Abstract
The effects on deployment accuracy of joint clearances and forces acting on the deployable mechanism are investigated. “A virtual massless link” is used to describe the joint clearance of the mechanism in the free state. Aiming at the following problems of multi-loop linkages mechanical system such as loop constraints coupling and complicated topology structure, the geometric relationships and the deploying error equations of deployable mechanism are provided based on Denavit-Hartenberg matrix by splitting multi-loop linkage into 3 single-loop linkages. In addition, with consideration of forces, “a virtual massless rope” is used instead of “virtual massless link” to describe the joint clearance for avoiding the extra singularities. And the criterion of mechanism in stable configuration is obtained by weighting coefficient method on the basis of minimum potential principle. The solving procedure of deploying error equations in the state of forces constrained is presented by combining Monte-Carlo method with genetic algorithm, it is an effective solution for the nonlinear objective function with multiple constraints and strong coupling. The results indicate that the appropriate forces acting on mechanism produce a significant effect on improving repeat accuracy, and the absolute accuracy can be improved with the future error compensation.
Highlights
Deployable mechanism has been widely applied in the supporting device of space equipment such as flexible solar panels, satellite antenna or space telescope for the characteristics of big stowed volume ratio, light weight, high structural accuracy, etc
The object of this study is to propose an accuracy analysis method for multi-loop mechanism with joint clearance and to provide an approach for improving the deployment accuracy without any redundant actuation added
The “virtual massless links” are used to replace the joint clearances of deployable mechanism which is in the free state
Summary
Deployable mechanism has been widely applied in the supporting device of space equipment such as flexible solar panels, satellite antenna or space telescope for the characteristics of big stowed volume ratio, light weight, high structural accuracy, etc. [23] have decoupled the multi-loop mechanism with joint clearances based on matrix method and particle swarm optimization, but they only have investigated the maximum deployment error. H. [24] provided a generalized method for error analysis of multi-loop mechanism with joint clearance on the base of screw theory, the effort to diminish the influence of joint clearance on the mechanism accuracy has not involved. The object of this study is to propose an accuracy analysis method for multi-loop mechanism with joint clearance and to provide an approach for improving the deployment accuracy without any redundant actuation added. According to the characteristics of deployment error model, the Monte-Carlo method and genetic algorithm are combined to solve and analyse the deployment error with forces constraint. This research provides a reference for error correction and system reliability analysis of mechanism
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