One of our customers has his machine on the front cover of H&P that is our controller on the front page too.
http://www.hydraulicspneumatics.com/CurrentIssue.aspx
The article.
http://www.hydraulicspneumatic...le/False/84769/Issue

These sawmill systems have scanners that can precisely scan logs to find the dimensions and then determine how best to cut the log. A lot of math is required to do the scan and determine the shape of the log. Then even more math is required to find the optimal cut. Finally the positions for each of the actuators are downloaded to the motion controllers and the motion controllers must move to positions quickly and accurately. Then they must hold position as the logs go through the machine. The chipper heads must hold position against the force of the log which tries to push the chipper heads out. Another more difficult task is to cut following the profile of the log. Logs are not straight, there is a curve to them and cutting straight lumber out of curved wood results in waste. These curves are downloaded to the motion controllers and the saws and chipper heads must follow the curve as a function of the logs position moving through the machinery. The data for the curve is a position for every 2cm along the length of the log and for each axis that is doing curve sawing. That is a lot of positions. The motion controller then follows this curve when activated by a photocell that tells the controller that the log is there. To follow along the curve at the right rate required slaving the hydraulic actuators to an encoder on the feed chain.

Finally, depending on the length of the logs there may be 2 or 3 logs in the system at the same time. The Veisto engineer must track the position of the logs using the encoders mentioned above and keep the data for that log matched with the log. By queueing up the log and its data there can be one log following immediately behind the previous log. There only needs to be a gap between the logs big enough to allow time for the actuators to move to the new set points. Obviously more logs can be processed if this gap is minimized which require fast actuator positioning.

The plot at the bottom of the article shows the motion of an actuator. The actuator's target and actual position and velocity, and the control signal can be plotted every millisecond if required. This way the people installing and tuning the hydraulic systems can be sure the system is tuned and the positioning is accurate.

The motion controllers have auto tuning that greatly reduces the tuning time and therefore the field time and makes it easier for the maintenance people to keep the system running like new.

Look at the last statement. When there are technical issues the Veisto engineers can send the computer data via e-mail and give us a call. We can analyze the graphs quickly as we see hundreds a year and many thousands through the years. We can then tell the engineers what to do next or usually how to solve the problem. All that is required is a cell phone connection to send the e-mail and make the call. Technology allows us to support systems all over the world.