Do Your Duty Cycle Diligence

In the Past, Gathering Duty Cycle Data From a Customer’s Installation Was a Logistical Nightmare

By Jason H. Stallard

As an oem provider of engines that go into numerous and often unique applications, it sometimes is difficult to know before delivery just what sorts of duty cycles a given engine will go through. Power generators could sit for weeks between maintenance starts and could only be needed to provide backup power once ever year or two. A line haul truck could spend two days crossing the U.S. and then a week running local deliveries. When the inevitable call comes in to troubleshoot an engine, the lack of data for that engine’s duty cycle makes diagnosing the problem all the more difficult.

In the past, gathering duty cycle data from a customer’s installation was a logistical nightmare. Getting permission, coordinating access to the engine, installing data collection equipment, training personnel, retrieving the data and analyzing it all made gathering this data undesirable for all but the most severe problem engines. Because of those difficulties, how customers used their engines on a daily basis was never understood well. However, now that technology is catching up with need, we are beginning to get the data needed to help to drive future designs.

Solid-state computers with sufficiently dense storage space now are small enough that we can install recording devices on-vehicle with minimal impact. Now that the cellular infrastructure is mature and providing coverage to a significant area of the country, we can collect the stored data and reconfigure the in-vehicle systems remotely; and this all can be done with off-the-shelf hardware instead of expensive and limiting systems such as satellite.

In the summer of 2007 Cummins launched a pilot program to outfit a fleet of vehicles with this off-the-shelf hardware combined with some custom software to facilitate recording, storing and transfer of data. In all, 40 engineering, field test and customer vehicles scattered around the U.S. and Canada, running line haul and local routes, collected more than 500 gigabytes of data, which were processed in near-real time. With this data we were able to examine historical data when engine failures occurred, predict failures before they happened and drive changes for platform development. We also found that the data-collection equipment was not always handled well, and several units were returned beaten up, filthy or destroyed.

Cummins learned several lessons from the pilot program. The chosen data-collection hardware was expensive and not rugged enough for some environments. Sensors required physical modification of some installations, which is undesirable for customer vehicles. While cell coverage was plentiful, the data throughput was less than ideal.

The total cost of the system prohibits large-scale deployment to more than 100 installations. Future duty cycle recording equipment will need to improve by incorporating distributed sensors that use wireless or existing vehicle networks; the form factor of the data collection device needs to be about the size of a car radio; and the remote data transfer rates need to increase to as near broadband as possible.

Cummins also learned that having a duty cycle recorder installed on a real-world working vehicle can benefit safety engineering.  During the summer pilot program, a couple of vehicles were involved in accidents and Cummins was able to review the data much like the flight data recorders on commercial airlines.  Cummins was able to determine the road speed, position, engine load and other diagnostic data before, during and shortly after the accidents. If the right set of data were being recorded at these times, the data would prove invaluable to our vehicle manufacturing customers.

Cummins sees duty cycle data becoming an integral part of our development, testing and support efforts. What started as a pilot of 40 vehicles quickly grew to more than 100. By 2010, we expect the number of installations to reach 500 and see the potential to eventually have every engine coming off the manufacturing line pre-installed with duty cycle recording capabilities.

Jason H. Stallard is a software engineer at Cummins in Columbus, Ind.

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