Study on Driver-In-the-Loop Test of a ESC Strategy

Abstract

With the shorter development cycle, how to validate and calibrate Electronic Stability Control (ESC) algorithm quickly, safely and reliably is more and more important. A Driver-In-the-Loop (DIL) test method is proposed for the development of ESC control strategy and calibration of the key parameters. It’s worthwhile from two aspects, the subjective evaluation from DIL is an important supplement for ESC. On the other hand, the result of DIL test is closer to the real vehicle conditions. In this paper, a hierarchical ESC controller is presented based on the regulation of yaw-moment firstly. In the upper controller, the yaw rate control module, vehicle slip angle control module and engine control module is designed respectively to determine the desired yaw-moment based on the estimation of the vehicle steering state. Then, the additional yaw moment is coordinated by the yaw moment from the yaw rate control module and vehicle slip-angle control module in the arbitration module. While in the lower controller, the braking wheel is selected first and desired wheel longitudinal force is obtained. Then, the desired wheel slip is calculated by estimation of wheel state and achieved by wheel-slip tracking. Finally, ESC control strategy is verified and calibrated by DIL and Model-in-the-loop (MIL) based on a NI PXI platform which consists of four parts: hardware system of ESC, signal acquisition and execution system, target computer and host computer. The comparative tests are implemented respectively according to the specification of ISO 3888 DLC with high/low-mu friction road and ISO 19364 steady-state circular test with low-mu road. The test results show that ESC control strategy meets the performance requirements of vehicle handling stability, and the calibration of controller’s key parameters can be implemented quickly through subjective evaluation considering the real driver’s behavior responses. Hence, the DIL test method provides more details approaching real vehicle test.