The order of collision1~2 objects from contact sensor

Question

From contact sensor, we can get contact objects (gazebo::physics::Contact).

The contact object includes followings.

std::string     collision1
    Name of the first collision object.
 
std::string     collision2
    Name of the second collision object.

How does Gazebo decide the order ?

And, how about following? Assumption:

(1) There is a contact between link_1 and link_2, 
(2) link_1 has contact sensor.

Among the resulted contact objects from sensor, if the objects' elements are like following,

 (1) collision1 specifies link_1
 (2) collision2 specifies link_2

wrench(i).body_1_force in those objects are forces from link_2 to link_1. Am I right?

The '1,2' things make me really confused. I really need help. Thanks.

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Originally posted by Daehyung Park on Gazebo Answers with karma: 47 on 2013-01-17

Post score: 0

Answer 1

The order of reported collisions is non-deterministic.

The wrenches reported by a contact sensor are the forces between the two links in contact.

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Originally posted by nkoenig with karma: 7676 on 2013-07-23

This answer was ACCEPTED on the original site

Post score: 0