How to Use FPGAs for Quadrature Encoder-based Motor Control Applications
Publication: EE Times Programmable Logic Designline
September 11, 2007 -- Precisely tracking speed, acceleration, and position of a motor's rotor is an essential requirement for many motor control applications found in everyday equipment such as fax machines, elevators, and medical equipment. A closed-loop control scheme is able to bring motor feedback information, such as back electromotive force (BEMF) voltage or supply current to the control system. Rotary encoding is a common mechanism for the delivery of accurate speed, acceleration, and position of the motor rotor.
Rotary encoders are commonly deployed in the closed-loop rotor systems used in a wide variety of applications from robotics and high end photographic lenses to opto-mechanical mice and trackballs to rotating radar platforms. A rotary encoder is an electro-mechanical device for converting the angular position of a shaft or axle to a digital code. For many applications and equipment that need to track object location, velocity and accelerations accurately, a rotary encoder offers a cost-effective solution.
Relative and Absolute are two primary types of rotary encoders. A quadrature encoder is in the relative encoder family and is most commonly used in high-speed motor control systems; it also facilitates the ability to determine motor direction.
By Glen Young. (Young is a Product Marketing Manager for Actel Corp.)
Reprinted from SOCcentral.com, your first stop for ASIC, FPGA, EDA, and IP news and design information.