Given the proliferation in research and scholarly attention afforded to innovation over the last three decades, a diverse range of innovation modelling processes exist in the literature (Rothwell, 1994 ; Tidd, 2006 ; du Preez and Louw, 2008 ; O’Raghallaigh et al., 2011 ). The existing catalogue of process models of innovation can be generally subdivided into three umbrella categories: (1) Linear (2) phased models, and (3) coupling, cyclical models.
Early models of innovation presented innovation as a linear phenomenon where each element/stage in the process was considered modular and unconnected to other parts of the innovation process (Rothwell, 1994), underpinned by a linear underpinning approach to innovation; “Technology push” and “demand pull”. The first generation technology push era of innovation models represents a simple linear structure which mapped innovation as a sequential process performed across discrete stages. Technology push (Figure. 1) is based on the assumption that new technological advances based on R&D and scientific discovery, preceded and ‘pushed’ technological innovation via applied research, engineering, manufacturing and marketing towards successful products or inventions as outputs. In the second generation market pull era a linear model depiction of innovation also applies, this time prioritizing the importance of market demand in driving innovation endeavors. What distinguishes this model from its predecessor is that rather than product development originating from scientific advances, new ideas originate in the marketplace, with R&D becoming reactive to these needs.
Figure 1 First and Second Generation Models
Source: Rothwell (1994)
It was found early on that these models did not survive empirical scrutiny as this representation oversimplified the innovation process. Indeed, Kline and Rosenberg (1986) note that models that depict innovation as “…a smooth, well-behaved linear process badly misspecify the nature and direction of the causal factors at work. Innovation is complex, uncertain, somewhat disorderly, and subject to changes of many sorts”.
Phased models serve as a management tool to map, systemize, control and review innovation progress across the sequential phases involved in an innovation project (Verworn and Herstatt, 2002) . Inputs and outputs for each phase are defined with management reviews at the end of each phase to determine the continuation of a project (“go-no-go”). The Stage-Gate process (Cooper, 2008) represents distinctive and orderly phases consists of a range of gates to evaluate the various stages in the innovation development journey. The advantages of such an approach is in reducing uncertainty and promoting completion of sub stages of the innovation process (Figure 2).
Figure 2 Stage Gate Model
Source: Cooper (1990)
3. Coupling/ cyclical models:
Mindful of the combination of technical activities occurring in the innovation process, the external forces of the market place, as well as the complex interac tions between the various stages of the process, researchers in the field of innovation have developed more complex and inclusive models based upon the limitations of linear and phased models (Leger and Swaminaham, 2007 ). For example, the Chain Linked innovation model (Kline and Rosenburg, 1986) combines both market pull and technology push orientations, and identifies multiple paths of innovation process incorporating feedback loops across the components of the innovaiton value chain. Kline and Rosenberg’s Chain Linked innovation model (Figure 3) combines both market pull and technology push orientations, identifies five paths of innovation process (C): starting with the perception of a new market opportunity and/or a new science and technology-based invention; this is necessarily followed by the ‘analytic design’ (D) for a new product or process, and subsequently leads to development, production and marketing.
Figure 3 Chain Linked Innovation Model
Source: Kline and Rosenberg (1986)
Departing from a linear conceptualisation, Berkhout’s Cyclic Innovation Model (CIM) developed in the nineties views the innovation process as more than just technical invention and describes the innovation arena by a ‘circle of change' linking changes in science (left) and industry (right), and changes in technology (top) and markets (bottom) (Berkhout et al.,2007) . As illustrated in Figure 4, the model architecture is not a chain but a circle: where ideas may start anywhere in the circle and proceed clockwise or anticlockwise. Equally, the model portrays a system of dynamic processes –with four ‘nodes of change’: scientific exploration, technological research, product creations and market transitions and between these nodes there are ‘cycles of change’.
Figure 4 Cyclical Innovation Model
Source: Berkhout et al. (2010)
 R. Rothwell, "Towards the fifth-generation innovation process," International Marketing Review, vol. 11, no. 1, pp. 7-31, 1994.
 J. Tidd, "A review of innovation models discussion paper 1," Science and Technology Policy Research Unit, Tanaka Business School, University of Sussex, 2006.
 N. du Preez and L. Louw, "A framework for managing the innovation process," in In: PICMET Proceedings, CapeTown, South Africa, 2008.
 P. O'Raghallaigh, D. Sammon and C. Murphy, "A re-conceptualisation of innovation models to support decision design," Journal of Decision Systems, vol. 20, no. 4, p. 369, 2011.
 S.J. Kline, and N. Rosenburg, “An overview of innovation,” in The Positive Sum Strategy: Harnessing Technology for Economic Growth., Washington, D.C, National Academy Press, 1986, pp. 275-305.
 B. Verworn and C. Herstatt, “The Innovation Process: an Introduction to Process Models.,” Working Paper No. 12, Technical University of Hamburg., 2002.
 R. Cooper, “Perspective: the stagegate idea to launch process update, what’s new, and NexGen system,” Journal of Product Innovation Management, vol. 25, no. 3, pp. 213-232, 2008.
 R. Cooper, “Stage-Gate Systems: a new tool for managing new products,” Business Horizons, vol. 33, pp. 44-56, 1990
 A. Leger and S. Swaminaham, “Innovation theories: relevance and implications for developing country innovation. Discussion Paper No. 743, .,” DIW Berlin, 2007.
 A. Berkhout, D. Hartmann and P. Trott, “Connecting Technological Capabilities with Market Needs using a Cyclic Innovation Model.,” R&D Management, vol. 40, no. 5, pp. 474-490, 2010.