Linear motion

[geniusintraining]

pneumatics will not?

Peter,

I am not debating with you just wanting to learn and not make mistakes, but why would something like this not work? I have seen some good (smooth rod-less cylinders) in pneumatic systems, I don’t know about if the speed would be able to be achieved, but in a slower application? two rod-less and one standard with a suction cup
EDIT: I think a servo would be best, but just wondering about the pneumatic down side.

 

[Peter Nachtwey]

GIT, that is exactly Laura should use unless there is some other reason. However, notice that the far end is not supported.

The problem with Laura's and the IronDerrickMan's technique is that the tuning should change as the cylinder reach farther from the rotary axis. In addition. The motion at the end of each lever or section is not linear.

 

[Lancie1]

Good job, GIT.

Each of the 60 locations (earlier I said 72 but Laura showed only 5 x 6 crates) could have 2 coordinates stored in PLC memory, X and Y distances for the X and Y motions to move to. The third, Z, distance to extend the suction cup, will always be a constant in GIT's scenario, assuming all bottles are same height. Another sensor will needed to detect the color of each bottle.

 

[laura]

Dear Friends.



Thank You for all the help given !



The plastic bottles in the beercrates, is actually a thread started, for helping me understanding to build a crane, that can move in any direction, and is able to repeat the movements.



I better explain !



What I really wish to perform, is a crane that I can steer, to pick up “things” from one position and move them to another position. The movements for every motor or cylinder, will be saved in the memory of the plc. This way, I want the plc, to be able to make a exact repetition of the crane movements.



I have build myself a robot, that is radiocontrolled. With this robot, I can for example empty the dishwasher, but it takes a lot of time. If the dishwasher is filled in the same order each time, I believe, that it is possible to build a robotarm, a “crane”, that remembers the movements, and thereby is able to empty the dishwasher itself, after I once have steered it through the whole emptying fase.



So I have a lot of dc-motors, both linear and rotary. But as I have understood, it is very difficult controlling such dc-motors.



I hope You guys still will come with good advice and ideas, cause I really need them.





laura

 

[geniusintraining]

Laura,

I don’t think it can be done as you wish…pneumatics don’t have the correct properties for this to work, you will even have a hard time with hydraulics. You could use the dc motor for the rotation axis, but I would stay away from pnenmatics

When you cantilever a weight like that on the end you need to have control, pneumatics have to much forgiveness in the properties, even if its built very good from the mechanical side its still going to be like a diving board, when you let go or grab it will load up like a spring with air.

You need to have a good mechanical platform to work with first, I have worked with and know a little about robotics (I love the movement and the speed), even a plc to track the position?, I’m not sure if that would also be the best option

Look at this site ABB they are one of the best http://www.abb.com/product/us/9AAC910011.aspx

 

[Lancie1]

Laura,

I see now that to empty a dishwasher, you need a robotic arm that can move to any position. It will also need a vision system, or your dishes will have to be placed at exactly the same spot each time.

Why do you think DC motor control is difficult? I like small 6 volt and 12 volt DC motors. Two PLC output relays will start, stop, and reverse any small DC motor, like those needed by your Robotic Dishwasher Emptying Machine.

You can add a master DC voltage controller to control the overall speed of all the DC motors on your robotic arm, or use a speed controller (simply a large variable resistor for small motors) for any motor that needs to be controlled at a separate speed.

 

[Peter Nachtwey]

You have got to be kidding.

A dishwasher unloader? Why not load it too? This cracks me up.
Seriously, I would have thought this would be about loading and unload ships. If I lived on the Faroe Islands I think I might be interested in growing vegetables or grain in green house, wind power, or processing fish. Seriously, all of these applications can benefit from technology and would be very practical.

 

[OkiePC]

Wow

Like Peter, I didn't see it coming.

Unlike Peter, I think that a servopneumatic system could work. The complexity of the "beercrate sorter" won't be easy (and therefore won't be cheap) though.

While we are on the subject, I'd like to build a servo pneumatic jumping spider to compete in the "Remote Control Car Wars" TV show. (I believe it's actually called Robot Wars, but that is a misnomer...it's really remote control car wars.)

I want to build a machine that works autonomously, with binocular vision, thinks for itself, defends itself with evasive maneuvers, and attacks the other non-robotic remote control cars, crushing them in it's eight-legged grip.

