Multiple-bump roadholding test: Description and metric interpretation

Abstract Road vehicle roadholding comprehends directional response to road inputs. This response is primarily a function of the roadway's frequency content and amplitude and the vehicle's inertial, suspension and tyre characteristics. There is also evidence that suspension kinematic and compliance steer properties can have a significant contribution (Rill, G. Steady state cornering on uneven roadways. SAE paper 860575, 1986). The multiple-bump roadholding test measures vehicle response to a periodic bump of varying frequency while cornering. By driving a vehicle at different speeds over a set of periodic bumps placed on circles of different diameters, it is possible to observe the response to different fundamental bump excitation frequencies at a particular lateral acceleration. This paper describes the test procedure, measured vehicle responses and the metrics calculated.