Designing A Baja Sae Vehicle 3-10-2007!7!12 24 Pm

SAE TECHNICAL PAPER SERIES

2000-01-2651

Rethinking the Design Paradigm: A Customer-Focused Approach to Designing a Mini-Baja Vehicle Brent Zollinger and Robert H. Todd Brigham Young Univ.

International Off-Highway & Powerplant Congress & Exposition Milwaukee, Wisconsin September 11-13, 2000 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A.

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2000-01-2651

Rethinking the Design Paradigm: A Customer-Focused Approach to Designing a Mini-Baja Vehicle Brent Zollinger and Robert H. Todd Brigham Young Univ.

Copyright © 2000 Society of Automotive Engineers, Inc

ABSTRACT This paper uses a case study to demonstrate how focusing on customer needs improves the success of product designs in the marketplace. A sampling of trends in modern design is presented, showcasing some methodologies that facilitate effective design. The work of the Brigham Young University mini-baja vehicle design team is studied. The team used a customer-focused design by developing the product specification directly from customer statements, and using matrices to evaluate the capacity of concepts to meet the specification. Lessons learned from the design process are considered.

INTRODUCTION A BYU Capstone design team—composed of mechanical and manufacturing engineers, engineering technologists, and an industrial designer—designed a vehicle for competition in the Mini-Baja West competition sponsored by SAE. Mini-Baja is an intercollegiate design competition where teams of undergraduate students design, build, and race a "one-person, four-wheeled, recreational vehicle [1]." The vehicles must be powered by an unmodified 5.97 kW (8-hp) engine and have a production cost of $2,500 or less if produced in 4,000 annual units. Vehicles are judged on sales, design, safety, and cost; they are also raced to determine performance capability in acceleration, hill climb, maneuverability, and four-hour durability. To ensure the vehicle would perform well in competition and be completed in time, structured design methods were used to define customer needs, create the product specification, and make conceptual design decisions. Detail design decisions were made using traditional design procedures. Design is a term that can connote a number of different meanings. New engineers often enter industry with the idea that design is only concerned with product function [2]. The product realization process (also known as total design and product design and development) is a catch phrase that refers to a holistic view of the design process. The term design in this paper refers to this holistic view. Design from this point of view is a cycle of

information processing and decision making with the objective of meeting the needs of customers and stakeholders throughout the entire product life cycle. The design is successful when it achieves a balance between factors—such as cost, performance specifications, tooling, ecology, etc.—which best meet the needs and wants of all the customers and stakeholders [3]. A good design concept has a tremendous effect on the overall success of the product. It is estimated that more than 70% of the life cycle cost of a product is determined by the design [4]. In 1991 the National Research Council published a report indicating, "The overall quality of engineering design in the United States is poor." And, "The best engineering design practices are not widely used in U.S. industry [4]." Engineering design in the U.S. lags behind competitors in addressing customer needs, decreasing lead-time, and accounting for the entire product life cycle, including manufacturing, customer use, disposal, and life cycle costs [5]. To stay competitive in coming years, practicing engineers will be required to rethink their design processes. They must become more involved in researching the needs and wants of customers and stakeholders (hereafter referred to as “customer needs”). It is hoped that the case study presented here will help practicing engineers understand the effects of focusing their design processes around meeting customer needs, and become familiar with some of the methodologies that can help facilitate this objective.

THE CUSTOMER FOCUSED DESIGN PARADIGM A large part of industry uses an outdated design paradigm, in which engineering designers act as problem solvers who optimize designs to meet specifications they have been given by others. Generally, they design inside their knowledge base, not considering a broad spectrum of alternatives. Frequently a mathematical model is used to decide upon values for design parameters. It is believed that the best possible design has been created because it has been optimized within the mathematical model. However, according to Pugh, over 95% of these designs fail in the market place [6]. His research indicates the vast majority of market failures occur

because the product specification does not accurately reflect customer needs [6].

dependent on the chosen judging criteria, and the weight that criteria are given [3].

