Suspension Parameter Measurement Using Side-Pull Test To Enhance Modeling of Vehicle Roll

This paper describes a new laboratory test facility for measuring suspension parameters that affect rollover. The Side-Pull mechanism rolls the test vehicle through a cable attached rigidly at its center of gravity (CG). Changes in wheel camber and wheel steer angles are measured as a function of body roll angle. The roll test simulates a steady-state cornering. Thus, both compliance and kinematic forces are fed simultaneously to the vehicle as they would be applied in a real cornering situation. The lateral load transfer, and roll angle as a function of simulated lateral acceleration is determined.

The Side-Pull Roll Measurement has advantages over the conventional roll tests where the rolling force couple is applied vertically. The Side-Pull mechanism rolls the vehicle in a unrestricted way with horizontal forces applied at the tire / pad contact and the CG location. Thus, the measurements take into account coupling of compliance with roll. The -Side-Pull method eliminates the need to run separate tests for suspension kinematics and compliance properties.

Description of the hardware and testing method is given. Results from the side-pull measurement for the 1997 Jeep Cherokee are compared with field test results and with conventional Suspension Parameter Measurement Device (SPMD) results. It is found that slow continuous side-pull test simulates closely the steady-state cornering. The results from superposition of kinematics and compliance are compared with the side-pull results. Recommendations are given for development of the Side-Pull Suspension Measurement Facility to make use of it in roll modeling.