Anti-Roll Stability Suspension Technology 2005-01-3522

All suspension systems have a common goal, which is to improve the ride in terms of comfort, handling, and safety. This is accomplished by influencing the motions afflicted by road irregularities to the wheels and axles while minimizing their affect on the vehicle body and frame. A successful design would therefore incorporate (1) a high Sprung-To-Unsprung-Mass-Ratio, (2) a Mass-Spring-Damper System between the vehicle body and the wheels, and (3) an anti-roll bar. Consequently, the wheels and axles endure the most of the motions caused by road irregularities while their affect is minimized on the vehicle body as desired.

The objective of the Anti-Roll Stability Suspension Technology (ARSST) is to become an industry standard active suspension system for all vehicles while simultaneously offering cost-effective and performance-enhancing control to improve vehicle handling, safety, and comfort. A unique characteristic about the system is that it is applicable to almost any type of vehicle including heavy trucks, recreational vehicles, military vehicles, busses, tractors, and passenger cars. The ARSST applies the ideas above and beyond by utilizing a powerful microprocessor that executes complex algorithms to control damping between the vehicle body and the wheels. The algorithms use thirteen attached sensors to compute the duty-cycle of a Pulse-Width-Modulated (PWM) electrical signal. The signal drives a single-valve solenoid that is coupled to a Suspension Control Unit (SCU). The SCU - installed on the vehicle corner between the wheel axle and vehicle frame - actuates the electrical signal using a hydraulic system, generating a force linearly proportional to the PWM duty-cycle. Accordingly, the force opposes piston movement in the SCU, damping the affect of road irregularities on the corner. Furthermore, an accelerometer sensor is used to prevent pitch and roll. This results in the added advantage of intelligently countering pitch and roll and also eliminating the anti-roll bar that is installed in a conventional fixed suspension system.

We refer to one vehicle corner, however there are four such corners, four independent PWM duty-cycle signals, and four SCUs.

Distinguished from conventional suspension systems, ARSST puts the theories of physics into application, intelligently applying constant variable damping force on the system to reduce vibrations on the vehicle chassis, thereby improving the ride for all occupants in the vehicle.

This paper provides a fundamental understanding of the theory and application of the ARSST, including the software control algorithms, system failure detection and handling functions, system components, the Suspension Control Unit components, and a detailed explication of the response of the system in the event of a road bump. Next, performance of the system is addressed, followed by a brief introduction to other suspension systems in the market.