Position checking sensor

I'm looking for sensor to be used with crane position tracking in dusty area. Every 1 meter when crane moving, we will have sensor to tell crane position when crane pass and detect. Then this crane can know its position, like position 1 give value 1, position 2 give value 2.

Anyone can recommend for this specific type of sensor. We may use many proximity to combine each tracking position but I hope some ready made solution.

You may be able to add a laser sensor with a 4-20 ma output and use the processor to determine position. It all depend on your line of sight. I am looking into this right now but my application is determining which position dumped product onto a conveyor (120 different positions). I am looking into effector, keyence, banner and sick. I have never worked on a crane so check the legalities of this first.

I'm afraid distance sensor will have problem if used in dusty of foggy area.

Are you just looking for a digital signal the PLC will count or a binary signal that codes a number or a true analog signal?

How long is the travel?
How many positions do you need to monitor?

I think at the simplest soution is a non-contact inductive proximity switch. Make sure it is pointed sideways or down, not up to prevent metal debris from accidentally setting it off.

You can set up a ya gang of these with different flags at each station to read binary codes. If you have 2 sensors, you can read 4 flag patterns. 5 sensors, you can read 32 flag patterns. (This includes no flags as a count so in reality, 2 sensors gives 3 positions, 5 sensors gives 31, etc)

If you need true analog output then you are probably looking at a string pot (search for Celesco). Or I think Stegman makes a system for measuring long systems like cranes.

Long time ago I needed something like that, my machine was a looper for a pipe mill. I needed to know where the machine was located in every moment. I used latched limit switches they latch on when the looper was going for left to right and unlatch when the looper was coming from right to left. I had seven of them and each one was connected to a indicator light in the console (No PLC), nowadays you can connect them to a plc. They were produced by Allen Bradley.

My travelling rang is 150 m. I'm thinking to use 7 proximities and every 1 meter will have unique steel plate to give different feedback. For crane motor, I will use encoder feedback to make precision control after get correction tracking from proximity.
To make system like this, I will need many steel plates with unique for each one. So I'm looking for some solution which ready made. There may have special sensor like this for electric train or AGV system.

Why not just put an encoder on the travel of the crane as well?

I work on automated crane systems and we often use the Pepprl+Fuchs WCS Positioning system. It has very good accuracy and comes with different interfaces. It provides absolute positioning. If dust settles inside the reader head it may be a problem but air borne dust is not a problem.

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Why not just put an encoder on the travel of the crane as well?
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Gear box with backlash, mechanical system can make final position different from encoder feedback especially in long travel range.

Take a look on
SICK = OLM200
or
Leuze electronic = BPS 34 S M 100 H


Both with Profibus interface

Have used the Sick OLM200 for solving a similar task, and have seen a solution with Leuze electronic that worked without problems.

in your thing you have to use gray code, another way is to use one sensor and move it up and down the steel rail.
and you can use two sensors next to each other and a steel rail with square teeths on them.
open an old mouse with a wheel in it and see how it works. it is quadruple
and yes many industrial solutions but i think this is schoolproject.
If you put it up on the lectric motor you can have a resolution of 1 mm.

For this application, current system use absolute encoder with very long belt for position tracking (10 year used). But the system is hard to maintenance for belt and sometime position tracking error due to belt slip. They try to find other way for easier maintenance and reliability. The accuracy can be +/- 20 mm. This system is used in steel plant for pre-chemical process which raw product will move to each chemical basin. Some of chemical is acid and can make fog to obstruct photo sensor on overhead crane. The PLC is old Siemens S5 and will be migrated together with finding new way of automatic position control.

WCS Positioning System from P+F looks good. I will check if we can install code rail only at some point like every 1 meter instead of very long continuous code rail.

Sick OLM200 is similar to WCS of P+F but use barcode technology which may have problem in harsh environment.

Thanks all your guys for valuable guide. I'm still have to study more on your sensor solution.

have a look in an elevator they use a metal band with a notch that activates a real switch, you only need notches where you have to stop. use two switches so you know the direction of movement and a counter.
from 1 side example:
if counter =64 and switch 1 is switched on you are at position 65 this is bassin number 4.
i made a small crane this way to show a ladder diagram. (it was playing the towers of hanoi with 5 discs. As this was small i had to stop past the position when going backwards and then advance forward until switch was made.
i can give example in codesys (iec 61131)