Abstract：The principle and virtues of the concept of inductive pulsed plasma thruster (IPPT) are introduced based on the interpretation of extensive literatures and expertise from experience. The stateoftheart for IPPT attained by oversea and domestic researchers are concluded by reviewing the institutes and programs, components and system integration experiments, modeling and numerical simulation. The technical challenges are identified and the approaches are proposed.    

Abstract：Aiming at the problem of Mars entry guidance, considering the constrained control and uncertainty of Mars atmosphere and detector’s parameters, the optimal robust guidance method with constrained control is proposed. Considering the parameter uncertainty of system, the optimal index of uncertain nonlinear system is transformed into an index of the nominal system. In consideration of the constrained control, a saturated function is introduced, and the guidance problem is transformed into solving the modified HJB equation. The neural network has the ability of approximation. The proposed HJB equation is solved with the neural network because the HJB equation is partial differential equation and there is a great deal of difficulty in solving it. The guidance method makes sure that the uncertain nonlinear systems have an optimal upper bound of performance index and that the method has robustness. Then, the method is applied to the Mars entry guidance. The simulation results show that the terminal conditions of Mars entry phase can be well guaranteed despite uncertainty of system, and that the control is in the constrained range, so the method is effective. Keywords： uncertain system; constrained control；HJB equation； Mars entry guidance

Abstract：Venus detection requires ultralongdistance transmission at lowbitrate, so Venus spacecraft need to keep digital antennas pointing to the earth. Compared with the earth spacecraft, Venus spacecraft are closer to the sun. So the fixed radiator is needed to maintain the temperature inside the spacecraft. Based on the antenna irregularly placed on the spacecraft, a design is provided to ensure that the data is transferred from Venus to the earth and that the heat dissipation surface is maintained away from the sun. Unlike other Venus spacecraft such as Venus Express and AKATSUKI equipped with two or more antennas to transmit data, this design is aimed to reduce the number of digital antennas to only one, meanwhile the two fixed plane is designed as a cooling surface. Two detailed strategies are also provided  to drive the attitude maneuver to ensure that the digital antenna always points to the earth while switching the cooling surface in a particular node.    

Abstract：A method for solid propellant microthruster array consumption estimation is proposed in this paper for attitude control of microsatellite in orbit entry stage. The microthruster unit call rule and attitude control laws of velocity damping and attitude capture are designed. Considering the uncertainty of each microthruster unit impulse output, we use the interval number to represent the microthruster unit torque output and then estimate the consumption of the microthruster unit for attitude control with interval algorithm. By means of the irrelevance of interval number, the interval computation process is improved, and the interval expansion induced by the interval integral is reduced. Numerical simulations demonstrate that the estimation method is not dependent on the probability characteristic of the microthruster unit torque output.  

Abstract：A method for integrated design of fault diagnosis and fault tolerant is proposed for a class of sensor fault. First, the sensor effectiveness factor and the controller gain are taken as a whole, so we can construct a combined output feedback controller via the theory of regional pole assignment. Then an optimal estimation method is given to estimate the sensor effectiveness factor in real time, which can be used to solve the controller gain. The well designed combined controller can ensure the system achieving a good performance while the realtime estimated sensor effectiveness factor can ensure the control is realtime and rapid. Finally, numerical simulations demonstrate the effectiveness of the proposed approach.    

  Abstract：To design the obstacle avoidance planning method for variable geometry truss (VGT), an equivalent manipulator model is proposed. The redundant problem in the forward kinematics of single VGT is analyzed and a truss geometry is obtained with the only solution if each varied link is specified. The obstacle avoidance planning for the equivalent model is designed using genetic algorithm and optimized variables of equivalent model are obtained. Accordingly, the length of each varied link is obtained and the geometry of VGT could also be computed with the forward kinematics. In the optimized geometry of VGT, distances among middle points of fixed links remain constant and angle differences among VGT modules are small. The effectiveness of the proposed algorithm is shown via numerical simulations.  

Abstract：With the development of the aerospace technology, the demand for small satellites is increasing gradually. The agility of small satellites is a critical parameter, in the viewpoint of application field expansion and mission return maximization. The control moment gyroscope (CMG) exhibits better performances in terms of torquepower and masstorque characteristics, which make it a key actuator for agile and precise attitude control. In this paper, a miniature CMG is developed for small satellites with 0.1 N·m·s angular momentum. The performance and the environmental tests of the CMG are discussed, which demonstrate that the requirement of small satellites attitude control is perfectly met.  

Abstract：9 degree of freedom motion simulator (9DOFMS) is the key equipment for calibration of cameratype rendezvous & docking sensor (CRDS) in spacecraft rendezvous and docking guidance navigation and control (GNC) subsystem, and it must be with high relative position precision. To meet this demand, the components of errors impacting this system’s integral indexes are analyzed systemically in this paper. At first, the relationship and interactions among the components of system errors are analyzed. Then the error model is built. By decomposing and redistributing the systematic precision index, 9DOFMS design fulfills the precision requirements.

Abstract：Flight control system is a very important part of the spacecraft onboard systems. Good design for testability (DFT) of flight control system can improve the system reliability and security, and reduce manufacturing cost. The methods of DFT of flight control system and multisignal flow graph model are introduced in detail. Then, based on Byzantine fault tolerant architecture, the verification of DFT of flight control system is demonstrated via software TMAS (testability modeling and analysis system).  

Abstract：Based on COMSOL soft, a method is established to model the discharge processing in Hall effect thruster (HET) channel. The drift diffusion of electron and ion of the plasma is taken as the kernel of the model. Combined with the electromagnetic field, flow and impact reactions inside plasma， the characteristics of HET and distribution of parameters in the channel can be evaluated with proper selection of equations, boundary conditions and solvers. Compared with the results in theory, numerical simulation results demonstrate the effectiveness of the proposed approach， and then the magnetic field optimization design is applied.  

Abstract：As a new work mode of agile satellite, dynamicimaging attitude maneuver mode has such characteristics as complicated maneuver, real time change of attitude and higher performance index. It is difficult to validate the maneuver mode in the existing test environment using current test method. An integration test scheme is designed to solve this problem. The design of test environment contains master control unit, dynamic model and data analysis system. The automatic test, target attitude calculation and visualization of test system are realized. Typical test conditions and performance test are included in the research of test method. The results show that the designed scheme can verify the correctness of function and the validity of performance index, which provides ideas for integration test of control system.  

  Abstract：A ground simulation and testing system is designed for the testing task of a 7DOFs space robot on a satellite. The designed system has two functions. First, it can be used for halfphysical simulations with the space robot simulator, in which way the electronic interfaces of the controller and the functions of the control software can be tested. Besides, it can also be used for fullphysical tests to verify the onorbit tasks, and a hanging equipment is utilized to deload the gravity of the space robot. Using the proposed testing system, the ground testing and verification tasks of the space robot are finished. By now, the satellite is launched, and the space robot finishes its onorbit experiments successfully. The proposed ground simulation and testing system can also be applied for testing other space robots on ground.