Rigid body guidance synthesis is a typical problem in mechanism design.In order to avoid the defects by traditional synthesis methods based on Burmester kinematic geometry theory,such as the limitation of mechanism structure type and the uncertainty of mechanism function,a generalized function oriented geometric synthesis method based on similarity transformation of the mechanism function modules was discussed.Since the standard mechanism modules were considered as basic design units for this method,the structure type of guidance mechanism modules need to be extended for a larger solution space,thereforethe geared linkage structure that can generate complex motion patterns was taken into account,aiming at the establishment of corresponding function module through kinematic analysis.At first,the transformation and mapping method between transmission function and guidance function were obtained through the configuration analysis of geared linkage,thus converting the transmission mechanism to the guidance mechanism through changing the rotation center of output gear.Secondly,the complex vector method was introduced for the kinematic analysis to obtain the guidance function,after that the geared linkage function module with full topology information was established,which included the transmission characteristics as well as the guidance characteristics,i.e. the relative dimensional parameters,the guidance angle performance, the guidance point trajectory and the motion geometric identifier.Then,in order to obtain the method for adjusting dimensional parameters of the preselected function module,a bidirectional mapping rule between relative dimensions and achievable guidance functions was revealed.At last,a practical guidance mechanism design task for powder production with partial parallel guidance function requirement was given, the similarity transformation of geometric identifier between geared linkage function module and the guidance task was presented, then the actual solution mechanism size and position parameters which meet the technical requirements were obtained. Finally the validity and practicability of the proposed generalized synthesis method were verified by the analysis of design results.
