Search Results

Battlefield reconnaissance is an integral part of today's integrated battlefield management system. Current reconnaissance technology typically requires land based vehicle systems to observe while stationary or, at best, significantly limits travel speeds while collecting data. By combining current Canadian Light Armored Vehicle based reconnaissance systems with the Center for Electromechanics (CEM) electronically controlled active Electromechanical Suspension System (EMS), opportunities exist to substantially increase cross-country speeds at which useful reconnaissance data may be collected. This report documents a study performed by The University of Texas Center for Electromechanics with funding from L3-ES to use existing modeling and simulation tools to explore potential benefits provided by EMS for reconnaissance on the move.

The University of Texas Center for Electromechanics (UT-CEM) has completed the successful design, integration and testing of a hybrid electric power and propulsion system incorporating a flywheel energy storage device. During testing, the improved drive train was shown to double acceleration rates while simultaneously reducing prime power usage in excess of 25% when compared to the same vehicle without the flywheel energy storage system. While the system was designed for and demonstrated on a transit bus, the technology described herein is applicable to a wide variety of applications, including additional mobile and marine power and propulsion systems. This paper (1) describes the drive train design with an overview of the critical components and (2) presents results from system-level testing of the transit bus with the integrated drive train.

As the need for energy storage increases on future hybrid electric vehicles, the desire for increased performance, energy/power densities, and component life increases proportionally. Flywheel batteries have demonstrated power density and life superiority over conventional chemical batteries; however, fears of unexpected and uncontained failures may prevent their widespread acceptance in the United States marketplace. The University of Texas at Austin Center for Electromechanics (UT-CEM) has designed, built, and tested a full-scale composite flywheel containment system for use in mobile applications. The flywheel containment system that will be described stems from an in-depth investigation into the type of faults that are most likely to occur in mobile applications. In all cases, the worst-case scenario results in a challenge to flywheel integrity; therefore, a comprehensive flywheel containment system is considered the “last line of defense” in protecting personnel and equipment.

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.

The use of a fuzzy logic controller for an active suspension system on a wheeled vehicle is investigated. Addressing the opposing goals of ride quality and bump stop avoidance are integrated into one control algorithm. Construction of the fuzzy rules base will be discussed comprehensively along with the membership function setup for both the input and output variables. Numerous quarter-car simulation comparisons will be performed of the fuzzy controller versus the standard skyhook damper controller. The comparisons will include a variety of terrain inputs. Laboratory testing of the fuzzy controller on a single wheel station system is also included.

The University of Texas Center for Electromechanics (UT-CEM) has been developing active suspension technology for off-road and on-road vehicles since 1993. The UT-CEM approach employs fully controlled electromechanical (EM) actuators to control vehicle dynamics and passive springs to efficiently support vehicle static weight. The program has completed three phases (full scale proof-of-principle demonstration on a quarter-car test rig; algorithm development on a four-corner test rig; and advanced EM linear actuator development) and is engaged in a full vehicle demonstration phase. Two full vehicle demonstrations are in progress: an off-road demonstration on a high mobility multiwheeled vehicle (HMMWV) and an on-road demonstration on a transit bus. HMMWV test results are indicating significant reductions in vehicle sprung mass accelerations with simultaneous increases in cross-country speed when compared to conventional passive suspension systems.

The University of Texas Center for Electro-mechanics (UT-CEM) has been developing active suspension technology for high-speed off-road applications since 1993. The UT-CEM system uses controlled electromechanical actuators to control vehicle dynamics with passive springs to support vehicle static weight. The program is currently in a full vehicle demonstration phase on a military high mobility multipurpose wheeled vehicle (HMMWV). This paper presents detailed test results for this demonstration vehicle, compared to the conventional passive HMMWV, in a series of tests conducted by the U.S. Army at Yuma Proving Grounds. Extensive data in plotted form are discussed, including accelerometer readings from 6 vehicle mounted accelerometers, corner displacement transducers, and current and power plots for the actuators.

The University of Texas at Austin Center for Electromechanics has developed an active suspension system that recovers, stores, and manages energy while actively controlling vehicle suspension activity. Tests described in this paper quantify increases in rolling resistance from flat to rough terrain, and demonstrate that active suspension systems can limit this increase to 50% of that experienced by passive suspension systems.

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.

The University of Texas at Austin Center for Electromechanics (UT-CEM) has conducted a set of simulations and full-scale experiments to determine suitable shock load design requirements for in-hub (wheel) propulsion motors for hybrid and all-electric combat vehicles. The characterization of these design parameters is required due to recent advancements in suspension technology that have made it feasible to greatly increase the tempo of battle. These suspension technologies allow vehicles to traverse off-road terrains with large rms values at greater speeds. As a result, design improvements for survivability of in-hub motors must be considered. Defining the design requirements for the improved survivability of in-hub motors is the driving factor for this research. Both modeling and experimental results demonstrate several realistic scenarios in which wheel hubs experience accelerations greater than 100g, sometimes at very low vehicle speeds.

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.