The new customer-focused design paradigm encourages engineering designers to participate in market research, and consider a broad range of concepts. They focus efforts on identifying and meeting customer needs before optimizing design parameters. This type of work requires not only analysis, but also synthesis and creativity. Design engineers work concurrently with marketing and production specialists, continually striving to improve designs. Continuous improvement in design is desirable since an “optimum” design is never possible in a dynamic marketplace.

The design process used by the BYU team was adapted from Ulrich and Eppinger’s concept development model, as seen in Figure 1 [8]. The design process does not include steps for preparing tooling and production since only one vehicle, a prototype, would be made. The steps most critical for ensuring a customer-focused design were included. However, market research focused on competition requirements rather than consumer studies because our end market was more oriented to the SAE Mini-Baja West competition than the retail market.

Despite the large array of design strategies that attempt to simplify design processes into a series of calculations, design is still very much an intuitive and creative activity [7]. Many design considerations require the use of subjective judgement. Because of this, optimization techniques may create a false sense of security, since they often ignore or inaccurately reflect important subjective design parameters, and may miss some customer needs. Also, optimization requires complex systems to be broken down into smaller components. When the small components of design are optimized the result is suboptimization of those components, often at the expense of the design as a whole system. While optimization strategies are a key to good design, they must be used with wisdom. Generating revenue is the primary reason for designing and manufacturing products. Revenue increases as the customers’ perception of value increases. Meeting the needs of every potential customer is difficult, since the needs of individual customers often vary and may even change over time. A successful product must not just meet the needs common to most customers at the beginning of the design process; it must have a short lead-time and be versatile enough to meet the needs of a variety of customers, even as those customers may change. Remember, the term customer is not limited to the end user, but includes all product stakeholders, such as marketing, production, and legal departments, the environment, and so on.

THE DESIGN PROCESS

To ensure the success of a structured design methodology, care must be taken to foster an environment conducive to design. Providing ample time for team communication and empowering team members with applicable resources encourages effective teamwork. In interdisciplinary teams, each member should be a specialist in their field and have background knowledge spanning other design fields [2]. Figure 1: Design process model used by BYU Mini-Baja team. Adapted from Ulrich and Eppinger. BYU Mini-Baja Team Design Process Identify Customer Needs

Establish Specifications

Analyze Competitive Products

Generate Product Concepts

Select a Product Concept

Preliminary Analysis of Concepts

Detail Design of Concept

Advanced Analysis and Prototyping

The key to ensuring successful customer-focused design is using an appropriate design process. There are as many processes as there are design teams. Each company must establish and refine a process that works to meet their situation [4]. In all cases, product design is most effective when done in multidisciplinary teams. However, the development process may include any combination of design tools and strategies, such as 3-D modeling, DFX, QFD, life-cycle analysis, function morphology, selection matrices, FMEA, or Taguchi methods [2,4,8,9,10].

A CASE STUDY IN PRODUCT DEVELOPMENT: MINI-BAJA VEHICLE

The design methodology used by the BYU Mini-Baja design team focuses on satisfying customer needs. The customer needs identified by the team are a product of detailed market research, and must be converted into a product specification that accurately reflects those needs in order to ensure a successful design. Concepts are evaluated using screening and scoring matrices, which judge the capacity to meet those specifications. The quality of the concepts selected with matrices is

Developing skill in design is best learned through experience. Case studies are an effective way to help convey lessons learned through experience to students of design. There is a danger in learning design through case studies however, since they must be presented sequentially when documented, giving the reader the illusion that the design process is sequential rather than simultaneous and iterative [9]. The case study

