| With the rapid development of micro/nano satellite technology,the demands of civil space and space defense missions such as space operation,rendezvous,constellation deployment,deep space exploration,staring imaging,deorbit in the end of lifetime and disposal of space debris are increasing day by day.Attitude and orbit maneuver will provide good technical support for micro/nano satellite to perform complex space missions.However,how to achieve attitude and orbit maneuver of micro/nano satellite under the restriction of weight,capacity,energy and cost will be a challenge.In this paper,the agile maneuvering micro/nano satellite is taken as the research object,and the attitude control strategies of attitude and orbit maneuvering micro/nano satellite are proposed respectively,and the existing problems are deeply studied.The main research works include:1.In order to meet the requirements of attitude maneuver for the complex space missions in LEO or MEO orbits,an attitude maneuver control strategy based on differential evolutionary(DE)path planning algorithm and non-singular finite time sliding mode controller was proposed.At first,the DE path planning algorithm with three stages(acceleration,constant speed and deceleration)based on Beta distribution was designed.Then it is used to optimize the time allocation of three stages to reduce the maximum angular velocity in attitude maneuver process as much as possible and improve the stability of the control system.In addition,the momentum wheel’s saturation problem and magnetorquer’s limited ability will increase the difficulty of the large angle maneuver.But the DE path planning algorithm can greatly improve the anti-saturation ability of the momentum wheel,then,it is guaranteed that the micro/nano satellite can realize attitude maneuver only by the momentum wheels and the magnetic torquer.Furthermore,an attitude maneuvering control algorithm for a micro/nano satellite based on a nonsingular finite-time sliding mode controller was proposed.The control algorithm can ensure the accuracy of attitude tracking during attitude maneuvering,and the design of sigm function can reduce chattering phenomenon in the sliding mode control process,so as to further improve the stability of the system.The hardware-in-loop simulation results revealed that the attitude control precision is 0.5°,the attitude maneuver ability is 2°/s.2.In order to meet the requirements of fast attitude maneuvering micro/nano satellite for complex mission of HEO or deep space,a fast attitude maneuver control strategy based on segmented sliding mode controller and joint actuator torque distribution strategy was proposed.First of all,a segmented sliding mode controller was designed which can guarantee rapid speed of convergence under different attitude states,and the hyperbolic tangent function was used in the exponential reaching law of the sliding mode controller to make the controller have stronger anti-saturation ability.In addition,a torque distribution strategy based on zero momentum wheel and micro thruster was designed.Then,the micro thruster provides the part of control torque and the dumping torque of momentum wheels,and the momentum wheel provides high accuracy control torque.The hardware-in-loop simulation results revealed that the attitude maneuver ability is 4°/s.3.In order to meet the requirement of high precision attitude stability control during orbit maneuver with micro-propulsion,a zero-momentum attitude control strategy based on integral model predictive control(MPC)was proposed.At first,the model predictive controller and the integral model predictive controller were designed based on the discrete state space model,then the controllers were analyzed and simulated,such as the unconstrained MPC,the sliding mode control,the PD control,the integral MPC.Then,the advantages and disadvantages of different control algorithms are summarized and compared from the aspects of chattering,time delay,steady-state error and code complexity,and the integral model predictive controller is finally selected by considering various engineering factors.Finally,an attitude control strategy of orbital maneuvering micro-nano satellite that micro-thrusters provide orbit maneuvering thrust was designed,and the magnetorquer can produce the disturbance torque compensation,and the momentum wheel provides high accuracy control torque.The hardware-in-loop simulation results revealed that the integral MPC algorithm can effectively offset the steady state error caused by the eccentric interference of micro-propeller,and in the process of orbital maneuver,the attitude control precision is 1° and the attitude stability is 0.2°/s.4.In order to meet the requirement of high precision attitude stability control during orbit maneuver with large thrust,a zero-momentum attitude control strategy based on disturbance observer and piece wise affine(PWA)MPC was proposed.At first,a disturbance observer was designed to estimate the eccentric torque of the solid thruster with large thrust,and the micro-thruster can compensate the eccentric torque in real time by the disturbance observer.Then,the PWA model was derived based on the state space model,and the PWA MPC strategy was designed,which can effectively solve the problem of strong nonlinearity and steady-state errors.The hardware-in-loop simulation results revealed that the attitude control precision is 1.5° during the period of orbital maneuver,and the attitude stability is 0.4°/s.5.In order to further verify the control strategy proposed in this paper,an attitude control system of agile maneuvering micro/nano satellite and real-time hardware-in-loop simulation platform was built.Firstly,the various components of the attitude control system was designed and tested,including ADCS,zero momentum wheel,magnetic torquer and magnetometer etc.Then,a semi-physical simulation platform based on Matlab/Simulink rapid prototyping and Vxworks real-time operating system was set up.At the same time,the attitude control system of agile maneuvering micro-nano satellite and the control strategy studied in this paper are verified by semi-physical simulation.Finally,the attitude control performance of agile maneuvering micro-nano satellite was further verified by the ‘Tianyuan-I’ mission.In this paper,the agile maneuvering micro/nano satellite attitude control in four different mission scenarios was studied in-depth,which expands the ability of attitude control of micro-nano satellites to perform complex space tasks and provides technical support for the practical application of the micro/nano satellite in the fields of civil aerospace. |
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