Session

Technical Session 7: Advanced Technologies I

Location

Utah State University, Logan, UT

Abstract

Satellites carry different payloads, but the basic design in hard- and software is generally similar for small satellites. For example, they all receive telecommands, distribute them and generate telemetry packets. Reusing existing components is desirable, especially with limited time and financial budgets. This is where the Corfu comes in, which we present in this work.

Corfu is a software framework for safety-critical on-board software. It follows a model-based approach. Developers formally define the structure of the software. The software design is app-centric, i.e. on-board software in Corfu is a composition of apps. Apps define a clear communication interface using a publish/-subscribe principle. This allows on-board software to connect apps among each other. Developers can use and connect apps in different on-board software and even on different missions. This encourages reusability.

Based on the information of software definition, Corfu applies two tasks: formal verification of the software structure and generation of source code. In the verification step, Corfu examines the timing properties across all apps that are included into the software. Having a formal definition that is used for both static analysis and code generation, makes in possible to identify structural problems early.

The generation process creates code that it can derive from the software specification. This includes communication handling, such as subscribing to topics, distributing telecommands and collecting telemetry. In addition, the generated code also covers thread handling. The result of the generation process is a collection of classes. Most of those classes are abstract, which include abstract methods that the developer fills with mission-specific code. Developers do this by inheriting from those abstract classes and overriding all the abstract methods by carrying out the desired behavior. Developers can focus on implementing the mission relevant code.

The software specification defines the communication interface between space and ground as well; therefore, it is sensible to use the same definition for the ground software. Corfu comes with a library for ground software, which parses the configuration file and makes it available to the developer. It also comes with a link interface towards the space segment. Based on the library, Corfu provides a ready-to-use generic ground software with a graphical user interface printing telemetry data and for sending telemetry — according to the software definition.

Beyond formal verification of the software definition, Corfu comes with an elaborated testing framework, which provides unit and integration tests to the developers. By generating test-specific classes, Corfu gives developers access to internal software parts to allow more accurate unit testing. By automatically sending telecommands and evaluating telemetry data, developers accomplish integration tests of the full on-board software stack.

Corfu already comes with applications and concepts that are common to general on-board software, such as publish/subscribe communication between applications, anomaly and event handling, telecommand distribution among applications, telemetry collection, housekeeper, etc.

Available for download on Saturday, August 07, 2021

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Aug 10th, 12:00 PM

Model-Based Framework for On-Board-Software

Utah State University, Logan, UT

Satellites carry different payloads, but the basic design in hard- and software is generally similar for small satellites. For example, they all receive telecommands, distribute them and generate telemetry packets. Reusing existing components is desirable, especially with limited time and financial budgets. This is where the Corfu comes in, which we present in this work.

Corfu is a software framework for safety-critical on-board software. It follows a model-based approach. Developers formally define the structure of the software. The software design is app-centric, i.e. on-board software in Corfu is a composition of apps. Apps define a clear communication interface using a publish/-subscribe principle. This allows on-board software to connect apps among each other. Developers can use and connect apps in different on-board software and even on different missions. This encourages reusability.

Based on the information of software definition, Corfu applies two tasks: formal verification of the software structure and generation of source code. In the verification step, Corfu examines the timing properties across all apps that are included into the software. Having a formal definition that is used for both static analysis and code generation, makes in possible to identify structural problems early.

The generation process creates code that it can derive from the software specification. This includes communication handling, such as subscribing to topics, distributing telecommands and collecting telemetry. In addition, the generated code also covers thread handling. The result of the generation process is a collection of classes. Most of those classes are abstract, which include abstract methods that the developer fills with mission-specific code. Developers do this by inheriting from those abstract classes and overriding all the abstract methods by carrying out the desired behavior. Developers can focus on implementing the mission relevant code.

The software specification defines the communication interface between space and ground as well; therefore, it is sensible to use the same definition for the ground software. Corfu comes with a library for ground software, which parses the configuration file and makes it available to the developer. It also comes with a link interface towards the space segment. Based on the library, Corfu provides a ready-to-use generic ground software with a graphical user interface printing telemetry data and for sending telemetry — according to the software definition.

Beyond formal verification of the software definition, Corfu comes with an elaborated testing framework, which provides unit and integration tests to the developers. By generating test-specific classes, Corfu gives developers access to internal software parts to allow more accurate unit testing. By automatically sending telecommands and evaluating telemetry data, developers accomplish integration tests of the full on-board software stack.

Corfu already comes with applications and concepts that are common to general on-board software, such as publish/subscribe communication between applications, anomaly and event handling, telecommand distribution among applications, telemetry collection, housekeeper, etc.