Gateway Integrates Wireless Sensors with Existing Aircraft Systems at "the Speed of Software"
sensors
Gateway Integrates Wireless Sensors with Existing Aircraft Systems at "the Speed of Software" (DRC-TOPS-42)
Architecture advances convergence of new wireless technology into preexisting systems
Overview
Innovators at NASA's Armstrong Flight Research Center have found a way to incorporate wireless sensor technology in aerospace vehicles without adding the complexity and tonnage normally associated with physically modifying existing avionics. The solution: A single universal wireless access point or "gateway" that can communicate between existing onboard systems and any subscribed wireless device. This gateway can be easily reprogrammed to communicate with any wireless device, allowing engineers to add new sensing technology "at the speed of software." Furthermore, this gateway approach means that once a wireless sensor has been tested on a research vehicle or platform, it can be immediately integrated into other vehicles outfitted with the gateway. The gateway's architecture also holds promise for other industries seeking ways to capitalize on the advantages of wireless sensors.
The Technology
In traditional hardwired avionics systems, sensor integration requires installation of literally tons of physical cable that significantly increases vehicle weight and the time it takes to develop, maintain, and modify systems. Cabling also consumes space available for profitable payloads. Armstrong's technology uses software to incorporate new wireless capability without physically modifying existing avionics.
How It Works
Armstrong's gateway uses a software defined radio (SDR) to control the flow of information between various wireless devices and a vehicle's avionics. An SDR can be reprogrammed to communicate with a variety wireless communication protocols and frequencies via straightforward software modules—as opposed to wireless sensor-specific hardware—effectively eliminating the need to modify a vehicle's existing avionics hardware architecture.
The gateway employs publish-subscribe network architecture. Before takeoff, flight computers reques—tor subscribe to—specific pieces of information from the SDR gateway. Wireless sensor devices then provide their respective sensor measurements to the SDR gateway, where they are distributed—or published—to any flight computer that has subscribed to a specific measurement.
Why It Is Better
Armstrong's technology simplifies the process of designing wireless avionics networks by providing a single point of communication between wireless and wired systems. It functions as a layer of abstraction between wireless sensors and the system with which they interface. This approach also ensures that no wireless device can directly communicate with a flight computer unless subscribed prior to takeoff, thus protecting the system from malicious or errant transmissions.
Although specifically designed for aerospace systems, the gateway is both platform- and implementation-agnostic, with the potential to foster convergence between wireless technologies and existing systems in other industries. A manufacturer can add industrial Internet-of-Things capability without having to integrate new wireless interfaces into its preexisting network.
The gateway serves as a universal interface with virtually any wireless device for such applications as connected logistics, predictive maintenance, asset tracking, and much more.
Benefits
- Rapid integration: Engineers can more quickly add off-the-shelf wireless sensors to existing hardwired systems.
- Reduced weight: Eliminating cabling offers dramatic weight reductions, enabling transport of more profitable payloads and/or better fuel economy.
- Lower costs: Reductions in cabling combined with decreased integration efforts make the wireless approach enabled by this gateway more economical.
- Streamlined industry infusion: Once proven on a research vehicle or platform, a wireless sensor can be immediately integrated into commercial aerospace vehicles.
Applications
- Testing: Aeronautic and automotive vehicles
- Systems health monitoring: Systems in long-term storage
- Industrial: Infrastructure, manufacturing, and the Internet of Things
Similar Results
High-Speed, Low-Cost Telemetry Access from Space
NASA's SDR uses Field-Programmable Gate Array (FPGA) technology to enable flexible performance on orbit. A first-generation FM-modulated transceiver is capable of operating at up to 1 Mbps downlink and 50 kbps uplink, full duplex. An FPGA performs Reed-Solomon (255,223) encoding, decoding, and bit synchronization, providing Consultative Committee for Space Data Systems (CCSDS) and Near Earth Network (NEN) telemetry protocol compatibility. The transceiver accepts data from the onboard flight computer via a source synchronous RS422 interface.
NASA's second-generation full duplex SDR, known as PULSAR (programmable ultra-lightweight system-adaptable radio, Figures 1 and 2 below) incorporates command receiver and telemetry transmitters, as well as updated processing and power capabilities. An S-band command receiver offers a max uplink data rate of 300 Kbps and built-in QPSK demodulation. X- and S-Band telemetry transmitters offer a max downlink data rate of 150 Mbps and flexible forward-error correction (FEC) using Reed-Solomon encoding (LDPC rate 7/8 and 1/2 convolution in development), and it uses QPSK modulation. The use of FEC adds an order of magnitude increase in telemetry throughput due to an improved coding gain. An onboard FPGA uses high-speed logic for uplink/downlink and encoding/decoding processes. Balloon flight testing has been conducted and is ongoing for PULSAR.