Cost Analysis

presented here is used to showcase an example of one team's attempt to incorporate customer-focused design methodologies into the design process. The Brigham Young University 1999 Mini-Baja team used a customer-focused methodology to design an offroad vehicle for the SAE Mini-Baja West competition. Focus was placed on meeting customer needs by giving the multidisciplinary team of engineers the responsibility for performing market research. The team derived the product specification directly from the findings of their research. Concept generation and selection processes were focused on meeting the criteria required by the product specification. The early stages of the design process of the Mini-Baja vehicle provide an effective means of studying the impact of the customer-driven approach to design. Competition of the vehicle at the Mini-Baja West competition provides a mechanism for determining design strengths and weaknesses in a controlled “marketplace.” For the team to win the competition, they must understand the needs of this artificial “marketplace” and use a design process that is appropriate for the product and its market.

DEFINING CUSTOMER NEEDS The team’s main

design goal was to produce a vehicle that met all of the needs of the product stakeholders, especially the end user, BYU’s Mini-Baja racing team. In order to identify as many customer needs as possible, team members interviewed previous race participants, studied competition rules, and reflected on personal desires for performance. Direct statements from these sources were recorded and classified into a hierarchy. These customer statements were converted into statements that expressed product attributes clearly and in detail. Rankings were assigned to each product attribute to indicate its importance. Some of the desired attributes and their importance rankings are found in Table 1. A significant amount of time was taken to ensure the list of product attributes reflected the true needs of customers, and that rankings accurately reflected customer priorities. Putting together the list of product attributes was done as a team, so the input of everyone that participated in the research was available. ID # 1 2 3 4 5 6 7 8 9 10 11 12

Product Attribute The vehicle is safe The vehicle adheres to competition rules The vehicle is fast The vehicle accelerates quickly The vehicle can climb steep hills The vehicle is reliable The vehicle is inexpensive The vehicle is light weight The vehicle is comfortable and fun to drive The vehicle is stable The vehicle is easy to service The vehicle looks good

Rank 5 5 5 5 4 4 3 3 3 3 2 2

Table 1: Abridged list of vehicle attributes, indicating their importance to customers by a ranking on a 1-5 scale.

CREATING THE PRODUCT SPECIFICATION A major key to any successful design is generating a product specification that accurately reflects customer needs and desires. Unfortunately design engineers do not always participate in the creation of the specification,

nor do they try to improve it. The specification should state constraints as broadly as possible to avoid premature elimination of possible concepts [10]. In our case, many constraints were imposed by the detailed requirements of the competition rules. The 45 product specifications the team created were classified as being relevant to the entire vehicle, including major subassemblies of the vehicle such as the frame, suspension, powertrain, braking, and steering subsystems. The 12-member team was divided into subteams that were responsible for the design of each of these major sub-systems. Time was allotted for the subteams to communicate their intentions with the rest of the team. This communication helped in selecting subsystem concepts that could be neatly incorporated together as a total system or vehicle. An abridged specification, consisting of a metric, test procedure and ideal value range, is found in Table 2. Each specification was taken directly from a product attribute, which is referenced by number. It is important that specifications reflect customer needs and desires accurately so compliance to the specification assures market success of the product. Some specifications cannot easily be defined numerically. To enable evaluation of such specifications, a subjective rating was used. It is not uncommon for inexperienced designers to create product specifications that are worded in such a way as to prematurely eliminate possible solutions and incorrectly reflect complex design issues [10]. The young BYU design team was no exception. Some team members felt the creation of the product specification was just a hoop to jump through, largely because they were anxious to get to the decision-making design phase. One failure of the specification was meeting product attribute #10, which requires the vehicle to be stable. The specification required that the vehicle could be tilted a large angle statically on two wheels before it would tip over. The team exceeded the requirement given in the specification, producing a design that could be tilted over 60º before tipping over, but the car still had some instability problems because the specification did not take into account all of the suspension characteristics necessary for dynamic stability. A better specification would have been to require the vehicle to complete a Uturn of a 10-foot radius at a specified speed without the wheels leaving the ground. This specification would allow for more design freedom by testing all parameters that contribute to stability simultaneously, rather than individually. Product attribute #4, which requires quick acceleration, was converted to a specification inaccurately because the test method timed the vehicle on pavement, not on dirt as would be required in the race. While the vehicle performed well on pavement, it did not do as well in the off-road acceleration contest because there was not ample brake friction on the rear axle to power brake at the starting line, increasing times by half a second. Had acceleration been tested off-road, the problem could have been corrected before the competition. Even with shortcomings in the product specification, it was a valuable aid to help focus the design on customer requirements. Knowing how well the design measured up against the specification indicated roughly how well the vehicle would do in its market—the competition. Confidence in a product requires both that the product

