Achieve Greater Control
Fraser Surrey Docks approached CFA when recurring failure of the analog electronics controlling Crane #2 threatened to force the company into decommissioning the aging workhorse. Capable of loading or offloading container ships at a remarkable speed and with a replacement cost ranging in the millions it was decided to attempt the installation of a PLC based device to monitor the analog systems aboard Crane #2.
In the event of certain known potential failures in the circuitry, compared against the requests for movements by the operator versus the actual motion of the machine, the PLC would over ride the existing controls and lock the load in place.
Techniques used in the software included basic DSP (digital signal processing) to detect failure of filter components in the power supply and yet be capable of ignoring normal “noise” caused by power components within the system.
Monitoring joystick positions in the operator cabin and comparing them to both the speed and direction of the load to recognize a runaway condition. Normal operations like pulling up to slow downward motion in a more aggressive manner had to be considered so as not to create false trips.
After development, installation and testing the entire unit went under the scrutiny of a group of Engineers from Transport Canada as well as the local Union and was granted a new lease on life.