This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) b...This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.展开更多
This study investigates the aerodynamic characteristics of a low-Reynolds-number airfoil at high angles of attack(AoA)from 0°to 90°,focusing on their relevance for micro and unmanned aerial vehicle(MAV/UAV)a...This study investigates the aerodynamic characteristics of a low-Reynolds-number airfoil at high angles of attack(AoA)from 0°to 90°,focusing on their relevance for micro and unmanned aerial vehicle(MAV/UAV)applications.Simulations are conducted using the k-ωshear stress transport(SST)turbulence model using ANSYS Fluent software.Among the key findings is that the lift coefficient CL increases from 1.2981 at 0°AoA to a peak of 2.034 at 11°before decreasing to 1.51 at 90°,indicating initial lift improvement followed by a reduction due to potential flow separation or stall.The drag coefficient CD increases from 0.0222 at 0°AoA to a peak of 0.3572 at 12°,and then decreases to 0.0467 at 90°,indicating initially increasing turbulence and separation,followed by stabilization in the flow regime.The lift-to-drag ratio L/D reaches its maximum of 32.334 at 90°AoA,highlighting improved aerodynamic efficiency at higher AoAs despite increased drag.The skin friction coefficient Cf shows a maximum of 0.046918 at the leading edge at 30°AoA and 0.0394262 at the trailing edge at 90°,indicating critical points of frictional drag.Additionally,the turbulence viscosity ratio at the LE peaks at 0.5586 at 30°AoA and drops to 0.004 at 90°,while it increases at the trailing edge,reaching 0.0394262 at 90°,showing heightened turbulence effects at high AoAs.The present numerical study,however,determines the lift coefficient to be 2.00.This yields a maximum percentage variation of 11.5%compared with the value in the literature.These results provide a comprehensive overview of how high-AoA conditions impact aerodynamic performance,offering valuable insights for optimizing airfoil design and improving MAV/UAV efficiency.展开更多
基金Sponsored by the China Postdoctoral Science Foundation(Grant No.2013M540857)the Fundamental Research Funds for the Central Universities(Grant No.FRF-TP-14-019A1)
文摘This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.
文摘This study investigates the aerodynamic characteristics of a low-Reynolds-number airfoil at high angles of attack(AoA)from 0°to 90°,focusing on their relevance for micro and unmanned aerial vehicle(MAV/UAV)applications.Simulations are conducted using the k-ωshear stress transport(SST)turbulence model using ANSYS Fluent software.Among the key findings is that the lift coefficient CL increases from 1.2981 at 0°AoA to a peak of 2.034 at 11°before decreasing to 1.51 at 90°,indicating initial lift improvement followed by a reduction due to potential flow separation or stall.The drag coefficient CD increases from 0.0222 at 0°AoA to a peak of 0.3572 at 12°,and then decreases to 0.0467 at 90°,indicating initially increasing turbulence and separation,followed by stabilization in the flow regime.The lift-to-drag ratio L/D reaches its maximum of 32.334 at 90°AoA,highlighting improved aerodynamic efficiency at higher AoAs despite increased drag.The skin friction coefficient Cf shows a maximum of 0.046918 at the leading edge at 30°AoA and 0.0394262 at the trailing edge at 90°,indicating critical points of frictional drag.Additionally,the turbulence viscosity ratio at the LE peaks at 0.5586 at 30°AoA and drops to 0.004 at 90°,while it increases at the trailing edge,reaching 0.0394262 at 90°,showing heightened turbulence effects at high AoAs.The present numerical study,however,determines the lift coefficient to be 2.00.This yields a maximum percentage variation of 11.5%compared with the value in the literature.These results provide a comprehensive overview of how high-AoA conditions impact aerodynamic performance,offering valuable insights for optimizing airfoil design and improving MAV/UAV efficiency.
