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A question about industrial robots
- 10-28-2005
jmdaly posted on October 28, 2005, 4:53 pm
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
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
Mike Ross posted on
Re: A question about industrial robots
[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.
Padu posted on
Re: A question about industrial robots
<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
Moe_Larry_Curly posted on
Re: A question about industrial robots
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
John Nagle posted on
Re: A question about industrial robots
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
Paolo posted on
Re: A question about industrial robots
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
Re: A question about industrial robots
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
Re: A question about industrial robots
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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