| The space station maneuvers by large angle when implementing missions such as rendezvous and docking. Aiming to the China’s space station project, this dissertation mainly investigated the path planning and control of Zero Propellant Maneuver(ZPM), which utilizes the Control Moment Gyroscopes(CMGs), and extended the study slightly with thrusters considered as well. The main results achieved are summarized as follows.The optimal maneuver paths for single objective are investigated. 1) The momentum-optimal, time-optimal and energy-optimal paths of ZPM, without considering the gimbal motion of CMGs, are planned. It is shown that the typical ZPM momentum-optimal path and the time-optimal path possess the same characteristic, and they are singular, and that generally the energy-optimal path saves significant energy while maintaining a smooth control profile. 2) The integrated path of ZPM considering the gimbal motion of Single Gimbal CMGs(SGCMGs) is planned for a good singularity performance. The path may be tracked during the maneuver to improve the maneuver performance. 3) A new large angle space station attitude maneuver concept, CMGs Aided Maneuver(CMGs AM), is proposed, which employs both the CMGs and the thruster as the actuators. The fuel-optimal CMGs AM path is planned. The CMGs AM effectively synthesizes the ZPM and thruster maneuver technique, with less maneuver time and less fuel consumption in contrast to the corresponding counterpart respectively.The multi-objective path planning problem for ZPM without considering the CMGs’ gimbal motion is studied. 1) The ZPM Multi-objective Optimization Problem(MOP) is formulated with three objectives considered, i.e., the CMGs peak momentum, maneuver time and maneuver energy. A sensitivity analysis approach is proposed. This method allows the tradeoffs between the performance indices to be investigated by utilizing the property of boundary conditions and Karush-Kuhn-Tucker(KKT) multiplier, avoiding the solving of the optimal control problems. 2) The tradeoffs regarding the CMGs peak momentum, maneuver time and maneuver energy in the ZPM MOP are investigated. It is proved that the minimum CMGs peak momentum decreases as the maneuver time increases, and the minimum maneuver energy decreases if a larger momentum is available from the CMGs. 3) The analysis results are verified and complemented by the numerical computations. The ZPM MOP is synthesized and a multi-objective optimal soluton is computed.The rapid planning for the space station attitude maneuver path is studied. 1) A new trajectory optimization method, the Rapid Path Planning(RRP) method, which effectively synthesizes the all-variable parameterization method and the part-variable parameterization method, is proposed to accomplish the rapid planning of paths with high performance. 2) The path planning utilizing the differential flatness property of model is studied. The equivalence between the state transformation singularity and control transformation singularity is proved to the feedback linearizable Multi-Input Multi-Output(MIMO) affine system. For the case with only earth gravity gradient environmental torque considered, four sets of flat output candidates, which stress on different types of maneuvers, are examined. It is shown that only large angle yaw maneuver is achievable. The essentially singular attitudes where no outputs could linearize the model are presented. It is shown that the large angle pitch or roll maneuver is easy to encounter singularity no matter what output functions are constructed. For the case with aerodynamic environmental torque considered as well, the singularity condition under a simple aerodynamic torque model is presented. It shows that the large angle yaw maneuver may encounter singularity. 3) A practical ZPM path planning algorithm is developed. Its essence is a path replanning method based on the path with CMGs momentum deviation, correcting the attitude profiles to realize the feasibility. 4) A free interval local RPP method is developed to achieve the rapid planning of CMGs AM path with good fuel objective.The control of ZPM is studied and the on-line planning steering law for SGCMGs is designed. 1) A new robust tracking control method is proposed. It adjusts the reference trajectory on-line to attenuate or even eliminate the disturbance effects arising from initial state errors, environmental torque modeling error and inertia error. The simulation results prove its effectiveness. 2) The Model Predictive Control(MPC) for ZPM, based on the RPP method, is investigated. It is shown the flexibility of ZPM is improved using MPC. 3) The predictive/tracking control method is studied for the synthesis of reliability, flexibility and optimality. The approach is verified through an attitude recovery maneuver example for the tumbling space station. 4) A novel SGCMGs on-line planning steering law is designed. The on-line gimbal path planning is achieved with a cascaded planning scheme. Simulation results show that using the proposed steering law, the gimbal motion profiles are much smoother and the performance index is greatly improved compared with the classical steering law.In this dissertation, the proposed RPP method, the robust tracking control method and the SGCMGs on-line planning steering law enrich the method system of the corresponding field. The sensitivity analysis for the tradeoffs among objectives in MOP and the singularity equivalence theorem for MIMO affine system are of some theoretical significance. The integrated ZPM considering CMGs’ gimbal motion and the CMGs AM is of certain practical value. The studies expand the large angle attitude maneuver technique system of space station. They are of reference value to save the fuel and enhance the performance of the large angle attitude maneuver mission for the future China’s space station. |
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