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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 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.

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.

In March of 1995, the University of Texas at Austin Center for Electromechanics (UT-CEM) began work on developing active suspension control algorithms for four-wheeled, off-road, rough terrain, vehicles. To serve as a test platform to validate simulations, a four corner test-rig, representing a military HMMWV at one third scale, was designed and fabricated. Multiwheel control algorithms were developed, based on single wheel concepts previously described in SAE publications. The four-wheel test-rig performance compared well with single wheel test-rig performance, showing that the active suspension concepts developed by UT-CEM, which do not require advanced terrain knowledge (i.e., no “look-ahead”), are compatible with full vehicle control.

Researchers at The University of Texas Center for Electromechanics recently completed design, fabrication, and preliminary testing of an Electromagnetic Active Suspension System (EMASS). The EMASS program was sponsored by the United States Army Tank Automotive and Armaments Command Center (TACOM) and the Defense Advanced Research Projects Agency (DARPA). A full scale, single wheel mockup of an M1 tank suspension was chosen for evaluating the EMASS concept. The specific goal of the program was to increase suspension performance so that cross-country terrain could be negotiated at speeds up to 17.9 m/s (40 mph) without subjecting vehicle occupants to greater than 0.5 gee rms. This paper is a companion paper to a previous SAE publication [1] that developed suspension theory and control approaches. This paper focuses on hardware implementation, software implementation, and experimental results.