Prototype

For other uses, see Prototype (disambiguation).

A prototype is an original type, form, or instance of something serving as a typical example, basis, or standard for other things of the same category. The word derives from the Greek πρωτότυπον (prototypon), "archetype, original", neutral of πρωτότυπος (prototypos), "original, primitive", from πρώτος (protos), "first" + τύπος (typos), "impression".

Semantics

In semantics, prototypes or proto instances combine the most representative attributes of a category. Prototypes are typical instances of a category that serve as benchmarks against which the surrounding, less representative instances are categorized (see Prototype Theory).

Design and modeling

In many fields, there is great uncertainty as to whether a new design will actually do what is desired. New designs often have unexpected problems. A prototype is often used as part of the product design process to allow engineers and designers the ability to explore design alternatives, test theories and confirm performance prior to starting production of a new product. Engineers use their experience to tailor the prototype according to the specific unknowns still present in the intended design. For example, some prototypes are used to confirm and verify consumer interest in a proposed design where as other prototypes will attempt to verify the performance or suitability of a specific design approach.

In many product development organizations, prototyping specialists are employed - individuals with specialized skills and training in general fabrication techniques that can help bridge between theoretical designs and the fabrication of prototypes.

There is no general agreement on what constitutes a "prototype" and the word is often used interchangeably with the word "model" which can cause confusion. In general, “prototypes” fall into four basic categories:

Proof-of-Principle Prototype (Model) (also called a breadboard). This type of prototype is used to test some aspect of the intended design without attempting to exactly simulate the visual appearance, choice of materials or intended manufacturing process. Such prototypes can be used to “prove” out a potential design approach such as range of motion, mechanics, sensors, architecture, etc. These types of models are often used to identify which design options will not work, or where further development and testing is necessary.

Form Study Prototype (Model). This type of prototype will allow designers to explore the basic size, look and feel of a product without simulating the actual function or exact visual appearance of the product. They can help assess ergonomic factors and provide insight into visual aspects of the product's final form. Form Study Prototypes are often hand-carved or machined models from easily sculpted, inexpensive materials (e.g., urethane foam), without representing the intended color, finish, or texture. Due to the materials used, these models are intended for internal decision making and are generally not durable enough or suitable for use by representative users or consumers.

Visual Prototype (Model) will capture the intended design aesthetic and simulate the color and surface textures of the intended materials. These models will be suitable for use in market research, packaging mock-ups, and photo shoots for sales literature.

Functional Prototype (Model) (also called a working prototype) will, to the greatest extent practical, attempt to simulate the final design, aesthetics, materials and functionality of the intended design. The construction of a fully working full-scale prototype and the ultimate test of concept, is the engineers' final check for design flaws and allows last-minute improvements to be made before larger production runs are ordered.

In general, prototypes will differ from the final production variant in three fundamental ways:

Prototypes are often constructed via non-production intent materials. Production materials may require manufacturing processes involving higher capital costs than what is practical for prototyping. Instead, engineers of prototying specialists will attempt to substitute materials with properties that simulate the intended final material.

Prototypes are generally constructed via non-production intent manufacturing processes. Often expensive and time consuming unique tooling is required to fabricate a custom designs. Prototypes will often compromise by using more flexible processes.

Prototypes are generally constructed from a design that has been developed to a lower level of fidelity than production intent. Final production designs often require extensive effort to capture high volume manufacturing detail. Such detail is generally unwarranted for prototypes as some refinement to the design is to be expected. Often prototypes are built using very limited engineering detail as compared to final production intent.

Engineers and prototyping specialists seek to understand the limitations of prototypes to exactly simulate the characteristics of their intended design. A degree of skill and experience is necessary to effectively use prototyping as a design verification tool.

It is important to realize that by their very definition, prototypes will represent some compromise from the final production design. Due to differences in materials, processes and design fidelity, it is possible that a prototype may fail to perform acceptably whereas the production design may have been sound. A counter-intuitive idea is that prototypes may actually perform acceptably whereas the production design may be flawed since prototyping materials and processes may occasionally outperform their production counterparts.

Building the full design is often expensive and can be time-consuming, especially when repeated several times -- building the full design, figuring out what the problems are and how to solve them, then building another full design. As an alternative, "rapid-prototyping" or "rapid application development" techniques are used for the initial prototypes, which implement part, but not all, of the complete design. This allows designers and manufacturers to rapidly and inexpensively test the parts of the design that are most likely to have problems, solve those problems, and then build the full design.

This counter-intuitive idea—that the quickest way to build something is, first to build something else—is shared by scaffolding and the telescope rule.

Mechanical and electrical engineering

A prototype of the Polish economy hatchback car Beskid 106 designed in the 1980s

Main article: rapid prototyping

The most common use of the word prototype is a functional, although experimental, version of a non-military machine (e.g., automobiles, domestic appliances, consumer electronics) whose designers would like to have built by mass production means, as opposed to a mockup, which is an inert representation of a machine's appearance, often made of some non-durable substance.

