2. Cornering Analyses

You use Driving Machine cornering analyses to evaluate your vehicle’s handling and dynamic response. Cornering analyses combine open- and closed-loop controllers of the steering, throttle, brake, gear, and clutch signals to perform complex analyses on your vehicle.

The cornering analyses include:

Braking in a turn - This is one of the most critical analyses encountered in everyday driving. The purpose of this analysis is to examine path and directional deviations caused by sudden braking during cornering. Typical results collected from the braking-in-turn test include lateral acceleration, variations in turn radius, and yaw angle as a function of longitudinal deceleration.

In a braking-in-turn analysis, the Driving Machine drives your full vehicle down a straight road, turns onto a skidpad, and then accelerates to achieve a desired lateral acceleration. Once the desired lateral acceleration is reached, the Driving Machine holds the longitudinal speed and radius constant for a time to let any transients settle. Then, it locks the steering wheel and brakes your full vehicle at a constant deceleration rate. It maintains the deceleration rate for a given duration or until the vehicle speed drops below 2.5 meters/second.

You can use the plot configuration, mdi_fva_bit.plt, in the shared ADAMS/Car database to generate the plots that are typically of interest for this type of analysis.

Constant radius cornering - For constant radius cornering analysis, the Driving Machine drives your full vehicle down a straight road, turns onto a skidpad, and then gradually increases velocity to build up lateral acceleration. One common use for a constant radius cornering analysis is to determine the understeer characteristics of the full vehicle.

Cornering with steer release - The vehicle performs a dynamic constant-radius cornering to achieve the prescribed conditions (radius and longitudinal velocity or longitudinal velocity and lateral acceleration). After the steady state prephase, the steering wheel closed-loop signal is released, simulating a release of the steering wheel. The analysis focuses primary on the path deviation, yaw characteristics, steering wheel measurements, roll angle, roll rate, and side-slip angle.

Lift-off turn-in - The purpose of this analysis is to examine path and directional deviations caused by suddenly lifting the throttle pedal during cornering and applying an additional ramp steering input.

Power-off during cornering - A steering controller drives the vehicle around a skid pad. When the prescribed conditions are achieved, the steering wheel is locked and the throttle demand is decreased to zero. This analysis allows you to determine the power-off effect on course holding and directional behavior of a vehicle whose steady-state circular path is disturbed by throttle power-off.

Typical results collected from the power-off cornering analysis include variations in the heading direction and longitudinal deceleration, as well as sideslip angle, yaw angle and gradient. Optionally, the clutch can be depressed during the throttle lift-off. In this case, you specify the duration that is takes to depress the clutch.