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The University of Texas at Austin Center for Electromechanics (UT-CEM) has been developing advanced suspension technology for high-speed off-road applications since 1993. During the course of the program, advanced simulation techniques, verified by hardware demonstrations, were developed and refined. Based on this experience, UT-CEM conducted a detailed simulation-based comparison of passive, semi-active, and full-active suspension systems for an 18,000 kg (20 ton) 8 x 8 vehicle. Performance metrics are proposed to compare crew comfort, crew effectiveness, on-board equipment effectiveness, and power/energy consumption. This paper presents the methodology and rationale for metrics used in the study, simulation results, and data from this trade study. Results indicate significant advantages offered by well-designed active systems compared to both passive and semi-active, in all metrics.

The University of Texas Center for Electromechanics (UT-CEM) has been developing active suspension technology for off-road vehicles since 1993. The UT-CEM approach employs fully controlled electromechanical actuators to control vehicle dynamics and passive springs to efficiently support vehicle static weight. The project described in this paper is one of a succession of projects toward the development of effective active suspension systems, primarily for heavy off-road vehicles. Earlier projects targeted the development of suitable electromechanical actuators. Others contributed to effective control electronics and associated software. Another project integrated a complete system including actuators, power electronics and control system onto a HMMWV and was demonstrated at Yuma Proving Grounds in Arizona.

Lower battery voltage enhances electric vehicle safety. A homopolar traction motor operates at low voltage because of its low internal impedance, and delivers torque independent of speed. A 48 VDC multi-pass, iron core homopolar traction motor was designed, fabricated, and tested in the laboratory. A MOSFET pulse width modulated controller was also designed and tested. The motor weighed 227 kg and used solid copper-graphite brushes. Laboratory testing of the motor verified the current-torque characteristic, but high brush wear prevented full speed and power demonstration. System studies show that a hybrid Ward-Leonard drive using a similar motor could yield significant cost and weight savings and improved fault tolerance over a traditional EV architecture.