Design of an Open-Loop Steering Robot Profile for Double Lane Change Maneuver Using Simulation

This paper presents a methodology for designing a simple open-loop steering robot profile to simulate a double lane change maneuver for track testing of a heavy tractor/trailer combination vehicle. For track testing of vehicles in a lane change type of maneuver, a human driver is typically used with a desired path defined with visual cues such as traffic cones. Such tests have been shown to result in poor test repeatability due to natural variation in driver steering behavior. While a steering robot may be used to overcome this repeatability issue, such a robot typically implements open-loop maneuvers and cannot be guaranteed to cause the vehicle to accurately follow a pre-determined trajectory. This paper presents a method using offline simulation to design an open-loop steering maneuver resulting in a realistic approximation of a double lane change maneuver. A high fidelity tractor/trailer model with a closed-loop driver steering control model was used to investigate the steering input required to realize the double lane change maneuver. A piecewise linear profile was constructed to approximate the time history of the closed-loop steering input. This open-loop profile was simulated with the vehicle model to ensure that the trajectory was followed with sufficient accuracy. Several of the data points in the open-loop profile were tuned to ensure that the final vehicle trajectory matched the initial trajectory. Results of track testing with the tractor-trailer vehicle equipped with steering robot show that the designed open-loop maneuver produces a realistic double lane change path of the vehicle with a high degree of test repeatability. The steering robot was used to trigger the data acquisition system, thus enabling the additional benefit of direct comparison of results from multiple runs without the need for extensive post-processing of data for time correlation. Track testing also confirms that increasing the magnitude of the profile setpoints results in a double lane change maneuver of more than one lane width while still returning the vehicle to the approximate original trajectory. Open-loop double lane change tests were successfully conducted on a dry asphalt surface to generate roll instability up to wheel lift and on a wet Jennite surface to induce yaw instability.