This paper discusses an improved design of vehicle-based mobile terrain profile measurement system that
derives the terrain profile by combining information from several different sensors measuring distance,
altitudes and position. The main challenge of the measurement system design is to derive the instantaneous
dynamic motion of the platform vehicle in order to correct the direct profile elevation measurement from a
set of laser optical sensors. By processing the velocity and attitude data from an Inertial Measurement Unit
(IMU) and the absolute position data from a Global Positioning System (GPS), a Kalman Filter/Smoother
algorithm is utilized in this sensor fusion application as a key step to obtain an accurate measurement of the
platform vehicle's dynamic motion. Through the implementation of this approach, not only is a high
accuracy of measurement during short-time vehicle dynamic motion achieved, the algorithm also
eliminates a sensor drift problem associated with the long term stability of the measurement system. The
hardware and software prototype of this design have been implemented, and initial field tests show that the
methodology has achieved good measurement accuracy.
The article presents the results of a large scale design space exploration for the hybridization of two off-road vehicles,
part of the Future Tactical Truck System (FTTS) family: Maneuver Sustainment Vehicle (MSV) and Utility Vehicle (UV). Series hybrid architectures are examined.
The objective of the paper is to illustrate a novel design methodology that allows for the choice of the optimal values of several vehicle parameters. The methodology consists in an extensive design space exploration, which involves running a large number of computer simulations with systematically varied vehicle design parameters, where each variant is paced through several different mission profiles, and multiple attributes of performance are measured. The resulting designs are filtered to choose the design tradeoffs that better satisfy the performance and fuel economy requirements. At the end, few promising vehicle configuration designs will be selected that will need additional detailed investigation including neglected metrics like ride and drivability.
Several powertrain architectures have been simulated. The design parameters include the number of axles in the vehicle (2 or 3), the number of electric motors per axle (1 or 2), the type of internal combustion engine, the type and quantity of energy storage system devices (batteries, electrochemical capacitors or both together).
An energy management control strategy has also been developed to provide efficiency and performance. The control parameters are tunable and have been included into the design space exploration.
The results show that the internal combustion engine and the energy storage system devices are extremely important for the vehicle performance.
A terrain severity measurement system utilizing non-contact optical scanning laser technologies employed in on-road profiling has been developed to make detailed measurements of the relative smoothness of all types of terrain from paved roads to extreme off-road conditions. The objectives included operation in all climatic conditions, simplified operation, and rapid availability of data. Accelerometers and inclinometers are used to measure laser sensor movement in order to eliminate measurement errors due to vehicle pitch and roll. A GPS receiver is used to correlate terrain profile information to position and elevation data. The end result is an accurate description of the longitudinal and lateral terrain profile that can be used to characterize the terrain and within vehicle modeling and simulation programs.
A large scale design space exploration can provide valuable insight into vehicle design tradeoffs being considered for the U.S. Army’s FMTV (Family of Medium Tactical Vehicles). Through a grant from TACOM (Tank-automotive and Armaments Command), researchers have generated detailed road, surface, and grade conditions representative of the performance criteria of this medium-sized truck and constructed a virtual powertrain simulator for both conventional and hybrid variants. The simulator incorporates the latest technology among vehicle design options, including scalable ultracapacitor and NiMH battery packs as well as a variety of generator and traction motor configurations. An energy management control strategy has also been developed to provide efficiency and performance.
A design space exploration for the family of vehicles involves running a large number of simulations with systematically varied vehicle design parameters, where each variant is paced through several different mission profiles and multiple attributes of performance are measured. The resulting designs are filtered to remove dominated designs, exposing the multi-criterial surface of optimality (Pareto optimal designs), and revealing the design tradeoffs as they impact vehicle performance and economy. The results are not yet definitive because ride and drivability measures were not included, and work is not finished on fine-tuning the modeled dynamics of some powertrain components. However, the work so far completed demonstrates the effectiveness of the approach to design space exploration, and the results to date suggest the powertrain configuration best suited to the FMTV mission.