An electronics designer often builds the first prototype from breadboard or stripboard or perfboard, typically using "DIP" packages. However, more and more often the first functional prototype is built on a "prototype PCB" almost identical to the production PCB, as PCB manufacturing prices fall and as many components are not available in DIP packages, but only available in SMT packages optimized for placing on a PCB.

Builders of military machines and aviation prefer the terms "experimental" and "service test".

Computer Programming/Computer Science

Main article: Software prototyping

In many programming languages, a function prototype is the declaration of a subroutine or function. (This term is rather C/C++-specific; other terms for this notion are signature, type and interface.) In prototype-based programming (a form of object-oriented programming), new objects are produced by cloning existing objects, which are called prototypes.

The term may also refer to the Prototype Javascript Framework.

Prototype software is often referred to as alpha grade, meaning it is the first version to run. Often only a few functions are implemented, the primary focus of the alpha is to have a functional base code on to which features may be added. Once alpha grade software has most of the required features integrated into it, it becomes beta software for testing of the entire software and to adjust the program to respond correctly during situations unforeseen during development.

Extreme programming uses iterative design to gradually add one feature at a time to the initial prototype, attempting to minimize "irreducible complexity".

Continuous learning approaches within organizations or businesses may also use the concept of business or process prototypes through software models.

Computer Engineering

In computer engineering, a prototype generally refers either to a breadboard (or evolutionary) prototype or a throwaway (or one-off) prototype. Breadboard prototypes are often simple in a development stage, focusing on a subset of the total requirements for a product. These prototypes usually are intended to evolve into the final design. Project managers may formally identify a component as prototype to communicate with stakeholders that the component may or may not comprise the techniques ultimately allocated to the product design, or to meet business objectives.

It should not be assumed that the prototype is merely for testing concepts (throwaway). That would be an aspect of a "research" project or "proof of concept." Prototypes provide the developers with a "working model" for demonstration or use by customers, quality-assurance, business analysts, and managers to confirm or make changes to requirements, help define interfaces, develop collaborating components, and to provide proof of incremental achievement of scheduled contractual agreements.

Scale modeling

In the field of scale modeling (which includes model railroading, vehicle modeling, airplane modeling, military modeling, etc.), a prototype is the real-world basis or source for a scale model—such as the real EMD GP38-2 locomotive—which is the prototype of Athearn's (among other manufacturers) locomotive model. Technically, any non-living object can serve as a prototype for a model, including structures, equipment, and appliances, and so on, but generally prototypes have come to mean full-size real-world vehicles including automobiles (the prototype 1957 Chevy has spawned many models), military equipment (such as M4 Shermans, a favorite among US Military modelers), railroad equipment, motor trucks, motorcycles, airplanes, and space-ships (real-world such as Apollo/Saturn Vs, or the ISS).

There is debate whether 'fictional' or imaginary items can be considered prototypes (such as Star Wars or Star Trek starships, since the feature ships themselves are models or CGI-artifacts); however, humans and other living items are never called prototypes, even when they are the basis for models and dolls (especially - action figures).

As of 2005, conventional rapid prototype machines cost around £25,000.[1]

Metrology

In the science and practice of metrology, a prototype is a human-made object that is used as the standard of measurement of some physical quantity to base all measurement of that physical quantity against. Sometimes this standard object is called an artifact. In the International System of Units (SI), the only prototype remaining in current use is the International Prototype Kilogram, a solid platinum-iridium cylinder kept at the Bureau International des Poids et Mesures (International Bureau of Weights and Measures) in Paris (more precisely in Sèvres) that, by definition is the mass of exactly one kilogram. Copies of this prototype are fashioned and issued to many nations to represent the national standard of the kilogram and are periodically compared to the Paris prototype.

Until 1960, the meter was defined by a platinum-iridium prototype bar with two scratch marks on it (that were, by definition, spaced apart by one meter), the International Prototype Metre, and in 1983 the meter was redefined to be the distance covered by light in 1/299,792,458 of a second (thus defining the speed of light to be 299,792,458 meters per second).

It is widely believed that the kilogram prototype standard will be replaced by a definition of the kilogram that will define another physical constant (likely either Planck's constant or the elementary charge) to a defined constant, thus obviating the need for the prototype and removing the possibility of the prototype (and thus the standard and definition of the kilogram) changing very slightly over the years because of loss or gain of atoms.

Pathology

In pathology, prototype refers to a disease, virus, etc which sets a good example for the whole category. For example, the vaccina virus is regarded as the virus prototype of poxviridae.

See also

• Mock-up
• Car design
• Pilot (experiment)
• Prototyping
• Rapid prototyping
• Rapid Application Development
• Software Prototyping
• Boilerplate (rocketry)
• Archetype