A question about industrial robots

Hi folks,
My name is John Daly and I work for a company called Neptec in Ottawa, Canada. We make 3d vision systems that we use for tracking the pose of
objects through space.
Recently, we've been looking into buying a 6 degree of freedom robot manipulator to use to help with our testing. We want to mount the object we're tracking on our motion controller (which will take the object through some trajectory that we specify.) We'll then use our vision system to estimate the pose of the object as it moves in space. We are doing this part now.
What we'd like to use a robot for is to feed the estimated object pose to the robot and have its end effector track the object as it moves, without the robot actually knowing the object's trajectory ahead of time. (Picture a satellite moving through space, and a robot manipulator following the motion.) This will be useful for demonstrating the viability of our vision system as a useful sensor for object tracking.
I've been tasked with looking around and finding a suitable robot platform for this kind of thing. But, I really don't know anything about industrial robots and their controllers. We need a robot that can support a paylod of up to 50 lbs, and has a reach of around 2 m. I've talked to a few companies that sell robots that would meet the payload requirements. But, based on what I've heard from people, no one seems to think there would be a way to send the measured pose to the robot as it's computed and have the robot track the object as it moves. It seems that a lot of these industrial system involve giving the robot a trajectory ahead of time and then letting it execute that.
So, I'm wondering if anyone could point me in the direction of some companies or products that would be able to provide something to accomplish what it is we're looking to do.
I really appreciate the help!
Sincerely,
-John Daly
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snipped-for-privacy@gmail.com wrote:

[snip]
I've controlled both Puma and Robotics Research robots with real-time commands. Admittedly, the real-time commanding of the Puma uses a special interface actually designed for real-time modifications to a preset directory, but you can make it work. Each robot will have some language specified wherein you can write your driver routines to accept and issue your commands.
Biggest problem in your area is many electric robots of the size you want don't have powerful enough wrists to hold a 50 lb payload in any orientation, especially for a significant CG offset. You may have to consider hydraulics.
--
Mike Ross

Instructions said Win98 or better, so I used Linux.
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John wrote:

<snip>
I've seen a video of a robot (a puma actuator if I'm not mistaken) that does exactly what you are describing, it plays ping pong against humans. It uses a set of fixed cameras in the room to calculate the trajectory of the ball in 3D real time and then move the end effector (and the racquet) to the calculated position the ball is expected to be.
http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tidB18
This is what I found online, but only because I was sloppy. You will be able to probe further.
Cheers
Padu
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John At the risk of appearing predjudiced (well, I AM, actually), I will say that Staubli www.staubli.com 864-433-190 Duncan SC USA is your best bet. They have done many, many applications of tracking trajectory data being sent to the robot controller from another computer in real time. With their CS8 controller, it has the capability of an almost infinite quantity of parallel processing tasks and blazingly fast speed for a robot processor. On top of that, it would be difficult to find another robot that can deliver, out of the box, a higher path accuracy or point location repeatability. Nothing on the planet can touch it.
For ~2m reach and 50 lbs payload (you need to define this better), you would have to consider something like their RX170 model. It ain't cheap.
Regards, Moe & The Boys

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sorry, typing too fast. That's 864-433-1980

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snipped-for-privacy@gmail.com wrote:

Do you really need 50lb capacity? Because most industrial robot arms are designed for high repeatability when positioning, they have to be unreasonably rigid. The usual result is that a robot that can lift 50 pounds with a reach of 2m will weigh about a ton. The Staubli RX170L suggested by someone else is a good example. Repeatability of 0.05mm requires a massive frame.
If you're just doing a demo, you may be better off with something smaller.
Less-rigid robots are available, and are typically used for spray painting.
                John Nagle
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In the industry it's quite common to use robots guided by cameras, in general for tasks as picking randomly positioned pieces from conveyors or following particular paths as in the deburring, soldering processes, etc. I used to work with ABB and Kuka robots. You can pass them the coordinates via serial port or ethernet or industrial busses.
ABB utilizes the x-y-z + quaternions for the coordinates, while Kuka uses the x-y-z and Euler angles notation. Both have instructions to convert between different systems of coordinates.
You should find the 50lbs/2m robot in the ABB 4400 or 6400 families of robot. Also Kuka reaches these payloads.
If you can't find the right combination of payload and working range in a traditional 6-axes robot, then take in consideration also the option of the 7th controlled axis: a linear track controlled by the robot itself. It enables to reach the working range you desire. It's a commercial option of the ABB robots, I think it's available in the Kukas as well.
A tip: There are already available 3-D sw simulators for those robots ('RobotStudio' from ABB, I don't remember the name of the Kuka's simulator). The simulator takes the robot program as input and displays the movements of the robot in a 3d environment, with the identical behavior as it would have in reality. It relies on the same software that runs on the robot controller, but it's more affordable than a real robot....
hth,
Paolo
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Hi everyone,
I'd like to thank you all for your responses! I've definitely been directed to some great resources thanks to your help!
Paolo, I have a question for you. I'm interested in how you accomplished the trajectory following with the ABB robot. The reason I ask is that I had contacted a used robot seller near our office and initially they suggested the ABB 6400 family of robots, but as I spoke with the person on the phone he told me that he didn't think I would be able to provide it with a path to follow in real time, and that the trajectory could only be set ahead of time.
I was really hoping that there would be a way to have the ABB robot follow a trajectory in real time, since he has good prices on the used models. So your post is encouraging! The man I spoke with said that the way to interface with the robot was through Robot Studio, and wasn't clear on how the robot interfaces to a computer.
So I'm wondering what would be needed to achieve real time trajectory tracking with the ABB robots?
Thank you for all your help!
-John
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I think the simplest way is to interface the robot with the pc via a rs-232 serial port. In the main loop of the robot program you can poll the serial port to detect new coordinates and then execute the movement. This method is 'real time' with the limit of the delay due to the serial trasmission and program elaboration time, but in general the mechanics is slower than the electronics.
In the standard set of instructions there are instructions for opening the communication channel and read the data , either already formatted as robot target or raw data to be manipulated (Open, Read, ReadAnyBin,....), then there are different way and parameters to accomplish the movement of the robot. For instance, you can start the first movement and then polling the serial port for the coordinates of the second target without having the robot reached the first one. If the communication is faster than the robot you can launch the second movement command before having reached the first target, leaving to the operating system of the robot to perform the task of setting a continuous movement between the first and second target.
In this way the limit would be the rate of robot targets that can be read and executed by the robot. I would consider a limit of four /five target per second. This solution is quite normal as it comes with the standard set of instructions. No need for the Robot Studio.
If you need a faster communication, ABB has developed a communication protocol called RAP. I think it runs over ethernet, but I never used it and I can't be more precise. Maybe the man that talked about RobotStudio as interface, was referring to this kind of application.
Do you already have a specification about the speed and accuracy you want from your system ? This is the sensible data for the feasibility study (costs apart),
ciao,
Paolo
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