Instant screw axis point synthesis of the RRSS mechanism

This paper presents a precision point synthesis of the RRSS motion generator, by specifying a set of successive points to the instantaneous screw axis. The method involves synthesizing RRSS mechanisms to achieve prescribed crank and coupler displacement angles by incorporating instant screw axis (ISA) points in the fixed axode point polynomial and calculating the R–R and S–S link parameters of this mechanism. The synthesis is facilitated by specific geometry of the RRSS mechanism, where the fixed axode is calculated as intersection of the R–R member plane and the S–S member axis. The RRSS fixed axode point polynomial was developed using the Cosine law approach introduced by Müller [Kansas State University Special Report No. 21, June 1962]. Complete expansion of the developed RRSS fixed axode point polynomial reveals that it is of order 56.