Created: 13/07/2022

Tags: shear force, fingervision, gelsight, markers

Link: https://personalrobotics.cs.washington.edu/publications/song2019shear.pdf

Status: Read once

What?

Successful bite acquistion is challenging without haptic feedback because of visual occlusion, and deformability of the food.

Skewering food with proper force is difficult. Skewering a grape and a carrot require different forces.

Why?

Current approach to regulate the force require F/T sensor on top of the fork or under the food plate which are not ideal.

Normal force sensing tactile sensors are not good because the contact between tactile sensor and tool (fork) happens not at the end of the tool but at the grasping position.

How?

By estimating the shear force at the contact area between tool and sensor, one can estimate the force at the fingertip of the tool and food.

Force calibration

• Convert the displacement of markers in pixels into real world Newton Units. Range of forces are in 0-30 N.
• Record data from F/T sensor and Gelsight frames until the force reaches 30 N.
• Compute the sensor values by averaging the pixelated vertical displacements of every marker on Gelsight.
• Repeat the above procedure 20 times for 3 different gripping forces

After that, synchronize sensor values with F/T values based on linear interpolation.