Ref #

Metric

1

Number of belts, chains, and sprockets without guards Amount of fuel lost in rollover

2 3 4 5 6 7 8 9

Stiffness of roll-cage material Number of driver-restraint points Distance to stop car from top speed Number of rules broken Top speed 50 yard drag race time Climbable hill angle Hours of driving without failure Cost to manufacture vehicle

11

Curb weight Ride smoothness rating Size range of drivers that can fit into vehicle Ease of steering rating Angle of tilt when vehicle is balanced on two wheels Ease of service rating

12

Aesthetic allure rating

10

Test Procedure Observation Turn vehicle upside down and look for dripping fuel. Calculate EI product of tubing Observe number of harness attachment points Measure distance to stop from 50 yard acceleration on dry pavement Race judges determine number of rules violated Instrument vehicle with speedometer Time 50 yard drag race on level pavement Drive vehicle up hills on hard-pack Time hours driven since last design change or repair Estimate cost based on 4,000 production units following Mini-Baja guidelines for costing Weigh vehicle Drivers will determine rating subjectively (1-10) Drivers of different heights will attempt to drive vehicle Drivers will determine rating subjectively (1-10) Tip vehicle with driver on two wheels and measure angle of frame with angle finder. Team mechanics will determine rating subjectively (1-10) Industrial designer will determine rating subjectively (1-10)

Target Values (Ideal–Acceptible) 0–0 0 – 2 drops 1,500 ksi – 760 ksi 5–4 15 ft – 30 ft 0–0 50 mph – 30 mph 6 sec. – 7.5 sec 35º – 22º 50 hrs. – 5 hrs. $2,300 - $2,499 350 lbs. – 450 lbs. 10 – 6 4' - 6'10" – 4'8" - 6'6" 10 – 5 60° – 40° 10 – 4 10 – 4

Table 2: Abridged list of product specifications including: metric, test procedure, and target value range.

meets the specification and that the specification accurately describes customer needs. Since the shortcomings in the specification were relatively minor, they did not prevent the design from being successful.

CONCEPTUAL DESIGN Conceptual design was divided into sub-systems: frame, suspension, powertrain, braking, and steering. This division of responsibility highlighted the importance of communication between the designers of the different systems. The decisions of one sub-team affected the decisions of another. Constant communication was required so complete vehicle concepts didn’t optimize one system at the expense of others. For instance, tests performed by the powertrain designers showed that using a differential with a small housing would increase track speed, but the rear suspension concept that was chosen by other designers would put too much stress on the small differential housing selected. This problem required the suspension and powertrain designers to work together to come up with a solution that would allow for synergy between the two systems. Working together the designers found that a trailing arm suspension design could be set up so that one of the rear wheels would unload around turns, allowing it to spin freely. This discovery allowed a low-cost solid axle to be used in place of the differential without eliminating the benefits

the differential would have provided. Through this lesson, the team learned that unnecessary divisions in design responsibility are undesirable because they require more iterations to ensure a successful composite design. Designers used screening and scoring matrices to ensure that a range of concepts was considered and that the chosen concept was the best alternative. Screening matrices ranked a large number of concepts, judging each to be better than, equal, or worse than a benchmark concept when evaluated against a series of selection criteria (see Table 3). Scoring matrices were used to further compare the concepts that faired well in screening. For scoring, concepts were assigned a numerical rating for each of the weighted criteria, as shown in Table 4. The outcome of these matrices is highly dependant on the criteria used to evaluate them, and the weight assigned to each criterion. Appropriate criteria were determined by considering customer needs as stated in the list of attributes and the product specification. A benefit of scoring matrices is that they discourage designers from jumping to a solution unnecessarily. Young engineers, especially, have a tendency jump to complicated or “high-tech” solutions [11].

