Multifunction I/O Boards : Distributed Sensor & Control I/O for Military Platforms
Typical Military platforms for Land, Sea or Air based deploys large numbers of sensors and heavily reliance on embedded electronics. With electronics sensing using MEMS miniatures fly by wire complex sensors and usage of electronic controlled actuators for controls IO towards replacing traditional mechanical driven system.
Electronics control system with higher performance and complex control system able to deliver today simple Automatic steering control to complete UAV/UGV control system.
Military platforms requires today’s demanding embedded system with lots of horse power processing for mission critical system.
Rise of Intelligence and Processing mission critical system
Military system designed and deployed around highly reliable COTS commercial off the shelf electronics architecture over a past two decade using open standard bus implementation. For harsh & rugged environment mission critical system, most widely bus architecture VME, VPX /open VPX, CPCI and PCI/PMC with SBC and IO sensor control sub systems.
Typical conventional Control system based on Processing engine using SBCs, Sensor interface IO and communication IO over VME, VPX /open VPX , CPCI, PCI/PMC modular system. A submarine or large Navy Vessel requires few 10,000’s of IO system for various controls like electrical generation, propulsion, engine turbine and various other critical management control systems.
With increase in demand of processing and large numbers of sensors interfaces, rise of Intelligent IO with preprocessing, high density mix and match IO interfaces using COTS architecture.
Intelligent IO provide multifunction capability with mix and match for various functionality using FPGA design concept as well as processing power without SBCs.
Multifunction IO implementation using FPGA based design help wide range of functionality like A/D ,D/A, Digital I/O , Discrete I/O , PWM, Encoder , RTD /Temp sensors , Synchro /Resolver , Differential IO and Serial IOs.
Simultaneously add on communication function like MIL-STD1553, ARINC, CAN and Serial IO available with protocol implementation using FPGA.
Besides executing the embedded application, also known in this case as the operational Flight Program (OFP), the sub system processing has to manage and control all of the I/O interfaces with Built-in Test (BIT), a must in military embedded systems.
Using Multifunction Intelligence IO customers eliminate the need to design custom board and data acquisition systems for most sense-and-response applications.
COTS designs incorporate an innovative mix of processors and FPGAs that perform complex and time-critical tasks such as motion control, process control, monitoring, data transfer, and Background Built-in-Test (BIT).
Distributed IO concept using Sensor Interface Unit ( SIU ) :
Moving to Distributed I/O
For example, simple conventional design, the system requires an input function that can measure the position of the steering wheel (A/D, S/D or Encoder), measure the position of the drive wheel around the vertical axis (another A/D, S/D or Encoder), and a D/A or PWM to actually drive an actuator to turn the wheel.
Here main processor computer requires to implement a control loop to perform this function. This computing sub system connected by a number of cables which run from the sensors and actuators back to the main processor sub system with I/O functions.
Now imagine a remote self-contained Distributed IO Sensor Interface Unit SIU, which similar all of the I/O functions needed to perform this task, as well as an Processing & intelligence. This Distributed IO SIU can be placed close to the sensors and actuators to implement the control loop necessary to perform the actual function. In this scenario, the main processor computer doesn’t need to implement a control loop, but would simply read the steering wheel position and only have to send a short message/ command to the remote Distributed IO SIU over redundant Gig E LAN.
This Distributed IO approach allows to place I/O points very near the actual sensors, pre-process the data, and then send the reduced data back to the mission processing.
Major Advantage of Distributed IO is reduction in cable length. Cable lennth reduction help in reduction of weight of long mutli sensors cables and also in reduced noise pickup, wire losses, ground loop potentials, and in many cases significantly reduced EMI.
Challenges for Large Mission critical system:
With large Mission critical system, few challenges over a decade customers looking forward to overcome,
- To reduce overall size of electronics and save cost & space
- To Lower power consumption to reduce heat and increase system reliability
- To Access and manage all I/O data with remote access using Ethernet /other VME , CPCI ,PCI Bus
- To verify & perform critical Heath check at start up BIT Built in test , continuous operational Background test.
- Sensor and Actuator cable break vs Sensor failure Detect /Verification.
With this above challenges, NAI introduced early this decade Multifunction IO with on board preprocessing FPGA design COTS architecture for VME, cPCI, VPX/open VPX, PCI and PMC for military system.
These “Intelligent” Multifunction IO boards provide another very important feature that minimizes system size and power (SWaP); the ability to perform multiple functions on one Board. In the past, many boards were available with 32 or 64 A/Ds or D/As, or discrete, as well as different types of communication functions (MIL-STD-1553, serial, ARINC429, CAN , etc.) and processing (SBCs). Also NAI have created multifunction VME, cPCI and VPX boards. These boards allow the system integrator to select from a large number of available functions, and incorporate smaller channel counts of many functions on one Module.
This is made possible through the ability of the base board FPGAs and processing to be programmed at final assembly to perform almost any task. For example, a single board can incorporate A/D, D/A, RTD, MIL-STD-1553, ARINC429 and discrete, just to name a few (dozens of different functions are available).
Through the use of NAI’s products, designers reduced card count by 50%— cutting the costs, system size, weight, and power consumption ( SWaP ) of the system.
In addition, the extensive test and diagnostic capabilities of the multifunction intelligence IO concept improved system maintainability by making it possible to trace and identify signal interference faults, such as open lines( cable break /short ) and undefined range faults ( over range Sensor , Short Sensor etc. ) Level for identification and action. Power on Built in test with continuous Background Test (operation) upto IO card, module and / or channel level identification, hardware & software alert and action items.