A new method for the determination of the degree of freedom of the hexapod mount based on screw theory has been
proposed. The method is applied to the mobility analysis of the four configurations of the hexapod mount, say the 3-3
configuration, 3-6 configuration, 6-3 configuration and 6-6 configuration. The conclusion which the DOF of the four
structures of the hexapod mount is zero and over-constraint does not exist has been derived by the analysis of the motion
screw systems of the four structures, and it also presents that the four structures are equivalent in DOFs and the DOF of
variation configuration of the hexapod mount is also zero and over-constraint does not exist, which provides a strong
theoretical support for the feasibility of the kinematic supporting of the optical module. The method also provides a reference
for the mobility analysis of other parallel manipulators.
The truss structure had the merits of simple configuration, reliable, flexible assembly, specific stiffness and strong design ability. It was widely used in the support structure of Space camera and large telescope at home and abroad. The article described and analyzed truss structures of ground-based telescopes, space-based telescopes and Space camera. Conclusions that some reference should be followed in the truss design process were given. Simultaneously it also introduced the basic knowledge of truss design optimization, including the optimization ideas of truss structure and optimization algorithm of truss structure, which laid a good foundation for optimal design of truss in future.