E New Concept 4

0 + 0 1 2 4 -3 6

0 + 0 0 1 3 3 -2 4

0 0 + 0 1 3 3 -2 4

F Last Year’s Model (Benchmark)

0 0 + + + + + 5 2 0 5 1

D New Concept 3

0 0 + 0 + 0 0 2 5 0 2 2

C New Concept 2

B New Concept 1

Selection Criteria Conforms to rules Easy to exit Fit all team members Aesthetically pleasing Comfortable to drive Manufacturability Weight Sum +'s Sum 0's Sum -'s Net Score Rank

A Variant of Last Year’s Model

Frame Concept Screening Matrix

0 0 0 0 0 0 0 0 7 0 0 3

Table 3: Screening matrix used to narrow field of concepts. Concepts were compared against a benchmark (F). Concepts in bold were considered further in the scoring matrix.

Frame Concept Scoring Matrix F Last Year’s Model (Benchmark)

Selection Criteria Conforms to rules Easy to exit Fit all team members Aesthetically pleasing Comfortable to drive Manufacturability Weight

A Variant of Last Year’s Model

B New Concept 1

Weight (%)

Rating

Score

Rating

Score

Rating

Score

20 10 10 15 10 15 20 Total Score Rank Continue?

3 3 3 3 3 3 3

0.6 0.3 0.3 0.45 0.3 0.45 0.6

3 4 4 5 4 4 5

0.6 0.4 0.4 0.75 0.4 0.6 1.0

3 4 5 5 4 5 5

0.6 0.4 0.5 0.75 0.4 0.75 1.0

3 3 No

4.15 2 Backup Choice

4.4 1 Develop

Table 4: Scoring matrix used to decide upon primary and secondary concepts.

The concept selection process for the frame/roll-cage resulted in a very successful design. The original concept drawing, drawn by the industrial design specialist on the team, can be seen in Figure 2. Manufacturing engineers were excited about the

aesthetic appeal of the concept drawing and also found that the frame could be made more easily than other concepts. The final frame design uses relatively large diameter tubing: 1.5-inch diameter, .035-inch wall thickness, 4130 alloy steel. The tubing is much lighter and stiffer than other options, making it difficult to bend in

Figure 2: Frame concept drawn by industrial design student Josh Thurber. This concept is referred to in matrices as “New Concept 1.” small radii. This obstacle was overcome by using tubes bent in large 130-inch, and 70-inch radii. The large radii can be bent easily on a three-point roller bender before cutting to length. This solution not only eliminates the need for local bends; it provides aesthetic appeal, provides more room for the driver and powertrain components, and lightens and strengthens the frame by eliminating several welded joints. Upon examination of the selection matrices in Tables 3 and 4, one important criterion appears to be absent— rollover protection. The main function of the frame/rollcage assembly is to protect the driver in the event of a rollover, so it would be natural to include it as a primary judging criterion. However, rollover protection is included in the "conforms to rules" criterion. Safety rules for the Mini-Baja competition specify minimum strength and stiffness requirements for the tubing used, and also indicate the location and number of certain tube members [1]. While these safety rules all but guarantee safety for the race participants, they do eliminate a large range of alternate concepts that would provide ample rollover protection. Conceptual design of the powertrain differed greatly from that of the frame. Many concepts were studied, and most of them had previously been used in the competition by other teams. Research and analysis was performed to identify the strengths and weaknesses of each design. The screening and scoring matrices enabled the designs to be evaluated according to the criteria that were established by customer needs research. The concept that was selected consists of a continuously variable transmission (CVT) driving the rear wheels through a gearbox transmission and a chain reduction. The gearbox transmission adds two speed ranges and a reverse gear to the CVT, which automatically adjusts its gear ratio depending on engine rpm and torque resistance of the gearbox input shaft. This concept was determined to be the least risky choice because the shift-on-the-fly gearbox transmission increased the gear range to exceed customer needs for top-speed and also hill-climbing performance. The second gear range was a critical factor in allowing the vehicle to place in the top three in the hill-climb event of the competition. The chain reduction was required to get the overall gear range low enough for the 5.97 kW (8-hp) engine, and to allow for gear range adjustably through a change in rear tire diameter choice. Since the power-source is limited by the competition rules, the rest of the powertrain must manage the limited power to achieve the desired specifications. Mathematical models and benchmarking were used to

