Two-fold symmetrical 6R foldable frame and its bifurcations

In this paper, we have discovered that a type of two-fold symmetrical 6R foldable frame proposed as a deployable core structure to support solar blankets in space applications is actually a line and plane-symmetric Bricard linkage. Using the singular value decomposition of the Jacobian matrix of closure equations, we are able to show that bifurcations exist during deployment of the frame. And the bifurcations cannot be avoided in current designs. However, we also identified a feasible area for design parameters in which bifurcations can be completely removed. A physical model has been made which proves that our conclusion is correct.