## Abstract

As seen in Chap. 3, the differential equations governing the behavior of stepper motors are nonlinear and several uncertainties are present in the dynamics. In accurate positioning applications, ignoring modeling of these uncertainties is detrimental to the motor performance. Many of the problems arising in the operation of the stepper motors, such as poor settling times, resonance phenomena, torque ripple, and positioning inaccuracy due to friction can be overcome by utilizing feedback control. In this chapter, the robust control designs advocated in the previous chapter are applied to various types of stepper motors to ensure good tracking performance. Some modifications to the control design methodology outlined in the previous chapter are made in order to account for unknown virtual and actual position-dependent control coefficients that arise in the dynamics of the stepper motors.

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## References

- 1.For electric motors, this pseudo control input is typically the phase current.Google Scholar
- 2.This commutation scheme is not only computationally less complex than the one proposed in [23], but also seems to improve the tracking performance as verified through our simulation studies.Google Scholar
- 3.The value of
*c*given in the table was the value used for controller computation.Google Scholar - 4.The gain k1 is a negative drift term, while the remaining gains are nonlinear damping terms used in the control law.Google Scholar
- 5.Refer to Chap. 3 for the modeling of cogging and drag forces.Google Scholar
- 6.If the bound in (7.170) does not contain a constant term in the bounding polynomial (i.e., ς = 0), then global asymptotic regulation of the yaw angle may be attained. In this case, σ3 = 0 is used for the adaptation law (7.174).Google Scholar