# How to calculate effort/torque values of a joint

I have a robotic arm with 6 DOF. For each joint, I get get the Joint Wrench, which is composed by the force and torque of the parent and child links of the joints. In other works, for joint 1 I can get ParentLinkForce, ParentLinkTorque, ChildLinkForce and ChildLinkTorque. Each of one is a 3D vector with x, y z.

My question is, how can I transform this to the current effort of the joint in N.m? So I can directly get the effort value of the torque after applying a torque action in the joint.