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
In this work, a mixed Kalman/H-infinity filter is designed for the attitude estimation of a low Earth orbit microsatellite and theexternal disturbance torques acting on it. The state vector will be formed by satellite...In this work, a mixed Kalman/H-infinity filter is designed for the attitude estimation of a low Earth orbit microsatellite and theexternal disturbance torques acting on it. The state vector will be formed by satellite’s attitude along with angular rates andthe external disturbances. An improved external disturbance modeled as a random walk acting (slowly varying) around threeaxis attitude was proposed. This external disturbance is mainly generated by the aerodynamic torque, the residual magneticmoment and the gravity gradient torque. The satellite has only magnetometer on board as the attitude sensor. The proposedalgorithm is tested using simulated data for a microsatellite, and the results of this study are tested in different scenarios. Thefirst two scenarios are the cases with and without uncertainty in the satellite’s inertia. The last scenario is extensive MonteCarlo simulations with uniformly distributed initial conditions of the Euler angle and angular rate. The major purpose ofthis work is to demonstrate that we can estimate external disturbances and attitude dynamic parameters of a satellite usinga simple filter that combines the best features of Kalman and H∞ filters. The simulation results show that the attitude RMSerror is less than ±1 deg (acceptable accuracy). Also, Monte Carlo simulation gives good results of the proposed filter. Thislatter estimates the attitude with accuracy less than 0.8 deg, the rate order is 1 milli-deg/s and the external disturbances around1.5 μNm.展开更多
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.
文摘In this work, a mixed Kalman/H-infinity filter is designed for the attitude estimation of a low Earth orbit microsatellite and theexternal disturbance torques acting on it. The state vector will be formed by satellite’s attitude along with angular rates andthe external disturbances. An improved external disturbance modeled as a random walk acting (slowly varying) around threeaxis attitude was proposed. This external disturbance is mainly generated by the aerodynamic torque, the residual magneticmoment and the gravity gradient torque. The satellite has only magnetometer on board as the attitude sensor. The proposedalgorithm is tested using simulated data for a microsatellite, and the results of this study are tested in different scenarios. Thefirst two scenarios are the cases with and without uncertainty in the satellite’s inertia. The last scenario is extensive MonteCarlo simulations with uniformly distributed initial conditions of the Euler angle and angular rate. The major purpose ofthis work is to demonstrate that we can estimate external disturbances and attitude dynamic parameters of a satellite usinga simple filter that combines the best features of Kalman and H∞ filters. The simulation results show that the attitude RMSerror is less than ±1 deg (acceptable accuracy). Also, Monte Carlo simulation gives good results of the proposed filter. Thislatter estimates the attitude with accuracy less than 0.8 deg, the rate order is 1 milli-deg/s and the external disturbances around1.5 μNm.
