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This paper describes an extension to the formulation of the equations of motion for a system of connected rigid bodies introduced previously. Formerly, the multibodies were restricted to either hinge or slide connections. Where applicable, the formulation has been extended to include full six degree-of- freedom (DOF) motion capability between connected bodies. In particular, consecutive bodies or lumped masses can be connected with 6 DOF springs and/or dampers. This capability will allow the user to integrate key flexible body dynamics with multiple rigid body dynamics. The connection topology is still limited to be that of a tree. Extending the topology to a full array connectivity will be investigated in the future. Once the topology restriction is removed, this work will incorporate full finite element modeling capability. This paper develops the modified vector operator equations of motion which give a set of nonlinear differential equations that are amenable to standard numerical integration techniques. This updated formulation has been implemented in FORTRAN code and embedded in several simulation packages being used to generate multibody spacecraft dynamics. For example, using a control system-based simulation software package interfaced with this multibody dynamics code, the tool can be used to include several key flexible body attributes. This tool allows one to rapidly input the dynamic model of a multibody system by simply entering the mass, geometry, spring/damper and connection (location of hinges and/or slides) properties. This provides the engineer the capability required to implement detailed simulation work with rapid turnaround. By removing the need for the timely task of developing the dynamic models of a spacecraft, the control system engineer can concentrate on designing the control system. Many different spacecraft configurations have been studied with this tool. An example of a spinning communication satellite deploying its wings (communication equipment) will be presented. Two modes will be included for each of the solar arrays. These results will be used to verify the effects of the solar array modes during the wings deployment.
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