A. M. Guenin

Electromechanical Active Suspension Demonstration for Off-Road Vehicles

The University of Texas Center for Electromechanics (UTCEM) has been developing active suspension technology for offroad 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 quartercar 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. Additionally, original projections of low power requirements for suspension actuators are being confirmed. The 3,400 kg (3.75 ton) vehicle being tested utilizes a 5 kW alternator to provide suspension power. Power conditioning circuits limit the continuous deliverable power to 4 kW, which corresponds to 1.2 kW/metric

Design and Performance Testing of an Advanced Integrated Power System with Flywheel Energy Storage

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.

Electromechanical Suspension Performance Testing

Abstract : Under contract DAAEO7-98-C-L020 testing was conducted at the U.S. Army Yuma Proving Grounds by the U.S. Army Tank-automotive and Armaments Command, Research, Development and Engineering Center and the University of Texas Center for Electromechanics during 8, 9, and 10 November 1999 between an active (electromechanical suspension) and passive High Mobility Multi-Purpose Wheeled Vehicle (HMMWV) to determine performance improvements. Two tests, RMS Courses and Lane Change Maneuver, produced the most complete performance results for Ride Quality and Maneuverability determination. For the Lane Change Maneuver, the active HMMWV has much less sprung mass (frame) acceleration, over 5 times reduction at higher speeds, than the passive HMMWV. For the active HMMWV, sprung mass acceleration remains mostly constant at around 0.1 gs to 55 MPH while the passive HMMWV shows noticeable increases, at times in excess of I g. For the RMS Courses, a comparison shows a 5 times reduction in absorbed power over courses 2 to 5 with the active HMMWV. The active HMMWV has much less sprung mass acceleration, over 4 times reduction at higher speeds, than the passive HMMWV. For the active HMMWV it remains mostly constant at around 0.75 gs to higher speeds while the passive HMMWV shows noticeable increases, at times in excess of 2 gs. Total peak power usage was in the range of 3 kW (RMS and Lane Change Maneuver Courses) and total peak regeneration in the range of 6 kW (RMS Courses) for the active suspension.

Dual Purpose Fuzzy Logic Controller for an Active Suspension System

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.