The high quality of diagnostic information is driving a change in the way these data are being used. Vehicle designers are devising techniques that use this information to determine when components and systems are going out of range, which indicates that it’s time for maintenance.
The field of predictive diagnostics, variously called prognostics, integrated health vehicle maintenance, and condition-based maintenance is expanding quickly. It leverages the growing number of sensors on vehicles along with the vast computing power on vehicles and in service facilities.
Fleet owners have been using prognostics to help reduce unplanned downtime. Panelists in a prognostics technical session at SAE 2013 World Congress said that it’s seeing mounting use in trucking, construction, agriculture, and other fields.
“The business case is clear for heavy-duty vehicles, but it’s a bit different for passenger cars,” said David Bernard Porter at Mahle Powertrain. “In construction and agriculture, they can lose a lot of money. Unscheduled downtime can cost $2000 per hour. In a passenger car, it’s more difficult to make a business case for this.”
Panelists said there’s still debate over how prognostic data will be used. Some contended that it’s best when operators and drivers are informed so they can take action. Others said that it’s beneficial to send data to a central facility where trends can be analyzed.
Managers at these facilities can also ensure that suggested steps are taken, reducing the chance that a stressed vehicle operator will delay necessary maintenance until a job is finished. Some panelists suggested that basic data can be given to drivers or operators, while more detailed information can be sent to remote sites for charting and analysis.
“There must be some measurements on board, you need certain types of information, starting with sensor information,” said Steven W. Holland, General Motors Global R&D. “It’s becoming increasingly attractive to move some processing off board.”
Deborah M. Freund of the Federal Motor Carrier Safety Administration detailed another way that these data can help owners. She described a transportation agency determination that a dozen new buses had premature tire and brake wear, while the rest didn’t. Technicians started looking at diagnostic data, comparing them to information from similar buses.
“They looked at brake pressure and other things, eventually pinning the wear issue to a misalignment of some parts. This gave the agency hard data for their talk with the bus manufacturer and its brake system suppliers. They got a solution in weeks. If they had not had the benefit of that data, it would have taken months or years,” she said.
Though many aspects of prognostics won’t fall under governmental control, Freund noted that heavy-duty diesel engines' aftertreatment systems will be monitored. That will help ensure that particulate filters, urea tanks, and other equipment continues to run properly over the long term.
“In many cases, such as new electronically controlled engines, prognostics is very important. You need to ensure that over their lifetime, these engines work the way they’re designed. The aftertreatment systems need to work well,” she said.