Computer-aided design is the use of computers to aid in the creation, modification, analysis, or optimization of a design. Designers have used computers for calculations since their invention. CAD software was popularized and innovated in the 1960s, although various developments were made between the mid-1940s and 1950s. Digital computers were used in power system analysis or optimization as early as proto-"Whirlwind" in 1949. Circuit design theory or power network methodology was algebraic, symbolic, and often vector-based.
1940s–1950s Between the mid-1940s and 1950s, various developments were made in computer software. Some of these developments include servo-motors controlled by generated pulse (1949), a digital computer with built-in operations to automatically coordinate transforms to compute radar related vectors (1951), and the graphic mathematical process of forming a shape with a digital machine tool (1952). In 1953, MIT researcher Douglas T. Ross saw the "interactive display equipment" being used by radar operators, believing it would be exactly what his SAGE-related data reduction group needed. Ross and the other researchers from the Massachusetts Institute of Technology Lincoln Laboratory were the sole users of the complex display systems installed for the pre-SAGE Cape Cod system. Ross claimed in an interview that they "used it for their own personal workstation." The designers of these early computers built utility programs to ensure programmers could debug software, using flowcharts on a display scope, with logical switches that could be opened and closed during the debugging session. They found that they could create electronic symbols and geometric figures to create simple circuit diagrams and flowcharts. These programs also enabled objects to be reproduced at will; it also was possible to change their orientation, linkage (flux, mechanical, lexical scoping), or scale. This presented numerous possibilities to them. Ross coined the term computer-aided design (CAD) in 1959.
1960s
The invention of the 3D CAD/CAM is often attributed to French engineer Pierre Bézier (Arts et Métiers ParisTech, Renault). Between 1966 and 1968, after his mathematical work concerning surfaces, he developed UNISURF to ease the design of parts and tools for the automotive industry. UNISURF then became the working base for the following generations of CAD software. In parallel, French carmaker Citroen had developed its design system SPAC (system de programmatic automatique Citroen) as part of its CAD/CAM solution SADUSCA (aid systems for the defining and the machining of bodywork surfaces), both based on the 1959 mathematical works of Paul de Casteljau. In 1968, it used an IBM 360-40, then 360-65 for batch jobs, but already had a graphical interface with an IBM 2250 prototype.
However, CAD may have been in use earlier at Boeing, having been used to help design the outer surface of Boeing's 727 airplane (which rolled out in 1962). Based on his human factors cockpit drawings, William Fetter from Boeing coined the term "computer graphic" in 1960. A computer graphics department was established in 1962, and by 1965 had begun to make movies by computer. In the 1960s, technological developments in the industries of aircraft, automotive, industrial control, and electronics provided advancements in the fields of three-dimensional surface construction, NC programming, and design analysis. Most of these developments were independent of one another and often not published until much later. Some of the mathematical description work on curves was developed in the early 1940s by Robert Issac Newton. In his 1957 novel The Door into Summer, Robert A. Heinlein hinted at the possibility of a robotic Drafting Dan. However, more substantial work on polynomial curves and sculptured surface was done by mathematician Paul de Casteljau from Citroen; Pierre Bézier from Renault; Steven Anson Coons from MIT; James Ferguson from Boeing; Carl de Boor, George David Birkhoff and Garibedian from GM in the 1960s; and W. Gordon and R. Riesenfeld from GM in the 1970s. The development of the Sketchpad system at MIT by Ivan Sutherland, who later created a graphics technology company with David Evans, was a turning point. The distinctive feature of Sketchpad was that it allowed a human to interact with a computer graphically; the design can be fed into the computer by drawing on a cathode ray tube (CRT) computer display (monitor) with a light pen. In effect, this feature of Sketchpad was a prototype for a graphical user interface, an indispensable feature of modern CAD. In 1963, under doctoral adviser Claude Shannon, Sutherland presented his PhD thesis paper, Sketchpad: A Man-Machine Graphical Communication System, at a Joint Computer Conference. In his paper, he said:
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