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This paper presents a simple and economical way to accurately estimate an initial position for linear hybrid stepping motor (LHSM) drives by utilizing dc excitation. In order to detect an absolute position of the mover, two preliminary tests are carried out under two different dc conditions: single-phase and two-phase dc excitation. The proposed algorithm has been successfully applied to a practical system with a rated initial load and stiction without causing any mechanical damage. The proposed scheme is not affected by the harmonic force ripple of the LHSM and its benefits are much more significant for multi-axis systems. The paper presents experimental results to prove the effectiveness of the scheme. Index Terms--DC excitation, initial load and stiction, initial position for LHSM drives.

Linear hybrid stepping motors (LHSMs) have a simple structure and provide ripple-free holding force at the aligned position. Despite these attractive features, however, an LHSM delivers strong thrust vibrations during position-to-position movement that are the dominant cause of the positioning error, mechanical stress, and acoustic noise. In order to overcome this defect, we have developed an active control scheme to damp the vibration of a [pi]/4-multiple-pitched LHSM by a feed-forward compensation signal. Utilizing an elaborate reluctance network based on the finite-element analysis to take the nonlinear magnetic properties into account, we model the LHSM with force ripple components as a nonlinear position-dependent function. We estimate the damping force signal from the Jacobian linearization observer. The positioning accuracy is significantly improved through a closed-loop control scheme for restraining the thrust ripple. Index Terms--Active control scheme, closed-loop control, feed-forward compensation, linear hybrid stepping motors (LHSMs), thrust vibrations.

This paper presents a [pi]/4-multiple-coupled two-phase linear hybrid stepping motor (LHSM) that has two windings per phase, one of which shares the other phase winding. The proposed motor shows a unique ability to deliver low cogging force without any complex control scheme or additional power electronics hardware in microstepping control. An analytical and experimental comparison between conventional [pi]/2- and [pi]/4-multiple-coupled LHSM confirms the effectiveness of the proposed design. Index Terms--Linear hybrid stepping motors, low cogging force, [pi]/4-multiple-coupled LHSM.