Inverse Kinematics Solutions

Ilian

Hi,

Our university recently acquired IRB1600 robots to replace our old Fanucs. I still have nearly no knowledge of RAPID, but I would like to make a small demo to my students. Particularly, I would like to show all inverse kinematics solutions for a given pose. With most industrial robots, there are parameters such as "elbow up/down" and "left/right", but with ABB robots, I understand that I can only specify a certain variable called confdata, but there is no geometric meaning!

How can I easily produce all eight inverse kinematic solutions for a suitably-chosen pose with our IRB1600 robots?

Thanks,

Ilian

Anders S

Hi Ilian,

In the "technical reference manual" that's delivered with the robot, you will find a description about the confdata and the geometric meaning. You will find it in the "Data types" chapter.

Ilian

Hi Anders,

I have surely read that part of the manual many times... But I still have no answer. For the IRB140, there is a cfx parameters (from 1 to 8), which specifies one of the eight solutions. However, for all other models, there is no such direct specification.

Imagine I need to specify a pose by pure computation and I want that the elbow be up, instead of down. The only way that I can specify this is by calculating approximately the inverse kinematics for that pose and retaining the approximate joint values for one of the eight solutions. Then, if I need the robot to attain that pose with this configuration (solution), I will need to specify in which quadrant are certain joint variables. This is way to difficult!!! Isn't there a simpler way of specifyling that I want the elbow to be up, for example?

Thanks.

Ilian

Anders S

Hi Ilian,

I recommend you use RobotStudio to find the correct configuration (solution). In RobotStudio there are a lot of tools to find the correct configuration. You can for example select a target (robot pose) and get a list of all possible solutions the robot can use to reach that specific target. And you will directly see the if the elbow is up or down etc. RobotStudio can also automatically find configurations for all targets in a robot path.
RobotStudio is free of charge for schools and universities. Contact your local ABB office for more information about RobotStudio.

Ilian

Hi Anders,

Thank you for your response. This definitely answers my questions. We have RobotStudio and I will try this.

Ilian