AGXMagneticJoint

AGX Magnetic Joint is a joint that behaves like a magnet using AGX Dynamics.

For implementation lock joint of AGX Dynamics is used.

Sample

The sample is below. When loading the sample project with Choreonoid and running the simulation, you can see the blue object stick together with the red object automatically (see above figure).

• project file: chorenoid/sample/AGXDynamics/agxMagneticJoint.cnoid

• body file: chorenoid/sample/AGXDynamics/agxMagneticJoint.body

How to write

AGX Magnetic Joint can be described and used as follows.

links:
  -
    name: Plug
    elements:
      -
        type: AGXMagneticJointDevice
        link1Name: Socket
        link2Name: Plug
        position1: [ 0, 0.25, 0 ]
        position2: [ 0, 0, -0.05 ]
        connectAxis1: [ 0, 1, 0 ]
        connectAxis2: [ 0, 0, 1 ]
        jointCompliance: 1e-6
        jointSpookDamping: 1.0
        validDistance: 1.0
        validAngle: 20

1. Set the links to connect with AGXMagneticJoint in linkName

2. Set which part of the link to connect in position and connectAxis

3. Set the force and speed of connection in jointCompliance and jointSpookDamping

4. Set the distance and angle at which connection becomes valid in validDistance and validAngle

position is the relative position from the link coordinate system, and connectAxis is the connection direction of the joint. For example, if you set each connectAxis to different directions as shown in the left figure below, the connection is made so that each connectAxis aligns.

Explanation of parameters

The parameters are described below.

parameter	default value	unit	default value	explanation
type: AGXMagneticJointDevice	-	-	string	declaration of using AGXMagneticJoint
link1Name	-	-	string	name of the link1
link2Name	-	-	string	name of the link2
position1	[0, 0, 0]	-	Vec3	position of the joint relative from the link1 coordinate
position2	[0, 0, 0]	-	Vec3	position of the joint relative from the link2 coordinate
connectAxis1	[0, 0, 1]	-	Unit Vec3	direction of the joint relative from the link1 coordinate
connectAxis2	[0, 0, 1]	-	Unit Vec3	direction of the joint relative from the link2 coordinate
jointCompliance	1e-8	m/N	double	compliance of the joint
jointSpookDamping	0.33	s	double	spook damping of the joint
validDistance	0	m	double	distance threshold when the magnetic joint effective
validAngle	0	degree	double	angle threshold when the magnetic joint effective