Matching Position and Velocity on-the-fly

April 18, 1997
Labeling, packaging, and bag-folding machines synchronize cutoff shears and other actuators to the same velocity as the piece they cut or sense

Labeling, packaging, and bag-folding machines synchronize cutoff shears and other actuators to the same velocity as the piece they cut or sense. Thus, the controllers must provide precision positioning and velocity matching between the two components. Although several different motion controllers might fit an application, the programming tools that come with it can make the difference between success and failure.

Motion controllers for these kinds of jobs require a segmented electronic cam, floating-point electronic gearing, and high-speed interrupt commands to handle on-the-fly position and velocity matching. For example, a typical flying cutoff machine controller uses the electronic cam to match the position and velocity of the rotating knife to the material on the web. The knife’s motion profile is divided into four position and velocity segments: acceleration, velocity matching, deceleration, and wait segments. The velocity of the knife is matched to the web speed in segment two because the change in position with respect to time is dx/dt or velocity. An encoder on the web is the cam source which ensures matched positions. Additional commands allow advance or retard (cam floating zero), amplitude (cam scale), and frequency (cam length) to be programmed dynamically. Thus, the speed of the knife is programmed on-the-fly to the required cutoff distance and frequency.

One controller also has other programmable commands for similar applications. For instance, in labeling machines, the labels hit the material on the web when the controller matches their velocity and position. The controller does this with floating-point electronic gearing to match velocity, and with the segmented electronic cam mode to match position. Packaging or bag making applications also can use the third feature, the highspeed interrupt. This interrupt command includes a programmable window to look for registration marks to protect against jamming machines.

Information for this article was provided by Gary J. Hagar, Acroloop Motion Control Systems Inc., Minneapolis. For more information on synchronizing systems

Sponsored Recommendations

The entire spectrum of drive technology

June 5, 2024
Read exciting stories about all aspects of maxon drive technology in our magazine.


May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Solenoid Valve Mechanics: Understanding Force Balance Equations

May 13, 2024
When evaluating a solenoid valve for a particular application, it is important to ensure that the valve can both remain in state and transition between its de-energized and fully...

Solenoid Valve Basics: What They Are, What They Do, and How They Work

May 13, 2024
A solenoid valve is an electromechanical device used to control the flow of a liquid or gas. It is comprised of two features: a solenoid and a valve. The solenoid is an electric...

Voice your opinion!

To join the conversation, and become an exclusive member of Machine Design, create an account today!