This paper presents an electromechanical hybrid model combining a driving circuit and a TWUSM. (1) A driving circuit model combining circuit components with the load-dependent equivalent circuit model is proposed to simulate the real electric network. (2) The teeth discretized method is employed to refine the contact status and interaction forces limited to the teeth space, which improves the accuracy of the rotor step response not only in the rising time, but also the steady value.

Parallel mechanism (PM) with limbs of embedding structures means that the limbs in the mechanism are connected in the coupling structure, so as to realize limb coupling, and the PM of common axes between limbs. Characterized by the compact structure, low cost and larger workspace, this kind of PM has very broad application prospects in engineering. In this paper, analysis and improvement are carried out on the input of a compact 3-DOF PM with limbs of embedding structures with larger workspace.

The Beam Constraint Model (BCM) may yield large predicting errors (> 5 %) when the applied axial force goes beyond a certain boundary. We mathematically determine the nondimensional boundary of the axial force by the conditions of the positive definite quadratic form of the strain energy expression and the buckling load expressions. If the axial force is beyond the boundary, the Chained Beam Constraint Model (CBCM) can be used instead.