Performances Comparison for a Rotating Shaft Suspended by 4-Axis Radial Active Magnetic Bearings via 𝜇-Synthesis, Loop-Shaping Design, and Sub(𝐻)_∞with Uncertainties

Table 1

Data for simulation.

Symbol	Description	S.I.
𝑚	mass of rotor	2.3 Kg
𝐼𝑃	polar moment of inertia	8×10^−4 Kg·m^2
𝐼𝑇	transverse moment of inertia	6×10^−2 Kg·m^2
𝑙𝑏𝐴	distance bearing 𝐴 from centre of mass 𝐺	0.241 m
𝑙𝑏𝐵	distance bearing 𝐵 from centre of mass 𝐺	0.139 m
𝑙𝑠𝐴	distance sensor 𝐴 from centre of mass 𝐺	0.241 m
𝑙𝑠𝐵	distance sensor 𝐵 from centre of mass 𝐺	0.119 m
𝐴𝑔(𝐴,𝐵)	pole surface	6.6×10^−5 m^2
𝑔0(𝐴,𝐵)	nominal gap	3.81×10^−4 m
𝛼	slope of bearings axis	45°
𝛽	angle of two electromagnet poles	45°
𝛼	slope of bearings axis	45°
𝑃𝑚,𝐼𝑇,𝐼𝑃	uncertainties percentage	10%
𝛿𝑚,𝐼𝑇,𝐼𝑃	range of uncertainties	[−1,1]
𝑘(𝑥,𝑦)(𝐴,𝐵)	displacement gain	144000 N/m
𝑘(𝑖𝑥,𝑖𝑦)(𝐴,𝐵)	current gain	38 N/A