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Development of On-board Weight and Center of Gravity Measurement System for Tactical Vehicles


OBJECTIVE: The objective of this effort is to develop an innovative, cost-effective and reliable on-board weight and center of gravity (W & CG) measurement system for tactical vehicles. DESCRIPTION: Tactical wheeled vehicles routinely carry payloads of varied configurations to support the operating forces"diverse missions. To ensure safety while maximizing payload capacity, it is imperative that the system weight and center of gravity (W & CG) be accurately and conveniently determined. During transport, appropriate W & CG need to be maintained to avoid overloading a vehicle"s axles or lift and tie-down restraints. Similarly, W & CG data is necessary to preserve a vehicle"s dynamic stability during operation. As an example, the vehicle"s W & CG, particularly vertical and lateral CG, need to stay below a certain limit to prevent rollover or braking failure. Additionally, for a vehicle equipped with a stability control or warning system, accurate W & CG data are required for the system to function effectively. Current methods to determine W & CG for tactical vehicles involve the use of truck scales, weight tables, and suspension methods for CG. However, these are not field-expedient and often inconvenient if not inaccurate or incomplete. Truck scales, for instance, are not readily available to the operating forces except at selected ports or maintenance facilities. The scales alone also do not provide vertical and lateral CG. Computing a system"s W & CG using literature is limited by the availability of highly specific data on a respective system"s CG as well as the relative positions of payloads. The later may need to be measured on-site. Suspension or other similar methods to determine CG typically have to be carried out by skilled technicians in a properly instrumented facility, e.g., Aberdeen Test Center. These currently available methods limit the availability of reliable W & CG data, which greatly affects the Marines"ability to safely optimize payloads. Presently, technologies exist that could effectively automate the collection of some W & CG data. Commercially available systems such as Onboard Truck Scales (Ref 1) offer to provide on-demand weight information using a network of pressure or strain sensors attached to a vehicle"s suspension system. More advanced systems, such as those proposed for on-board aircraft weight and balance apparatus (Ref 2) could, in addition to weight, compute longitudinal and lateral CG using additional load and incline sensors along with a suitable computer algorithm. For vertical CG, which remains challenging to measure, there are potential approaches that involve using dynamic input, e.g., system axial accelerations, and analyzing system modal frequencies (Ref 3). These advances present opportunities to develop a novel and effective W & CG measurement system; however, considerable technical challenges remain. Most notably, on-board CG measurement technology, particularly for vertical CG, is still in early stage of development and primarily intended for aircraft use. More research and development are needed to fully mature or expand these concepts, and adapt them to military vehicle applications. The US Marine Corps seeks innovative approaches toward the development of an on-board system to measure weight and longitudinal, lateral, and vertical CG of tactical vehicles (Ref. 4-5). Proposed concepts should include necessary hardware, software, and user interface to enable automatic, real-time or near real-time capturing and reporting of W & CG. The measured W & CG should be within 3% of the vehicle actual W & CG. Additionally, the research and development should address system robustness against military vehicles environmental and operational conditions (Ref. 4-5) Proposals that address a low maintenance and acquisition cost, simplicity in design and operation, employ open architecture design principles, and demonstrate as ease of integration into the host vehicle are of a particular interest. PHASE I: The company will develop concepts for an on-board W & CG measuring system for tactical vehicles. Using a Medium Tactical Vehicle Replacement (MTVR, Ref 4-5) as the baseline platform, demonstrate analytically and/or experimentally the system can automatically measure and report the vehicle"s weight and center of gravity in real or near-real time. Provide a Phase II development plan with performance goals and key technical milestones, and that will address technical risk reduction. PHASE II: Based on the results of Phase I and the Phase II development plan, develop a detailed design and performance specification. Fabricate a prototype system and demonstrate experimentally that target performance is met at different payload configurations. Demonstrate experimentally that the prototype system can withstand the vehicle specified environmental and operational conditions. Evaluation results will be used to refine the prototype into an initial design that will meet Marine Corps requirements. Prepare a Phase III development plan to transition the technology to Marine Corps use. PHASE III: If Phase II is successful, the company will be expected to support the Marine Corps in transitioning the technology for Marine Corps use. Collaborate with government and industry partners to produce and integrate the W & CG system in a tactical vehicle (MTVR) for evaluation to determine its effectiveness in an operationally relevant environment. Demonstrate manufacturability and cost reduction. Support the Marine Corps for test and validation to certify and qualify the system for Marine Corps use. PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: The technology can be applied to civilian trucks and other commercial fleets to maximize load-carrying capacity while maintaining or enhancing transport and operation safety.
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