The inverse kinematics of a free-floating variable geometry truss are formulated in conjunction with the conservation of momentum, and the Moore-Penrose inverse is employed to give the solution. Based on the generalized Jacobian matrix, a two-order solution of task priority is derived, and its possible applications to obstacle avoidance, shape control, and free-endplane control are also discussed. Moreover, the issues of the dynamic singularities of a free-floating variable geometry truss are addressed, and an approach through actively handling the orientation of the free-endplane of a free-floating variable geometry truss is proposed to reduce the coupling of singularities with its dynamic parameters. With the aim of applications in space engineering, a free-floating variable geometry truss model is manufactured and set up in the laboratory, and a distributed control architecture is constructed to provide it with an effective parallel control. Finally, a docking experiment with this model is carried out.Shenyang Huang received his B.Eng. degree in applied machanics from Huazhong University of Science and Technology, China, in 1983 and the M.Eng. and Ph.D. degrees, both in computational mechanics, from Dalian

Since an intelligent variable geometry truss (IVGT) is usually equipped with large numbers of redundant actuators for the sake of providing adaptivity, a distributed control is considered a promising approach to dealing with its motion control. In this case, a modeling approach and an integrated model is a key to constructing distributed control systems from both hardware and software. To this end, this paper proposes an object-oriented modeling approach. Through decomposing the control problem domain underlying VGTs into objects, an object model can be obtained to represent various object abstractions and the relationships among these objects. It is shown in this paper that an object model of VGTs is exactly the integrated model for their knowledge organizations as well as the control architectures. Two control schemes resulting from the object models-a hierarchical distributed control and an autonomous distributed control-are discussed in particular. To verify the concepts addressed in this paper, an experimental prototype of IVGTs was manufactured, with a two-level hierarchical distributed control system equipped. With this prototype, an experiment is carried out, simulating a self-construction of space structures with IVGTs in a null gravity space.

No abstract

No abstract

No abstract