner interaction for language learning. It starts with a discussion of the roles that learner learner interaction plays in language learning from two points of view pedagogic and psycholinguistic, which is followed by a brief guideline for organizing group work in class.
文摘The present paper reports on a small-scale project that investigates two main questions： （1） whether EFL （English as a Foreign Language） learners prefer working in pairs or small groups; and （2） what factors they take into consideration when they are free to choose their partners in pair work activities. To investigate the research questions, a questionnaire was developed and distributed among 96 Iranian intermediate EFL students who participated in the study on a voluntary basis. The findings showed that 45% of the participants preferred pair work, 26% preferred group work, and 29% reported it made no difference to them. The results also indicated that learners select their partners based on four factors： age, proficiency, familiarity and language learning motivation. Gender and popularity with the whole class were among the factors that the participants did not pay attention to when opting for a partner.
