A NEW multiplexed electronic system can now deliver critical data throughout an ambulance.
Medtec, the ambulance manufacturing affiliate of Oshkosh Truck Corporation, is using the Command Zone electronics system to deliver crucial information about the vehicle and makes it possible to make on-the-fly adjustments to a variety of functions throughout the ambulance using a newly introduced compact color graphics display that puts system control at a driver's fingertips.
Collaborating with HED Inc, a developer of multiplexing technology in Hartford, Wisconsin, Medtec added this advanced system to handle multiple electrical signals emanating from all over the vehicle, passing through a single data link cable to a central processor. Vehicle activity is trafficked by controlled area network (CAN) and shown on a display where it can be seen by those who must run, service, design, and upgrade this equipment.
Since the late 1990s with the introduction of the J1939 protocol, Oshkosh has installed this technology on thousands of Pierce fire trucks. Based on this accumulated experience, Oshkosh recently moved the Command Zone system into the military market, starting with their Medium Tactical Vehicle Replacement (MTVR) wrecker. Oshkosh has other military truck models using the Command Zone concept that are ready to go into production.
The J1939 standard is a high-speed 250 kbs protocol that provides registered addresses and architecture, enabling vehicle components such as the anti-lock braking system, the engine, transmission modules, and the various electronic and hydraulic systems to essentially talk to one another.
CAN technology is ideal for the mission at Medtec to develop a customized vehicle for the needs of specific departments and EMTs. To maximize the advantages of these features, a console-mounted control with its 480×234 size VGA screen is the window into the system that provides drivers with an abundance of information and an array of control functions.
Vehicle status is within an easy glance. Real-time data can include alternator voltage, amperage, and other readings presented in a trend format rather than simply static digital data.
Other data not necessarily part of the vehicle itself such as oxygen tank pressure can be presented as animations. These were coded into the system by Fischer and the Medtec designers. The screen module design also allows the ambulance drivers to make changes to the layout and other graphics.
Additionally, the screen also carries a pictorial for the driver of the ambulance doors. For example the instant an EMT comes charging out of the rear, that open door appears on the screen. The screen tracks the many compartment, rear, side, and cab doors (the # varies) on the vehicle to make sure all of them are shut when the ambulance speeds off to the next location.
Vehicle designers and owners have the option to configure the module push buttons to handle whatever function they desire within the scope of the CAN system's control of vehicle's components.
Buttons have an electrical interlock to prevent them from being accidentally activated or de-activated.
As the ambulance is on route to its destination, it is vitally important for the driver to have up-to-the-second patient status information, affecting decisions on whether to switch on the siren and the lights and start barreling through traffic. For ease of processing a simple color code keeps the driver informed.
Drivers can see patient condition with the help of video that can come up on the screen. Camera images also expand the driver's view around the outside of the ambulance. Flip on the left turn signal and a view of the driver side automatically comes on the screen, eliminating those blind spots for the driver. Additionally the floodlights can be programmed to turn on when a compartment door is opened.
Put the transmission into reverse and up comes a view of the rear of the vehicle. At night the rear light also turns on at the same time to illuminate the area. In short, the prime benefit of the panel is that it enables the driver to focus attention on just two fields of vision — the road ahead and the screen — giving all that is needed to respond to patient condition and what's going on outside the ambulance.
On the ambulance, engineers have positioned modules throughout the unit to be near the components and systems that the CAN system monitors and controls. The twisted pair of wires that comprise the CANbus circuitry hook the module up to a central processing module.
All together the modules currently on the Medtec ambulance have 64 inputs and 88 outputs. Many undedicated slots are available for future additions to the system.
Using a laptop with standard programs developed by HED, a technician can configure contact points and diagnose problems with the hardware, software, or sub-systems on the vehicle. For a vehicle that must spend time out on the road rather than the shop, the Command Zone allows system options and other reprogramming to be completed remotely using a modem.
The Command Zone system gives Medtec the ability to produce an ambulance with a lot more benefits than standard units. “For the past 30 to 40 years you had few components that were electronic,” says Jacob Fischer, the lead engineer for the Medtec ambulance upgrade. “Now you have technology that allows you to offer almost unlimited features.”