Game Theoretic Approach to Post-Docked Satellite Control

This paper studies the interaction between two satellites after docking. In order to maintain the docked state with uncertainty in the motion of the target vehicle, a game theoretic controller with Stackelberg strategy to minimize the interaction between the satellites is considered. The small perturbation approximation leads to LQ differential game scheme, which is validated to address the docking interactions between a service vehicle and a target vehicle. The open-loop solution are compared with Nash strategy, and it is shown that less control efforts are obtained with Stackelberg strategy

Simulation of spacecraft attitude dynamics using TREETOPS and model-specific computer Codes

The simulation of spacecraft attitude dynamics and control using the generic, multi-body code called TREETOPS and other codes written especially to simulate particular systems is discussed. Differences in the methods used to derive equations of motion--Kane's method for TREETOPS and the Lagrangian and Newton-Euler methods, respectively, for the other two codes--are considered. Simulation results from the TREETOPS code are compared with those from the other two codes for two example systems. One system is a chain of rigid bodies; the other consists of two rigid bodies attached to a flexible base body. Since the computer codes were developed independently, consistent results serve as a verification of the correctness of all the programs. Differences in the results are discussed. Results for the two-rigid-body, one-flexible-body system are useful also as information on multi-body, flexible, pointing payload dynamics

Functional/thermal verification and validation of an S-band radio for the nanosatellites

© 2018 COSPAR An S-band radio designed with commercial-grade components for the nanosatellites is functionally and thermally characterized for quiet transmission. The QPSK modulation impairments are minor over −20 °C to +50 °C at 24, 26, 28 and 30 dBm RF levels. The channel response is linear in error vector magnitude, frequency, phase, amplitude and IQ errors. On the average, the stability of amplifier bias and nonlinearity gives −22 dBc maximum upper/lower adjacent channel power and 1.27 MHz occupied channel bandwidth. The acceptable level test results provide good confidence toward robust space-to-earth transmission in variable solar weather at low earth orbital altitudes

Rapid, automated, test, verification and validation for the CubeSats

Bringing up of a small-scale mission assurance and engineering workflow is described. The experiences learned in the ZACUBE-1 mission prompted the development of an automated systems engineering platform leadingto conformity in system design, test, and verification. The platform implements the methodology of systems engineering by coordinating diverse elements of the lifecycle and by incorporating the tools involved. The phase B/C activities of system modelling, simulations, prototyping, and design may be unified to a compounding effect and raising the level of the system view. The Verification and Validation (V&V) is achieved by integrating a test and measurement facility to the platform. With the platform, we accomplish rapid electrical and functional test and verification of the CubeSat subsystems and thermal validation in 20 °C to +50 °C cycle. The platform is automated by an application software which executes functional and thermal environment tests and provides support for requirements flow, system definition, embedded development, and simulations by integrating real-time target hardware. The platform is exploited in validating an S-band communications subsystem while economizing time and obtaining valuable insight into transmission performance under thermal loading