How to use the Robotiq 2-finger Gripper Secure Grip feature and low-force mode

Etienne_Samson 2016-04-21

Back in 2015, seeking to offer integrated solutions to end-users, we brought the following updates on the 2-Finger Adaptive Robot Gripper:

• Low Force Mode: Handle fragile and soft objects, was improved with the latest firmware release

• Secure Grip feature: Secure uneven objects or objects that tend to slip (embedded feature)

Low force mode and Secure Grip are implemented with firmware 1.3.0 and above, to get the latest firmware update, please contact support@robotiq.com and send us your product serial number.

Low Force Code details :
When force setting (see this post on how to set force and speed) is set to 0, the Gripper will turn to "low force mode" enabling the lowest possible force, and disabling the Secure Grip feature. Use this force when picking fragile and deformable object. The image below shows expected grip force when picking a soft deformable object (detailed charts for various payload material can be found inside the Gripper manual section 4.5) :
zoom

Secure Grip feature details :
Secure Grip feature is automatically enable for any force setting between 1 and 255 (0 disable it, to allow Low Force Mode). This feature works by enabling a small continuous current applied to the Gripper motor, thus, when the payload slips, the motor enter motion, and the Gripper close automatically on the part to keep grip of it.

If you want to learn about the control feature of the 2F (85 or 140), read this blog post by @mathbelanger Mathieu Bélanger-Barrette and watch the following video (some nice beats included) :

https://www.youtube.com/watch?v=dpz93170dAk

Sebastien 2016-10-04

@Etienne_Samson
Concerning the low force mode, I am working on picking a soft part that we don't want to deform much during picking. We are using the 2F85 gripper to pick the object. So if I understand the charts and the above post correctly, I should have speed set to a minimum and force set to 0 to achieve the lowest possible force right?
Do you know if the requested go to position asked to the gripper has an impact on the force applied to the object? Also the lowest force I should expect from my 2F85 gripper according to the graph would be around 15N. That would be the total pressure force applied on the part and not only coming from one finger right? (See diagram below)

Annick_Mottard 2016-10-04

@Sebastien
You are correct: you need to set both the force and the speed to 0 in order to apply the lowest amount of force possible on an object. You should consider that setting the force to 0 will disable the continuous gripping feature described in the video posted above. The requested position does not have an impact on the force applied to an object. If you want to pick an object, I would recommend you simply use the close command (or open, depending on how you want to pick the object).

The graph posted above is for 30 OO durometer materials. Therefore, you need to consider you material's hardness to validate the amount of force that will be applied. The Gripper's instruction manual contains more graphs for different hardness types.

If, by looking at the graph, you assume the gripper will apply 15N, it means each finger applies 15N.