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Linkage mechanisms have been investigated for ages. The characteristics of planar four-bar linkages, though most fundamental of all, have laid the theoretical foundation of research and advancement of other linkages. Most papers have focused only on the standard crank-driven, torque-input four-bars, leaving the coupler-driven, force-input types comparatively less studied. Transmission performance is an important issue of mechanism design. In this thesis, an index that couples the coupler curve and the transmissivity of mechanical advantage for the coupler-driven, force-input four-bar is proposed. The new index, called the CCTMA, is used when its shape, length, curvature, and symmetry are inspected. A WS curve and a WS angle are also defined to facilitate the use and understanding of the CCTMA. A straightforward procedure is also presented for designing coupler-driven, force-input four-bar linkages. The idea of the CCTMA is introduced into the design process to exclude input coupler points what have unsatisfactory transmission properties. This procedure is also valid for improving existing coupler-driven, force-input four-bar mechanisms.

This research uses Transmissivity Index (TI) and other transmission indices to analyze the transmission performance by applying those indices to coupler-driven mechanisms with sliders. Other estimative transmission indices include Total Transmission Index (TTI) and Transmissible Mechanical Advantage (TMA). The point with best transmission performance is ¡§Effective Point,¡¨ and the combination of the effective points becomes ¡§Locus of Effective Points¡¨. In addition, this research puts the influence of mechanisms with sliders including slider-friction into consideration, and also analyzes two inverses of mechanisms with sliders. Then we can extend to study the transmission performance of six-bar mechanisms. Finally, we apply the research result into some examples, such as ping pong table mechanism, four-bar and six-bar windows operator mechanisms, rowing exercise mechanism, so that we can find the better transmission performance of those mechanisms.

This article is based on several nouns about transmission performance such as limiting positions, manipulation angle, transmission angle and mechanical advantage. In order to analyse the transmission performance of the coupler-driven and crank-output linkage mechanism, this article has developed an index called Transmissivity of Mechanical Advantage (TMA) for designers, besides this useful index, this article has identified a new noun as Total Transmission Coupler Point, that means after acting a force on the same direction of coupler point moving instantly, then the output force on the crank will act on it¡¦s moving direction and make the Transmissivity Index be the best as 1. For the designers of the coupler-driven linkage mechanisms, the transmission performance and the position where the force acts on involves to coupler curves very much. Based on the result of this research, the designers are able to choose the most proper coupler curves, and the best position of the coupler point would be designed. The designers are able to pick the best one among several similar coupler curves, and also they can certainly get a best range of either the length or the angle of the coupler designed when they were designing the coupler-driven type 4-bar linkage or the Stephenson¡¦s III 6-bar linkage. The applying force must change the direction all the time when a coupler-driven mechanism is driven, and it makes this type of mechanism seems to be uncommon, but it doesn¡¦t mean this kind of mechanism is not worth of application. On the other hand, the short of research about this type of mechanism makes the designers feel helpless when they were trying to analyse the transmission performance of mechanisms were designed. This article develops not only the theorem of analysis but also builds computer programs to help the designers to analyse the transmission performance quickly and correctly