Origin Of Stepper Motors

The origin of stepper motors can be traced back to the early 20th century, with their development going through several key stages.

 

Origins and Early Inventions (1918–1923)
1918: American inventor Frank W. Wood applied for a patent (granted in 1922, patent number US 1,408,555) to make the rotor step by step by energizing different combinations of five sets of stator coils. This is one of the important technological prototypes of stepper motors.

1919: Briton C.L. Walker obtained a British patent for a reactive stepper motor, using a toothed stator-rotor structure, laying the foundation for variable reluctance (VR) stepper motors.

1920: C.B. Chicken and J.H. Tain obtained a U.S. patent proposing a "sandwich structure" design, which increased torque in a small volume and further promoted practical application.

 

First Practical Applications (1920s)
Around 1923: The British Navy applied the above principles to remote-controlled gun systems and cannon aiming control systems on warships, using reactive stepper motors (VR type) and switching current directions via rotary switches to achieve precise angle control.
During the same period, this technology was also applied to the drive devices for torpedo launch direction, marking the stepper motor's transition from the laboratory to military engineering applications.

 

Technological Evolution and Naming
Initially called the "step-by-step motor," it gradually became known as the stepping motor or step motor.
Its working principle is based on electromagnetic torque, rotating the rotor "step by step" by changing the energizing sequence of the stator windings, with each step corresponding to a fixed angle (step angle).