RFID-Enabled Wireless Instrumentation
With a form factor close to a deck of playing cards, the system interrogator has custom software to interface with and service a population of sensor tags at the required data rates. Each EPCglobal C1G2 sensor tag uses incident interrogator energy to charge its small integrated circuit (IC), which reads an internal memory bank, encodes identification data, and uses that information to modulate and backscatter a reply to the interrogator using reflected interrogator energy. Two tag interfaces allow the attached processor to power the reading/writing of data to the tag memory and then allows the interrogator to power the reading of the tag memory data. When neither of the two interfaces are engaged, the RFID IC is completely powered down. Reading and writing tag memory consumes relatively little power compared to the power draw of active transmitter/receiver protocols like Bluetooth, Zigbee, and Wi-Fi. Compared to passive sensing protocols, this wireless instrumentation system enables sampling of a larger population of tags without the computational burden associated with surface acoustic wave (SAW) sensing. RFID-Enabled Wireless Instrumentation technology allows the RFID interrogator to write data through the interface of a sensor tag memory bank using only interrogator power. With only minimal cost to the sensors power budget, the microcontroller unit can read that data out over the serial interface. The sensor can transmit and receive data at no effective cost to its small coin cell battery power supply.
This technology is readiness level (TRL) 8 (actual system completed and "flight qualified" through test and demonstration) and the innovation is now available for your company to license. Please note that NASA does not manufacture products itself for commercial sale.
Low Weight Flight Controller Design
Increasing demand for smaller UAVs (e.g., sometimes with wingspans on the order of six inches and weighing less than one pound) generated a need for much smaller flight and sensing equipment. NASA Langley's new sensing and flight control system for small UAVs includes both an active flight control board and an avionics sensor board. Together, these compare the status of the UAVs position, heading, and orientation with the pre-programmed data to determine and apply the flight control inputs needed to maintain the desired course.
To satisfy the small form-factor system requirements, micro-electro-mechanical systems (MEMS) are used to realize the various flight control sensing devices. MEMS-based devices are commercially available single-chip devices that lend themselves to easy integration onto a circuit board. The system uses less energy than current systems, allowing solar panels planted on the vehicle to generate the systems power. While the lightweight technology was designed for smaller UAVs, the sensors could be distributed throughout larger UAVs, depending on the application.
Unique Datapath Architecture Yields Real-Time Computing
The DLC platform is composed of three key components: a NASA-designed field programmable gate array (FPGA) board, a NASA-designed multiprocessor on-a-chip (MPSoC) board, and a proprietary datapath that links the boards to available inputs and outputs to enable high-bandwidth data collection and processing.
The inertial measurement unit (IMU), camera, Navigation Doppler Lidar (NDL), and Hazard Detection Lidar (HDL) navigation sensors (depicted in the diagram below) are connected to the DLC’s FPGA board. The datapath on this board consists of high-speed serial interfaces for each sensor, which accept the sensor data as input and converts the output to an AXI stream format. The sensor streams are multiplexed into an AXI stream which is then formatted for input to a XAUI high speed serial interface. This interface sends the data to the MPSoC Board, where it is converted back from the XAUI format to a combined AXI stream, and demultiplexed back into individual sensor AXI streams. These AXI streams are then inputted into respective DMA interfaces that provide an interface to the DDRAM on the MPSoC board. This architecture enables real-time high-bandwidth data collection and processing by preserving the MPSoC’s full ability.
This sensor datapath architecture may have other potential applications in aerospace and defense, transportation (e.g., autonomous driving), medical, research, and automation/control markets where it could serve as a key component in a high-performance computing platform and/or critical embedded system for integrating, processing, and analyzing large volumes of data in real-time.
Low-Profile Wireless Sensor
The low-profile sensor is configured with a spiral electrical trace on flexible substrate. In typical inductor designs, the space between traces is designed to minimize parasitic conductance to reduce the impact of the capacitance to neighboring electronics. In the low-profile sensor, however, greater capacitance is desired to allow the operation of an inductor-capacitor circuit. This allows the traces to be closer together, decreasing the
overall size of the spiral trace.
The sensor receives a signal from the accompanying magnetic field data acquisition system. Once electrically active, the sensor produces its own harmonic magnetic field as the inductor stores and releases magnetic energy. The antenna of the measurement acquisition system is switched from a transmitting to a receiving mode to acquire the magnetic-field response of the sensor. The magnetic-field response attributes of frequency, amplitude, and bandwidth of the inductor correspond to the physical property states measured by the sensor. The received response is correlated to calibration data to determine the physical property measurement. When multiple sensors are inductively coupled, the data acquisition system needs to activate and read
only one sensor to obtain measurement data from all of them.
