Related Experiment Video
Updated: May 17, 2026

Real-Time DC-dynamic Biasing Method for Switching Time Improvement in Severely Underdamped Fringing-field Electrostatic MEMS Actuators
Published on: August 15, 2014
Strategic active-brake energy dissipation for transformer-coupled ultrasonic motors: Step-size minimization and
Qichong Ma1, Song Pan1, Jianing Xu1
1Nanjing University of Aeronautics and Astronautics, China.
None:
Ultrasonic motors (USMs) inherently exhibit a finite mechanical resolution and pronounced residual vibration once the driving signal is removed, limiting their suitability for ultra-precision positioning. This paper introduces an active-brake circuit that momentarily short-circuits the transformer primary at shutdown, releases stored energy, and forces the stator to enter the vibration attenuation state. The technique reduces the minimum incremental step by 75.38% (from 22.14arcsec to 5.45arcsec) and suppresses normalized overshoot from 77% to 68% across the entire operational frequency band. Owing to its low component count-only a single relay-the active-brake module can be retrofitted to any existing transformer-based USM driver without modifying steady-state drive parameters or control firmware. It offers an immediate hardware-level upgrade for high-precision positioning, lithography, and precision-optics applications.
Related Concept Videos
Energy Losses in Transformers
There are four main reasons for energy losses in transformers.
The first cause can be the high resistance of the copper windings...
Magnetic Damping
If, however, the bob is a slotted metal plate, the magnet produces a much smaller effect. When a slotted metal plate enters the field, an emf is induced by the change in flux; however, it is less effective because the slots limit the...
Electro-mechanical Systems
A key component of the DC motor is the armature, a rotating circuit positioned within a magnetic field. As an electric current passes through the...
Time-Domain Interpretation of PD Control
Consider the example of control of motor torque. Initially, a positive...
Torque On A Current Loop In A Magnetic Field
Consider a rectangular current-carrying loop containing N turns of wire, placed in a uniform magnetic field. The net force on a current-carrying loop...
Transmission Shafts: Problem Solving
Next, use bending moment diagrams for the shaft to...
