I am working in Crane Industry at a Port. The Ship-to-Shore Crane drivers are crazy about speed. They always bang and break the Spreaders. We are using an old TSX17xxx PLC on the Spreader. I want to control them such that at what ever speed they come to the Container, their speed is brought to CRAWLING.
Regards
William M.C.Wali
Mombasa.Kenya.

 

Take a look at SonaSwitch. It is used in Anti-Collision applications. But must not get wet.

http://www.edpcompany.com/sonaindex.html

 

The problem seems to me to be that you need the distance from the hoist to the container. Which means a sensor on the hoist or a sensor on the trolley for distance to the container and an encoder on the the hoist motor to convert revolutions to distance the hoist has travled from the trolley and then subtract the distance the sensor on the trolley has measured. I have done something similar using a laser sensor from a Swedish manufacturer but cant think of the name. They will need to know the distance you need to measure and any inteference with the light you encounter to specify the laser. This wont be cheap. The laser I used was about $4,000. Good luck

 

http://www.trimble.com/factoryautomation.html