Figure 3: Shaded Pro/Engineer model depicting the layout of powertrain components. determine appropriate gear-ratio ranges. Powertrain concepts were created in conjunction with suspension, frame, and braking to take advantage of any opportunities for function integration. For instance, the drive axle incorporates an inboard disk brake and acts as a suspension member in the trailing-arm rear suspension. A single, non-telescoping, universal joint on each side of the axle allows it to move with the suspension. Axial motion of the rear axle is prevented by mounted bearings, placed directly inboard of each Ujoint, which transfer thrust loads to the frame. Figure 3 shows a shaded Pro/Engineer CAD model of the powertrain components.

DETAIL DESIGN During the conceptual design stage the design team amassed a list of hundreds of detail design questions that had to be answered. By this stage, the major components and concepts had already been finalized. Remaining questions included such details as, “What bearings should be used on the front wheels?” “What diameter should the steering wheel be?” and “How should the throttle connect to the pedal?” The market success of products greatly depends on the quality of detail design [12]. The vehicle excelled in some areas due to good detail design, but poor detail design in other areas prevented the vehicle from winning the competition. A major factor in the quality of the detail design is the design methods used. Some detail design work required standard engineering analysis techniques, some required good intuition and judgement, and some required critical concept selection.

Figure 4: Photo of finished vehicle prototype.

Pro/Engineer, a solid-modeling software package, was used extensively in both the conceptual and detail design stages. The software allowed for various design iterations to occur quickly. It also was used to work out assembly details and clearances. One of the main benefits of virtual design is facilitation of communication between designers. The creation of the solid model occurred before construction began, facilitating simultaneous design of the separate sub-systems. Designers of the separate sub-systems worked out assembly and interface issues early, resulting in less time lost due to useless iterations. CAD models were used for the design of major detail, and were not used for less-significant details. When deciding what bearings should be used on the front wheels, standard engineering analysis techniques were used. Loads that would be imposed on the bearings were calculated and the desired life to failure was decided. Bearings were then selected using the selection procedures recommended by the bearing manufacturer. Selecting the bearings was a traditional engineering problem, and the bearings performed well, as predicted. The design of the steering wheel did not require any engineering calculations, rather it was an exercise of intuitive judgement. Since the wheel would be rotated over 180° to either side, a traditional circular style was chosen, as opposed to a butterfly or ¾ circle. Two diameters were readily available: 25 cm (10 in.) and 36 cm (14 in.). The 25 cm diameter steering wheel was chosen to allow more room for drivers to enter and exit the vehicle. It was also judged that the car was easy enough to steer that a larger lever-arm was unnecessary. Even though using intuitive judgement as a design tool involves some risk, it can never be avoided in any design task. Risk can be reduced when a larger sampling of people are used to give subjective input, and when multiple prototypes are constructed for testing. In this case, two alternatives where considered as well as the opinion of most of the potential drivers. As a result, the steering wheel performed very well, and was comfortable for all of the drivers. Designing the link between the engine throttle and the accelerator pedal required generating and implementing a concept. The novice designers felt this linkage was a

