Army vehicle electronics networking is complex and challenging due to vendor-specific devices and interfaces. Military vehicles require 100% network uptime and security. The network must reduce vehicle clutter, focus on saving soldiers’ lives, and provide minimum latency. Battle requirements change frequently, and vehicle electronics are added ad-hoc to the existing network. This work introduces an open-standard architecture approach that offers non-proprietary solutions with good interoperability, security, scalability, performance benefits, and cost savings.

As an architecture development use case, this work assumes the following core electronic devices: four sensors, four display devices, and one weapon station. Network architecture development for these devices involves requirements, communication protocols, network topology, and bandwidth.

A communication protocol in a network allows inter-device interactions. Unique interfaces in Army vehicle electronics complicate network scalability and performance. A common bus is recommended for a network to allow all devices to communicate in a standard, single interface. The Gigabit (GB) Ethernet, CAN bus, USB 2.0, and IEEE 1394 protocols are the open-standard candidates for a common bus network communication protocol. Each of the protocols was evaluated. In the evaluation and selection process, for each protocol, and for each factor, a ranking was assigned. Each protocol’s rankings were added and the highest-ranked protocol was selected.

The GB Ethernet data rate is at Gb/s (supports 1-100 Gb/s), the IEEE 1394 is at 49 Mb/s, the USB is at 480 Mb/s, and the CAN is at 1Mb/s. Due to low data transmission rate, the CAN is not a good video bus, but IEEE 1394 is good for video. The USB 2.0 data rate is very low compared to GB Ethernet. In summary, the GB Ethernet had good data transmission rate and minimum technical risk. It is scalable and commercial networking hardware is available.

In general, electronics need to process video, image, and other mission-critical data. The network must satisfy each data type’s bandwidth requirements. To support a continuous 3 Gb/s and a frequent 0.37 Gb/s data transfer rate to reduce re-acquisition cost for future expansion/scalability, the 10-Gb network bandwidth and the network devices to support it were recommended.

A star network topology offers greater advantages over ring, mesh, tree, and bus. The star network is scalable and has minimal performance or operational impacts. Star networks are tolerant to single device failures. Request messages do not pass through multiple devices before reaching the target. Each device is isolated by a link that connects it to the central hub. Multiple cable types can be used within a network. Based on this evaluation, multiple star networks were recommended for device connections. Every device goes through either a router or a switch. Each device has at least two network paths to reach other devices (redundancy).

Army vehicles operate in different terrains. The electronics on the vehicle continuously monitor and feed mission-critical information to the crew. Each vehicle will have electronic devices and weapons to carry out missions. For effective operation of these devices, a solid, fault-tolerant network is needed. In the recommended architecture, the sensors continuously, or on demand, capture data. The data is displayed, processed, distributed, and stored. The captured data enables crewmembers to take actions and eliminate enemy forces using onboard weapons.

Two 10-Gb Ethernet router networks with three 10-Gb Ethernet switch networks were used for fault tolerance and reduced single-point failures. Physical connection schemes for sensors, displays, weapon station, storage, and computer resources were developed. Sensors are connected to two router networks, which provide high availability and redundancy, and minimize single-point failures. The Ethernet switch allows easy expansion of additional sensors. If any one of the network channels is broken, the sensors can be accessed via available redundant channels. Gateways are used for protocol conversions (CAN to Ethernet). The router connections allow other devices to interact with sensors. The weapon station is capable of operating on its own without a network resource.

The vehicle computers are the master processing power for data recording, processing, storage, and distribution. The recommended physical connection allows these devices to access sensors, displays, and weapon stations. Two computers are recommended for load balancing and a common time module for synchronized time across the network.

The display devices have the capability to interact with any devices in the network with proper access controls. Two types of sensor data capturing mechanisms, i.e. batch mode (automatic) and user-initiated, are recommended. The user-initiated capture client software resides in all the onboard display devices. The client interfaces with the service software in the master computer. The client component has a display device-specific unique identification. Crewmembers request sensor data using the client software’s controls. The client software executes a request for data from the service running on the master computer. The request input has the user ID, password, sensor type, and the unique ID. The request is accepted by the service software and is validated. If the requested sensor is a secure data, the service software validates the access authority and then fulfils the request.The data is sent to the display device and is stored in the central storage for playback. The batch (automatic) capture service software running on the master computer automatically captures all the sensor data continuously and stores in the central storage for later playback.

The data processing software resides in the vehicle master computer and is invoked when display controls issue appropriate commands to execute a specific function. It validates user credentials, encrypts data, and provides processing modules for data distribution, storage, compression, validation, event logging, sensor data recording, and executing weapon controls. This software controls the data distribution and data storage software modules.

The architecture uses standard technologies and promotes open architecture standards. The 10-Gb Ethernet data bus for this network is faster, scalable, and capable of handling at least five additional sensors and displays. Built-in firewalls and network management software on router devices reduce risks and development costs.

development costs.

This work was done by Macam S. Dattathreya for the U.S. Army RDECOM-TARDEC. ARL-0094

Defense Tech Briefs Magazine

This article first appeared in the October, 2011 issue of Defense Tech Briefs Magazine.

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