Problem with touch sensor on mico hand

[ljklonepiece]

Dear Marc,

I have some questions about the force sensors on the mico arm
In addition to the two sensors on the tip portion of the finger, I added two more on the left and the right side of the finger.
The four force sensors are highlighted in the image here
https://drive.google.com/file/d/0B3-BbM ... sp=sharing

The model of the hand is here
https://drive.google.com/file/d/0B3-BbM ... sp=sharing

Let me denote the four sensors as tip_right, tip_left, side_right,side_left
I take the readings from each sensor and set the threshold to be 1.0 to tell if there is a contact or not,
for example, for tip_right, i compared absolute force value in y direction with 1.0 ; for side_right, I compared absolute force value in z direction with 1.0.

My problem is that sometimes even if the right side of the hand is visually in contact with objects, the value is actually less than 1.0
Also, even if the tip is not in contact with the object, it will report value greater than 1.0

Here is one concrete outputs from force sensors where there should be contact on the right but no contact on the tip

Code: Select all

right tip is : 0.021119389683008 0.874152302742 0.41735100746155
left tip is : 0.017332082614303 1.1696652173996 0.45861998200417
right side is : 0.043939583003521 -0.1336342394352 -1.5682989358902
left side is : 0.029980074614286 -0.4895646572113 0.029980074614286

As you may see, the second value of left tip is greater than 0.

I think there are two reasons:
1. the threshold may be not accurate
2. the position and orientation of the force sensors is wrongly set.

The correct contact detection is really important to my application.
Do you have any thoughts and suggestions?

Thanks a lot in advance!

Yours sincerely,
Juekun

[coppelia]

Hello Juekun,

the link of the picture you shared is broken. In your scene file, it seems you have shifted the original force sensors and pads. The parts you added seem also strangely positionned (when you invert all visible layers).

Make sure that the pads are not colliding with other parts of the fingers, which will result in a strange force sensor reading. Turn on collision point display (Display contact points) in the general dynamic properties.

Cheers