Error model analysis of 2-RSSS spatial mechanism

The position error sources of a low speed 2-RSSS spatial mechanism were studied. Firstly, error model of this mechanical system was built considering realistic joint characteristics, namely, joints with clearance was presented. A simplified model was built under the assumption of two-force principle, error of the clearance joints was represented by linkages' length. The simplifications not only simplify the process of solving the problem but also maintain the accuracy. Secondly, the error sensitivity matrix of the spatial mechanism derived in parameterization form. The invariants in it were figured out by a series of numerical examples. The analytical expressions were straightforward and numerical computation can provide precise amounts. Thirdly, numerical examples verified the results of the semi-analytical method. Finally, designing guidelines for low speed 2-RSSS spatial mechanism are given.