A typical underwater vehicle is a complex system involving a large number of subsystems. Some of the main subsystems are Main Computer System (MCS), Engine Control Unit (ECS), Recording System (IIRS), and onboard batteries. The project involves the design and development of an Engine Control Unit (ECS) for an underwater vehicle.

In the current system the MCS carries out the functions of the ECS. As the MCS is a complex subsystem itself and carries out a large number of functions, there was a need to isolate the ECS functions from the MCS. This required the development of an independent ECS which interfaces with the existing vehicle embedded system. The NI cRIO platform was chosen as the platform of choice for the ECS primarily due to its size, and ruggedness.

An engine control unit (ECS) needs to be developed using proven hardware, which takes over the engine control functions from the existing MCS.

Hardware Details

The hardware consists of the NI cRIO system with the following modules.

• CRIO 9002 controller
• NI 9205 – 32 channel analog input module
• NI 9263 – 4 channel analog output module
• NI 9477 – 32 channel digital output module
• AVIOK MIL 1553 module

The system accuracy specifications are as specified by the cRIO manufacturer and are as follows:

• Analog input channels : 16 bit accuracy on all channels at +-10V range
• Analog Output channels : 16 bit accuracy on all channels at +-10V range

The sampling rate of the system for analog inputs as well as digital inputs would be 100 samples/sec for each channel. The acquired data will also be logged at this rate. The update rate for analog outputs as well as digital outputs will be 100 samples/sec for each channel.

The RPM signal as it is a frequency signal will be sampled at an appropriate sampling rate (approximately 2kHz as maximum signal frequency is 640 Hz)). But RPM values will also be updated at 100 samples/sec.

Solution

The following are the features provided in the software:

• Test Panel: The test panel is used for viewing acquired data from the ECS through Ethernet
• Configure: This button would allow the user to access the configuration panel.
• Alarms: This button is for configuring alarms.
• File transfer: This is for transferring data from ECS to host pc.
• Offline: This is for viewing offline data and generating reports.

The ECS would start acquiring data once it is powered ON, and would transmit this data to the ECS test panel. Alarm checking and control operations which are explained later will occur simultaneously with data acquisition. The acquired data can be seen on the remote laptop on the ECS Test Panel as shown in the figures below.