32 | SIMPACK News | March 2014 SIMPACK News | March 2014 | 33

CUSTOMER APPLICATION | Liu Wei, Vehicle Engineering, Qingdao University

Modeling, Simulation and Dynamic Analyses of a Closed Single-Track Vehicle

The need for mobility and transpor-tation are becoming increasingly important. More energy-efficient trans-portation options — including electric vehicles — are being developed to meet the performance demands of today’s clients. The Monotracer is a comfortable single-track electric vehicle protected from weather and accidents by a closed cabin.This study focuses on the Monotracer. It will illustrate the fundamentals of driv-ing dynamics for this single-track vehi-cle, and reproduce them in a simulated model. At a later stage in the project, the pendulum and oscillating behavior

of the Monotracer at low speeds will be analyzed.

BACKGROUND AND KEY PROJECT CHALLENGES At its current stage of development, the Monotracer exhibits oscillating motions at low speeds on straight roads. The driver can feel these vibrations, particularly through the handlebars. The strength of the vibra-tion depends on the vehicle’s speed; the slower the Monotracer goes, the greater the amplitude of the pen-dulum motions. The strongest oscillations occur between 30 km/h and 50 km/h. At 60 km/h, the Monotracer stabilizes itself and drives straight without oscillating behavior.

Such oscillations are observed in typical motorcycles only at very high (> 250 km/h) or very low speeds (< 12 km/h).

GOALS AND OBJECTIVES In cooperation with the FHNW University of Applied Sciences and Arts Northwestern Switzerland, a simulation-capable model of the Monotracer was created and validated.

Vehicle parameters were also important, and had to be defined accordingly. Perfor-mance tests were also

necessary to define the model. With these, the driving dynamics simulations of the program could be optimized and adapted to the program. Through such processes, the influence of geometry on driving be-

“...a simulation-capable model of the Monotracer was created and validated.”

Fig. 1: Peraves AG Monotracer

test, test and control system included four acceleration sensors, A/D and D/A boards, a dSPACE Auto-Box control system with the control software, four MR dampers and four electronic current drivers, and a data acqui-sition instrument. The acceleration sensors were adopted to measure the accelerations at various points on the front and rear sus-pensions. The data acquisition instrument used in the ride comfort test is shown in Fig. 17. The location of acceleration sensors placement is shown in Fig. 18.When vehicle speed reaches 80 km/h on a random highway road, the vertical accel-

eration of front and rear sprung masses are shown in Figs. 19, 20, 21 and 22 (the red line showing the passive suspension, and the green line the semi-active suspension).The handling stability testing of the light bus with semi-active suspensions is shown in Fig. 23. In addition to the testing instru-ments used in the ride comfort experiment, a gyro was used to test the heeling angle and yaw angular velocity of the vehicle body. In the handling stability test, six stakes were laid out on the test site (30 m spacing), and the test bus passed through all stakes at a constant speed of 50 km/h (shown in

Fig. 23).The heeling angle and yaw angular velocity of the vehicle body is shown in Figs. 24 and 25 (the red line show-ing the passive suspension, and the green line the semi-active suspen-sion). As seen from these figures, the semi-active controller applied on MR dampers effectively reduces the roll and yaw motions of the vehicle body, and the effect of semi-active suspen-sion is reflected in the handling stabil-ity test.

CONCLUSIONThe ride comfort and handling stabili-ty results confirm that the semi-active controller based on a neural network can effectively suppress the vertical vibration of the suspension and the heave, pitch and roll motion of the vehicle body. The conflict between ride comfort and handling stability can be solved, and both aspects can be improved simultaneously.

REFERENCES[1] Alex, R. and Wang, P. Z., “New Resolu-tion of Fuzzy Regression Analysis,” Pro-ceedings of the IEEE International Confer-ence on Systems, Man and Cybernetics, vol. 2, pp. 2019–2021, 1998.

