Affordable Vehicle Avionics (AVA)
aerospace
Affordable Vehicle Avionics (AVA) (TOP2-274)
Common Modular Avionics System for Nano-Launchers offering affordable access to space
Overview
NASA Ames Research Center has developed a novel low-cost, self-contained Guidance, Navigation and Control (GNC) subsystem for developers and operators of small-payload Space Launch Vehicles (SLVs). Small satellites are becoming ever more capable of performing valuable missions for both government and commercial customers. However, currently these satellites can only be launched affordably as secondary payloads which makes it difficult for the small satellite mission to launch when needed into the desired orbit, and with acceptable risk. NASA's Affordable Vehicle Avionics (AVA) technology offers access to space for small-payload SLV operators with an ability to provide dedicated launch to Low Earth Orbit (LEO), when and where they need. AVA demonstrates a self-contained GNC subsystem that can be integrated and operated at a fraction of the recurring costs of existing units.
The Technology
Significant contributors to the cost of launching nano- and micro-satellites to orbit are the costs of software, and Guidance, Navigation and Control (GNC) avionics systems that steer, navigate and control the launch vehicles, sequence stage separation, deploy payloads, and pass data to Telemetry. The high costs of these GNC avionics systems are due in part to the current practice of developing unique, custom, single-use hardware and software for each launch, and requiring high-precision measurements of position and attitude states. NASA Ames Research Center has developed and tested a low-cost avionics system prototype called Affordable Vehicle Avionics (AVA). AVA integrates a low-cost moderately-precise sensor suite with an advanced error-correcting software package to provide GNC for space launch vehicles in a package smaller than a multilayer sandwich (100 mm x 120 mm x 69 mm; 4in x 4.7in x 2.7in), and with a mass of less than 0.84kg (2lbs). The invention provides a common suite of avionics components and demonstration software that deliver affordable, capable GNC with flexible I/O which is applicable to a variety of nano/micro-sat launch vehicles at less than 10 percent of the cost to procure current state-of-the-art GNC avionics. Affordable Vehicle Avionics' (AVA's) approach to drastically reduce costs includes: (1) use of low-cost "tactical-grade" Commercial-off-the-Shelf MicroElectroMechanical Systems (MEMS) inertial measurement unit, wherein adequate navigation precision is achieved by fusing outputs from a Global Positioning System receiver, inertial sensors and a magnetic field vector sensor in an extended Kalman filter formulation that corrects inertial sensor biases; (2) a streamlined "cookbook" approach to define an effective process for launch vehicle developers to design, simulate, verify and support assembly, integration and testing of their SLVs, driven by high-fidelity six degrees of freedom SLV simulations and real-time hardware-in-loop tests to validate guidance, navigation and control for early test flights.
Development Status:
As of spring 2020, AVA has flown twice in its current configuration on a suborbital platform. Its navigation and control functions were successfully demonstrated for roll-rate control within a tight deadband onboard the first flight test, and it successfully issued attitude pointing commands to a failed reaction control subsystem and it issues issued a rocket-motor ignition command on a second flight test. To date, failure of SLV components other than AVA (e.g., electrical power) has precluded demonstration of navigation and control of an orbital or sub-orbital launch system, which remains to be demonstrated.
AVA development was accomplished using a single magnetometer-based magnetic field vector sensor to provide attitude observability during free-fall (inter-stage coast periods). Therefore, the current tested AVA configuration is susceptible to magnetic/electric fields produced by other components and payloads onboard the SLV, so care must be exercised to either mount AVA well away from sources of such fields and or to incorporate magnetic/electric field barriers on field emitters if separation from emitters is inadequate. Also, licensees may wish to provide new AVA inputs from a pair of external horizon sensors to provide more accurate attitude navigation during coast phases of the SLV mission.
Benefits
- Small and light-weight
- Common suite of avionics and demonstration software made available to several launch providers
- Self-contained guidance system
- Lab tested and qualified to survive the launch environment
- Common suite of avionics and software made available to several launch providers
- Leverage commercial-off-the-shelf COTS hardware (sensors and flight processor)
- Maintain performance and reliability
Applications
- Nano/micro/small-spacecraft space launch vehicle industry
- If augmented by additional attitude-measurement sensors: Small-satellite industry including spacecraft attitude determination & control, orbit maintenance, and support of payloads for imaging, communications, and remote sensing
- Space industry
Similar Results
Cost Optimized Test of Spacecraft Avionics and Technologies(COTSAT) Modular Spacecraft Software Architecture
The goal of COTSAT as a technology demonstration unit is to demonstrate the ability for drastic cost reduction in spacecraft design and to develop methods and technologies for maximizing reuse of developed spacecraft hardware, software and related technology on future missions. This approach will enable for rapid response capabilities given advances in rapid prototyping.
COTSAT consists of the following sub-systems:
- An artificial environment container, which comprises much of the satellite structure, is used to contain the single atmosphere environment. The artificial atmosphere container is used to replicate an Earth-like atmosphere, allowing the use of Commercial-Off-The Shelf (COTS) hardware and electronics which were not necessarily originally designed to operate in the vacuum environment of space.
- A key design element in the bus structure of COTSAT is the modular platform upon which the bus is assembled. This structure allows for a logic-flow integration of components leading to ideal placement of electronics.
- The Electrical Power System (EPS) architecture utilizes a distributed power and self-monitor approach.
