Universal Robots Forum

Apply force along the tangential direction of the base joint

Hello,
I’m using force mode to apply a force in any directions.
Now I can apply a force of 160N in most directions.
But when I want to apply a force of 160N parallel to the tangential direction of the base joint, the force can only reach about 70N.
How to make it work?

Thanks in advance

Hi nijs255,

As you have already found, the maximum force that the robot is able to apply depends on the pose. In some poses, the joints’ configuration will just be able to yield a greater torque than in others.

For instance, a move relative to the tangent of the Base Joint would effectively only be able to rely on the work of some of the joints.

Notice that the safety settings also affect the upper limit of the applied forces/torques. But that doesn’t seem to be relevant here, as you can achieve the desired force in other directions.

In the end, the best solution would be to rearrange the setup of the robot. Ideally either mounting it on the wall or ceiling – but just moving the workpiece could be enough to see a change.

I know it probably wasn’t the answer that you were looking for, but good luck with your project non the less.

Thank you spbe!
Your reply answers some of my questions.

Could you tell me in what poses the robot can apply force big enough?
And in what poses the robot’s force is much lower?

We unfortunately don’t have a chart documenting the maximum achievable force based on the pose of the arm. In my own experience, you can generally achieve the highest values by applying a force straight down (-Z in the Base Feature) as well as perpendicular to the Z-axis of the base, with the arm in a middle position between fully stretch out and fully retracted. (If that makes sense).

Basically, in the area between the Outer Workspace Limit and the Inner Workspace Limit: Universal Robots - What is a singularity?

But again, this is just my own small observations. In the end, the only reliable method for you would be to test it out with the physical robot in various poses.

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Thanks for your advice!
It can be useful.