[2] Kazemian, H.B., “Developments of Fuzzy PID Controllers,” Expert Systems, vol. 22, no. 5, pp. 254–264, 2005.[3] Peng, B.B. and Huang, X.Q., “A Simulation Test Method for a Half Semi-active Vehicle Suspension Based on the Hierarchical Modeling Method,” 2006 IEEE International Conference on Vehicular Electronics and Safety, ICVES, pp. 63–67, 2006.[4] Cong, S. and Liang, Y., “PID-like Neural Net-work Nonlinear Adaptive Control for Uncertain Multivariable Motion Control Systems,” IEEE Transactions on Industrial Electronics, vol. 56, no. 10, pp. 3872–3879, 2009.[5] Hahm, D., Koh, H.-M., Ok, S.-Y., Park, W., Chung, C. and Park, K.-S., “Cost-effectiveness Evaluation of MR Damper System for Cable-stayed Bridges Under Earthquake Excitation,” Proceedings of the 3rd International Conference on Bridge Maintenance, Safety and Manage-ment — Bridge Maintenance, Safety, Manage-ment, Life-Cycle Performance and Cost, pp. 301–302, 2006.[6] Guo, A.X., Cui, L.L. and Li, H., “Structural Control of Seismically Induced Pounding of El-evated Bridges by Using Magnetorheological Dampers,” Proceedings of the 3rd International Conference on Bridge Maintenance, Safety and Management — Bridge Maintenance, Safety, Management, Life-Cycle Performance and Cost, pp. 685–686, 2006.[7] Ramli, R., Pownall, M., Levesley, M. and Crolla, D.A., “Dynamic Analysis of Semi-active Suspen-sion Systems Using a Co-simulation Approach,” Multi-Body Dynamics: Monitoring and Simulation Techniques-III, pp. 391–399, 2004.[8] Lee, S.H. and Hwang, Y.S., “A Study on a Sce-nario Using the PID Method,” Progress in Nuclear Energy, vol. 51, no. 2, pp. 253–257, 2009.[9] Hong, S. R., Wereley, N. M., Choi, Y. T. and Choi, S.B., “Analytical and Experimental Valida-tion of a Nondimensional Bingham Model for Mixed-mode Magnetorheological Dampers,” Journal of Sound and Vibration, vol. 312, no. 3, pp. 399–417, 2008.[10] Guo, Shuqi, Li, Shaohua and Yang, Shaopu, “Semi-active Vehicle Suspension Systems with Magnetorheological Dampers,” 2006 IEEE Inter-national Conference on Vehicular Electronics and Safety, ICVES, pp. 403–406, 2006.[11] Bouc, R., “Forced Vibration of Mechanical System with Hysteresis,” Proc., 4th Conf. on Non-linear Oscillation, Prague, Czechoslovakia, 1967.[12] Wen, Y. K., “Method for Random Vibration of Hysteretic Systems,” Journal Engineering Me-chanics, ASCE, 102, pp. 249–263, 1976.[13] Spencer, B. F., Jr., Dyke, S. J., Sain, M. K. and Carlson, J. D., “Phenomenological Model of a Magneto-rheological Damper.” Journal of En-gineering Mechanics, ASCE, 123, pp. 230–238, 1996.

Fig. 24: Heeling angle data of handling stability test(red = passive, green = semi-active)

Fig. 23: Handling stability test

Fig. 25: Yaw angular velocity data of handling stability test (red = passive, green = semi-active)

0.00 25.00

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Thomas Dreier, University of Applied Sciences and Arts Northwestern Switzerland, Institute of Automation | CUSTOMER APPLICATION

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34 | SIMPACK News | March 2014 SIMPACK News | March 2014 | 35

CUSTOMER APPLICATION | Thomas Dreier, University of Applied Sciences and Arts Northwestern Switzerland, Institute of Automation Thomas Dreier, University of Applied Sciences and Arts Northwestern Switzerland, Institute of Automation | CUSTOMER APPLICATION

havior could be examined. At the end of the project, a functionally compatible model of the Peraves AG Monotracer MTE-150 was created, with which the driving behavior of a given driving situation could be simulated. This main goal was broken down into parts: Monotracer stabilization, modeling, and driving dynamics tests of oscillation.