- The Command and Data Handling (C&DH) subsystem provides a number of critical capabilities, including spacecraft health and status monitoring, communication, payload science data management and subsystem management.
- The COTSAT communications architecture incorporates four independent communications paths.
- The software architecture consists of modular, independent software daemons for each subsystem or capability such as the star tracker, the Inertial Measurement Unit (IMU), the reaction wheels, the main executive, the communications system, the control system and the payload.
- The COTSAT has a three-axis Attitude Determination And Control System (ADACS), using four reaction wheels and three magnetic torque coils.
- To aid in technology development and testing, the COTSAT hardware and technology performance has been verified by a number of prototype test-beds. There have been three major test platforms during the development cycle.
Safe2Ditch Technology
Safe2Ditch is a crash management system that resides on a small processor onboard a small Unmanned Aerial Vehicle (UAV). The system's exclusive mission is emergency management to get the vehicle safely to the ground in the event of an unexpected critical flight issue. It uses the remaining control authority and battery life of the crippled vehicle in an optimal way to reach the safest ditch location possible. It performs this mission autonomously, without any assistance from a safety pilot or ground station. In the event of an imminent crash, Safe2Ditch uses its intelligent algorithms, knowledge of the local area, and knowledge of the disabled vehicle's remaining control authority to select and steer to a crash location that minimizes risk to people and property. As it approaches the site, it uses machine vision to inspect the selected site to ensure that it is clear as expected.
SmallSat Standardized Architecture
SmallSat Standardized Architecture is architecture that is modularized, pressurizable, thermally controlled spacecraft-designed to host ruggedized commercial off-the-shelf (COTS) instrumentation in a terrestrial-like environment on orbit. The architecture takes advantage of a pressurizable volume for both spacecraft and payload systems. The pressurizable volume provides multiple benefits, primarily in thermal design. By maintaining one atmosphere of pressure inside the SmallSat, materials that might otherwise outgas and/or fail and/or cause significant contamination issues, are no longer a concern. This also means that certain vibration-absorbing materials/designs used in COTS hardware can be used on orbit. Additionally, printed circuit boards do not have to be redesigned for thermal requirements, plus conformal coating and contamination bake-outs are no longer required.
The SmallSat architecture is designed to take advantage of the United States Air Force (USAF) Rideshare Program and the Evolved Expendable Launch Vehicle Secondary Payload Adaptor (ESPA) ring. The ESPA ring comes in two sizes: standard and Grande. The architecture has two main configurations, one designed for the ESPA Grande, and the other for the standard ESPA ring. The ESPA Grande version is a hockey-puck-shaped spacecraft bus measuring approximately 40 inches in diameter and 20 inches in height. This version takes full advantage of the ESPA Grandes 300-kilogram capability per attachment point.
Modular Robotic Vehicle (MRV)
The Modular Robotic Vehicle (MRV) is a vehicle designed for transportation in congested areas. The MRV is relatively small, easy to maneuver and park. The MRV was designed without a central power plant, transmission, fuel tank, and direct mechanical linkages between driver input devices and the actuators used to accelerate, brake and/or steer the car. These core vehicle functions are located at the corners of the vehicle in a modular electric corner assembly or eCorner. Because the MRV uses a by-wire control system, substantial space and weight is conserved compared to conventional designs. Moreover, the functional capabilities that are provided by the individual eCorners enable control of the vehicle in a variety of different operating modes.
The eCorners provide significant flexibility in driving options. For example, the driving mode can be switched so that all four wheels point and move in the same direction achieving an omni-directional motion or all wheels can be pointed perpendicular to the center of the vehicle allowing rotation around its center axis. This mode makes some driving maneuvers like parallel parking as easy as driving next to the spot, turning the wheels 90 degrees, and driving into the open spot in a sideways motion. Each eCorner includes its own redundancy to protect for electrical failures within the systems. The driver can choose to control the vehicle with a conventional steering wheel or add inputs through a multi-axis joystick for additional control in some of the more advanced drive modes. The vehicle has the propulsion motors located inside of each eCorner with the capability of producing 190 ft-lbs of torque with a current top speed of 40 mph. An active thermal control loop maintains the temperatures of these high powered motors and a separate thermal loop cools the avionics and the custom lithium-ion battery packs. The linked vehicles are able to exchange or share control data and electrical power. Finally, the MRV has remote driving control capability.
Near-Real Time Verification and Validation of Autonomous Flight Operations
NASA's Extensible Traffic Management (xTM) system allows for distributed management of the airspace where disparate entities collaborate to maintain a safe and accessible environment. This digital ecosystem relies on a common data generation and transfer framework enabled by well-defined data collection requirements, algorithms, protocols, and Application Programming Interfaces (APIs). The key components in this new paradigm are:
Data Standardization: Defines the list of data attributes/variables that are required to inform and safely perform the intended missions and operations.
Automated Real Time And/or Post-Flight Data Verification Process: Verifies system criteria, specifications, and data quality requirements using predefined, rule-based, or human-in-the-loop verification.
Autonomous Evolving Real Time And/or Post-Flight Data Validation Process: Validates data integrity, quantity, and quality for audit, oversight, and optimization.
The verification and validation process determines whether an operation’s performance, conformance, and compliance are within known variation. The technology can verify thousands of flight operations in near-real time or post flight in the span of a few minutes, depending on networking and computing capacity. In contrast, manual processing would have required hours, if not days, for a team of 2-3 experts to review an individual flight.
