Abstract: To address the difficulty in comprehensively evaluating magnetic-force nonlinearity, release stability, actuator dynamics, and thrust-inversion uncertainty prior to hardware implementation of active magnetic-levitation microthrust measurement platforms, a 3 kg-class active magnetic-levitation microthrust measurement platform was considered, and a comprehensive evaluation workflow comprising magnetic-force calculation, vertical closed-loop control, horizontal thrust inversion, and uncertainty propagation was established. A two-dimensional axisymmetric magnetostatic model was used to obtain the mapping relationship among gap, current, and axial magnetic force. The nonlinear magnetic-force model, current closed-loop model, and vertical dynamic model were then coupled to analyze the effects of release-position error, actuator capability, position noise, and control delay on stable levitation. The results show that, at a design gap of 3.50 mm and a bias current of 0.30 A, the axial magnetic force is 29.430 N. With a current limit of ±0.50 A, a current-loop bandwidth of 100 Hz, and a simulation duration of 0.50 s, the initial position-error range satisfying the stable-levitation requirement for measurement is ?47 to 149 μm. Position noise and control delay have a more pronounced effect near the stability boundary. When the position-noise standard deviation is 5 μm and the additional control delay is 3 ms, the proportions of samples satisfying stable levitation are 0.91 at the equilibrium point and 0.50 near the negative boundary. Horizontal thrust-inversion analysis shows that, when thrust buildup and angular viscous damping are neglected, the simplified constant-thrust model underestimates the steady-state thrust. At a thrust of 50 μN, the relative standard uncertainties for thrust application durations of 1, 3, and 5 s are 2.09%, 1.34%, and 1.33%, respectively. The proposed evaluation workflow can provide a reference for magnetic-circuit parameter selection, release control, thrust application duration selection, and thrust-inversion uncertainty evaluation of similar active magnetic-levitation microthrust measurement platforms.

Key words: active magnetic-levitation, microthrust measurement, electric propulsion, thrust inference, uncertainty analysis