Road profile control methods for laboratory vehicle road simulators

The use of laboratory road simulators has become quite common in the automotive industry. Although laboratory road simulators have reduced testing time, two obstacles to improving process automation remain. First, since traditional simulation control parameters are specimen dependent, new data must be acquired for each specimen to ensure accurate test results, significantly adding to the time and cost of the testing process. The second impediment is that current simulator control is achieved using an open-loop iterative process, which is time consuming, requires a skilled test engineer, and cannot account for changes in the test vehicle´s parameters due to design evolution or suspension degradation as the durability test proceeds. This paper will demonstrate two major process improvements in road simulator control. The first is a method to reduce the need for new data to be acquired to account for vehicle configuration changes. This will be accomplished by including a model of missing dynamics, specifically the tire, in the control loop to enable road-profile simulation control. The second improvement involves the demonstration of an improved on-line control process using an H-infinity approach that allows for frequency dependent weightings to represent sensor noise W_n, and model uncertainty W_u. Performance will be specified by the weighting W_e