Disturbance compensation for iterative control of suspension durability test rigs

Endurance testing of the chassis, components and vehicle axles is a safety issue and therefore an essential part of the vehicle development process. In the automotive industry, durability experiments of vehicle axles are carried out in laboratories using multi-channel durability test rigs. The accurate load data replication of field measured data is important to obtain convincing durability results. Cross-coupling effects by channel interactions degrade the control accuracy of these rigs. Therefore, an iterative control method is applied to adapt all control inputs to compensate coupling induced disturbances. State-of-the-art processes require a high amount of test rig measurements to generate optimal control inputs which damage specimens preliminarily. In this article, a new method for disturbance compensation is presented. In the following, this method is compared to control input adaption without disturbance compensation and control input adaption with state-of-the-art disturbance compensation. All three methods are applied to an iterative control of a suspension rig and analyzed in terms of convergence speed, control accuracy and computational effort. The investigations revealed, that compensation methods generally increase the computational effort. The state-of-the-art compensation method became unstable for the considered steering maneuver while accurate control with fast convergence was achieved when applying the new compensation technique presented in this article. The significant increase of convergence speed justifies the additional computational effort compared to methods without compensation.