9.4 Design Methodology
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spacecraft system were changed/added to meet user requirements. The onboard maintenance of OBDH subsystem was generally implemented through software design.
The software should be designed to be able to inject the program uploading blocks
and be commanded by ground to correct or replace a software module that had been
identified as faulty, change the flight procedure or operation parameters, and hang,
delete, activate, create process and etc.
Change or modification of operation parameters of flight software could be considered as the simplest on orbit maintenance of software. Some modifications, additions,
deletions, updates and even redefinitions of flight software are the means of on orbit
maintenance. Loading a new software module from ground station was implemented
in the original flight program by “screw up". It could modify the original sessions,
add and activate new session in order to modify the functions and operation manner
of OBDH software based on hardware status to overcome the difficulties encountered
during flight.
9.5 Testing and Verification
9.5.1 Simulation and Test Environment for OBDH Subsystem
The subsystem simulation test environment was designed to meet requirements of the
functional and performance testing of OBDH subsystem. The system was designed to
be used in test of OBDH subsystem, which could also support software debugging,
software confirmation and test, simulation verification of entire information flow,
fault diagnosis, onboard-ground interface test and joint test with other subsystems.
The test system was composed of the hardware platform and the software running
in devices to control and perform simulation test, which could improve automation
of test process. The composition of subsystem simulation and test environment is
shown in Fig. 9.8.
9.5.2 Content of Verification
The content of test and verification of the OBDH subsystem in all development phases
of the Chang’E-3 lunar lander included electrical performance test of devices, environmental test, software test, subsystem test, joint interface test with other subsystems, as well as electrical performance test, environment test and onboard-ground
interface test of the lunar lander.
Because of strict constraint of mass, OBDH subsystem devices of the Chang’E-3
lunar lander were designed with high integration, powerful function, many external
interfaces and complex interface between internal functional units. The reliability
329
spacecraft system were changed/added to meet user requirements. The onboard maintenance of OBDH subsystem was generally implemented through software design.
The software should be designed to be able to inject the program uploading blocks
and be commanded by ground to correct or replace a software module that had been
identified as faulty, change the flight procedure or operation parameters, and hang,
delete, activate, create process and etc.
Change or modification of operation parameters of flight software could be considered as the simplest on orbit maintenance of software. Some modifications, additions,
deletions, updates and even redefinitions of flight software are the means of on orbit
maintenance. Loading a new software module from ground station was implemented
in the original flight program by “screw up". It could modify the original sessions,
add and activate new session in order to modify the functions and operation manner
of OBDH software based on hardware status to overcome the difficulties encountered
during flight.
9.5 Testing and Verification
9.5.1 Simulation and Test Environment for OBDH Subsystem
The subsystem simulation test environment was designed to meet requirements of the
functional and performance testing of OBDH subsystem. The system was designed to
be used in test of OBDH subsystem, which could also support software debugging,
software confirmation and test, simulation verification of entire information flow,
fault diagnosis, onboard-ground interface test and joint test with other subsystems.
The test system was composed of the hardware platform and the software running
in devices to control and perform simulation test, which could improve automation
of test process. The composition of subsystem simulation and test environment is
shown in Fig. 9.8.
9.5.2 Content of Verification
The content of test and verification of the OBDH subsystem in all development phases
of the Chang’E-3 lunar lander included electrical performance test of devices, environmental test, software test, subsystem test, joint interface test with other subsystems, as well as electrical performance test, environment test and onboard-ground
interface test of the lunar lander.
Because of strict constraint of mass, OBDH subsystem devices of the Chang’E-3
lunar lander were designed with high integration, powerful function, many external
interfaces and complex interface between internal functional units. The reliability