Specifications

81
Drivers:
0: Main.ArmModel.Drivers.ElbowMotion (1constr.)
Other:
- none!
Total number of constraints:
Joints: 10
Drivers: 1
Other: 0
Total: 11
-------------------------------------------------------------
The ModelInformation operation allows you to investigate in detail how many constraints are missing and
which ones they may be. Let us shift the missing driver back in:
//---------------------------------
AnyKinEqSimpleDriver ShoulderMotion = {
AnyRevoluteJoint &Jnt = ..Jnts.Shoulder;
DriverPos = {-100*pi/180};
DriverVel = {30*pi/180};
Reaction.Type = {Off};
}; // Shoulder driver
//---------------------------------
AnyKinEqSimpleDriver ElbowMotion = {
AnyRevoluteJoint &Jnt = ..Jnts.Elbow;
DriverPos = {90*pi/180};
DriverVel = {45*pi/180};
Reaction.Type = {Off};
}; // Elbow driver
... and try something else:
//---------------------------------
AnyKinEqSimpleDriver ShoulderMotion = {
AnyRevoluteJoint &Jnt = ..Jnts.Shoulder;
DriverPos = {-100*pi/180};
DriverVel = {30*pi/180};
Reaction.Type = {On};
}; // Shoulder driver
//---------------------------------
AnyKinEqSimpleDriver ElbowMotion = {
AnyRevoluteJoint &Jnt = ..Jnts.Elbow;
DriverPos = {90*pi/180};
DriverVel = {45*pi/180};
Reaction.Type = {On};
}; // Elbow driver
What we have done here is to switch the reaction forces in the two joint drivers on. This is equivalent to
imbedding motors into the joints, and it means that the system will obtain enough reaction forces to cary
the loads without help from any muscles, corresponding to the statically determinate situation 2 listed
above. Loading the model does not bring about any warnings, but if you run the InverseDynamicAnalysis
you will get the following message for each time step:
'ArmStudy': The muscles in the model are not loaded due to kinetically over-constrained mechanical
system.