140 Layouts of spatial motion structures
Bennett linkages connected to them the two together would have more
than one degree of mobility because each can move independently. Goldberg (1943) found that links BC and CF could be welded together, resulting in the Goldberg 5R linkage. However, the same process cannot be
repeated if other adjacent Bennett linkages are involved unless the Bennett
linkages degenerate to planar 4R linkages. Hence, this assembly is in
general not mobile.
7.2.2 Case II
Should the layout given in Figure 7.2(f ) be selected, the building block
inscribed by the square tile is a Bennett linkage with extended links, Figure
7.4(a), and if the revolute joints are kept at A, B, C and D, an assembly
Figure 7.3 Several Bennett linkages connected side by side.
(a)
(b)
Figure 7.4 (a) A Case II building block based on the Bennett linkage and (b) assembly of the building blocks.
Bennett linkages connected to them the two together would have more
than one degree of mobility because each can move independently. Goldberg (1943) found that links BC and CF could be welded together, resulting in the Goldberg 5R linkage. However, the same process cannot be
repeated if other adjacent Bennett linkages are involved unless the Bennett
linkages degenerate to planar 4R linkages. Hence, this assembly is in
general not mobile.
7.2.2 Case II
Should the layout given in Figure 7.2(f ) be selected, the building block
inscribed by the square tile is a Bennett linkage with extended links, Figure
7.4(a), and if the revolute joints are kept at A, B, C and D, an assembly
Figure 7.3 Several Bennett linkages connected side by side.
(a)
(b)
Figure 7.4 (a) A Case II building block based on the Bennett linkage and (b) assembly of the building blocks.