ABSTRACT Advanced powertrain test, which is simulating real road load condition, was performed on the dynamic test bed. This cutting edge system can reproduce real road resistance based upon the vehicle dynamic model and wheel slip model. This wheel slip function is simulating the real behavior of the powertrain wheel as close as possible at each wheel independently. Additionally, low inertia of dynamometer motor themselves is another advantage for this purpose. This test bed is capable of testing all kinds of 2WD and 4WD powertrain configuration regardless of transmission type. Also, vehicle configuration can be mounted and tested on this test bed with small addition of supporting system alternatively. For the application, a four wheel drive powertrain was mounted on the test bed and driveline noise and vibration behavior such as transfer rattling noise and tip in/out shock were reproduced on this test bed. For validating these tests, torsional vibration behavior was measured at both the powertrain/vehicle on the test bed and the vehicle on the real road respectively and their similarity will be shown. As another application, 4WD driveline performance tests were done on this test bed and on the real road such as 12% roller lane test and climbing start from rest on the 33% hill. Their identical behavior of speed and torque of each wheel shows the usefulness of these powertrain tests. On the basis of reproducing various driving modes, successful correlation between powertrain test and vehicle road test could be accomplished and these innovative results shed the light on the possibility of powertrain front loading development,which can provide us the opportunity to save development time/cost and to increase the reliability of the powertrain in earlier stage or before the start of vehicle development. 1. INTRODUCTION Road load bench test has been an important issue for powertrain developing engineers for predicting the behavior of engine and transmission when they mounted on the vehicle in spite of non-negligible differences with real road test results. However, as the technologies of electrical motor and its control are advanced rapidly, gaps between the result from bench test and that from the vehicle test are getting lower and lower. Moreover, combination of analysis skills with them makes closer road load simulation which can perfectly reproduce the actual driving condition than before. These days, advanced powertrain test bed systems and upgraded vehicle models are combined together. In this paper, the definition of highly dynamic test bed, their control strategies and the way how they can simulate real road load condition will be explained. As an application example, NVH and driveline performance of 4WD powertrain tests will be presented with their test processes and accompanying results which are validating the powertrain test. Vehicle test result will be added for showing the successful correlation with the powertrain test results. These cutting edge powertrain tests can provide us the chance to restructure the development process of powertrain and vehicle through moving the large amount of development actions to the earlier stage before building the proto type vehicle. At the end of this paper, Front Loading NVH Test on the Highly Dynamic Powertrain Test Bed2011-01-1512 Published 05/17/2011 Jaegon Yoo Hyundai Motor Company Klaus Pfeiffer AVL LIST GmbH Koo-Tae Kang Hyundai Motor Company Copyright © 2011 SAE International doi:10.4271/2011-01-1512Downloaded from SAE International by University of British Columbia, Thursday, August 02, 2018future application will be mentioned in wide range of vehicle development. 2. MAIN SUBJECT 2.1. HIGHLY DYNAMIC POWERTRAIN TEST BED Figure 1. Powertrain configuration on the test bed 2.1.1. Descriptions of Test Bed When the dynamometer has the capable of changing their speed faster than 10,000 rpm per second, this system can be called dynamic. Also, it can be called highly dynamic, if it