Improving vehicle performance and operator ergonomics: Commercial application of smart materials and systems

Abstract

This article will discuss how controllable material technology, such as the use of active magnetorheological dampers, improves primary and secondary suspensions of vehicle. Although relatively new to the marketplace, semiactive suspensions in commercial automobiles and off-highway vehicles have been proven through the use of active magnetorheological dampers since 1998. In fact, magnetorheological suspension dampers are found today on the commercial vehicles of an increasing number of automotive original equipment manufacturers and leading off-highway original equipment manufacturers. Magnetorheological fluid dampers are simple in design and have the advantage of no moving parts. The resistive force from a magnetorheological damper is generated as iron particles, suspended in the magnetorheological fluid, pass through a magnetic field controlled by the electrical current passing through an electric coil contained within a moving piston surrounded by the fluid. By adjusting the current to the damper coil in response to feedback from vehicle sensors and a controller, the damping response of the suspension can be optimized and controlled in real time to provide optimal operator comfort. The magnetorheological damper system has a full-scale step response of less than 10 ms. Sophisticated control algorithms adapt to large changes in payload, enabling the vehicle to meet ride metrics without pneumatic load leveling. Other benefits of the magnetorheological damping system include higher speed in North Atlantic Treaty Organization double-lane change tests, reduced risk of rollover, improved accuracy of mounted weapons, and improved vehicle durability and readiness.