Collision/ part detection

Nata_lia

Hello,
I have this situation.
My robot needs to go and drop a part in a slot. There are  160 different slots. I have created a routine to follow this pattern and robot would do this job fine in normal operation. But for the safety reason i want to add some mechanism to double check if there is already a part in the slot or not before i drop the part.

Notes: I cant use sensors because we don't want to use sensors for all 160 slots in a table.

I am trying to do something with collision detection so that robot can stop and  go to next slot. Some body has any idea and their opinion about this? Please help me.

or, Is there some kind of sensors so that i can mount only one sensor in robot and i dont have to use any reflectors or other sensor complement in each of the slots.

Thank you very much to everyone in advance, Help me out with your ideas please.

Natalia

SjoLi

Natalia,

the are different types of sensors you can mount to your gripper.

- Pressure

- Visual

- A currentsensor (mainly used in arcwelding systems)

You can mount the at the side or top of your gripper.

After dropping the part you can make a small routine to let the sensor to check if the part is at the desired position.

-> Move to pick position

-> Pick part

-> Move to drop position

-> Drop part

-> Move to check position (turn gripper upside down for example)

-> Check if part is at desired location

If OK

-> Start from beginning

If NOT OK

-> Errorhandling instruction

good luck

Nata_lia

Hi, Thanks for your opinion, I already have used a counter variable to track the slot number. Can you give me names of some specific sensor that might be helpful in my case. I want to use a sensor only in the robot arm  but not in all the slots so that we have to use only one sensor.

Marcel

Hi

You could use a light beam sensor like Sick WT18 and use the SearchL instruction.

Best regards

Marcel

SjoLi

The type of switch is dependant on the product and available size.

You can get advise from any sensorhandler in your neighbourhood.

As long as you can provide an input for the robot when the product is found. Other than that it does not realy matter what kind it is.

One sensor type I forgot to mention was a magnetic swith (only works with magnetic materials ofcourse)

good luck

Nata_lia

Thanks Guys, That was really very helpful.

CaptainAwesome

Hey Natalia, 

depending on your setup you could use a normal web cam and some computer vision to find out if a slot is filled. Cheap & quickly implementable. Using the SDK, you could then tell the robot whether the slot is free or not.

Nata_lia

That sounds like an idea. But I don't have any idea on C vision and ABB SDK, I did some image processing for MATLAB and other High Level Programming Paltform but nothing in this area.

Could you provide me some info about how I can integrate webcam and compare two images in the case of robot programming?

CaptainAwesome

Hi Natalia. From the top of my mind, I would propose the following:

- Take a photograph where all slots are empty. 

- Mark the regions of each cell manually (a lot of work, probably!)

- Take a photograph during operation

- take the difference of the two images (maybe compensating lighting or similar)

- find a metric or heuristic to analyze the difference of the two images in each cell and decide whether it is full or not.

this is just a rough idea, there might be better ways to do this!

regards, CA

EDIT: btw, i would use OpenCV for this, it is a powerful library for computer vision. Using the SDK example, you can then communicate to the robot, e.g. the robot asks "is cell 135 full", the PC replies, robot takes appropriate action.

sounds like a fun project :-D

CaptainAwesome2012-09-27 10:07:55

dardesm

Natalia i suggest to call Cognex

Good Luck