''The problems with many of the ATVs and utility vehicles out there today are that they're unsafe, unreliable and uncomfortable when driving over rough terrain,'' says Will Myers, Director of Engineering for a vehicle design firm called Zeus.

Whereas some design engineers densely pack performance into their vehicles at the expense of drivability and reliability, Zeus is adept at consistently overcoming the myriad obstacles involved in compact vehicle design, producing fresh perspectives on automotive systems and delivering superior vehicle dynamics in small off-road machines.

While juggling the run-of-the-mill design challenges, Myers and the rest of the Zeus team also must combine their resources to solve problems with respect to packaging systems in narrow compartments, modifying components for off-road performance, procuring parts for prototypes and facilitating occupant comfort and safety.

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Zeus employs state-of-the-art software throughout the design process, including SolidWorks, Visual Nastran, COSMOS and proprietary programs developed in-house.

SolidWorks is instrumental for forming the initial shapes to represent the basic geometry of the vehicle and later to create various 3D solid models of various components and systems.

Visual Nastran, which integrates with SolidWorks, simulates real motion of mechanisms for analyzing structure, vehicle dynamics and kinematics.

COSMOS, a specialized finite element analysis (FEA) program, is helpful in identifying high- and low-stress areas on a part given a specific set of conditions.

Finally, Zeus uses a combination of commercially available software and custom-developed programs to define and optimize the vehicle suspension and drivetrain for a controlled ride and safe handling off-road.

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Guided by a design specification from the Office of Naval Research (ONR) and the Marine Corps Vehicle Group, Zeus is in its second year of a contract to design and build a prototype of a V-22 aircraft-transportable vehicle that is 60 inches wide, 60.2 inches tall and less than 200 inches long.

To meet such tight constraints, Zeus uses solid modeling to package all of the necessary components efficiently within the vehicle.

''What makes our vehicle unique from a powertrain layout standpoint is that we were able to maximize our suspension travel and keep four-wheel drive in a compact space,'' reveals Design Engineer Hayden Barr.

''Typically, you have to make a trade-off,'' continues Barr. In a vehicle that powers all four wheels simultaneously, the design must allow the wheels to rotate at different speeds, especially as the vehicle rounds curves, so each powered shaft needs a differential to distribute power between the left and right sides.

''Had we used a production differential to one side of the engine on the front end, we would have had a hard time getting any suspension travel at all because there would be a much shorter half-shaft on one side than on the other,'' he describes.

''We had a custom differential made with an offset drive, essentially allowing us to achieve a high suspension travel to track width ratio, and use inexpensive off the shelf CV axles and propshafts.''

While the LS-MEV is powered by a turbocharged 164 hp diesel engine, Zeus has considered the use of electric propulsion. As a compact vehicle design firm, Zeus is continually reviewing new ways to save space or use allotted space more effectively, and electric systems lend the ability to flexibly configure the drivetrain. A diesel electric drivetrain is a necessary step in Zeus's forward push towards more compact designs.

The military will evaluate the ONR vehicle as a Light-Strike Medical Evacuation Vehicle, so the Zeus team took special precautions in the design to ensure optimal performance in the field. With wheel travel measuring 10 inches in front and in back, the vehicle can absorb the large bumps that accompany severe, broken or rugged terrain for a comfortable ride.

In addition to a four-wheel independent suspension and high power density engine, the vehicle has front and rear disk brakes, two-piece wheels and constant ground clearance regardless of payload.

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However, custom-designing a prototype that is unlike anything else currently available in the market—from scratch, no less—calls for collective ingenuity that must carry over into the build process. ''Every part that we put on the vehicle is modified,'' remarks Design Engineer Troy Canalichio. ''The vehicle is required to climb a 60% grade, so we had to modify the oil pan and pick-up tube to make sure the engine would not be starved of oil during a climb.'' Myers relates, ''One of the major challenges is that there are a lot of companies that make all kinds of parts for smaller cars and off-road cars, including accessories and things like that. When building the prototype, we have to research and find appropriate vendors. After we find them, we have to determine whether their cost and quality are adequate for what we need.''

Because Zeus orders components in very small quantities at one time, many suppliers withhold discounts or flat out refuse to furnish bids. ''Most times we're only ordering for one to five prototypes,'' he says.

While each engineer on the project team has assigned vehicle systems and is responsible for coordinating the purchase of all corresponding parts, there is one engineer responsible for purchasing all machined parts.

Another engineer has the charge of buying all sheet metal parts, and a third engineer is dedicated to ordering all fasteners. Using web resources and choosing from up to a dozen competitive bids for an individual component, Zeus maintains a stocked inventory of supplies for building its mock-ups and prototypes.

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Comfort, Safety and Reliability

Between the design and build processes, Zeus constructs a wooden vehicle mock-up using plywood, foamcore and selected hardware to simulate the basic structure and mechanical components such as pedals, steering wheel and other controls. The mock-up gives an accurate representation of the vehicle's cabin and gives a true-to-life context for looking at the ergonomics, or human factors engineering, of the proposed design. Working with such a compact envelope requires meticulous studies when determining the exact placements of the seats, pedals, steering column components, etc. Everything from the dash configuration to the gauge height has an effect on operator comfort and safety. Zeus places great emphasis on designing ergonomically sound systems. By taking into consideration both the strengths and weaknesses of the human and mechanical components of the vehicle during use, Zeus can reduce occupant fatigue, promote ease of use and ensure a comfortable safe ride in the field. Founded on a safety platform, Zeus consults with automotive safety experts and biomechanists when designing passenger restraint systems such as protective bars and seatbelts. For superior safety performance, the LS-MEV not only features shoulder harnesses similar to those typically seen in racecars but also boasts a ''smart suspension'' system for a smooth, computer-controlled ride. ''The computer actively changes the spring stiffness and damping, adjusting to the loading conditions that it senses,'' declares Canalichio.

Regardless of payload and a narrow track width, the vehicle is able to sustain an optimized, stable ride due to the built-in automated airbag suspension and magnetorheological shocks.

Although the challenges of compact vehicle design are numerous, with each new solid model or slightly modified component, with every system design breakthrough or fully assembled prototype for testing, Zeus is drawing closer and closer to a smaller, more powerful, better performing ''perfect'' design for the off-road user.

Myers puts simply, ''We're trying to provide performance safety, reliability and comfort in one vehicle that is small enough to go where full-size vehicles cannot go.''

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Contact Will Harvey at info@gozeus.com or 479.439.6110, x111, to request additional information about specific models.