Solution region-based synthesis methodology for spatial HCCC linkages

This paper proposes a HCCC linkage synthesis theory and methodology for four specified poses. The mechanism consists of one helical joint and three cylindrical joints, and has 1-DOF. Compared with 1-DOF RCCC linkages, HCCC linkages can achieve more motion space. And compared with 2-DOF 4C linkages, HCCC linkages have simply driving control system. Therefore, the synthesis theory and methodology of the motion generation mechanism for spatial HCCC linkages have theoretical significance and may have some application prospects. The synthesis process is divided into two parts. The first part determines the direction vectors of the linkages, the second part determines the position vectors of the linkages. In the second part, the synthesis equations are deduced. Finally, a 7th degree equation is obtained. Using this equation, all the HCCC linkage solutions can be obtained. These solutions can be displayed in a designated plane area. The plane area is called solution region. Defective solutions can be eliminated using a defect analysis method. Consequently, designers can directly select useful linkages from the solution region. Two examples are provided to illustrate that the synthesis method is simple and convenient to design a spatial HCCC linkage for four specified poses. (C) 2019 Elsevier Ltd. All rights reserved.