detail, and left its design to intuitive judgement, a detail design method. In theory this concept should have been decided following the procedure described previously in the Conceptual Design section. A bicycle brake cable was used as the link because that was the first reasonable concept the designers thought of. No analysis was done on the cable because the designers were not familiar with applicable analysis techniques, and judged that the cable would be under similar stresses as on a bicycle. The design failure occurred when the cable attachment points were decided upon at the last minute. The attachment point at the pedal consisted of a bolt and washer. The washer was modified with a groove for the cable to seat in. When the bolt was tightened, the washer pressed the cable against the pedal to secure it. This attachment point was located at the bottom of the pedal to allow concealment of the cable assembly. Since the pivot of the pedal was located towards the bottom, the cable was pulled along an arc with a 5 cm (2 in.) radius when the pedal was actuated. This radius proved to be too small, forcing the cable to bend at the bolt from 0º to 90º along the throw of the pedal. This bending caused a fatigue action that caused the cable to fail after only 20 hours of service. Unfortunately, the failure occurred in the beginning of the durability competition. The failure of the throttle cable took the vehicle out of th contention for first place, and the vehicle finished 12 out of 72 registered entrants. Previous toth the durability portion of the race, the vehicle was 5 overall, and before the failure, it was on track to win the overall event. These results are remarkable considering none of the design team had participated in the Mini-Baja competition in previous years. The vehicle performed well in the hill-climb and maneuverability competitions, but perhaps the most significant indicator of the design quality is the number of complements received. The general consensus of those who drove the vehicle is that it is comfortable, easy to control, capable on various terrain, and attractive (See Figure 4). The lessons that were learned from this failure should be noted. First, all conceptual design is important, and should be carried out using conceptual design strategies. These strategies require that a range of concepts be considered and compared with criteria identified by market research. Second, if design or analysis techniques do not exist, research and testing is required to identify failure modes and how to guard against them. Third, design concepts should always be reviewed to prevent poor designs from being implemented. Reducing product development time is often at odds with improving the quality of detail design. Achieving both requires more time be taken initially to ensure that customer needs are understood by all involved in the design. Designers who take the time to understand customer needs will be able to screen out poor concepts more quickly, and will not waste time developing product attributes that do not add value to the customer. The detail design phase requires designers to know when intuitive judgement can be used. Testing of a full-scale prototype can provide information on every detail, eliminating the need for individual prototypes for each detail. However, each component of a full-product prototype must be evaluated individually to determine how close to failure it will come during testing, since testing a full-product to failure will not reveal components that are near failure. Product development time is reduced when steps are integrated and decisions are

made carefully so that numerous iterations are not required. Just as with production processes, making sure things are done right the first time reduces waste in the design process.

CONCLUSION The product realization process for various products and design teams differs greatly, as it should. Improvements to this process must be made on a case by case basis. Some principles apply to all processes, and can be used to help identify areas in which to make improvements for each case. One such principle is making sure engineering designers understand the needs and wants of all product customers and stakeholders. This often requires engineers to become involved with marketing and manufacturing activities. Tools, such as concept selection matrices and customer-focused specifications, help engineers incorporate the needs of their customers in their designs. And while subjective decisions will never be eliminated from design work, a better understanding of customer needs will always improve the quality of such judgements, producing designs with greater market success.

ACKNOWLEDGMENTS Thanks to the 1999 Brigham Young University Senior Mini-Baja Team and Coaches: Robert Todd, Chris Jones, Andrew Woodings, McKay Asay, Geoff Carlson, David Comstock, Rogelio Flores, Brett Hassell, Ryan Hubbard, Scott Johnson, Barry Lewis, Benjamin Pack, Kevin Paulson, Josh Thurber, and Brent Zollinger.

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