Clever cleat

Purdue University researchers have developed a system that automatically detects damage to critical suspension components in military vehicles when they are driven over a speed bump diagnostic cleat containing sensors.

'Our aim is to save time and maintenance costs, but more importantly to reduce downtime by catching damage before it leads to failure in the field,' said Douglas Adams, an associate professor of mechanical engineering and director of Purdue University's Center for Systems Integrity.

Purdue is working with the US Army and Honeywell International to develop the technology further.

The vehicles are driven over the 'tactical wheeled vehicle diagnostic cleat', which is like a rubber-jacketed speed bump equipped with sensors called triaxial accelerometers.

The system measures vibrations created by forces that a vehicle's tyres apply to the cleat. Damage is detected in the tyres, wheel bearings and suspension components by using signal processing software to interpret the sensor data.

'Let's say one of the tyres is severely under pressure,' Adams said. 'The cleat tells you to turn around and fill up that tyre because you are about to embark on a 10-hour mission with this vehicle. Or, you are returning the vehicle to the depot and the cleat tells you that the right rear suspension has a problem in the shock absorber or a critical bolt in the front suspension is broken. The maintenance personnel don't have to troubleshoot the vehicle. They know what to fix.'

He added that the system could also be used in commercial applications to test civilian vehicles.

The researchers have filed for a patent on the technique, which has been nominated as a US Army invention of the year by the US Army's Tank Automotive Research, Development and Engineering Center in Warren, Michigan.

The researchers tested their system in experiments with high-mobility multi-purpose wheeled vehicles, or Humvees, and also developed a computational model to simulate how the system works.

'Our simulated model showed us that we were capable of using the system accurately to detect damage to vehicle components, and our experiments with actual vehicles validated the model,' said Adams. 'The system was sensitive to as little as a five per cent change in the stiffness of the suspension.'

Findings show the method is capable of accurately identifying damage to vehicle tyres and the suspension. A damaged coil spring in the front suspension of a Humvee was detected even when tyre pressure was varied widely in an attempt to confuse the system.

Future research could focus on refining the signal processing software to more precisely identify specific components in the vehicle's suspension system.