Specifications

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When you right-click the ElbowNode you can select "Insert object name" from the context menu. This writes
the full path of the node into the Elbow joint definition where you placed the cursor. Notice that this method
inserts the absolute and not the relative path. Repeat the pocess to expand the ForeArm segment and insert
its ElbowNode in the line below to obtain this:
AnyRevoluteJoint Elbow = {
Axis = z;
AnyRefNode &UpperArmNode = Main.ArmModel.Segs.UpperArm.ElbowNode;
AnyRefNode &ForeArmNode = Main.ArmModel.Segs.ForeArm.ElbowNode;
}; // Elbow joint
Seems like everything is connected now. So why do we still get the annoying error message:
Model Warning: Study 'Main.ArmStudy' contains too few kinematic constraints to be
kinematically determinate.
when we reload the model? The explanation is that we have connected the model but we have not specified
its position yet. Each of the two joints can still take any angular position, so there are two degrees of
freedom left to specify before AnyBody can determine the mechanism's position. This is taken care of by
kinematic drivers.
They are one of the subjects of Lesson 4: Definition of movement
.