An interrupt based approach for complete automation of spacecraft checkout operations in a multi tasked environment

This paper aims to bring out the interrupt driven approach, taken for the design of checkout software in a completely automated environment. The Checkout Software is used for the complete automation of spacecraft checkout operations during Integrated Spacecraft Testing (IST). The checkout operations carried out for spacecraft testing include acquisition of multiple chains of telemetry in real time, processing, display, analysis and archival of parameters; Telecommand generation and monitoring; command, control and monitoring of checkout equipments. In order to build a system which can automate the checkout operations with a closed loop approach, a single point command and control is required. The checkout operation automation suite has a multitude of software packages, each dedicated for a specific functionality, executing in parallel. Some of these tasks may require commanding the spacecraft as part of its execution. The Interrupt Handler based design for the checkout software ensures that there is a single point interface for commanding the spacecraft, by sequencing the checkout operations based on their priority, thereby, providing a multitasked environment for faster Spacecraft testing. This Interrupt Handler, acts as a core module in scheduling the checkout operations, detecting events, notifying the test engineer and handling anomalous conditions in an intelligent manner. This paper covers the interrupt handler design used for automated operation of the checkout software, its interface with other packages in the automation software suite, the priority based scheduling mechanism used for servicing the interrupts and the generic approach taken for absorbing new interrupt requirements based on expertise for building a robust system commanding the spacecraft to validate its behaviour; in a controlled environment without human intervention.