Robotic Arm

J

Jibit

Registered
Does anyone have any ideas for this? I need a device that is very accurate and precise. It needs to be able to locate itself at several different spots on an X and Y axis (speed not a factor). At these several locations it needs to travel on a Z axis between variable speeds of .2m/s and 2m/S (the speed at which it retracts is not a concern). I can only think of a robotic arm. The problem is the Z axis and the variable speeds. The device needs to be very accurate. I was thinking of mounting solenoids on a board in the locations I need them but I wouldn't be able to vary the speed and it may not be a consistent speed. Any ideas? I'm looking for something cheap and easy.

David O'Donnell
'97 Mark VIII LSC "Maxine II" (RIP Maxine I, 5-16-03)
'91 Mark VII BB "Monica"
'67 Thunderbird "Molly"
 
RE: Robotic Arm

I was thinking of something like a plotter for schematics or architecture layouts. I would have no control of the speed on the z axis though.

David O'Donnell
'97 Mark VIII LSC "Maxine II" (RIP Maxine I, 5-16-03)
'91 Mark VII BB "Monica"
'67 Thunderbird "Molly"
 
RE: Robotic Arm

Hi David

Building computer operated machinery is what I do for a living , accurate and cheap dont go together ...a PLC to operate this unit you want to build will start at $200.00 for only a few inputs and outputs, one with 16 inputs and 16 outputs ,a fairly common configuration for a small project is $900.00 you will need sensors at points to stop at $80.00, each if you want to use a glass scale for stopping in any position $800 to $1000.00 each ,one for each axis. Then you have programing ,$350.00 an hour..Here is the problem with your project, any time you move on any axis, all are the same , just different directions, the computer has to know where the axis is at all times ,so it has to count something to keep track ,there are many different ways ,and the more accurate the more expensive. Using a glass scale for instance , the computer counts lines printed on the glass the more accurate the spacing between the lines the more acurate the movement...If the glass should get dirty the computer can see several lines as one and the accuracy fails..Air cyl now have the ability to stop accuratly in the middle of their motion, but a basic system will start at $1500.00 without an air cyl . ...Varying speed is typicaly done using DC motors and speed control boards , but accuracy and speed control would use a pulse DC motor and control , the motor price starting at about $250.00 if the load is very small ..Ok having said that , if you give me more details on what you are trying to do maybe I can can help , but your previous explanation , doesnt have near enough detail , for me to help , and sounds very costly...This is very long but it does offer some real insite into your question.. I hope it answers your questions,and is not too discouraging...

John aka Topcat
 
RE: Robotic Arm

John

Gees , I thought my long but simplistic answer may have too much information for the question ...I am currently involved in a project involving that very technology , parts supplied by someone else ,interesting to see where they came from, item for item...I will say though the encoder system is modular and although it seems less expensive at first look , by the time you are done puting a package together it is not cheap , or only slightly cheaper..but I think motor controls for brushless DC motors and AC motors is the future ,already started..interesting link...


John aka Topcat
 
RE: Robotic Arm

..but I think motor controls for brushless DC motors and AC motors is the future...
Click to expand...

A couple of recent examples I recently have worked on ...

A solid state synchronous speed control capable of controlling up to four 75 HP AC motors on a rotary drill capable of delivering over 150,000 foot-pounds at a precisely variable 1 to 6 RPM. This unit turns a 14 foot diameter drill bit with precision control of the RPMs while maintaining full torque capacity even with only two motors being driven.

A position and speed indicator of a man and materials hoist used in concrete lining of mine shafts. Control of the 250HP electric motor driven hoist is crucial to operational safety and efficiency. Hoisting speeds are monitored up to the maximum allowable 500 feet per minute and positioning is accurate to one hundreth of a foot in a typical thousand foot mine shaft.
 
RE: Robotic Arm

Hey,

Why can't I read all the replies? I logged in and back out but the 3 replies that were here before are gone and the page still says that it has 6 replies, what gives?

David O'Donnell
'97 Mark VIII LSC "Maxine II" (RIP Maxine I, 5-16-03)
'91 Mark VII BB "Monica"
'67 Thunderbird "Molly"
 
RE: Robotic Arm

Nevermind!

David O'Donnell
'97 Mark VIII LSC "Maxine II" (RIP Maxine I, 5-16-03)
'91 Mark VII BB "Monica"
'67 Thunderbird "Molly"
 
RE: Robotic Arm

I was a little misleading with the money issue. What I meant was I don't want to be spending large amounts of money on a device that does things that I don't need. Just the bare minimum. The load is going to be minimal on the motors. Except for the weight of the setup the only other load would be the equivalent of IC's or a couple of coins at most. Basically my task at hand is developing a test apparatus that would determine at which points a sensor would detect an item through a field specified by the manufacturer. Now that you mentioned the DC motor that can be controlled at variable speeds, I've got an idea. I think I'm going to take an old oversized drill press an use its mechanism to raise and lower the press for the Y axis, use a vice grip mechanism for the x axis, and then use the DC motor to move the item on the Z axis. The reason behind the drill press and vice grip is because the gears on both allow for very small increments. Very cave man but I think it may work.

David O'Donnell
'97 Mark VIII LSC "Maxine II" (RIP Maxine I, 5-16-03)
'91 Mark VII BB "Monica"
'67 Thunderbird "Molly"
 
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