position sensor? 1

| have a frame of bays 5*4, that's 20 locations,and a robot arm that is moved in the x and y axis with 2 motor belts.
I want to control this robot.Do you have any ideas of how I can know the current location of the robot arm.
Many thanks for your help

 

[dbaird]

Encoder feedback on the motors should provide accurate position information.

David Baird
dbaird@gemcity.com

Sr Controls Engineer

EET degree.

Journeyman Electrician.

 

[nbucska]

Could you give us more info ? <nbucska@pcperipherals.com>

 

[JayMaechtlen]

Depends on how you control the motors.
1. If you control them with a computer-type device,then you should check out the small motor control packages.
&quot;Encoders&quot; are pulse-signalling devices which may be integrated into a motor assembly. The computer controll device will count pulses from each motor, and thereby can determine how far the device has travelled from a known reference point.
2. to control without computer (or maybe even with), use prox sensors or limit switches to detect when the unit reaches each point of interest.
let us know how it goes!

Jay

 

[charlie300]

If you use rotary encoders you are still going to want to use proximity switches to determine &quot;home&quot; position, or where the encoder counts are referenced from. Overtravel proximity switches are sometimes used for safety as well, in case the encoder &quot;counts wrong&quot;.

They have linear, optical scale encoders, which actually measure location on an encoded track, but they are a more expensive solution.

 

[bline1112]

You might begin by answering the following:
1)how accurate do I need to be?
2)how fast do I need to do it?
3)how critical is an error?
4)how often will this process change?
The successful selection of the best control (which may include position info) initially hinges on the basic requirements of your application. Control technology continues to be quite specific with selections made to accommodate the most pervasive constraints (hopefully well understood in the beginning).

 

[ktheb]

bline112 asked very good questions.

you should also answer the following:

1. what kind of motors are installed on the robot?
2. will i use these motors?
3. what is my budget for motion control boards or plcs?

 

[jarvis]

What if you had a switch for each column, each with a different voltage level hooked to the switch. Then did the same for the rows. You could then use a\d converters to determine the position.

Or..

You could use twenty AND gates(one for each bin), with the inputs tied to the corrusponding row and column. The output of that gate would corruspond to that bin. This would tell you when you got to a particular bin, but may work well for navigation. If you hooked up a pannel of LEDs to the gates, you could get a nice visual. Or you could hook them up to a multiplexor and use the output to feed a computer.