This paper mainly studies the comparison of the global vehicle models and the effects of the inertial parameters due to the center of gravity(CG)positions when we consider that the vehicle has only one CG.This paper p...This paper mainly studies the comparison of the global vehicle models and the effects of the inertial parameters due to the center of gravity(CG)positions when we consider that the vehicle has only one CG.This paper proposes a new nonlinear model vehicle model which considers both unsprung mass and sprung mass CG.The CG positions and inertial parameters effects are analyzed in terms of the published vehicle dynamics models.To this end,two 14 degree-of-freedom(DOF)vehicle models are developed and compared to investigate the vehicle dynamics responses due to the different CG height and inertial parameters concepts.The proposed models describe simultaneously the vehicle motion in longitudinal,lateral and vertical directions as well as roll,pitch and yaw of the vehicle about corresponding axis.The passive and active moments and the forces acting on the vehicle are also described and they are considered as a direct consequence of acceleration,braking and steering maneuvers.The proposed model M1 takes both the CG of sprung mass,unsprung mass and total vehicle mass into account.The second model M2 assumes that the vehicle is one solid body which has a single CG as reported in majority of literature.The two vehicle models are compared and analyzed to evaluate vehicle ride and handling dynamic responses under braking/acceleration and cornering maneuvers.Simulation results show that the proposed model M1 could offer analytically some abilities and driving performances,as well as improved roll and pitch in a very flexible manner compared to the second model M2.展开更多
The first pictures of the earth were taken from a balloon in the mid-19^(th) century and thus started‘earth observation’.Aerial missions in the 20^(th) century enabled the build-up of outstanding photographic librar...The first pictures of the earth were taken from a balloon in the mid-19^(th) century and thus started‘earth observation’.Aerial missions in the 20^(th) century enabled the build-up of outstanding photographic libraries and then with Landsat-1,the first civilian satellite launched in 1972,digital images of the earth became an operational reality.The main roles of earth observation have become scientific,economic and strategic,and the role of synthetic aperture radar(SAR)is significant in this overall framework.Radar image exploitation has matured and several operational programs regularly use SAR data for input and numerous applications are being further developed.The technological development of interferometry and polarimetry has helped further develop these radar based applications.This paper highlights this role through a description of actual applications and projects,and concludes with a discussion of some challenges for which SAR systems may provide significant assistance.展开更多
The attitude estimation has been viewed as one of the key technologies in space research works.It is used to convert the sensor measurement data to an estimated attitude using different estimation methods.However,beca...The attitude estimation has been viewed as one of the key technologies in space research works.It is used to convert the sensor measurement data to an estimated attitude using different estimation methods.However,because of the difficulty of space missions and tight computational budget most estimators suffer from height consuming which render them unsuitable.In this paper,the latter problem is addressed based on a new configuration for on board attitude determination and control system(ADCS)implementation based on in-Orbit Flight Data.The proposed configuration is a combination ofαβfilter and Triad algorithm using the concept of sensor fusion with Magnetometer and Sun-sensor,it is applied for linearized satellite model,when the satellite has small deviations in the attitude angles(in imaging mission),and its simulation results are compared to the in-orbit attitude of Alsat-1which was estimated using small Euler angles based the Extended Kalman Filter(EKF)implemented on board Alsat-1.The primary goal of the addressed problem is to perform a low computational budget and good accuracy in the same time.It found that the proposed configuration has acceptable performances and a reduced computational budget.Its simulation results are similar to the real results of Alsat-1,having an absolute error less than one degree.展开更多
文摘This paper mainly studies the comparison of the global vehicle models and the effects of the inertial parameters due to the center of gravity(CG)positions when we consider that the vehicle has only one CG.This paper proposes a new nonlinear model vehicle model which considers both unsprung mass and sprung mass CG.The CG positions and inertial parameters effects are analyzed in terms of the published vehicle dynamics models.To this end,two 14 degree-of-freedom(DOF)vehicle models are developed and compared to investigate the vehicle dynamics responses due to the different CG height and inertial parameters concepts.The proposed models describe simultaneously the vehicle motion in longitudinal,lateral and vertical directions as well as roll,pitch and yaw of the vehicle about corresponding axis.The passive and active moments and the forces acting on the vehicle are also described and they are considered as a direct consequence of acceleration,braking and steering maneuvers.The proposed model M1 takes both the CG of sprung mass,unsprung mass and total vehicle mass into account.The second model M2 assumes that the vehicle is one solid body which has a single CG as reported in majority of literature.The two vehicle models are compared and analyzed to evaluate vehicle ride and handling dynamic responses under braking/acceleration and cornering maneuvers.Simulation results show that the proposed model M1 could offer analytically some abilities and driving performances,as well as improved roll and pitch in a very flexible manner compared to the second model M2.
文摘The first pictures of the earth were taken from a balloon in the mid-19^(th) century and thus started‘earth observation’.Aerial missions in the 20^(th) century enabled the build-up of outstanding photographic libraries and then with Landsat-1,the first civilian satellite launched in 1972,digital images of the earth became an operational reality.The main roles of earth observation have become scientific,economic and strategic,and the role of synthetic aperture radar(SAR)is significant in this overall framework.Radar image exploitation has matured and several operational programs regularly use SAR data for input and numerous applications are being further developed.The technological development of interferometry and polarimetry has helped further develop these radar based applications.This paper highlights this role through a description of actual applications and projects,and concludes with a discussion of some challenges for which SAR systems may provide significant assistance.
文摘The attitude estimation has been viewed as one of the key technologies in space research works.It is used to convert the sensor measurement data to an estimated attitude using different estimation methods.However,because of the difficulty of space missions and tight computational budget most estimators suffer from height consuming which render them unsuitable.In this paper,the latter problem is addressed based on a new configuration for on board attitude determination and control system(ADCS)implementation based on in-Orbit Flight Data.The proposed configuration is a combination ofαβfilter and Triad algorithm using the concept of sensor fusion with Magnetometer and Sun-sensor,it is applied for linearized satellite model,when the satellite has small deviations in the attitude angles(in imaging mission),and its simulation results are compared to the in-orbit attitude of Alsat-1which was estimated using small Euler angles based the Extended Kalman Filter(EKF)implemented on board Alsat-1.The primary goal of the addressed problem is to perform a low computational budget and good accuracy in the same time.It found that the proposed configuration has acceptable performances and a reduced computational budget.Its simulation results are similar to the real results of Alsat-1,having an absolute error less than one degree.
