positioning system

[joelmclaren]

Hi everyone

I work for car seating company in the UK and we are having an issue with our operators not fitting a specific set of screws.

There for I took on the project of making an inductive pen which the operators would need to use in their process to check if the screws are present.

However this presented another issue that the operators would then proceed to use the inductive not on the screws but on another piece of metal which they would just tap 4 times to cheat the test.

This has led me to find out if it would be possible to develop a positioning system that detects where the pen is and will only let the pen activate once in four different locations to ensure that its detecting the screws and not some other piece of metal.

so what products from diligent would allow me to detect position and only allow the inductive pen to activate in specific positions via PLC.

I don't have much knowledge on this topic as I've only been an apprentice engineer for 8 months so explanations are very much welcome.

below I have attached a very very simple diagram of the setup we have for the inductive pen including the 4 positions it'd need to locate.

thanks, Joel

 

[D@n]

@joelmclaren,

The more I think about this, the  more I'm coming to the conclusion that: If you can't trust your employees to do "what's right", then you've got bigger problems then figuring out where a sensor is located.

Dan

[joelmclaren]

@D@n

A handful of the operators will do it to make the process quicker even if its the wrong thing to do; this is why I need a positioning system so they are required to do it.

[elodg]

I will refrain from the socio-political aspects of this question. Purely from the technical perspective, I am thinking replacing that manual labour step with cameras and image recognition. I cannot think of anything else that is easier to implement and close to impossible to cheat.

[joelmclaren]

@elodg

We have attempted to use vision systems in the past and have had no luck due to the nature of the product we make.

The build pallets which the seats are built on can vary in height along with the variation in high adjustment on the seats means that vision systems struggle to identify the part. in addition to this they are other variables that we aren't able to control that results in vision systems not being reliable and has caused downtime at our factory.

[Notarobot]

Hi @elodg

In my opinion, the first option to consider is to use either unique optical or RFID (NFC) tag on every screw. This will allow to register that every one was approached.

The second check whether the screw was tightened can be obtained if you equip every screwdriver with something like  LSM9DS0 inertial module:3D accelerometer, 3D gyroscope, 3D magnetometer. This will tell you how many revolutions the screwdriver made and potentially even 3D coordinates of the sensor. Of course this will require a processor to digest these data. Some smartphones are equipped with similar sensors and could be used for experimentation. They also can read optical ID or RFID NFC, can be connected to a database and monitor the progress. There are also commercial sensors for IoT that include gyroscope sensor.

Some of Digilent boards could be used for these tasks but, in my opinion, your choice should be based on availability of software libraries and examples.

In any case this seems to be fun project.

Good luck!