AUSTIN, Texas—An electrical suspension system for cars and trucks developed by researchers at The University of Texas at Austin has demonstrated a fivefold reduction of shock and vibration to the passengers, double the off-road top speed and better handling in cornering, all resulting in improved off-road fuel economy.
Researchers at the Center for Electromechanics of The University of Texas at Austin designed the electrical system to replace conventional systems composed of springs and shock absorbers. Tests conducted over the last two years at the U.S. Army’s Yuma Proving Grounds showed significant improvement over conventional systems, which could provide an advantage for military vehicles as well as for civilian applications.
Dan Herrera of the U.S. Army Tank-Automotive and Armaments Command in Warren, Mich., said, "These test results show our research investment is paying off. These positive test results were needed to enable technology transition from laboratory demonstrations to significantly enhanced military capabilities of speed, agility and maneuverability."
The Army sponsored the testing, as well as much of the research and development. The Texas Advanced Technology Program provided additional research funding.
The University of Texas at Austin researchers, based at the J.J. Pickle Research Campus north of the main campus, installed the system on a High Mobility Multipurpose Wheeled Vehicle (HMMWV) supplied by the Army. The testing on off-road courses, using the Army’s professional test drivers, permitted comparisons between a conventional and an electrical suspension. On these courses, the electrical suspension demonstrated a fivefold reduction in the shock and vibration delivered to the driver, passengers or load. Because of this reduction, a very smooth ride could be maintained at normal speeds, making tasks such as writing or operating laptop computers much more convenient. Alternatively, if the normal bounce is tolerable, the speed can be doubled.
Improved stability during cornering and braking was achieved through control of the vehicle’s height, pitch and roll. Pitch is the tendency of a vehicle to tilt forward during braking, and roll is the tendency to rock side-to-side on turns. Traditionally, vehicles with comfortable rides have soft suspension systems that minimize ride vibrations but are difficult to maneuver due to excessive pitch and roll. At the other extreme, stiff suspensions have good handling but provide a bumpy ride. The electrical suspension uses a soft spring to provide a good ride and an electromechanical system to minimize pitch and roll for excellent handling. Moreover, dynamic adjustment of the vehicle’s center of gravity during turning reduces rollover risk.
The improved fuel economy occurs because the active suspension system consumes significantly less power than today’s system when used on rough roads or in off-road uses. The amount of savings is highly dependent on specific driving conditions, including the roughness of the route. But in one set of tests, the newly developed suspension appeared to be about 30 percent more efficient than existing systems.
Dr. Joseph Beno, project director at the Center for Electromechanics of The University of Texas at Austin, said, "The successful Army tests have gotten us excited about both the military and civilian applications of this technology. Civilian applications could range from ambulances, to sport utility vehicles, to large trucks."
For ambulances, a significantly smoother, more level ride with appropriate banking into turns could permit a wider range of in-route services to be performed safely. Sport utility vehicles would benefit from improved ride and handling, both on-road and off-road. Depending on the routes traveled, there also may be an improvement in fuel economy. Large trucks using this suspension should provide a gentler ride for sensitive cargo, improved handling for high speed maneuvering and reduced pavement wear.
The key components of the university-developed system are an electric motor driving a rack and pinion at each wheel, accelerometers and an advanced control system. The electrical and mechanical components were designed so they could be assembled using commercially available parts. The sensing and control software were developed and optimized specifically for this application.
For further information contact Beno or Dr. Robert Hebner at the Center for Electromechanics, (512) 232-1627.