PHYSICAL STABILIZATION THEORY OF A SINGLE-TRACK VEHICLE Vehicle stabilization is an important compo-nent of the dynamic pendulum motion testing on the Monotracer. The basic stabilizing moments of a motorcycle are the result of the centrifugal forces of the spinning wheels. All stabilizing moments can be derived from these forces. The cen-trifugal force results from the inertia and rotational speed of the rotating wheel. In accordance with stabilization theory, a motorcycle moves straight as long as the moments gener-ated through struc-tural measures do not exceed the stabilizing gyroscopic moment.

MONOTRACER MODELThe model for the project was very simple. It was created with the additional

Fig. 2: Steering behavior of the Monotracer on a straight road with released handlebar; test speed 40 km/h

Fig. 3: Monotracer model in SIMPACK

SIMPACK licenses Automotive and Delft MF-Tyre/MF-Swift 6.1.2. The model consists of a chassis similar to a CAD drawing of the original Monotracer, the handlebars which have the form of the original CAD drawing, and the front and rear tires (Fig. 3). The cor-responding Force Elements have also been

included. Two wheel dampers were cre-ated in the model. The wheels also included wheel/ground contacts. For the validation, different lateral impacts and steering angles were simulated. General parameters are defined as part of the modeling process. Among the most important parameters are mass and the inertia of various components. Videos from test drives were analyzed to determine the vehicles movement on a straight road. By the end, a model was created that expresses the driving dynamics characteristics of the examined motorcycle.

DYNAMIC TESTS WITH THE MODELDynamic tests are an important aspect of this project. The questions of where the pendulum oscillations at low speeds come from, or how they can be reduced, can now be studied through various theses and experiments performed on the model. The dynamics of a motorcycle are determined by the overall structure: from the entire system’s geometry, inertia and wheels.

Therefore, the oscillations could be originating from a number of places, and it is unlikely that the properties of each individual piece could

be understood and physically accounted for. For these reasons, a simple model was

“..., measure to suppress the pendulum vibration

could be found.”

Fig. 4: 2D-view of the model

Fig. 5: Influence of the head angle on vibration

Fig. 6: Influence of the total weight on oscillation; the red curve shows the relationship with half of the original mass

created that limited itself on account of the stabilization theory of the steering system and its components.The first experiment studied the influence of the pendulum by changing the steering geometry. With the movements of the head angle, the running of the tires and the entire steering system changed. The studies have shown that by reducing the head angle, pendulum oscillations become smaller, but cannot be eliminated altogether. The origin of the pendulum oscillations that exist at low speeds could not be determined by this investigation. Fig. 5 shows the vibration behavior of various head angles.The second experiment regards the mass distribution of the entire motorcycle. The pendulum oscillations of the Monotracer are, like the centrifugal forces of the individual wheels, dependent on speed. These parallels were studied. The centrifugal force of a wheel is defined at a constant speed, and the motorcycle must be stabilized with this force. If the vehicle is too heavy or the force is too small, the motorcycle will not be entirely stable (Fig. 6). This hypothesis was proved by two studies. For one, the inertia of the wheel was increased; for the other, the total system mass was reduced. Both tests had an eliminating effect on the Monotracer’s pendulum oscillations. RESULTSAll objectives for the project were met. The resulting model can be used for dynamic studies and corresponds to the original Monotracer. As a result of the studies conducted on the model, measures to suppress the pendulum vibration could be found. The increase in wheel inertia is one of the most important measures. Its impact on driving safety must be taken into account, as does the decrease in overall mass, which can be taken into consideration for further developments. In this way, the study demonstrated solutions for improving the dynamic behavior of the Monotracer.

REFERENCES[1] Cocco G.; translated by Schwarz, W.; "Motorrad-Technik pur : Funktion — Konstruk-tion — Fahrwerk", 2001.[2] Bayer B.; "Das Pendeln und Flattern von Krafträdern", Untersuchungen zur Fahrdynamik von Krafträdern unter beso, 1986. [3] SIMPACK AG; "SIMPACK Trainingmanual"; Automotive SIMPACK Training course.[4] Stoffregen J.; "Motorradtechnik. Grundlagen und Konzepte von Motor, Antrieb und Fahrwerk", ATZ/MTZ refenrence book, 2012.