A characteristic triangle method on input vectors of scissor lift mechanism and its applications in modeling and analysis

Abstract

Scissor mechanism, a basic element of structure and mechanism, can be used to make lots of deployable structures and functional motion devices. In such structures or devices, input configuration and parameter settings of actuator in scissor mechanism are variable and very important to structural forces and kinematics, however, has not been investigated systematically. Former researches on input vectors only consider a mechanism with decided input configuration and parameter settings. To supply a universal model for design purpose, a CHAracteristic Triangle (CHAT) is herein reported to calculate input vectors. The CHAT can be picked up from each of six input configurations of single group scissor lift mechanism. Based on former works and authors' simulations, several value rules of input vectors in scissor mechanism are discovered, summarized, and approved via mathematics analysis. One of those rules shows that the maximum input force always occurs in the beginning position of lifting. Which indicates extreme importance of initial lift angle to design. Meanwhile, a further research on typology refines six input configurations into more detailed value cases according to possible parameter settings. Among them, three constant lift force cases, two singular cases and other cases are discussed individually. Typology and value rules are significant to power selection, mechanism configuration design and dimension optimization. Validity of presented equations is approved by four reported samples. Not limit to studied single group mechanisms, CHAT can also be found easily in every linear driven scissor lift mechanism such as multiple group mechanism, parallel mechanism, or nonstandard connected single group mechanism. Thus, presented universal equations are suitable for widespread applications with scissor mechanism.