Stepper motor drive modes: In a stepper motor controller, the half-step sequence is selected when which design goal is most important?

Introduction / Context:
Stepper motors can be driven in several modes: wave drive (one phase on), full-step (two phases on), half-step (alternate one/two phases), and microstepping. Half-step mode inserts intermediate positions between full steps, doubling the resolution and producing smoother motion than pure full-step operation.

Given Data / Assumptions:

• Half-step alternates between single-phase and dual-phase energization.
• Full-step provides one position per phase pair state; half-step doubles the count.
• Torque varies slightly between single-phase and dual-phase half-steps.

Concept / Approach:
When finer angular resolution is needed but microstepping is unnecessary or unavailable, half-step is a simple solution. For a motor that is 15° per full step, half-step yields 7.5° per step; for a 1.8° full-step motor, half-step yields 0.9°. This improves positioning granularity and can reduce resonance at low speeds.

Step-by-Step Solution:

Verification / Alternative check:
Consult motor datasheets or run simulations: commanded half-step sequences produce twice as many distinct rotor positions per revolution as full-step sequences at the same coil wiring.

Why Other Options Are Wrong:

• Larger steps: Full-step or wave drive meet that, not half-step.
• More torque: Dual-phase full-step typically yields higher holding torque than single-phase portions of half-step.
• Less torque or maximum speed: Not the primary motivation; half-step targets resolution and smoothness.

Common Pitfalls:
Expecting constant torque at every half-step position; forgetting current control differences between single- and dual-phase states; assuming half-step solves all resonance issues without mechanical damping.

Final Answer:
Smaller steps are desirable