Automated Trailer\Dock Alignment

Hello, all!

This is a PLC indirect question.

I have trailers with conveyors inside which connect to dock conveyors when parked. The conveyors are bi-directional - trailer material comes out to the dock conveyors and then another material gets loaded back via same conveyors.

While the docks are designed to handle 95% of alignment, sometimes the trailer conveyors' and dock conveyors' heights don't match. I'm in search for a mechanism or sensor\detection that the two conveyors aren't at the right alignment (height and side-to-side).

Could someone please advise?

I guess the dock conveyors wouldn't really move?
You could have fixed sensors which would determine whether the trailer conveyor was in a fixed acceptable range
or you could use a laser distance sensor on the x-axis and y-axis to determine the exact position of the conveyor

mass89 said:

I guess the dock conveyors wouldn't really move?
You could have fixed sensors which would determine whether the trailer conveyor was in a fixed acceptable range
or you could use a laser distance sensor on the x-axis and y-axis to determine the exact position of the conveyor

Click to expand...

Both trailer and dock conveyors are currently fixed and giving them an option to move (for now) is the least feasible due to the nature of equipment.

Could you please elaborate on the laser x-y sensor idea? Preferably with the examples of the sensor..

alexbeatle said:

Both trailer and dock conveyors are currently fixed and giving them an option to move (for now) is the least feasible due to the nature of equipment.

Could you please elaborate on the laser x-y sensor idea? Preferably with the examples of the sensor..

Click to expand...

Side to side alignment can be done with retro-reflective photo sensors. Sensors on the dock, reflectors on the trailer when the doors are open .. perhaps.

A simple light system could show move left (red), right (blue) or straight back (green). Distance measurement could indicate with solid color (more than 3 feet) slow flash (1 to 3 feet) or fast flash (under 1 foot) Just an example.

Up and down ... the trailers would need air suspension. Or perhaps the wheels could drive up on a levelling ramp. Complicated

To know if perfect alignment is here you could put a magnetically keyed sensor on top of the dock connection, with matching magnets on the trailers.

If the magnet was too high or low the sensor would not be tripped, as a normal proxy sensor may detect the frame of the conveyor.

This however would not tell you if it was high, low, left or right - just exact.

Aabeck said:

To know if perfect alignment is here you could put a magnetically keyed sensor on top of the dock connection, with matching magnets on the trailers.

If the magnet was too high or low the sensor would not be tripped, as a normal proxy sensor may detect the frame of the conveyor.

This however would not tell you if it was high, low, left or right - just exact.

Click to expand...

Very interesting! I will look at this....is the coding particular to a switch? If a magnet is broken will the switch need replacing?

Was thinking of the light curtains. One on the dock, one on the trailer. But your approach seems more robust.

IFM 3d Sensors of course! Any excuse!
https://www.ifm.com/us/en/category/020/020_020/020_020_010#!/S/BD/DM/1/D/0/F/0/T/24

It's like a vision system, except light isn't so much of an issue. Oh, and it's 3d.

We've found the most consistent solution is the comination of mechanical guides for the trailer wheels and an electro-mechanical lock between the trailer and building. The trailer was positioned square to dock and aligned with conveyor system. ( We have the same type). We then lagged the wheel guides in place. They were high enough to clear drifted snow and painted to glow in the dark. It took a bit for the drivers to get used to them. No more crawling under trailers to fake switches or crawling into trailers to unjam stuck pallets. My back feels better just writing this!