I bet there's enough talent here to actually make that happen. I just haven't figured out how to store enough pneumatic energy onboard to be able to survive a 5 minute match...


PEC

 

[laura]

Thanks again.


To geniusintraining: --> even a plc to track the position?, I’m not sure if that would also be the best option. What do You mean by this ?

Yes the ABB's robots look very nice......I bet they cost a fortune.


To Lancie1: because of the violent reaction time of the dc-motors, I believed it would be difficult controlling them. Yes maybe I should look into a master DC voltage controller and the
variable resistor.



To Peter Nachtwey: Ofcourse, If the robot can empty the machine, it would also be used for filling it.
Please feel free, to tell about all of Your ideas regarding the Islands.

 

[laura]

Hello.

What do You think about this robot-idea ?


laura

 

[geniusintraining]

A robot would be ideal...but you yourself said “I bet they cost a fortune.” Yes, they are expensive, but if you are talking replacing a 4 people (that would be a 3x4 sch 24x7) in the production world it would and does pay for itself, a robot does not call in sick, does not have all the other associated cost that normal employees have.

In our case a person would take our product and put it into a cutter... That’s ideal for a robot, but loading a dishwasher? I don’t think it is repetitive enough for the cost of a robot to off set the cost of a unskilled worker


Remember I told you that I fell on my face and to use the KISS concept... This is what I did, it looks simple enough but, there were things that I did not consider like inerta... the side view shows the cylinder, I would pull a vacuum on our product it would lift the base over the transfer wheels and rotate 90deg then drop back down and start the transfer wheels again...simple? yes, but when you factor the speed that I needed to run at and the weight of the parts...It worked great, I just had no control over what it was doing.

My point learn from others mistakes and don't make you own(when possible)

 

[Peter Nachtwey]

Not much

What do You think about this robot-idea ?

If you would have said what you were really trying to do I bet you wouldn't have got all the replies you did.

Did you see the engineering meeting thread? I have some idea of how much effort this would take. You can see that it is possible; it just takes a lot of knowledge from several different people with specialties in different areas.
I can tell by your questions that this project is beyond your grasp for right now. Try something simpler. Why not process potatoes? Seriously, we have trees and potatoes here. We don't have much need for dishwasher unloaders that cost $100,000, break, don't stay calibrated, take up space in the kitchen and make a lot of noise with all that compressed air or hydraulic power unit running.

I think you can find something more beneficial to do. Processing potatoes comes to mind. We have trees and potatoes here. We have made French fry scanners that can find chlorophyll, rot, skin and high sugar content and can cut the defects out. That was a challenge that took years of research and building prototypes.

Why does it have to be a robot or look like a robot. I think people are hung up on that.



Don't mind me though. I am just a stick in the mud.

 

[laura]

Thanks again.

I agree, that a dishwasher itself, maybe wouldn't be the most costeffective product on the market. I just imagine, that if it was possible to build this "machine", that it could be used for other things also.

Put some wheels on it, with some kind of position tracker, and You could end up with a robot, that can do the most of the householding, if You just show it how to, once.

Peter what do You mean by: Processing potatoes comes to mind. We have trees and potatoes here. ??

laura

 

[Peter Nachtwey]

Just that. We have trees and potatoes here so that is where we started.

Peter what do You mean by: Processing potatoes comes to mind. We have trees and potatoes here. ??

The point is that you should look around where you are and see what can be improved. It wouldn't make sense for us to try to get into cotton or tobacco processing when that is in the southeastern US.
In the Pacific northwest we have trees and potatoes so much of our business has been involved with processing potatoes and wood.

If you must make a robot then try something much simpler.
http://www.irobot.com/

Even a simple vacuum robot would be a challenge and it doesn't use a PLC. You would have to get into embedded micro controllers and programming in C or assembly. Eventually you will need to design your own hardware and find ways to package it.

Try one of these
http://www.rabbitsemiconductor.com/


and see if you like it.

The fuddy duddy stick in the mud lightens up a bit.

I think the RoboCup would be fun but not very practical.
http://www.robocup.org/ The closest I have come to doing anything like that was writing chess and reversi programs and entering them into tournaments many years go. Now I just make motion controller and compete against the world so there isn't time for chess, reversi or robots. However, the competition is good because you learn your strengths and weaknesses versus others.

 

[vidi0816]

I agree with Tom Stalcup...